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<?php
// This file is part of Moodle - http://moodle.org/
//
// Moodle is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// Moodle is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with Moodle.  If not, see <http://www.gnu.org/licenses/>.

/**
 * @package   mod_forum
 * @copyright 1999 onwards Martin Dougiamas  {@link http://moodle.com}
 * @license   http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
 */

defined('MOODLE_INTERNAL') || die();

/** Include required files */
require_once(__DIR__ . '/deprecatedlib.php');
require_once($CFG->libdir.'/filelib.php');

/// CONSTANTS ///////////////////////////////////////////////////////////

define('FORUM_MODE_FLATOLDEST', 1);
define('FORUM_MODE_FLATNEWEST', -1);
define('FORUM_MODE_THREADED', 2);
define('FORUM_MODE_NESTED', 3);

define('FORUM_CHOOSESUBSCRIBE', 0);
define('FORUM_FORCESUBSCRIBE', 1);
define('FORUM_INITIALSUBSCRIBE', 2);
define('FORUM_DISALLOWSUBSCRIBE',3);

/**
 * FORUM_TRACKING_OFF - Tracking is not available for this forum.
 */
define('FORUM_TRACKING_OFF', 0);

/**
 * FORUM_TRACKING_OPTIONAL - Tracking is based on user preference.
 */
define('FORUM_TRACKING_OPTIONAL', 1);

/**
 * FORUM_TRACKING_FORCED - Tracking is on, regardless of user setting.
 * Treated as FORUM_TRACKING_OPTIONAL if $CFG->forum_allowforcedreadtracking is off.
 */
define('FORUM_TRACKING_FORCED', 2);

define('FORUM_MAILED_PENDING', 0);
define('FORUM_MAILED_SUCCESS', 1);
define('FORUM_MAILED_ERROR', 2);

if (!defined('FORUM_CRON_USER_CACHE')) {
    /** Defines how many full user records are cached in forum cron. */
    define('FORUM_CRON_USER_CACHE', 5000);
}

/**
 * FORUM_POSTS_ALL_USER_GROUPS - All the posts in groups where the user is enrolled.
 */
define('FORUM_POSTS_ALL_USER_GROUPS', -2);

define('FORUM_DISCUSSION_PINNED', 1);
define('FORUM_DISCUSSION_UNPINNED', 0);

/// STANDARD FUNCTIONS ///////////////////////////////////////////////////////////

/**
 * Given an object containing all the necessary data,
 * (defined by the form in mod_form.php) this function
 * will create a new instance and return the id number
 * of the new instance.
 *
 * @param stdClass $forum add forum instance
 * @param mod_forum_mod_form $mform
 * @return int intance id
 */
function forum_add_instance($forum, $mform = null) {
    global $CFG, $DB;

require_once($CFG->dirroot.'/mod/forum/locallib.php');

$forum->timemodified = time();

if (empty($forum->assessed)) {
        $forum->assessed = 0;
    }

if (empty($forum->ratingtime) or empty($forum->assessed)) {
        $forum->assesstimestart  = 0;
        $forum->assesstimefinish = 0;
    }

$forum->id = $DB->insert_record('forum', $forum);
    $modcontext = context_module::instance($forum->coursemodule);

if ($forum->type == 'single') {  // Create related discussion.
        $discussion = new stdClass();
        $discussion->course        = $forum->course;
        $discussion->forum         = $forum->id;
        $discussion->name          = $forum->name;
        $discussion->assessed      = $forum->assessed;
        $discussion->message       = $forum->intro;
        $discussion->messageformat = $forum->introformat;
        $discussion->messagetrust  = trusttext_trusted(context_course::instance($forum->course));
        $discussion->mailnow       = false;
        $discussion->groupid       = -1;

$message = '';

$discussion->id = forum_add_discussion($discussion, null, $message);

if ($mform and $draftid = file_get_submitted_draft_itemid('introeditor')) {
            // Ugly hack - we need to copy the files somehow.
            $discussion = $DB->get_record('forum_discussions', array('id'=>$discussion->id), '*', MUST_EXIST);
            $post = $DB->get_record('forum_posts', array('id'=>$discussion->firstpost), '*', MUST_EXIST);

$options = array('subdirs'=>true); // Use the same options as intro field!
            $post->message = file_save_draft_area_files($draftid, $modcontext->id, 'mod_forum', 'post', $post->id, $options, $post->message);
            $DB->set_field('forum_posts', 'message', $post->message, array('id'=>$post->id));
        }
    }

forum_update_calendar($forum, $forum->coursemodule);
    forum_grade_item_update($forum);

$completiontimeexpected = !empty($forum->completionexpected) ? $forum->completionexpected : null;
    \core_completion\api::update_completion_date_event($forum->coursemodule, 'forum', $forum->id, $completiontimeexpected);

return $forum->id;
}

/**
 * Handle changes following the creation of a forum instance.
 * This function is typically called by the course_module_created observer.
 *
 * @param object $context the forum context
 * @param stdClass $forum The forum object
 * @return void
 */
function forum_instance_created($context, $forum) {
    if ($forum->forcesubscribe == FORUM_INITIALSUBSCRIBE) {
        $users = \mod_forum\subscriptions::get_potential_subscribers($context, 0, 'u.id, u.email');
        foreach ($users as $user) {
            \mod_forum\subscriptions::subscribe_user($user->id, $forum, $context);
        }
    }
}

/**
 * Given an object containing all the necessary data,
 * (defined by the form in mod_form.php) this function
 * will update an existing instance with new data.
 *
 * @global object
 * @param object $forum forum instance (with magic quotes)
 * @return bool success
 */
function forum_update_instance($forum, $mform) {
    global $CFG, $DB, $OUTPUT, $USER;

require_once($CFG->dirroot.'/mod/forum/locallib.php');

$forum->timemodified = time();
    $forum->id           = $forum->instance;

if (empty($forum->assessed)) {
        $forum->assessed = 0;
    }

if (empty($forum->ratingtime) or empty($forum->assessed)) {
        $forum->assesstimestart  = 0;
        $forum->assesstimefinish = 0;
    }

$oldforum = $DB->get_record('forum', array('id'=>$forum->id));

// MDL-3942 - if the aggregation type or scale (i.e. max grade) changes then recalculate the grades for the entire forum
    // if  scale changes - do we need to recheck the ratings, if ratings higher than scale how do we want to respond?
    // for count and sum aggregation types the grade we check to make sure they do not exceed the scale (i.e. max score) when calculating the grade
    if (($oldforum->assessed<>$forum->assessed) or ($oldforum->scale<>$forum->scale)) {
        forum_update_grades($forum); // recalculate grades for the forum
    }

if ($forum->type == 'single') {  // Update related discussion and post.
        $discussions = $DB->get_records('forum_discussions', array('forum'=>$forum->id), 'timemodified ASC');
        if (!empty($discussions)) {
            if (count($discussions) > 1) {
                echo $OUTPUT->notification(get_string('warnformorepost', 'forum'));
            }
            $discussion = array_pop($discussions);
        } else {
            // try to recover by creating initial discussion - MDL-16262
            $discussion = new stdClass();
            $discussion->course          = $forum->course;
            $discussion->forum           = $forum->id;
            $discussion->name            = $forum->name;
            $discussion->assessed        = $forum->assessed;
            $discussion->message         = $forum->intro;
            $discussion->messageformat   = $forum->introformat;
            $discussion->messagetrust    = true;
            $discussion->mailnow         = false;
            $discussion->groupid         = -1;

$message = '';

forum_add_discussion($discussion, null, $message);

if (! $discussion = $DB->get_record('forum_discussions', array('forum'=>$forum->id))) {
                print_error('cannotadd', 'forum');
            }
        }
        if (! $post = $DB->get_record('forum_posts', array('id'=>$discussion->firstpost))) {
            print_error('cannotfindfirstpost', 'forum');
        }

$cm         = get_coursemodule_from_instance('forum', $forum->id);
        $modcontext = context_module::instance($cm->id, MUST_EXIST);

$post = $DB->get_record('forum_posts', array('id'=>$discussion->firstpost), '*', MUST_EXIST);
        $post->subject       = $forum->name;
        $post->message       = $forum->intro;
        $post->messageformat = $forum->introformat;
        $post->messagetrust  = trusttext_trusted($modcontext);
        $post->modified      = $forum->timemodified;
        $post->userid        = $USER->id;    // MDL-18599, so that current teacher can take ownership of activities.

if ($mform and $draftid = file_get_submitted_draft_itemid('introeditor')) {
            // Ugly hack - we need to copy the files somehow.
            $options = array('subdirs'=>true); // Use the same options as intro field!
            $post->message = file_save_draft_area_files($draftid, $modcontext->id, 'mod_forum', 'post', $post->id, $options, $post->message);
        }

$DB->update_record('forum_posts', $post);
        $discussion->name = $forum->name;
        $DB->update_record('forum_discussions', $discussion);
    }

$DB->update_record('forum', $forum);

$modcontext = context_module::instance($forum->coursemodule);
    if (($forum->forcesubscribe == FORUM_INITIALSUBSCRIBE) && ($oldforum->forcesubscribe <> $forum->forcesubscribe)) {
        $users = \mod_forum\subscriptions::get_potential_subscribers($modcontext, 0, 'u.id, u.email', '');
        foreach ($users as $user) {
            \mod_forum\subscriptions::subscribe_user($user->id, $forum, $modcontext);
        }
    }

forum_update_calendar($forum, $forum->coursemodule);
    forum_grade_item_update($forum);

return true;
}

/**
 * Given an ID of an instance of this module,
 * this function will permanently delete the instance
 * and any data that depends on it.
 *
 * @global object
 * @param int $id forum instance id
 * @return bool success
 */
function forum_delete_instance($id) {
    global $DB;

if (!$forum = $DB->get_record('forum', array('id'=>$id))) {
        return false;
    }
    if (!$cm = get_coursemodule_from_instance('forum', $forum->id)) {
        return false;
    }
    if (!$course = $DB->get_record('course', array('id'=>$cm->course))) {
        return false;
    }

$context = context_module::instance($cm->id);

// now get rid of all files
    $fs = get_file_storage();
    $fs->delete_area_files($context->id);

$result = true;

\core_completion\api::update_completion_date_event($cm->id, 'forum', $forum->id, null);

// Delete digest and subscription preferences.
    $DB->delete_records('forum_digests', array('forum' => $forum->id));
    $DB->delete_records('forum_subscriptions', array('forum'=>$forum->id));
    $DB->delete_records('forum_discussion_subs', array('forum' => $forum->id));

if ($discussions = $DB->get_records('forum_discussions', array('forum'=>$forum->id))) {
        foreach ($discussions as $discussion) {
            if (!forum_delete_discussion($discussion, true, $course, $cm, $forum)) {
                $result = false;
            }
        }
    }

forum_tp_delete_read_records(-1, -1, -1, $forum->id);

forum_grade_item_delete($forum);

// We must delete the module record after we delete the grade item.
    if (!$DB->delete_records('forum', array('id'=>$forum->id))) {
        $result = false;
    }

return $result;
}

/**
 * Indicates API features that the forum supports.
 *
 * @uses FEATURE_GROUPS
 * @uses FEATURE_GROUPINGS
 * @uses FEATURE_MOD_INTRO
 * @uses FEATURE_COMPLETION_TRACKS_VIEWS
 * @uses FEATURE_COMPLETION_HAS_RULES
 * @uses FEATURE_GRADE_HAS_GRADE
 * @uses FEATURE_GRADE_OUTCOMES
 * @param string $feature
 * @return mixed True if yes (some features may use other values)
 */
function forum_supports($feature) {
    switch($feature) {
        case FEATURE_GROUPS:                  return true;
        case FEATURE_GROUPINGS:               return true;
        case FEATURE_MOD_INTRO:               return true;
        case FEATURE_COMPLETION_TRACKS_VIEWS: return true;
        case FEATURE_COMPLETION_HAS_RULES:    return true;
        case FEATURE_GRADE_HAS_GRADE:         return true;
        case FEATURE_GRADE_OUTCOMES:          return true;
        case FEATURE_RATE:                    return true;
        case FEATURE_BACKUP_MOODLE2:          return true;
        case FEATURE_SHOW_DESCRIPTION:        return true;
        case FEATURE_PLAGIARISM:              return true;

default: return null;
    }
}

/**
 * Obtains the automatic completion state for this forum based on any conditions
 * in forum settings.
 *
 * @global object
 * @global object
 * @param object $course Course
 * @param object $cm Course-module
 * @param int $userid User ID
 * @param bool $type Type of comparison (or/and; can be used as return value if no conditions)
 * @return bool True if completed, false if not. (If no conditions, then return
 *   value depends on comparison type)
 */
function forum_get_completion_state($course,$cm,$userid,$type) {
    global $CFG,$DB;

// Get forum details
    if (!($forum=$DB->get_record('forum',array('id'=>$cm->instance)))) {
        throw new Exception("Can't find forum {$cm->instance}");
    }

$result=$type; // Default return value

$postcountparams=array('userid'=>$userid,'forumid'=>$forum->id);
    $postcountsql="
SELECT
    COUNT(1)
FROM
    {forum_posts} fp
    INNER JOIN {forum_discussions} fd ON fp.discussion=fd.id
WHERE
    fp.userid=:userid AND fd.forum=:forumid";

if ($forum->completiondiscussions) {
        $value = $forum->completiondiscussions <=
                 $DB->count_records('forum_discussions',array('forum'=>$forum->id,'userid'=>$userid));
        if ($type == COMPLETION_AND) {
            $result = $result && $value;
        } else {
            $result = $result || $value;
        }
    }
    if ($forum->completionreplies) {
        $value = $forum->completionreplies <=
                 $DB->get_field_sql( $postcountsql.' AND fp.parent<>0',$postcountparams);
        if ($type==COMPLETION_AND) {
            $result = $result && $value;
        } else {
            $result = $result || $value;
        }
    }
    if ($forum->completionposts) {
        $value = $forum->completionposts <= $DB->get_field_sql($postcountsql,$postcountparams);
        if ($type == COMPLETION_AND) {
            $result = $result && $value;
        } else {
            $result = $result || $value;
        }
    }

return $result;
}

/**
 * Create a message-id string to use in the custom headers of forum notification emails
 *
 * message-id is used by email clients to identify emails and to nest conversations
 *
 * @param int $postid The ID of the forum post we are notifying the user about
 * @param int $usertoid The ID of the user being notified
 * @return string A unique message-id
 */
function forum_get_email_message_id($postid, $usertoid) {
    return generate_email_messageid(hash('sha256', $postid . 'to' . $usertoid));
}

/**
 *
 * @param object $course
 * @param object $user
 * @param object $mod TODO this is not used in this function, refactor
 * @param object $forum
 * @return object A standard object with 2 variables: info (number of posts for this user) and time (last modified)
 */
function forum_user_outline($course, $user, $mod, $forum) {
    global $CFG;
    require_once("$CFG->libdir/gradelib.php");
    $grades = grade_get_grades($course->id, 'mod', 'forum', $forum->id, $user->id);
    if (empty($grades->items[0]->grades)) {
        $grade = false;
    } else {
        $grade = reset($grades->items[0]->grades);
    }

$count = forum_count_user_posts($forum->id, $user->id);

if ($count && $count->postcount > 0) {
        $result = new stdClass();
        $result->info = get_string("numposts", "forum", $count->postcount);
        $result->time = $count->lastpost;
        if ($grade) {
            if (!$grade->hidden || has_capability('moodle/grade:viewhidden', context_course::instance($course->id))) {
                $result->info .= ', ' . get_string('grade') . ': ' . $grade->str_long_grade;
            } else {
                $result->info = get_string('grade') . ': ' . get_string('hidden', 'grades');
            }
        }
        return $result;
    } else if ($grade) {
        $result = new stdClass();
        if (!$grade->hidden || has_capability('moodle/grade:viewhidden', context_course::instance($course->id))) {
            $result->info = get_string('grade') . ': ' . $grade->str_long_grade;
        } else {
            $result->info = get_string('grade') . ': ' . get_string('hidden', 'grades');
        }

//datesubmitted == time created. dategraded == time modified or time overridden
        //if grade was last modified by the user themselves use date graded. Otherwise use date submitted
        //TODO: move this copied & pasted code somewhere in the grades API. See MDL-26704
        if ($grade->usermodified == $user->id || empty($grade->datesubmitted)) {
            $result->time = $grade->dategraded;
        } else {
            $result->time = $grade->datesubmitted;
        }

return $result;
    }
    return NULL;
}

/**
 * @global object
 * @global object
 * @param object $coure
 * @param object $user
 * @param object $mod
 * @param object $forum
 */
function forum_user_complete($course, $user, $mod, $forum) {
    global $CFG,$USER, $OUTPUT;
    require_once("$CFG->libdir/gradelib.php");

$grades = grade_get_grades($course->id, 'mod', 'forum', $forum->id, $user->id);
    if (!empty($grades->items[0]->grades)) {
        $grade = reset($grades->items[0]->grades);
        if (!$grade->hidden || has_capability('moodle/grade:viewhidden', context_course::instance($course->id))) {
            echo $OUTPUT->container(get_string('grade').': '.$grade->str_long_grade);
            if ($grade->str_feedback) {
                echo $OUTPUT->container(get_string('feedback').': '.$grade->str_feedback);
            }
        } else {
            echo $OUTPUT->container(get_string('grade') . ': ' . get_string('hidden', 'grades'));
        }
    }

if ($posts = forum_get_user_posts($forum->id, $user->id)) {

if (!$cm = get_coursemodule_from_instance('forum', $forum->id, $course->id)) {
            print_error('invalidcoursemodule');
        }
        $context = context_module::instance($cm->id);
        $discussions = forum_get_user_involved_discussions($forum->id, $user->id);
        $posts = array_filter($posts, function($post) use ($discussions) {
            return isset($discussions[$post->discussion]);
        });
        $entityfactory = mod_forum\local\container::get_entity_factory();
        $rendererfactory = mod_forum\local\container::get_renderer_factory();
        $postrenderer = $rendererfactory->get_posts_renderer();

echo $postrenderer->render(
            $USER,
            [$forum->id => $entityfactory->get_forum_from_stdclass($forum, $context, $cm, $course)],
            array_map(function($discussion) use ($entityfactory) {
                return $entityfactory->get_discussion_from_stdclass($discussion);
            }, $discussions),
            array_map(function($post) use ($entityfactory) {
                return $entityfactory->get_post_from_stdclass($post);
            }, $posts)
        );
    } else {
        echo "<p>".get_string("noposts", "forum")."</p>";
    }
}

/**
 * Filters the forum discussions according to groups membership and config.
 *
 * @deprecated since 3.3
 * @todo The final deprecation of this function will take place in Moodle 3.7 - see MDL-57487.
 * @since  Moodle 2.8, 2.7.1, 2.6.4
 * @param  array $discussions Discussions with new posts array
 * @return array Forums with the number of new posts
 */
function forum_filter_user_groups_discussions($discussions) {

debugging('The function forum_filter_user_groups_discussions() is now deprecated.', DEBUG_DEVELOPER);

// Group the remaining discussions posts by their forumid.
    $filteredforums = array();

// Discard not visible groups.
    foreach ($discussions as $discussion) {

// Course data is already cached.
        $instances = get_fast_modinfo($discussion->course)->get_instances();
        $forum = $instances['forum'][$discussion->forum];

// Continue if the user should not see this discussion.
        if (!forum_is_user_group_discussion($forum, $discussion->groupid)) {
            continue;
        }

// Grouping results by forum.
        if (empty($filteredforums[$forum->instance])) {
            $filteredforums[$forum->instance] = new stdClass();
            $filteredforums[$forum->instance]->id = $forum->id;
            $filteredforums[$forum->instance]->count = 0;
        }
        $filteredforums[$forum->instance]->count += $discussion->count;

}

return $filteredforums;
}

/**
 * Returns whether the discussion group is visible by the current user or not.
 *
 * @since Moodle 2.8, 2.7.1, 2.6.4
 * @param cm_info $cm The discussion course module
 * @param int $discussiongroupid The discussion groupid
 * @return bool
 */
function forum_is_user_group_discussion(cm_info $cm, $discussiongroupid) {

if ($discussiongroupid == -1 || $cm->effectivegroupmode != SEPARATEGROUPS) {
        return true;
    }

if (isguestuser()) {
        return false;
    }

if (has_capability('moodle/site:accessallgroups', context_module::instance($cm->id)) ||
            in_array($discussiongroupid, $cm->get_modinfo()->get_groups($cm->groupingid))) {
        return true;
    }

return false;
}

/**
 * @deprecated since 3.3
 * @todo The final deprecation of this function will take place in Moodle 3.7 - see MDL-57487.
 * @global object
 * @global object
 * @global object
 * @param array $courses
 * @param array $htmlarray
 */
function forum_print_overview($courses,&$htmlarray) {
    global $USER, $CFG, $DB, $SESSION;

debugging('The function forum_print_overview() is now deprecated.', DEBUG_DEVELOPER);

if (empty($courses) || !is_array($courses) || count($courses) == 0) {
        return array();
    }

if (!$forums = get_all_instances_in_courses('forum',$courses)) {
        return;
    }

// Courses to search for new posts
    $coursessqls = array();
    $params = array();
    foreach ($courses as $course) {

// If the user has never entered into the course all posts are pending
        if ($course->lastaccess == 0) {
            $coursessqls[] = '(d.course = ?)';
            $params[] = $course->id;

// Only posts created after the course last access
        } else {
            $coursessqls[] = '(d.course = ? AND p.created > ?)';
            $params[] = $course->id;
            $params[] = $course->lastaccess;
        }
    }
    $params[] = $USER->id;
    $coursessql = implode(' OR ', $coursessqls);

$sql = "SELECT d.id, d.forum, d.course, d.groupid, COUNT(*) as count "
                .'FROM {forum_discussions} d '
                .'JOIN {forum_posts} p ON p.discussion = d.id '
                ."WHERE ($coursessql) "
                .'AND p.deleted <> 1 '
                .'AND p.userid != ? '
                .'AND (d.timestart <= ? AND (d.timeend = 0 OR d.timeend > ?)) '
                .'GROUP BY d.id, d.forum, d.course, d.groupid '
                .'ORDER BY d.course, d.forum';
    $params[] = time();
    $params[] = time();

// Avoid warnings.
    if (!$discussions = $DB->get_records_sql($sql, $params)) {
        $discussions = array();
    }

$forumsnewposts = forum_filter_user_groups_discussions($discussions);

// also get all forum tracking stuff ONCE.
    $trackingforums = array();
    foreach ($forums as $forum) {
        if (forum_tp_can_track_forums($forum)) {
            $trackingforums[$forum->id] = $forum;
        }
    }

if (count($trackingforums) > 0) {
        $cutoffdate = isset($CFG->forum_oldpostdays) ? (time() - ($CFG->forum_oldpostdays*24*60*60)) : 0;
        $sql = 'SELECT d.forum,d.course,COUNT(p.id) AS count '.
            ' FROM {forum_posts} p '.
            ' JOIN {forum_discussions} d ON p.discussion = d.id '.
            ' LEFT JOIN {forum_read} r ON r.postid = p.id AND r.userid = ? WHERE p.deleted <> 1 AND (';
        $params = array($USER->id);

foreach ($trackingforums as $track) {
            $sql .= '(d.forum = ? AND (d.groupid = -1 OR d.groupid = 0 OR d.groupid = ?)) OR ';
            $params[] = $track->id;
            if (isset($SESSION->currentgroup[$track->course])) {
                $groupid =  $SESSION->currentgroup[$track->course];
            } else {
                // get first groupid
                $groupids = groups_get_all_groups($track->course, $USER->id);
                if ($groupids) {
                    reset($groupids);
                    $groupid = key($groupids);
                    $SESSION->currentgroup[$track->course] = $groupid;
                } else {
                    $groupid = 0;
                }
                unset($groupids);
            }
            $params[] = $groupid;
        }
        $sql = substr($sql,0,-3); // take off the last OR
        $sql .= ') AND p.modified >= ? AND r.id is NULL ';
        $sql .= 'AND (d.timestart < ? AND (d.timeend = 0 OR d.timeend > ?)) ';
        $sql .= 'GROUP BY d.forum,d.course';
        $params[] = $cutoffdate;
        $params[] = time();
        $params[] = time();

if (!$unread = $DB->get_records_sql($sql, $params)) {
            $unread = array();
        }
    } else {
        $unread = array();
    }

if (empty($unread) and empty($forumsnewposts)) {
        return;
    }

$strforum = get_string('modulename','forum');

foreach ($forums as $forum) {
        $str = '';
        $count = 0;
        $thisunread = 0;
        $showunread = false;
        // either we have something from logs, or trackposts, or nothing.
        if (array_key_exists($forum->id, $forumsnewposts) && !empty($forumsnewposts[$forum->id])) {
            $count = $forumsnewposts[$forum->id]->count;
        }
        if (array_key_exists($forum->id,$unread)) {
            $thisunread = $unread[$forum->id]->count;
            $showunread = true;
        }
        if ($count > 0 || $thisunread > 0) {
            $str .= '<div class="overview forum"><div class="name">'.$strforum.': <a title="'.$strforum.'" href="'.$CFG->wwwroot.'/mod/forum/view.php?f='.$forum->id.'">'.
                $forum->name.'</a></div>';
            $str .= '<div class="info"><span class="postsincelogin">';
            $str .= get_string('overviewnumpostssince', 'forum', $count)."</span>";
            if (!empty($showunread)) {
                $str .= '<div class="unreadposts">'.get_string('overviewnumunread', 'forum', $thisunread).'</div>';
            }
            $str .= '</div></div>';
        }
        if (!empty($str)) {
            if (!array_key_exists($forum->course,$htmlarray)) {
                $htmlarray[$forum->course] = array();
            }
            if (!array_key_exists('forum',$htmlarray[$forum->course])) {
                $htmlarray[$forum->course]['forum'] = ''; // initialize, avoid warnings
            }
            $htmlarray[$forum->course]['forum'] .= $str;
        }
    }
}

/**
 * Given a course and a date, prints a summary of all the new
 * messages posted in the course since that date
 *
 * @global object
 * @global object
 * @global object
 * @uses CONTEXT_MODULE
 * @uses VISIBLEGROUPS
 * @param object $course
 * @param bool $viewfullnames capability
 * @param int $timestart
 * @return bool success
 */
function forum_print_recent_activity($course, $viewfullnames, $timestart) {
    global $USER, $DB, $OUTPUT;

// do not use log table if possible, it may be huge and is expensive to join with other tables

$allnamefields = user_picture::fields('u', null, 'duserid');
    if (!$posts = $DB->get_records_sql("SELECT p.*,
                                              f.course, f.type AS forumtype, f.name AS forumname, f.intro, f.introformat, f.duedate,
                                              f.cutoffdate, f.assessed AS forumassessed, f.assesstimestart, f.assesstimefinish,
                                              f.scale, f.maxbytes, f.maxattachments, f.forcesubscribe,
                                              f.trackingtype, f.rsstype, f.rssarticles, f.timemodified, f.warnafter, f.blockafter,
                                              f.blockperiod, f.completiondiscussions, f.completionreplies, f.completionposts,
                                              f.displaywordcount, f.lockdiscussionafter,
                                              d.name AS discussionname, d.firstpost, d.userid AS discussionstarter,
                                              d.assessed AS discussionassessed, d.timemodified, d.usermodified, d.forum, d.groupid,
                                              d.timestart, d.timeend, d.pinned, d.timelocked,
                                              $allnamefields
                                         FROM {forum_posts} p
                                              JOIN {forum_discussions} d ON d.id = p.discussion
                                              JOIN {forum} f             ON f.id = d.forum
                                              JOIN {user} u              ON u.id = p.userid
                                        WHERE p.created > ? AND f.course = ? AND p.deleted <> 1
                                     ORDER BY p.id ASC", array($timestart, $course->id))) { // order by initial posting date
         return false;
    }

$modinfo = get_fast_modinfo($course);

$strftimerecent = get_string('strftimerecent');

$managerfactory = mod_forum\local\container::get_manager_factory();
    $entityfactory = mod_forum\local\container::get_entity_factory();

$discussions = [];
    $capmanagers = [];
    $printposts = [];
    foreach ($posts as $post) {
        if (!isset($modinfo->instances['forum'][$post->forum])) {
            // not visible
            continue;
        }
        $cm = $modinfo->instances['forum'][$post->forum];
        if (!$cm->uservisible) {
            continue;
        }

// Get the discussion. Cache if not yet available.
        if (!isset($discussions[$post->discussion])) {
            // Build the discussion record object from the post data.
            $discussionrecord = (object)[
                'id' => $post->discussion,
                'course' => $post->course,
                'forum' => $post->forum,
                'name' => $post->discussionname,
                'firstpost' => $post->firstpost,
                'userid' => $post->discussionstarter,
                'groupid' => $post->groupid,
                'assessed' => $post->discussionassessed,
                'timemodified' => $post->timemodified,
                'usermodified' => $post->usermodified,
                'timestart' => $post->timestart,
                'timeend' => $post->timeend,
                'pinned' => $post->pinned,
                'timelocked' => $post->timelocked
            ];
            // Build the discussion entity from the factory and cache it.
            $discussions[$post->discussion] = $entityfactory->get_discussion_from_stdclass($discussionrecord);
        }
        $discussionentity = $discussions[$post->discussion];

// Get the capability manager. Cache if not yet available.
        if (!isset($capmanagers[$post->forum])) {
            $context = context_module::instance($cm->id);
            $coursemodule = $cm->get_course_module_record();
            // Build the forum record object from the post data.
            $forumrecord = (object)[
                'id' => $post->forum,
                'course' => $post->course,
                'type' => $post->forumtype,
                'name' => $post->forumname,
                'intro' => $post->intro,
                'introformat' => $post->introformat,
                'duedate' => $post->duedate,
                'cutoffdate' => $post->cutoffdate,
                'assessed' => $post->forumassessed,
                'assesstimestart' => $post->assesstimestart,
                'assesstimefinish' => $post->assesstimefinish,
                'scale' => $post->scale,
                'maxbytes' => $post->maxbytes,
                'maxattachments' => $post->maxattachments,
                'forcesubscribe' => $post->forcesubscribe,
                'trackingtype' => $post->trackingtype,
                'rsstype' => $post->rsstype,
                'rssarticles' => $post->rssarticles,
                'timemodified' => $post->timemodified,
                'warnafter' => $post->warnafter,
                'blockafter' => $post->blockafter,
                'blockperiod' => $post->blockperiod,
                'completiondiscussions' => $post->completiondiscussions,
                'completionreplies' => $post->completionreplies,
                'completionposts' => $post->completionposts,
                'displaywordcount' => $post->displaywordcount,
                'lockdiscussionafter' => $post->lockdiscussionafter,
            ];
            // Build the forum entity from the factory.
            $forumentity = $entityfactory->get_forum_from_stdclass($forumrecord, $context, $coursemodule, $course);
            // Get the capability manager of this forum and cache it.
            $capmanagers[$post->forum] = $managerfactory->get_capability_manager($forumentity);
        }
        $capabilitymanager = $capmanagers[$post->forum];

// Get the post entity.
        $postentity = $entityfactory->get_post_from_stdclass($post);

// Check if the user can view the post.
        if ($capabilitymanager->can_view_post($USER, $discussionentity, $postentity)) {
            $printposts[] = $post;
        }
    }
    unset($posts);

if (!$printposts) {
        return false;
    }

echo $OUTPUT->heading(get_string('newforumposts', 'forum').':', 3);
    $list = html_writer::start_tag('ul', ['class' => 'unlist']);

foreach ($printposts as $post) {
        $subjectclass = empty($post->parent) ? ' bold' : '';
        $authorhidden = forum_is_author_hidden($post, (object) ['type' => $post->forumtype]);

$list .= html_writer::start_tag('li');
        $list .= html_writer::start_div('head');
        $list .= html_writer::div(userdate_htmltime($post->modified, $strftimerecent), 'date');
        if (!$authorhidden) {
            $list .= html_writer::div(fullname($post, $viewfullnames), 'name');
        }
        $list .= html_writer::end_div(); // Head.

$list .= html_writer::start_div('info' . $subjectclass);
        $discussionurl = new moodle_url('/mod/forum/discuss.php', ['d' => $post->discussion]);
        if (!empty($post->parent)) {
            $discussionurl->param('parent', $post->parent);
            $discussionurl->set_anchor('p'. $post->id);
        }
        $post->subject = break_up_long_words(format_string($post->subject, true));
        $list .= html_writer::link($discussionurl, $post->subject, ['rel' => 'bookmark']);
        $list .= html_writer::end_div(); // Info.
        $list .= html_writer::end_tag('li');
    }

$list .= html_writer::end_tag('ul');
    echo $list;

return true;
}

/**
 * Return grade for given user or all users.
 *
 * @global object
 * @global object
 * @param object $forum
 * @param int $userid optional user id, 0 means all users
 * @return array array of grades, false if none
 */
function forum_get_user_grades($forum, $userid = 0) {
    global $CFG;

require_once($CFG->dirroot.'/rating/lib.php');

$ratingoptions = new stdClass;
    $ratingoptions->component = 'mod_forum';
    $ratingoptions->ratingarea = 'post';

//need these to work backwards to get a context id. Is there a better way to get contextid from a module instance?
    $ratingoptions->modulename = 'forum';
    $ratingoptions->moduleid   = $forum->id;
    $ratingoptions->userid = $userid;
    $ratingoptions->aggregationmethod = $forum->assessed;
    $ratingoptions->scaleid = $forum->scale;
    $ratingoptions->itemtable = 'forum_posts';
    $ratingoptions->itemtableusercolumn = 'userid';

$rm = new rating_manager();
    return $rm->get_user_grades($ratingoptions);
}

/**
 * Update activity grades
 *
 * @category grade
 * @param object $forum
 * @param int $userid specific user only, 0 means all
 * @param boolean $nullifnone return null if grade does not exist
 * @return void
 */
function forum_update_grades($forum, $userid=0, $nullifnone=true) {
    global $CFG, $DB;
    require_once($CFG->libdir.'/gradelib.php');

if (!$forum->assessed) {
        forum_grade_item_update($forum);

} else if ($grades = forum_get_user_grades($forum, $userid)) {
        forum_grade_item_update($forum, $grades);

} else if ($userid and $nullifnone) {
        $grade = new stdClass();
        $grade->userid   = $userid;
        $grade->rawgrade = NULL;
        forum_grade_item_update($forum, $grade);

} else {
        forum_grade_item_update($forum);
    }
}

/**
 * Create/update grade item for given forum
 *
 * @category grade
 * @uses GRADE_TYPE_NONE
 * @uses GRADE_TYPE_VALUE
 * @uses GRADE_TYPE_SCALE
 * @param stdClass $forum Forum object with extra cmidnumber
 * @param mixed $grades Optional array/object of grade(s); 'reset' means reset grades in gradebook
 * @return int 0 if ok
 */
function forum_grade_item_update($forum, $grades=NULL) {
    global $CFG;
    if (!function_exists('grade_update')) { //workaround for buggy PHP versions
        require_once($CFG->libdir.'/gradelib.php');
    }

$params = array('itemname'=>$forum->name, 'idnumber'=>$forum->cmidnumber);

if (!$forum->assessed or $forum->scale == 0) {
        $params['gradetype'] = GRADE_TYPE_NONE;

} else if ($forum->scale > 0) {
        $params['gradetype'] = GRADE_TYPE_VALUE;
        $params['grademax']  = $forum->scale;
        $params['grademin']  = 0;

} else if ($forum->scale < 0) {
        $params['gradetype'] = GRADE_TYPE_SCALE;
        $params['scaleid']   = -$forum->scale;
    }

if ($grades  === 'reset') {
        $params['reset'] = true;
        $grades = NULL;
    }

return grade_update('mod/forum', $forum->course, 'mod', 'forum', $forum->id, 0, $grades, $params);
}

/**
 * Delete grade item for given forum
 *
 * @category grade
 * @param stdClass $forum Forum object
 * @return grade_item
 */
function forum_grade_item_delete($forum) {
    global $CFG;
    require_once($CFG->libdir.'/gradelib.php');

return grade_update('mod/forum', $forum->course, 'mod', 'forum', $forum->id, 0, NULL, array('deleted'=>1));
}

/**
 * This function returns if a scale is being used by one forum
 *
 * @global object
 * @param int $forumid
 * @param int $scaleid negative number
 * @return bool
 */
function forum_scale_used ($forumid,$scaleid) {
    global $DB;
    $return = false;

$rec = $DB->get_record("forum",array("id" => "$forumid","scale" => "-$scaleid"));

if (!empty($rec) && !empty($scaleid)) {
        $return = true;
    }

return $return;
}

/**
 * Checks if scale is being used by any instance of forum
 *
 * This is used to find out if scale used anywhere
 *
 * @global object
 * @param $scaleid int
 * @return boolean True if the scale is used by any forum
 */
function forum_scale_used_anywhere($scaleid) {
    global $DB;
    if ($scaleid and $DB->record_exists('forum', array('scale' => -$scaleid))) {
        return true;
    } else {
        return false;
    }
}

// SQL FUNCTIONS ///////////////////////////////////////////////////////////

/**
 * Gets a post with all info ready for forum_print_post
 * Most of these joins are just to get the forum id
 *
 * @global object
 * @global object
 * @param int $postid
 * @return mixed array of posts or false
 */
function forum_get_post_full($postid) {
    global $CFG, $DB;

$allnames = get_all_user_name_fields(true, 'u');
    return $DB->get_record_sql("SELECT p.*, d.forum, $allnames, u.email, u.picture, u.imagealt
                             FROM {forum_posts} p
                                  JOIN {forum_discussions} d ON p.discussion = d.id
                                  LEFT JOIN {user} u ON p.userid = u.id
                            WHERE p.id = ?", array($postid));
}

/**
 * Gets all posts in discussion including top parent.
 *
 * @param   int     $discussionid   The Discussion to fetch.
 * @param   string  $sort           The sorting to apply.
 * @param   bool    $tracking       Whether the user tracks this forum.
 * @return  array                   The posts in the discussion.
 */
function forum_get_all_discussion_posts($discussionid, $sort, $tracking = false) {
    global $CFG, $DB, $USER;

$tr_sel  = "";
    $tr_join = "";
    $params = array();

if ($tracking) {
        $tr_sel  = ", fr.id AS postread";
        $tr_join = "LEFT JOIN {forum_read} fr ON (fr.postid = p.id AND fr.userid = ?)";
        $params[] = $USER->id;
    }

$allnames = get_all_user_name_fields(true, 'u');
    $params[] = $discussionid;
    if (!$posts = $DB->get_records_sql("SELECT p.*, $allnames, u.email, u.picture, u.imagealt $tr_sel
                                     FROM {forum_posts} p
                                          LEFT JOIN {user} u ON p.userid = u.id
                                          $tr_join
                                    WHERE p.discussion = ?
                                 ORDER BY $sort", $params)) {
        return array();
    }

foreach ($posts as $pid=>$p) {
        if ($tracking) {
            if (forum_tp_is_post_old($p)) {
                 $posts[$pid]->postread = true;
            }
        }
        if (!$p->parent) {
            continue;
        }
        if (!isset($posts[$p->parent])) {
            continue; // parent does not exist??
        }
        if (!isset($posts[$p->parent]->children)) {
            $posts[$p->parent]->children = array();
        }
        $posts[$p->parent]->children[$pid] =& $posts[$pid];
    }

// Start with the last child of the first post.
    $post = &$posts[reset($posts)->id];

$lastpost = false;
    while (!$lastpost) {
        if (!isset($post->children)) {
            $post->lastpost = true;
            $lastpost = true;
        } else {
             // Go to the last child of this post.
            $post = &$posts[end($post->children)->id];
        }
    }

return $posts;
}

/**
 * An array of forum objects that the user is allowed to read/search through.
 *
 * @global object
 * @global object
 * @global object
 * @param int $userid
 * @param int $courseid if 0, we look for forums throughout the whole site.
 * @return array of forum objects, or false if no matches
 *         Forum objects have the following attributes:
 *         id, type, course, cmid, cmvisible, cmgroupmode, accessallgroups,
 *         viewhiddentimedposts
 */
function forum_get_readable_forums($userid, $courseid=0) {

global $CFG, $DB, $USER;
    require_once($CFG->dirroot.'/course/lib.php');

if (!$forummod = $DB->get_record('modules', array('name' => 'forum'))) {
        print_error('notinstalled', 'forum');
    }

if ($courseid) {
        $courses = $DB->get_records('course', array('id' => $courseid));
    } else {
        // If no course is specified, then the user can see SITE + his courses.
        $courses1 = $DB->get_records('course', array('id' => SITEID));
        $courses2 = enrol_get_users_courses($userid, true, array('modinfo'));
        $courses = array_merge($courses1, $courses2);
    }
    if (!$courses) {
        return array();
    }

$readableforums = array();

foreach ($courses as $course) {

$modinfo = get_fast_modinfo($course);

if (empty($modinfo->instances['forum'])) {
            // hmm, no forums?
            continue;
        }

$courseforums = $DB->get_records('forum', array('course' => $course->id));

foreach ($modinfo->instances['forum'] as $forumid => $cm) {
            if (!$cm->uservisible or !isset($courseforums[$forumid])) {
                continue;
            }
            $context = context_module::instance($cm->id);
            $forum = $courseforums[$forumid];
            $forum->context = $context;
            $forum->cm = $cm;

if (!has_capability('mod/forum:viewdiscussion', $context)) {
                continue;
            }

/// group access
            if (groups_get_activity_groupmode($cm, $course) == SEPARATEGROUPS and !has_capability('moodle/site:accessallgroups', $context)) {

$forum->onlygroups = $modinfo->get_groups($cm->groupingid);
                $forum->onlygroups[] = -1;
            }

/// hidden timed discussions
            $forum->viewhiddentimedposts = true;
            if (!empty($CFG->forum_enabletimedposts)) {
                if (!has_capability('mod/forum:viewhiddentimedposts', $context)) {
                    $forum->viewhiddentimedposts = false;
                }
            }

/// qanda access
            if ($forum->type == 'qanda'
                    && !has_capability('mod/forum:viewqandawithoutposting', $context)) {

// We need to check whether the user has posted in the qanda forum.
                $forum->onlydiscussions = array();  // Holds discussion ids for the discussions
                                                    // the user is allowed to see in this forum.
                if ($discussionspostedin = forum_discussions_user_has_posted_in($forum->id, $USER->id)) {
                    foreach ($discussionspostedin as $d) {
                        $forum->onlydiscussions[] = $d->id;
                    }
                }
            }

$readableforums[$forum->id] = $forum;
        }

unset($modinfo);

} // End foreach $courses

return $readableforums;
}

/**
 * Returns a list of posts found using an array of search terms.
 *
 * @global object
 * @global object
 * @global object
 * @param array $searchterms array of search terms, e.g. word +word -word
 * @param int $courseid if 0, we search through the whole site
 * @param int $limitfrom
 * @param int $limitnum
 * @param int &$totalcount
 * @param string $extrasql
 * @return array|bool Array of posts found or false
 */
function forum_search_posts($searchterms, $courseid=0, $limitfrom=0, $limitnum=50,
                            &$totalcount, $extrasql='') {
    global $CFG, $DB, $USER;
    require_once($CFG->libdir.'/searchlib.php');

$forums = forum_get_readable_forums($USER->id, $courseid);

if (count($forums) == 0) {
        $totalcount = 0;
        return false;
    }

$now = floor(time() / 60) * 60; // DB Cache Friendly.

$fullaccess = array();
    $where = array();
    $params = array();

foreach ($forums as $forumid => $forum) {
        $select = array();

if (!$forum->viewhiddentimedposts) {
            $select[] = "(d.userid = :userid{$forumid} OR (d.timestart < :timestart{$forumid} AND (d.timeend = 0 OR d.timeend > :timeend{$forumid})))";
            $params = array_merge($params, array('userid'.$forumid=>$USER->id, 'timestart'.$forumid=>$now, 'timeend'.$forumid=>$now));
        }

$cm = $forum->cm;
        $context = $forum->context;

if ($forum->type == 'qanda'
            && !has_capability('mod/forum:viewqandawithoutposting', $context)) {
            if (!empty($forum->onlydiscussions)) {
                list($discussionid_sql, $discussionid_params) = $DB->get_in_or_equal($forum->onlydiscussions, SQL_PARAMS_NAMED, 'qanda'.$forumid.'_');
                $params = array_merge($params, $discussionid_params);
                $select[] = "(d.id $discussionid_sql OR p.parent = 0)";
            } else {
                $select[] = "p.parent = 0";
            }
        }

if (!empty($forum->onlygroups)) {
            list($groupid_sql, $groupid_params) = $DB->get_in_or_equal($forum->onlygroups, SQL_PARAMS_NAMED, 'grps'.$forumid.'_');
            $params = array_merge($params, $groupid_params);
            $select[] = "d.groupid $groupid_sql";
        }

if ($select) {
            $selects = implode(" AND ", $select);
            $where[] = "(d.forum = :forum{$forumid} AND $selects)";
            $params['forum'.$forumid] = $forumid;
        } else {
            $fullaccess[] = $forumid;
        }
    }

if ($fullaccess) {
        list($fullid_sql, $fullid_params) = $DB->get_in_or_equal($fullaccess, SQL_PARAMS_NAMED, 'fula');
        $params = array_merge($params, $fullid_params);
        $where[] = "(d.forum $fullid_sql)";
    }

$selectdiscussion = "(".implode(" OR ", $where).")";

$messagesearch = '';
    $searchstring = '';

// Need to concat these back together for parser to work.
    foreach($searchterms as $searchterm){
        if ($searchstring != '') {
            $searchstring .= ' ';
        }
        $searchstring .= $searchterm;
    }

// We need to allow quoted strings for the search. The quotes *should* be stripped
    // by the parser, but this should be examined carefully for security implications.
    $searchstring = str_replace("\\\"","\"",$searchstring);
    $parser = new search_parser();
    $lexer = new search_lexer($parser);

if ($lexer->parse($searchstring)) {
        $parsearray = $parser->get_parsed_array();

$tagjoins = '';
        $tagfields = [];
        $tagfieldcount = 0;
        foreach ($parsearray as $token) {
            if ($token->getType() == TOKEN_TAGS) {
                for ($i = 0; $i <= substr_count($token->getValue(), ','); $i++) {
                    // Queries can only have a limited number of joins so set a limit sensible users won't exceed.
                    if ($tagfieldcount > 10) {
                        continue;
                    }
                    $tagjoins .= " LEFT JOIN {tag_instance} ti_$tagfieldcount
                                        ON p.id = ti_$tagfieldcount.itemid
                                            AND ti_$tagfieldcount.component = 'mod_forum'
                                            AND ti_$tagfieldcount.itemtype = 'forum_posts'";
                    $tagjoins .= " LEFT JOIN {tag} t_$tagfieldcount ON t_$tagfieldcount.id = ti_$tagfieldcount.tagid";
                    $tagfields[] = "t_$tagfieldcount.rawname";
                    $tagfieldcount++;
                }
            }
        }
        list($messagesearch, $msparams) = search_generate_SQL($parsearray, 'p.message', 'p.subject',
                                                              'p.userid', 'u.id', 'u.firstname',
                                                              'u.lastname', 'p.modified', 'd.forum',
                                                              $tagfields);
        $params = array_merge($params, $msparams);
    }

$fromsql = "{forum_posts} p
                  INNER JOIN {forum_discussions} d ON d.id = p.discussion
                  INNER JOIN {user} u ON u.id = p.userid $tagjoins";

$selectsql = " $messagesearch
               AND p.discussion = d.id
               AND p.userid = u.id
               AND $selectdiscussion
                   $extrasql";

$countsql = "SELECT COUNT(*)
                   FROM $fromsql
                  WHERE $selectsql";

$allnames = get_all_user_name_fields(true, 'u');
    $searchsql = "SELECT p.*,
                         d.forum,
                         $allnames,
                         u.email,
                         u.picture,
                         u.imagealt
                    FROM $fromsql
                   WHERE $selectsql
                ORDER BY p.modified DESC";

$totalcount = $DB->count_records_sql($countsql, $params);

return $DB->get_records_sql($searchsql, $params, $limitfrom, $limitnum);
}

/**
 * Get all the posts for a user in a forum suitable for forum_print_post
 *
 * @global object
 * @global object
 * @uses CONTEXT_MODULE
 * @return array
 */
function forum_get_user_posts($forumid, $userid) {
    global $CFG, $DB;

$timedsql = "";
    $params = array($forumid, $userid);

if (!empty($CFG->forum_enabletimedposts)) {
        $cm = get_coursemodule_from_instance('forum', $forumid);
        if (!has_capability('mod/forum:viewhiddentimedposts' , context_module::instance($cm->id))) {
            $now = time();
            $timedsql = "AND (d.timestart < ? AND (d.timeend = 0 OR d.timeend > ?))";
            $params[] = $now;
            $params[] = $now;
        }
    }

$allnames = get_all_user_name_fields(true, 'u');
    return $DB->get_records_sql("SELECT p.*, d.forum, $allnames, u.email, u.picture, u.imagealt
                              FROM {forum} f
                                   JOIN {forum_discussions} d ON d.forum = f.id
                                   JOIN {forum_posts} p       ON p.discussion = d.id
                                   JOIN {user} u              ON u.id = p.userid
                             WHERE f.id = ?
                                   AND p.userid = ?
                                   $timedsql
                          ORDER BY p.modified ASC", $params);
}

/**
 * Get all the discussions user participated in
 *
 * @global object
 * @global object
 * @uses CONTEXT_MODULE
 * @param int $forumid
 * @param int $userid
 * @return array Array or false
 */
function forum_get_user_involved_discussions($forumid, $userid) {
    global $CFG, $DB;

$timedsql = "";
    $params = array($forumid, $userid);
    if (!empty($CFG->forum_enabletimedposts)) {
        $cm = get_coursemodule_from_instance('forum', $forumid);
        if (!has_capability('mod/forum:viewhiddentimedposts' , context_module::instance($cm->id))) {
            $now = time();
            $timedsql = "AND (d.timestart < ? AND (d.timeend = 0 OR d.timeend > ?))";
            $params[] = $now;
            $params[] = $now;
        }
    }

return $DB->get_records_sql("SELECT DISTINCT d.*
                              FROM {forum} f
                                   JOIN {forum_discussions} d ON d.forum = f.id
                                   JOIN {forum_posts} p       ON p.discussion = d.id
                             WHERE f.id = ?
                                   AND p.userid = ?
                                   $timedsql", $params);
}

/**
 * Get all the posts for a user in a forum suitable for forum_print_post
 *
 * @global object
 * @global object
 * @param int $forumid
 * @param int $userid
 * @return array of counts or false
 */
function forum_count_user_posts($forumid, $userid) {
    global $CFG, $DB;

return $DB->get_record_sql("SELECT COUNT(p.id) AS postcount, MAX(p.modified) AS lastpost
                             FROM {forum} f
                                  JOIN {forum_discussions} d ON d.forum = f.id
                                  JOIN {forum_posts} p       ON p.discussion = d.id
                                  JOIN {user} u              ON u.id = p.userid
                            WHERE f.id = ?
                                  AND p.userid = ?
                                  $timedsql", $params);
}

/**
 * Given a log entry, return the forum post details for it.
 *
 * @global object
 * @global object
 * @param object $log
 * @return array|null
 */
function forum_get_post_from_log($log) {
    global $CFG, $DB;

$allnames = get_all_user_name_fields(true, 'u');
    if ($log->action == "add post") {

return $DB->get_record_sql("SELECT p.*, f.type AS forumtype, d.forum, d.groupid, $allnames, u.email, u.picture
                                 FROM {forum_discussions} d,
                                      {forum_posts} p,
                                      {forum} f,
                                      {user} u
                                WHERE p.id = ?
                                  AND d.id = p.discussion
                                  AND p.userid = u.id
                                  AND u.deleted <> '1'
                                  AND f.id = d.forum", array($log->info));

} else if ($log->action == "add discussion") {

return $DB->get_record_sql("SELECT p.*, f.type AS forumtype, d.forum, d.groupid, $allnames, u.email, u.picture
                                 FROM {forum_discussions} d,
                                      {forum_posts} p,
                                      {forum} f,
                                      {user} u
                                WHERE d.id = ?
                                  AND d.firstpost = p.id
                                  AND p.userid = u.id
                                  AND u.deleted <> '1'
                                  AND f.id = d.forum", array($log->info));
    }
    return NULL;
}

/**
 * Given a discussion id, return the first post from the discussion
 *
 * @global object
 * @global object
 * @param int $dicsussionid
 * @return array
 */
function forum_get_firstpost_from_discussion($discussionid) {
    global $CFG, $DB;

return $DB->get_record_sql("SELECT p.*
                             FROM {forum_discussions} d,
                                  {forum_posts} p
                            WHERE d.id = ?
                              AND d.firstpost = p.id ", array($discussionid));
}

/**
 * Returns an array of counts of replies to each discussion
 *
 * @param   int     $forumid
 * @param   string  $forumsort
 * @param   int     $limit
 * @param   int     $page
 * @param   int     $perpage
 * @param   boolean $canseeprivatereplies   Whether the current user can see private replies.
 * @return  array
 */
function forum_count_discussion_replies($forumid, $forumsort = "", $limit = -1, $page = -1, $perpage = 0,
                                        $canseeprivatereplies = false) {
    global $CFG, $DB, $USER;

if ($limit > 0) {
        $limitfrom = 0;
        $limitnum  = $limit;
    } else if ($page != -1) {
        $limitfrom = $page*$perpage;
        $limitnum  = $perpage;
    } else {
        $limitfrom = 0;
        $limitnum  = 0;
    }

if ($forumsort == "") {
        $orderby = "";
        $groupby = "";

} else {
        $orderby = "ORDER BY $forumsort";
        $groupby = ", ".strtolower($forumsort);
        $groupby = str_replace('desc', '', $groupby);
        $groupby = str_replace('asc', '', $groupby);
    }

$params = ['forumid' => $forumid];

if (!$canseeprivatereplies) {
        $privatewhere = ' AND (p.privatereplyto = :currentuser1 OR p.userid = :currentuser2 OR p.privatereplyto = 0)';
        $params['currentuser1'] = $USER->id;
        $params['currentuser2'] = $USER->id;
    } else {
        $privatewhere = '';
    }

if (($limitfrom == 0 and $limitnum == 0) or $forumsort == "") {
        $sql = "SELECT p.discussion, COUNT(p.id) AS replies, MAX(p.id) AS lastpostid
                  FROM {forum_posts} p
                       JOIN {forum_discussions} d ON p.discussion = d.id
                 WHERE p.parent > 0 AND d.forum = :forumid
                       $privatewhere
              GROUP BY p.discussion";
        return $DB->get_records_sql($sql, $params);

} else {
        $sql = "SELECT p.discussion, (COUNT(p.id) - 1) AS replies, MAX(p.id) AS lastpostid
                  FROM {forum_posts} p
                       JOIN {forum_discussions} d ON p.discussion = d.id
                 WHERE d.forum = :forumid
                       $privatewhere
              GROUP BY p.discussion $groupby $orderby";
        return $DB->get_records_sql($sql, $params, $limitfrom, $limitnum);
    }
}

/**
 * @global object
 * @global object
 * @global object
 * @staticvar array $cache
 * @param object $forum
 * @param object $cm
 * @param object $course
 * @return mixed
 */
function forum_count_discussions($forum, $cm, $course) {
    global $CFG, $DB, $USER;

static $cache = array();

$now = floor(time() / 60) * 60; // DB Cache Friendly.

$params = array($course->id);

if (!isset($cache[$course->id])) {
        if (!empty($CFG->forum_enabletimedposts)) {
            $timedsql = "AND d.timestart < ? AND (d.timeend = 0 OR d.timeend > ?)";
            $params[] = $now;
            $params[] = $now;
        } else {
            $timedsql = "";
        }

$sql = "SELECT f.id, COUNT(d.id) as dcount
                  FROM {forum} f
                       JOIN {forum_discussions} d ON d.forum = f.id
                 WHERE f.course = ?
                       $timedsql
              GROUP BY f.id";

if ($counts = $DB->get_records_sql($sql, $params)) {
            foreach ($counts as $count) {
                $counts[$count->id] = $count->dcount;
            }
            $cache[$course->id] = $counts;
        } else {
            $cache[$course->id] = array();
        }
    }

if (empty($cache[$course->id][$forum->id])) {
        return 0;
    }

$groupmode = groups_get_activity_groupmode($cm, $course);

if ($groupmode != SEPARATEGROUPS) {
        return $cache[$course->id][$forum->id];
    }

if (has_capability('moodle/site:accessallgroups', context_module::instance($cm->id))) {
        return $cache[$course->id][$forum->id];
    }

require_once($CFG->dirroot.'/course/lib.php');

$modinfo = get_fast_modinfo($course);

$mygroups = $modinfo->get_groups($cm->groupingid);

// add all groups posts
    $mygroups[-1] = -1;

list($mygroups_sql, $params) = $DB->get_in_or_equal($mygroups);
    $params[] = $forum->id;

if (!empty($CFG->forum_enabletimedposts)) {
        $timedsql = "AND d.timestart < $now AND (d.timeend = 0 OR d.timeend > $now)";
        $params[] = $now;
        $params[] = $now;
    } else {
        $timedsql = "";
    }

$sql = "SELECT COUNT(d.id)
              FROM {forum_discussions} d
             WHERE d.groupid $mygroups_sql AND d.forum = ?
                   $timedsql";

return $DB->get_field_sql($sql, $params);
}

/**
 * Get all discussions in a forum
 *
 * @global object
 * @global object
 * @global object
 * @uses CONTEXT_MODULE
 * @uses VISIBLEGROUPS
 * @param object $cm
 * @param string $forumsort
 * @param bool $fullpost
 * @param int $unused
 * @param int $limit
 * @param bool $userlastmodified
 * @param int $page
 * @param int $perpage
 * @param int $groupid if groups enabled, get discussions for this group overriding the current group.
 *                     Use FORUM_POSTS_ALL_USER_GROUPS for all the user groups
 * @param int $updatedsince retrieve only discussions updated since the given time
 * @return array
 */
function forum_get_discussions($cm, $forumsort="", $fullpost=true, $unused=-1, $limit=-1,
                                $userlastmodified=false, $page=-1, $perpage=0, $groupid = -1,
                                $updatedsince = 0) {
    global $CFG, $DB, $USER;

$timelimit = '';

$now = floor(time() / 60) * 60;
    $params = array($cm->instance);

$modcontext = context_module::instance($cm->id);

if (!has_capability('mod/forum:viewdiscussion', $modcontext)) { /// User must have perms to view discussions
        return array();
    }

if (!empty($CFG->forum_enabletimedposts)) { /// Users must fulfill timed posts

if (!has_capability('mod/forum:viewhiddentimedposts', $modcontext)) {
            $timelimit = " AND ((d.timestart <= ? AND (d.timeend = 0 OR d.timeend > ?))";
            $params[] = $now;
            $params[] = $now;
            if (isloggedin()) {
                $timelimit .= " OR d.userid = ?";
                $params[] = $USER->id;
            }
            $timelimit .= ")";
        }
    }

$groupmode    = groups_get_activity_groupmode($cm);

if ($groupmode) {

if (empty($modcontext)) {
            $modcontext = context_module::instance($cm->id);
        }

// Special case, we received a groupid to override currentgroup.
        if ($groupid > 0) {
            $course = get_course($cm->course);
            if (!groups_group_visible($groupid, $course, $cm)) {
                // User doesn't belong to this group, return nothing.
                return array();
            }
            $currentgroup = $groupid;
        } else if ($groupid === -1) {
            $currentgroup = groups_get_activity_group($cm);
        } else {
            // Get discussions for all groups current user can see.
            $currentgroup = null;
        }

if ($groupmode == VISIBLEGROUPS or has_capability('moodle/site:accessallgroups', $modcontext)) {
            if ($currentgroup) {
                $groupselect = "AND (d.groupid = ? OR d.groupid = -1)";
                $params[] = $currentgroup;
            } else {
                $groupselect = "";
            }

} else {
            // Separate groups.

// Get discussions for all groups current user can see.
            if ($currentgroup === null) {
                $mygroups = array_keys(groups_get_all_groups($cm->course, $USER->id, $cm->groupingid, 'g.id'));
                if (empty($mygroups)) {
                     $groupselect = "AND d.groupid = -1";
                } else {
                    list($insqlgroups, $inparamsgroups) = $DB->get_in_or_equal($mygroups);
                    $groupselect = "AND (d.groupid = -1 OR d.groupid $insqlgroups)";
                    $params = array_merge($params, $inparamsgroups);
                }
            } else if ($currentgroup) {
                $groupselect = "AND (d.groupid = ? OR d.groupid = -1)";
                $params[] = $currentgroup;
            } else {
                $groupselect = "AND d.groupid = -1";
            }
        }
    } else {
        $groupselect = "";
    }
    if (empty($forumsort)) {
        $forumsort = forum_get_default_sort_order();
    }
    if (empty($fullpost)) {
        $postdata = "p.id, p.subject, p.modified, p.discussion, p.userid, p.created";
    } else {
        $postdata = "p.*";
    }

if (empty($userlastmodified)) {  // We don't need to know this
        $umfields = "";
        $umtable  = "";
    } else {
        $umfields = ', ' . get_all_user_name_fields(true, 'um', null, 'um') . ', um.email AS umemail, um.picture AS umpicture,
                        um.imagealt AS umimagealt';
        $umtable  = " LEFT JOIN {user} um ON (d.usermodified = um.id)";
    }

$updatedsincesql = '';
    if (!empty($updatedsince)) {
        $updatedsincesql = 'AND d.timemodified > ?';
        $params[] = $updatedsince;
    }

$discussionfields = "d.id as discussionid, d.course, d.forum, d.name, d.firstpost, d.groupid, d.assessed," .
    " d.timemodified, d.usermodified, d.timestart, d.timeend, d.pinned, d.timelocked";

$allnames = get_all_user_name_fields(true, 'u');
    $sql = "SELECT $postdata, $discussionfields,
                   $allnames, u.email, u.picture, u.imagealt $umfields
              FROM {forum_discussions} d
                   JOIN {forum_posts} p ON p.discussion = d.id
                   JOIN {user} u ON p.userid = u.id
                   $umtable
             WHERE d.forum = ? AND p.parent = 0
                   $timelimit $groupselect $updatedsincesql
          ORDER BY $forumsort, d.id DESC";

return $DB->get_records_sql($sql, $params, $limitfrom, $limitnum);
}

/**
 * Gets the neighbours (previous and next) of a discussion.
 *
 * The calculation is based on the timemodified when time modified or time created is identical
 * It will revert to using the ID to sort consistently. This is better tha skipping a discussion.
 *
 * For blog-style forums, the calculation is based on the original creation time of the
 * blog post.
 *
 * Please note that this does not check whether or not the discussion passed is accessible
 * by the user, it simply uses it as a reference to find the neighbours. On the other hand,
 * the returned neighbours are checked and are accessible to the current user.
 *
 * @param object $cm The CM record.
 * @param object $discussion The discussion record.
 * @param object $forum The forum instance record.
 * @return array That always contains the keys 'prev' and 'next'. When there is a result
 *               they contain the record with minimal information such as 'id' and 'name'.
 *               When the neighbour is not found the value is false.
 */
function forum_get_discussion_neighbours($cm, $discussion, $forum) {
    global $CFG, $DB, $USER;

if ($cm->instance != $discussion->forum or $discussion->forum != $forum->id or $forum->id != $cm->instance) {
        throw new coding_exception('Discussion is not part of the same forum.');
    }

$neighbours = array('prev' => false, 'next' => false);
    $now = floor(time() / 60) * 60;
    $params = array();

$modcontext = context_module::instance($cm->id);
    $groupmode    = groups_get_activity_groupmode($cm);
    $currentgroup = groups_get_activity_group($cm);

// Users must fulfill timed posts.
    $timelimit = '';
    if (!empty($CFG->forum_enabletimedposts)) {
        if (!has_capability('mod/forum:viewhiddentimedposts', $modcontext)) {
            $timelimit = ' AND ((d.timestart <= :tltimestart AND (d.timeend = 0 OR d.timeend > :tltimeend))';
            $params['tltimestart'] = $now;
            $params['tltimeend'] = $now;
            if (isloggedin()) {
                $timelimit .= ' OR d.userid = :tluserid';
                $params['tluserid'] = $USER->id;
            }
            $timelimit .= ')';
        }
    }

// Limiting to posts accessible according to groups.
    $groupselect = '';
    if ($groupmode) {
        if ($groupmode == VISIBLEGROUPS || has_capability('moodle/site:accessallgroups', $modcontext)) {
            if ($currentgroup) {
                $groupselect = 'AND (d.groupid = :groupid OR d.groupid = -1)';
                $params['groupid'] = $currentgroup;
            }
        } else {
            if ($currentgroup) {
                $groupselect = 'AND (d.groupid = :groupid OR d.groupid = -1)';
                $params['groupid'] = $currentgroup;
            } else {
                $groupselect = 'AND d.groupid = -1';
            }
        }
    }

$params['forumid'] = $cm->instance;
    $params['discid1'] = $discussion->id;
    $params['discid2'] = $discussion->id;
    $params['discid3'] = $discussion->id;
    $params['discid4'] = $discussion->id;
    $params['disctimecompare1'] = $discussion->timemodified;
    $params['disctimecompare2'] = $discussion->timemodified;
    $params['pinnedstate1'] = (int) $discussion->pinned;
    $params['pinnedstate2'] = (int) $discussion->pinned;
    $params['pinnedstate3'] = (int) $discussion->pinned;
    $params['pinnedstate4'] = (int) $discussion->pinned;

$sql = "SELECT d.id, d.name, d.timemodified, d.groupid, d.timestart, d.timeend
              FROM {forum_discussions} d
              JOIN {forum_posts} p ON d.firstpost = p.id
             WHERE d.forum = :forumid
               AND d.id <> :discid1
                   $timelimit
                   $groupselect";
    $comparefield = "d.timemodified";
    $comparevalue = ":disctimecompare1";
    $comparevalue2  = ":disctimecompare2";
    if (!empty($CFG->forum_enabletimedposts)) {
        // Here we need to take into account the release time (timestart)
        // if one is set, of the neighbouring posts and compare it to the
        // timestart or timemodified of *this* post depending on if the
        // release date of this post is in the future or not.
        // This stops discussions that appear later because of the
        // timestart value from being buried under discussions that were
        // made afterwards.
        $comparefield = "CASE WHEN d.timemodified < d.timestart
                                THEN d.timestart ELSE d.timemodified END";
        if ($discussion->timemodified < $discussion->timestart) {
            // Normally we would just use the timemodified for sorting
            // discussion posts. However, when timed discussions are enabled,
            // then posts need to be sorted base on the later of timemodified
            // or the release date of the post (timestart).
            $params['disctimecompare1'] = $discussion->timestart;
            $params['disctimecompare2'] = $discussion->timestart;
        }
    }
    $orderbydesc = forum_get_default_sort_order(true, $comparefield, 'd', false);
    $orderbyasc = forum_get_default_sort_order(false, $comparefield, 'd', false);

if ($forum->type === 'blog') {
         $subselect = "SELECT pp.created
                   FROM {forum_discussions} dd
                   JOIN {forum_posts} pp ON dd.firstpost = pp.id ";

$subselectwhere1 = " WHERE dd.id = :discid3";
         $subselectwhere2 = " WHERE dd.id = :discid4";

$comparefield = "p.created";

$sub1 = $subselect.$subselectwhere1;
         $comparevalue = "($sub1)";

$sub2 = $subselect.$subselectwhere2;
         $comparevalue2 = "($sub2)";

$orderbydesc = "d.pinned, p.created DESC";
         $orderbyasc = "d.pinned, p.created ASC";
    }

$prevsql = $sql . " AND ( (($comparefield < $comparevalue) AND :pinnedstate1 = d.pinned)
                         OR ($comparefield = $comparevalue2 AND (d.pinned = 0 OR d.pinned = :pinnedstate4) AND d.id < :discid2)
                         OR (d.pinned = 0 AND d.pinned <> :pinnedstate2))
                   ORDER BY CASE WHEN d.pinned = :pinnedstate3 THEN 1 ELSE 0 END DESC, $orderbydesc, d.id DESC";

$nextsql = $sql . " AND ( (($comparefield > $comparevalue) AND :pinnedstate1 = d.pinned)
                         OR ($comparefield = $comparevalue2 AND (d.pinned = 1 OR d.pinned = :pinnedstate4) AND d.id > :discid2)
                         OR (d.pinned = 1 AND d.pinned <> :pinnedstate2))
                   ORDER BY CASE WHEN d.pinned = :pinnedstate3 THEN 1 ELSE 0 END DESC, $orderbyasc, d.id ASC";

$neighbours['prev'] = $DB->get_record_sql($prevsql, $params, IGNORE_MULTIPLE);
    $neighbours['next'] = $DB->get_record_sql($nextsql, $params, IGNORE_MULTIPLE);
    return $neighbours;
}

/**
 * Get the sql to use in the ORDER BY clause for forum discussions.
 *
 * This has the ordering take timed discussion windows into account.
 *
 * @param bool $desc True for DESC, False for ASC.
 * @param string $compare The field in the SQL to compare to normally sort by.
 * @param string $prefix The prefix being used for the discussion table.
 * @param bool $pinned sort pinned posts to the top
 * @return string
 */
function forum_get_default_sort_order($desc = true, $compare = 'd.timemodified', $prefix = 'd', $pinned = true) {
    global $CFG;

if (!empty($prefix)) {
        $prefix .= '.';
    }

$dir = $desc ? 'DESC' : 'ASC';

if ($pinned == true) {
        $pinned = "{$prefix}pinned DESC,";
    } else {
        $pinned = '';
    }

$sort = "{$prefix}timemodified";
    if (!empty($CFG->forum_enabletimedposts)) {
        $sort = "CASE WHEN {$compare} < {$prefix}timestart
                 THEN {$prefix}timestart
                 ELSE {$compare}
                 END";
    }
    return "$pinned $sort $dir";
}

/**
 *
 * @global object
 * @global object
 * @global object
 * @uses CONTEXT_MODULE
 * @uses VISIBLEGROUPS
 * @param object $cm
 * @return array
 */
function forum_get_discussions_unread($cm) {
    global $CFG, $DB, $USER;

$now = floor(time() / 60) * 60;
    $cutoffdate = $now - ($CFG->forum_oldpostdays*24*60*60);

$params = array();
    $groupmode    = groups_get_activity_groupmode($cm);
    $currentgroup = groups_get_activity_group($cm);

if ($groupmode) {
        $modcontext = context_module::instance($cm->id);

if ($groupmode == VISIBLEGROUPS or has_capability('moodle/site:accessallgroups', $modcontext)) {
            if ($currentgroup) {
                $groupselect = "AND (d.groupid = :currentgroup OR d.groupid = -1)";
                $params['currentgroup'] = $currentgroup;
            } else {
                $groupselect = "";
            }

} else {
            //separate groups without access all
            if ($currentgroup) {
                $groupselect = "AND (d.groupid = :currentgroup OR d.groupid = -1)";
                $params['currentgroup'] = $currentgroup;
            } else {
                $groupselect = "AND d.groupid = -1";
            }
        }
    } else {
        $groupselect = "";
    }

if (!empty($CFG->forum_enabletimedposts)) {
        $timedsql = "AND d.timestart < :now1 AND (d.timeend = 0 OR d.timeend > :now2)";
        $params['now1'] = $now;
        $params['now2'] = $now;
    } else {
        $timedsql = "";
    }

$sql = "SELECT d.id, COUNT(p.id) AS unread
              FROM {forum_discussions} d
                   JOIN {forum_posts} p     ON p.discussion = d.id
                   LEFT JOIN {forum_read} r ON (r.postid = p.id AND r.userid = $USER->id)
             WHERE d.forum = {$cm->instance}
                   AND p.modified >= :cutoffdate AND r.id is NULL
                   $groupselect
                   $timedsql
          GROUP BY d.id";
    $params['cutoffdate'] = $cutoffdate;

if ($unreads = $DB->get_records_sql($sql, $params)) {
        foreach ($unreads as $unread) {
            $unreads[$unread->id] = $unread->unread;
        }
        return $unreads;
    } else {
        return array();
    }
}

/**
 * @global object
 * @global object
 * @global object
 * @uses CONEXT_MODULE
 * @uses VISIBLEGROUPS
 * @param object $cm
 * @return array
 */
function forum_get_discussions_count($cm) {
    global $CFG, $DB, $USER;

$now = floor(time() / 60) * 60;
    $params = array($cm->instance);
    $groupmode    = groups_get_activity_groupmode($cm);
    $currentgroup = groups_get_activity_group($cm);

if ($groupmode) {
        $modcontext = context_module::instance($cm->id);

} else {
            //seprate groups without access all
            if ($currentgroup) {
                $groupselect = "AND (d.groupid = ? OR d.groupid = -1)";
                $params[] = $currentgroup;
            } else {
                $groupselect = "AND d.groupid = -1";
            }
        }
    } else {
        $groupselect = "";
    }

$timelimit = "";

if (!empty($CFG->forum_enabletimedposts)) {

$modcontext = context_module::instance($cm->id);

$sql = "SELECT COUNT(d.id)
              FROM {forum_discussions} d
                   JOIN {forum_posts} p ON p.discussion = d.id
             WHERE d.forum = ? AND p.parent = 0
                   $groupselect $timelimit";

return $DB->get_field_sql($sql, $params);
}

// OTHER FUNCTIONS ///////////////////////////////////////////////////////////

/**
 * @global object
 * @global object
 * @param int $courseid
 * @param string $type
 */
function forum_get_course_forum($courseid, $type) {
// How to set up special 1-per-course forums
    global $CFG, $DB, $OUTPUT, $USER;

if ($forums = $DB->get_records_select("forum", "course = ? AND type = ?", array($courseid, $type), "id ASC")) {
        // There should always only be ONE, but with the right combination of
        // errors there might be more.  In this case, just return the oldest one (lowest ID).
        foreach ($forums as $forum) {
            return $forum;   // ie the first one
        }
    }

// Doesn't exist, so create one now.
    $forum = new stdClass();
    $forum->course = $courseid;
    $forum->type = "$type";
    if (!empty($USER->htmleditor)) {
        $forum->introformat = $USER->htmleditor;
    }
    switch ($forum->type) {
        case "news":
            $forum->name  = get_string("namenews", "forum");
            $forum->intro = get_string("intronews", "forum");
            $forum->introformat = FORMAT_HTML;
            $forum->forcesubscribe = FORUM_FORCESUBSCRIBE;
            $forum->assessed = 0;
            if ($courseid == SITEID) {
                $forum->name  = get_string("sitenews");
                $forum->forcesubscribe = 0;
            }
            break;
        case "social":
            $forum->name  = get_string("namesocial", "forum");
            $forum->intro = get_string("introsocial", "forum");
            $forum->introformat = FORMAT_HTML;
            $forum->assessed = 0;
            $forum->forcesubscribe = 0;
            break;
        case "blog":
            $forum->name = get_string('blogforum', 'forum');
            $forum->intro = get_string('introblog', 'forum');
            $forum->introformat = FORMAT_HTML;
            $forum->assessed = 0;
            $forum->forcesubscribe = 0;
            break;
        default:
            echo $OUTPUT->notification("That forum type doesn't exist!");
            return false;
            break;
    }

$forum->timemodified = time();
    $forum->id = $DB->insert_record("forum", $forum);

if (! $module = $DB->get_record("modules", array("name" => "forum"))) {
        echo $OUTPUT->notification("Could not find forum module!!");
        return false;
    }
    $mod = new stdClass();
    $mod->course = $courseid;
    $mod->module = $module->id;
    $mod->instance = $forum->id;
    $mod->section = 0;
    include_once("$CFG->dirroot/course/lib.php");
    if (! $mod->coursemodule = add_course_module($mod) ) {
        echo $OUTPUT->notification("Could not add a new course module to the course '" . $courseid . "'");
        return false;
    }
    $sectionid = course_add_cm_to_section($courseid, $mod->coursemodule, 0);
    return $DB->get_record("forum", array("id" => "$forum->id"));
}

/**
 * Return rating related permissions
 *
 * @param string $options the context id
 * @return array an associative array of the user's rating permissions
 */
function forum_rating_permissions($contextid, $component, $ratingarea) {
    $context = context::instance_by_id($contextid, MUST_EXIST);
    if ($component != 'mod_forum' || $ratingarea != 'post') {
        // We don't know about this component/ratingarea so just return null to get the
        // default restrictive permissions.
        return null;
    }
    return array(
        'view'    => has_capability('mod/forum:viewrating', $context),
        'viewany' => has_capability('mod/forum:viewanyrating', $context),
        'viewall' => has_capability('mod/forum:viewallratings', $context),
        'rate'    => has_capability('mod/forum:rate', $context)
    );
}

/**
 * Validates a submitted rating
 * @param array $params submitted data
 *            context => object the context in which the rated items exists [required]
 *            component => The component for this module - should always be mod_forum [required]
 *            ratingarea => object the context in which the rated items exists [required]
 *
 *            itemid => int the ID of the object being rated [required]
 *            scaleid => int the scale from which the user can select a rating. Used for bounds checking. [required]
 *            rating => int the submitted rating [required]
 *            rateduserid => int the id of the user whose items have been rated. NOT the user who submitted the ratings. 0 to update all. [required]
 *            aggregation => int the aggregation method to apply when calculating grades ie RATING_AGGREGATE_AVERAGE [required]
 * @return boolean true if the rating is valid. Will throw rating_exception if not
 */
function forum_rating_validate($params) {
    global $DB, $USER;

// Check the component is mod_forum
    if ($params['component'] != 'mod_forum') {
        throw new rating_exception('invalidcomponent');
    }

// Check the ratingarea is post (the only rating area in forum)
    if ($params['ratingarea'] != 'post') {
        throw new rating_exception('invalidratingarea');
    }

// Check the rateduserid is not the current user .. you can't rate your own posts
    if ($params['rateduserid'] == $USER->id) {
        throw new rating_exception('nopermissiontorate');
    }

// Fetch all the related records ... we need to do this anyway to call forum_user_can_see_post
    $post = $DB->get_record('forum_posts', array('id' => $params['itemid'], 'userid' => $params['rateduserid']), '*', MUST_EXIST);
    $discussion = $DB->get_record('forum_discussions', array('id' => $post->discussion), '*', MUST_EXIST);
    $forum = $DB->get_record('forum', array('id' => $discussion->forum), '*', MUST_EXIST);
    $course = $DB->get_record('course', array('id' => $forum->course), '*', MUST_EXIST);
    $cm = get_coursemodule_from_instance('forum', $forum->id, $course->id , false, MUST_EXIST);
    $context = context_module::instance($cm->id);

// Make sure the context provided is the context of the forum
    if ($context->id != $params['context']->id) {
        throw new rating_exception('invalidcontext');
    }

if ($forum->scale != $params['scaleid']) {
        //the scale being submitted doesnt match the one in the database
        throw new rating_exception('invalidscaleid');
    }

// check the item we're rating was created in the assessable time window
    if (!empty($forum->assesstimestart) && !empty($forum->assesstimefinish)) {
        if ($post->created < $forum->assesstimestart || $post->created > $forum->assesstimefinish) {
            throw new rating_exception('notavailable');
        }
    }

//check that the submitted rating is valid for the scale

// lower limit
    if ($params['rating'] < 0  && $params['rating'] != RATING_UNSET_RATING) {
        throw new rating_exception('invalidnum');
    }

// upper limit
    if ($forum->scale < 0) {
        //its a custom scale
        $scalerecord = $DB->get_record('scale', array('id' => -$forum->scale));
        if ($scalerecord) {
            $scalearray = explode(',', $scalerecord->scale);
            if ($params['rating'] > count($scalearray)) {
                throw new rating_exception('invalidnum');
            }
        } else {
            throw new rating_exception('invalidscaleid');
        }
    } else if ($params['rating'] > $forum->scale) {
        //if its numeric and submitted rating is above maximum
        throw new rating_exception('invalidnum');
    }

// Make sure groups allow this user to see the item they're rating
    if ($discussion->groupid > 0 and $groupmode = groups_get_activity_groupmode($cm, $course)) {   // Groups are being used
        if (!groups_group_exists($discussion->groupid)) { // Can't find group
            throw new rating_exception('cannotfindgroup');//something is wrong
        }

if (!groups_is_member($discussion->groupid) and !has_capability('moodle/site:accessallgroups', $context)) {
            // do not allow rating of posts from other groups when in SEPARATEGROUPS or VISIBLEGROUPS
            throw new rating_exception('notmemberofgroup');
        }
    }

// perform some final capability checks
    if (!forum_user_can_see_post($forum, $discussion, $post, $USER, $cm)) {
        throw new rating_exception('nopermissiontorate');
    }

return true;
}

/**
 * Can the current user see ratings for a given itemid?
 *
 * @param array $params submitted data
 *            contextid => int contextid [required]
 *            component => The component for this module - should always be mod_forum [required]
 *            ratingarea => object the context in which the rated items exists [required]
 *            itemid => int the ID of the object being rated [required]
 *            scaleid => int scale id [optional]
 * @return bool
 * @throws coding_exception
 * @throws rating_exception
 */
function mod_forum_rating_can_see_item_ratings($params) {
    global $DB, $USER;

// Check the component is mod_forum.
    if (!isset($params['component']) || $params['component'] != 'mod_forum') {
        throw new rating_exception('invalidcomponent');
    }

// Check the ratingarea is post (the only rating area in forum).
    if (!isset($params['ratingarea']) || $params['ratingarea'] != 'post') {
        throw new rating_exception('invalidratingarea');
    }

if (!isset($params['itemid'])) {
        throw new rating_exception('invaliditemid');
    }

$post = $DB->get_record('forum_posts', array('id' => $params['itemid']), '*', MUST_EXIST);
    $discussion = $DB->get_record('forum_discussions', array('id' => $post->discussion), '*', MUST_EXIST);
    $forum = $DB->get_record('forum', array('id' => $discussion->forum), '*', MUST_EXIST);
    $course = $DB->get_record('course', array('id' => $forum->course), '*', MUST_EXIST);
    $cm = get_coursemodule_from_instance('forum', $forum->id, $course->id , false, MUST_EXIST);

// Perform some final capability checks.
    if (!forum_user_can_see_post($forum, $discussion, $post, $USER, $cm)) {
        return false;
    }

return true;
}

/**
 * This function prints the overview of a discussion in the forum listing.
 * It needs some discussion information and some post information, these
 * happen to be combined for efficiency in the $post parameter by the function
 * that calls this one: forum_print_latest_discussions()
 *
 * @global object
 * @global object
 * @param object $post The post object (passed by reference for speed).
 * @param object $forum The forum object.
 * @param int $group Current group.
 * @param string $datestring Format to use for the dates.
 * @param boolean $cantrack Is tracking enabled for this forum.
 * @param boolean $forumtracked Is the user tracking this forum.
 * @param boolean $canviewparticipants True if user has the viewparticipants permission for this course
 * @param boolean $canviewhiddentimedposts True if user has the viewhiddentimedposts permission for this forum
 */
function forum_print_discussion_header(&$post, $forum, $group = -1, $datestring = "",
                                        $cantrack = true, $forumtracked = true, $canviewparticipants = true, $modcontext = null,
                                        $canviewhiddentimedposts = false) {

global $COURSE, $USER, $CFG, $OUTPUT, $PAGE;

static $rowcount;
    static $strmarkalldread;

if (empty($modcontext)) {
        if (!$cm = get_coursemodule_from_instance('forum', $forum->id, $forum->course)) {
            print_error('invalidcoursemodule');
        }
        $modcontext = context_module::instance($cm->id);
    }

if (!isset($rowcount)) {
        $rowcount = 0;
        $strmarkalldread = get_string('markalldread', 'forum');
    } else {
        $rowcount = ($rowcount + 1) % 2;
    }

$post->subject = format_string($post->subject,true);

$canviewfullnames = has_capability('moodle/site:viewfullnames', $modcontext);
    $timeddiscussion = !empty($CFG->forum_enabletimedposts) && ($post->timestart || $post->timeend);
    $timedoutsidewindow = '';
    if ($timeddiscussion && ($post->timestart > time() || ($post->timeend != 0 && $post->timeend < time()))) {
        $timedoutsidewindow = ' dimmed_text';
    }

echo "\n\n";
    echo '<tr class="discussion r'.$rowcount.$timedoutsidewindow.'">';

$topicclass = 'topic starter';
    if (FORUM_DISCUSSION_PINNED == $post->pinned) {
        $topicclass .= ' pinned';
    }
    echo '<td class="'.$topicclass.'">';
    if (FORUM_DISCUSSION_PINNED == $post->pinned) {
        echo $OUTPUT->pix_icon('i/pinned', get_string('discussionpinned', 'forum'), 'mod_forum');
    }
    $canalwaysseetimedpost = $USER->id == $post->userid || $canviewhiddentimedposts;
    if ($timeddiscussion && $canalwaysseetimedpost) {
        echo $PAGE->get_renderer('mod_forum')->timed_discussion_tooltip($post, empty($timedoutsidewindow));
    }

echo '<a href="'.$CFG->wwwroot.'/mod/forum/discuss.php?d='.$post->discussion.'">'.$post->subject.'</a>';
    echo "</td>\n";

// Picture
    $postuser = new stdClass();
    $postuserfields = explode(',', user_picture::fields());
    $postuser = username_load_fields_from_object($postuser, $post, null, $postuserfields);
    $postuser->id = $post->userid;
    echo '<td class="author">';
    echo '<div class="media">';
    echo '<span class="float-left">';
    echo $OUTPUT->user_picture($postuser, array('courseid'=>$forum->course));
    echo '</span>';
    // User name
    echo '<div class="media-body">';
    $fullname = fullname($postuser, $canviewfullnames);
    echo '<a href="'.$CFG->wwwroot.'/user/view.php?id='.$post->userid.'&course='.$forum->course.'">'.$fullname.'</a>';
    echo '</div>';
    echo '</div>';
    echo "</td>\n";

// Group picture
    if ($group !== -1) {  // Groups are active - group is a group data object or NULL
        echo '<td class="picture group">';
        if (!empty($group->picture) and empty($group->hidepicture)) {
            if ($canviewparticipants && $COURSE->groupmode) {
                $picturelink = true;
            } else {
                $picturelink = false;
            }
            print_group_picture($group, $forum->course, false, false, $picturelink);
        } else if (isset($group->id)) {
            if ($canviewparticipants && $COURSE->groupmode) {
                echo '<a href="'.$CFG->wwwroot.'/user/index.php?id='.$forum->course.'&group='.$group->id.'">'.$group->name.'</a>';
            } else {
                echo $group->name;
            }
        }
        echo "</td>\n";
    }

if (has_capability('mod/forum:viewdiscussion', $modcontext)) {   // Show the column with replies
        echo '<td class="replies">';
        echo '<a href="'.$CFG->wwwroot.'/mod/forum/discuss.php?d='.$post->discussion.'">';
        echo $post->replies.'</a>';
        echo "</td>\n";

if ($cantrack) {
            echo '<td class="replies">';
            if ($forumtracked) {
                if ($post->unread > 0) {
                    echo '<span class="unread">';
                    echo '<a href="'.$CFG->wwwroot.'/mod/forum/discuss.php?d='.$post->discussion.'#unread">';
                    echo $post->unread;
                    echo '</a>';
                    echo '<a title="'.$strmarkalldread.'" href="'.$CFG->wwwroot.'/mod/forum/markposts.php?f='.
                         $forum->id.'&d='.$post->discussion.'&mark=read&return=/mod/forum/view.php&sesskey=' .
                         sesskey() . '">' . $OUTPUT->pix_icon('t/markasread', $strmarkalldread) . '</a>';
                    echo '</span>';
                } else {
                    echo '<span class="read">';
                    echo $post->unread;
                    echo '</span>';
                }
            } else {
                echo '<span class="read">';
                echo '-';
                echo '</span>';
            }
            echo "</td>\n";
        }
    }

echo '<td class="lastpost">';
    $usedate = (empty($post->timemodified)) ? $post->created : $post->timemodified;
    $parenturl = '';
    $usermodified = new stdClass();
    $usermodified->id = $post->usermodified;
    $usermodified = username_load_fields_from_object($usermodified, $post, 'um');

// In QA forums we check that the user can view participants.
    if ($forum->type !== 'qanda' || $canviewparticipants) {
        echo '<a href="'.$CFG->wwwroot.'/user/view.php?id='.$post->usermodified.'&course='.$forum->course.'">'.
             fullname($usermodified, $canviewfullnames).'</a><br />';
        $parenturl = (empty($post->lastpostid)) ? '' : '&parent='.$post->lastpostid;
    }

echo '<a href="'.$CFG->wwwroot.'/mod/forum/discuss.php?d='.$post->discussion.$parenturl.'">'.
          userdate_htmltime($usedate, $datestring).'</a>';
    echo "</td>\n";

// is_guest should be used here as this also checks whether the user is a guest in the current course.
    // Guests and visitors cannot subscribe - only enrolled users.
    if ((!is_guest($modcontext, $USER) && isloggedin()) && has_capability('mod/forum:viewdiscussion', $modcontext)) {
        // Discussion subscription.
        if (\mod_forum\subscriptions::is_subscribable($forum)) {
            echo '<td class="discussionsubscription">';
            echo forum_get_discussion_subscription_icon($forum, $post->discussion);
            echo '</td>';
        }
    }

echo "</tr>\n\n";

}

/**
 * Return the markup for the discussion subscription toggling icon.
 *
 * @param stdClass $forum The forum object.
 * @param int $discussionid The discussion to create an icon for.
 * @return string The generated markup.
 */
function forum_get_discussion_subscription_icon($forum, $discussionid, $returnurl = null, $includetext = false) {
    global $USER, $OUTPUT, $PAGE;

if ($returnurl === null && $PAGE->url) {
        $returnurl = $PAGE->url->out();
    }

$o = '';
    $subscriptionstatus = \mod_forum\subscriptions::is_subscribed($USER->id, $forum, $discussionid);
    $subscriptionlink = new moodle_url('/mod/forum/subscribe.php', array(
        'sesskey' => sesskey(),
        'id' => $forum->id,
        'd' => $discussionid,
        'returnurl' => $returnurl,
    ));

if ($includetext) {
        $o .= $subscriptionstatus ? get_string('subscribed', 'mod_forum') : get_string('notsubscribed', 'mod_forum');
    }

if ($subscriptionstatus) {
        $output = $OUTPUT->pix_icon('t/subscribed', get_string('clicktounsubscribe', 'forum'), 'mod_forum');
        if ($includetext) {
            $output .= get_string('subscribed', 'mod_forum');
        }

return html_writer::link($subscriptionlink, $output, array(
                'title' => get_string('clicktounsubscribe', 'forum'),
                'class' => 'discussiontoggle iconsmall',
                'data-forumid' => $forum->id,
                'data-discussionid' => $discussionid,
                'data-includetext' => $includetext,
            ));

} else {
        $output = $OUTPUT->pix_icon('t/unsubscribed', get_string('clicktosubscribe', 'forum'), 'mod_forum');
        if ($includetext) {
            $output .= get_string('notsubscribed', 'mod_forum');
        }

return html_writer::link($subscriptionlink, $output, array(
                'title' => get_string('clicktosubscribe', 'forum'),
                'class' => 'discussiontoggle iconsmall',
                'data-forumid' => $forum->id,
                'data-discussionid' => $discussionid,
                'data-includetext' => $includetext,
            ));
    }
}

/**
 * Return a pair of spans containing classes to allow the subscribe and
 * unsubscribe icons to be pre-loaded by a browser.
 *
 * @return string The generated markup
 */
function forum_get_discussion_subscription_icon_preloaders() {
    $o = '';
    $o .= html_writer::span(' ', 'preload-subscribe');
    $o .= html_writer::span(' ', 'preload-unsubscribe');
    return $o;
}

/**
 * Print the drop down that allows the user to select how they want to have
 * the discussion displayed.
 *
 * @param int $id forum id if $forumtype is 'single',
 *              discussion id for any other forum type
 * @param mixed $mode forum layout mode
 * @param string $forumtype optional
 */
function forum_print_mode_form($id, $mode, $forumtype='') {
    global $OUTPUT;
    if ($forumtype == 'single') {
        $select = new single_select(new moodle_url("/mod/forum/view.php", array('f'=>$id)), 'mode', forum_get_layout_modes(), $mode, null, "mode");
        $select->set_label(get_string('displaymode', 'forum'), array('class' => 'accesshide'));
        $select->class = "forummode";
    } else {
        $select = new single_select(new moodle_url("/mod/forum/discuss.php", array('d'=>$id)), 'mode', forum_get_layout_modes(), $mode, null, "mode");
        $select->set_label(get_string('displaymode', 'forum'), array('class' => 'accesshide'));
    }
    echo $OUTPUT->render($select);
}

/**
 * @global object
 * @param object $course
 * @param string $search
 * @return string
 */
function forum_search_form($course, $search='') {
    global $CFG, $PAGE;
    $forumsearch = new \mod_forum\output\quick_search_form($course->id, $search);
    $output = $PAGE->get_renderer('mod_forum');
    return $output->render($forumsearch);
}

/**
 * @global object
 * @global object
 */
function forum_set_return() {
    global $CFG, $SESSION;

if (! isset($SESSION->fromdiscussion)) {
        $referer = get_local_referer(false);
        // If the referer is NOT a login screen then save it.
        if (! strncasecmp("$CFG->wwwroot/login", $referer, 300)) {
            $SESSION->fromdiscussion = $referer;
        }
    }
}

/**
 * @global object
 * @param string|\moodle_url $default
 * @return string
 */
function forum_go_back_to($default) {
    global $SESSION;

if (!empty($SESSION->fromdiscussion)) {
        $returnto = $SESSION->fromdiscussion;
        unset($SESSION->fromdiscussion);
        return $returnto;
    } else {
        return $default;
    }
}

/**
 * Given a discussion object that is being moved to $forumto,
 * this function checks all posts in that discussion
 * for attachments, and if any are found, these are
 * moved to the new forum directory.
 *
 * @global object
 * @param object $discussion
 * @param int $forumfrom source forum id
 * @param int $forumto target forum id
 * @return bool success
 */
function forum_move_attachments($discussion, $forumfrom, $forumto) {
    global $DB;

$fs = get_file_storage();

$newcm = get_coursemodule_from_instance('forum', $forumto);
    $oldcm = get_coursemodule_from_instance('forum', $forumfrom);

$newcontext = context_module::instance($newcm->id);
    $oldcontext = context_module::instance($oldcm->id);

// loop through all posts, better not use attachment flag ;-)
    if ($posts = $DB->get_records('forum_posts', array('discussion'=>$discussion->id), '', 'id, attachment')) {
        foreach ($posts as $post) {
            $fs->move_area_files_to_new_context($oldcontext->id,
                    $newcontext->id, 'mod_forum', 'post', $post->id);
            $attachmentsmoved = $fs->move_area_files_to_new_context($oldcontext->id,
                    $newcontext->id, 'mod_forum', 'attachment', $post->id);
            if ($attachmentsmoved > 0 && $post->attachment != '1') {
                // Weird - let's fix it
                $post->attachment = '1';
                $DB->update_record('forum_posts', $post);
            } else if ($attachmentsmoved == 0 && $post->attachment != '') {
                // Weird - let's fix it
                $post->attachment = '';
                $DB->update_record('forum_posts', $post);
            }
        }
    }

return true;
}

/**
 * Returns attachments as formated text/html optionally with separate images
 *
 * @global object
 * @global object
 * @global object
 * @param object $post
 * @param object $cm
 * @param string $type html/text/separateimages
 * @return mixed string or array of (html text withouth images and image HTML)
 */
function forum_print_attachments($post, $cm, $type) {
    global $CFG, $DB, $USER, $OUTPUT;

if (empty($post->attachment)) {
        return $type !== 'separateimages' ? '' : array('', '');
    }

if (!in_array($type, array('separateimages', 'html', 'text'))) {
        return $type !== 'separateimages' ? '' : array('', '');
    }

if (!$context = context_module::instance($cm->id)) {
        return $type !== 'separateimages' ? '' : array('', '');
    }
    $strattachment = get_string('attachment', 'forum');

$fs = get_file_storage();

$imagereturn = '';
    $output = '';

$canexport = !empty($CFG->enableportfolios) && (has_capability('mod/forum:exportpost', $context) || ($post->userid == $USER->id && has_capability('mod/forum:exportownpost', $context)));

if ($canexport) {
        require_once($CFG->libdir.'/portfoliolib.php');
    }

// We retrieve all files according to the time that they were created.  In the case that several files were uploaded
    // at the sametime (e.g. in the case of drag/drop upload) we revert to using the filename.
    $files = $fs->get_area_files($context->id, 'mod_forum', 'attachment', $post->id, "filename", false);
    if ($files) {
        if ($canexport) {
            $button = new portfolio_add_button();
        }
        foreach ($files as $file) {
            $filename = $file->get_filename();
            $mimetype = $file->get_mimetype();
            $iconimage = $OUTPUT->pix_icon(file_file_icon($file), get_mimetype_description($file), 'moodle', array('class' => 'icon'));
            $path = file_encode_url($CFG->wwwroot.'/pluginfile.php', '/'.$context->id.'/mod_forum/attachment/'.$post->id.'/'.$filename);

if ($type == 'html') {
                $output .= "<a href=\"$path\">$iconimage</a> ";
                $output .= "<a href=\"$path\">".s($filename)."</a>";
                if ($canexport) {
                    $button->set_callback_options('forum_portfolio_caller', array('postid' => $post->id, 'attachment' => $file->get_id()), 'mod_forum');
                    $button->set_format_by_file($file);
                    $output .= $button->to_html(PORTFOLIO_ADD_ICON_LINK);
                }
                $output .= "<br />";

} else if ($type == 'text') {
                $output .= "$strattachment ".s($filename).":\n$path\n";

} else { //'returnimages'
                if (in_array($mimetype, array('image/gif', 'image/jpeg', 'image/png'))) {
                    // Image attachments don't get printed as links
                    $imagereturn .= "<br /><img src=\"$path\" alt=\"\" />";
                    if ($canexport) {
                        $button->set_callback_options('forum_portfolio_caller', array('postid' => $post->id, 'attachment' => $file->get_id()), 'mod_forum');
                        $button->set_format_by_file($file);
                        $imagereturn .= $button->to_html(PORTFOLIO_ADD_ICON_LINK);
                    }
                } else {
                    $output .= "<a href=\"$path\">$iconimage</a> ";
                    $output .= format_text("<a href=\"$path\">".s($filename)."</a>", FORMAT_HTML, array('context'=>$context));
                    if ($canexport) {
                        $button->set_callback_options('forum_portfolio_caller', array('postid' => $post->id, 'attachment' => $file->get_id()), 'mod_forum');
                        $button->set_format_by_file($file);
                        $output .= $button->to_html(PORTFOLIO_ADD_ICON_LINK);
                    }
                    $output .= '<br />';
                }
            }

if (!empty($CFG->enableplagiarism)) {
                require_once($CFG->libdir.'/plagiarismlib.php');
                $output .= plagiarism_get_links(array('userid' => $post->userid,
                    'file' => $file,
                    'cmid' => $cm->id,
                    'course' => $cm->course,
                    'forum' => $cm->instance));
                $output .= '<br />';
            }
        }
    }

if ($type !== 'separateimages') {
        return $output;

} else {
        return array($output, $imagereturn);
    }
}

////////////////////////////////////////////////////////////////////////////////
// File API                                                                   //
////////////////////////////////////////////////////////////////////////////////

/**
 * Lists all browsable file areas
 *
 * @package  mod_forum
 * @category files
 * @param stdClass $course course object
 * @param stdClass $cm course module object
 * @param stdClass $context context object
 * @return array
 */
function forum_get_file_areas($course, $cm, $context) {
    return array(
        'attachment' => get_string('areaattachment', 'mod_forum'),
        'post' => get_string('areapost', 'mod_forum'),
    );
}

/**
 * File browsing support for forum module.
 *
 * @package  mod_forum
 * @category files
 * @param stdClass $browser file browser object
 * @param stdClass $areas file areas
 * @param stdClass $course course object
 * @param stdClass $cm course module
 * @param stdClass $context context module
 * @param string $filearea file area
 * @param int $itemid item ID
 * @param string $filepath file path
 * @param string $filename file name
 * @return file_info instance or null if not found
 */
function forum_get_file_info($browser, $areas, $course, $cm, $context, $filearea, $itemid, $filepath, $filename) {
    global $CFG, $DB, $USER;

if ($context->contextlevel != CONTEXT_MODULE) {
        return null;
    }

// filearea must contain a real area
    if (!isset($areas[$filearea])) {
        return null;
    }

// Note that forum_user_can_see_post() additionally allows access for parent roles
    // and it explicitly checks qanda forum type, too. One day, when we stop requiring
    // course:managefiles, we will need to extend this.
    if (!has_capability('mod/forum:viewdiscussion', $context)) {
        return null;
    }

if (is_null($itemid)) {
        require_once($CFG->dirroot.'/mod/forum/locallib.php');
        return new forum_file_info_container($browser, $course, $cm, $context, $areas, $filearea);
    }

static $cached = array();
    // $cached will store last retrieved post, discussion and forum. To make sure that the cache
    // is cleared between unit tests we check if this is the same session
    if (!isset($cached['sesskey']) || $cached['sesskey'] != sesskey()) {
        $cached = array('sesskey' => sesskey());
    }

if (isset($cached['post']) && $cached['post']->id == $itemid) {
        $post = $cached['post'];
    } else if ($post = $DB->get_record('forum_posts', array('id' => $itemid))) {
        $cached['post'] = $post;
    } else {
        return null;
    }

if (isset($cached['discussion']) && $cached['discussion']->id == $post->discussion) {
        $discussion = $cached['discussion'];
    } else if ($discussion = $DB->get_record('forum_discussions', array('id' => $post->discussion))) {
        $cached['discussion'] = $discussion;
    } else {
        return null;
    }

if (isset($cached['forum']) && $cached['forum']->id == $cm->instance) {
        $forum = $cached['forum'];
    } else if ($forum = $DB->get_record('forum', array('id' => $cm->instance))) {
        $cached['forum'] = $forum;
    } else {
        return null;
    }

$fs = get_file_storage();
    $filepath = is_null($filepath) ? '/' : $filepath;
    $filename = is_null($filename) ? '.' : $filename;
    if (!($storedfile = $fs->get_file($context->id, 'mod_forum', $filearea, $itemid, $filepath, $filename))) {
        return null;
    }

// Checks to see if the user can manage files or is the owner.
    // TODO MDL-33805 - Do not use userid here and move the capability check above.
    if (!has_capability('moodle/course:managefiles', $context) && $storedfile->get_userid() != $USER->id) {
        return null;
    }
    // Make sure groups allow this user to see this file
    if ($discussion->groupid > 0 && !has_capability('moodle/site:accessallgroups', $context)) {
        $groupmode = groups_get_activity_groupmode($cm, $course);
        if ($groupmode == SEPARATEGROUPS && !groups_is_member($discussion->groupid)) {
            return null;
        }
    }

// Make sure we're allowed to see it...
    if (!forum_user_can_see_post($forum, $discussion, $post, NULL, $cm)) {
        return null;
    }

$urlbase = $CFG->wwwroot.'/pluginfile.php';
    return new file_info_stored($browser, $context, $storedfile, $urlbase, $itemid, true, true, false, false);
}

/**
 * Serves the forum attachments. Implements needed access control ;-)
 *
 * @package  mod_forum
 * @category files
 * @param stdClass $course course object
 * @param stdClass $cm course module object
 * @param stdClass $context context object
 * @param string $filearea file area
 * @param array $args extra arguments
 * @param bool $forcedownload whether or not force download
 * @param array $options additional options affecting the file serving
 * @return bool false if file not found, does not return if found - justsend the file
 */
function forum_pluginfile($course, $cm, $context, $filearea, $args, $forcedownload, array $options=array()) {
    global $CFG, $DB;

if ($context->contextlevel != CONTEXT_MODULE) {
        return false;
    }

require_course_login($course, true, $cm);

$areas = forum_get_file_areas($course, $cm, $context);

// filearea must contain a real area
    if (!isset($areas[$filearea])) {
        return false;
    }

$postid = (int)array_shift($args);

if (!$post = $DB->get_record('forum_posts', array('id'=>$postid))) {
        return false;
    }

if (!$discussion = $DB->get_record('forum_discussions', array('id'=>$post->discussion))) {
        return false;
    }

if (!$forum = $DB->get_record('forum', array('id'=>$cm->instance))) {
        return false;
    }

$fs = get_file_storage();
    $relativepath = implode('/', $args);
    $fullpath = "/$context->id/mod_forum/$filearea/$postid/$relativepath";
    if (!$file = $fs->get_file_by_hash(sha1($fullpath)) or $file->is_directory()) {
        return false;
    }

// Make sure groups allow this user to see this file
    if ($discussion->groupid > 0) {
        $groupmode = groups_get_activity_groupmode($cm, $course);
        if ($groupmode == SEPARATEGROUPS) {
            if (!groups_is_member($discussion->groupid) and !has_capability('moodle/site:accessallgroups', $context)) {
                return false;
            }
        }
    }

// Make sure we're allowed to see it...
    if (!forum_user_can_see_post($forum, $discussion, $post, NULL, $cm)) {
        return false;
    }

// finally send the file
    send_stored_file($file, 0, 0, true, $options); // download MUST be forced - security!
}

/**
 * If successful, this function returns the name of the file
 *
 * @global object
 * @param object $post is a full post record, including course and forum
 * @param object $forum
 * @param object $cm
 * @param mixed $mform
 * @param string $unused
 * @return bool
 */
function forum_add_attachment($post, $forum, $cm, $mform=null, $unused=null) {
    global $DB;

if (empty($mform)) {
        return false;
    }

if (empty($post->attachments)) {
        return true;   // Nothing to do
    }

$context = context_module::instance($cm->id);

$info = file_get_draft_area_info($post->attachments);
    $present = ($info['filecount']>0) ? '1' : '';
    file_save_draft_area_files($post->attachments, $context->id, 'mod_forum', 'attachment', $post->id,
            mod_forum_post_form::attachment_options($forum));

$DB->set_field('forum_posts', 'attachment', $present, array('id'=>$post->id));

return true;
}

/**
 * Add a new post in an existing discussion.
 *
 * @param   stdClass    $post       The post data
 * @param   mixed       $mform      The submitted form
 * @param   string      $unused
 * @return int
 */
function forum_add_new_post($post, $mform, $unused = null) {
    global $USER, $DB;

$discussion = $DB->get_record('forum_discussions', array('id' => $post->discussion));
    $forum      = $DB->get_record('forum', array('id' => $discussion->forum));
    $cm         = get_coursemodule_from_instance('forum', $forum->id);
    $context    = context_module::instance($cm->id);
    $privatereplyto = 0;

// Check whether private replies should be enabled for this post.
    if ($post->parent) {
        $parent = $DB->get_record('forum_posts', array('id' => $post->parent));

if (!empty($parent->privatereplyto)) {
            throw new \coding_exception('It should not be possible to reply to a private reply');
        }

if (!empty($post->isprivatereply) && forum_user_can_reply_privately($context, $parent)) {
            $privatereplyto = $parent->userid;
        }
    }

$post->created    = $post->modified = time();
    $post->mailed     = FORUM_MAILED_PENDING;
    $post->userid     = $USER->id;
    $post->privatereplyto = $privatereplyto;
    $post->attachment = "";
    if (!isset($post->totalscore)) {
        $post->totalscore = 0;
    }
    if (!isset($post->mailnow)) {
        $post->mailnow    = 0;
    }

$post->id = $DB->insert_record("forum_posts", $post);
    $post->message = file_save_draft_area_files($post->itemid, $context->id, 'mod_forum', 'post', $post->id,
            mod_forum_post_form::editor_options($context, null), $post->message);
    $DB->set_field('forum_posts', 'message', $post->message, array('id'=>$post->id));
    forum_add_attachment($post, $forum, $cm, $mform);

// Update discussion modified date
    $DB->set_field("forum_discussions", "timemodified", $post->modified, array("id" => $post->discussion));
    $DB->set_field("forum_discussions", "usermodified", $post->userid, array("id" => $post->discussion));

if (forum_tp_can_track_forums($forum) && forum_tp_is_tracked($forum)) {
        forum_tp_mark_post_read($post->userid, $post);
    }

if (isset($post->tags)) {
        core_tag_tag::set_item_tags('mod_forum', 'forum_posts', $post->id, $context, $post->tags);
    }

// Let Moodle know that assessable content is uploaded (eg for plagiarism detection)
    forum_trigger_content_uploaded_event($post, $cm, 'forum_add_new_post');

return $post->id;
}

/**
 * Update a post.
 *
 * @param   stdClass    $newpost    The post to update
 * @param   mixed       $mform      The submitted form
 * @param   string      $unused
 * @return  bool
 */
function forum_update_post($newpost, $mform, $unused = null) {
    global $DB, $USER;

$post       = $DB->get_record('forum_posts', array('id' => $newpost->id));
    $discussion = $DB->get_record('forum_discussions', array('id' => $post->discussion));
    $forum      = $DB->get_record('forum', array('id' => $discussion->forum));
    $cm         = get_coursemodule_from_instance('forum', $forum->id);
    $context    = context_module::instance($cm->id);

// Allowed modifiable fields.
    $modifiablefields = [
        'subject',
        'message',
        'messageformat',
        'messagetrust',
        'timestart',
        'timeend',
        'pinned',
        'attachments',
    ];
    foreach ($modifiablefields as $field) {
        if (isset($newpost->{$field})) {
            $post->{$field} = $newpost->{$field};
        }
    }
    $post->modified = time();

if (!$post->parent) {   // Post is a discussion starter - update discussion title and times too
        $discussion->name      = $post->subject;
        $discussion->timestart = $post->timestart;
        $discussion->timeend   = $post->timeend;

if (isset($post->pinned)) {
            $discussion->pinned = $post->pinned;
        }
    }
    $post->message = file_save_draft_area_files($newpost->itemid, $context->id, 'mod_forum', 'post', $post->id,
            mod_forum_post_form::editor_options($context, $post->id), $post->message);
    $DB->update_record('forum_posts', $post);
    // Note: Discussion modified time/user are intentionally not updated, to enable them to track the latest new post.
    $DB->update_record('forum_discussions', $discussion);

forum_add_attachment($post, $forum, $cm, $mform);

if (isset($newpost->tags)) {
        core_tag_tag::set_item_tags('mod_forum', 'forum_posts', $post->id, $context, $newpost->tags);
    }

if (forum_tp_can_track_forums($forum) && forum_tp_is_tracked($forum)) {
        forum_tp_mark_post_read($USER->id, $post);
    }

// Let Moodle know that assessable content is uploaded (eg for plagiarism detection)
    forum_trigger_content_uploaded_event($post, $cm, 'forum_update_post');

return true;
}

/**
 * Given an object containing all the necessary data,
 * create a new discussion and return the id
 *
 * @param object $post
 * @param mixed $mform
 * @param string $unused
 * @param int $userid
 * @return object
 */
function forum_add_discussion($discussion, $mform=null, $unused=null, $userid=null) {
    global $USER, $CFG, $DB;

$timenow = isset($discussion->timenow) ? $discussion->timenow : time();

if (is_null($userid)) {
        $userid = $USER->id;
    }

// The first post is stored as a real post, and linked
    // to from the discuss entry.

$forum = $DB->get_record('forum', array('id'=>$discussion->forum));
    $cm    = get_coursemodule_from_instance('forum', $forum->id);

$post = new stdClass();
    $post->discussion    = 0;
    $post->parent        = 0;
    $post->privatereplyto = 0;
    $post->userid        = $userid;
    $post->created       = $timenow;
    $post->modified      = $timenow;
    $post->mailed        = FORUM_MAILED_PENDING;
    $post->subject       = $discussion->name;
    $post->message       = $discussion->message;
    $post->messageformat = $discussion->messageformat;
    $post->messagetrust  = $discussion->messagetrust;
    $post->attachments   = isset($discussion->attachments) ? $discussion->attachments : null;
    $post->forum         = $forum->id;     // speedup
    $post->course        = $forum->course; // speedup
    $post->mailnow       = $discussion->mailnow;

$post->id = $DB->insert_record("forum_posts", $post);

// TODO: Fix the calling code so that there always is a $cm when this function is called
    if (!empty($cm->id) && !empty($discussion->itemid)) {   // In "single simple discussions" this may not exist yet
        $context = context_module::instance($cm->id);
        $text = file_save_draft_area_files($discussion->itemid, $context->id, 'mod_forum', 'post', $post->id,
                mod_forum_post_form::editor_options($context, null), $post->message);
        $DB->set_field('forum_posts', 'message', $text, array('id'=>$post->id));
    }

// Now do the main entry for the discussion, linking to this first post

$discussion->firstpost    = $post->id;
    $discussion->timemodified = $timenow;
    $discussion->usermodified = $post->userid;
    $discussion->userid       = $userid;
    $discussion->assessed     = 0;

$post->discussion = $DB->insert_record("forum_discussions", $discussion);

// Finally, set the pointer on the post.
    $DB->set_field("forum_posts", "discussion", $post->discussion, array("id"=>$post->id));

if (!empty($cm->id)) {
        forum_add_attachment($post, $forum, $cm, $mform, $unused);
    }

if (isset($discussion->tags)) {
        core_tag_tag::set_item_tags('mod_forum', 'forum_posts', $post->id, context_module::instance($cm->id), $discussion->tags);
    }

if (forum_tp_can_track_forums($forum) && forum_tp_is_tracked($forum)) {
        forum_tp_mark_post_read($post->userid, $post);
    }

// Let Moodle know that assessable content is uploaded (eg for plagiarism detection)
    if (!empty($cm->id)) {
        forum_trigger_content_uploaded_event($post, $cm, 'forum_add_discussion');
    }

return $post->discussion;
}

/**
 * Deletes a discussion and handles all associated cleanup.
 *
 * @global object
 * @param object $discussion Discussion to delete
 * @param bool $fulldelete True when deleting entire forum
 * @param object $course Course
 * @param object $cm Course-module
 * @param object $forum Forum
 * @return bool
 */
function forum_delete_discussion($discussion, $fulldelete, $course, $cm, $forum) {
    global $DB, $CFG;
    require_once($CFG->libdir.'/completionlib.php');

$result = true;

if ($posts = $DB->get_records("forum_posts", array("discussion" => $discussion->id))) {
        foreach ($posts as $post) {
            $post->course = $discussion->course;
            $post->forum  = $discussion->forum;
            if (!forum_delete_post($post, 'ignore', $course, $cm, $forum, $fulldelete)) {
                $result = false;
            }
        }
    }

forum_tp_delete_read_records(-1, -1, $discussion->id);

// Discussion subscriptions must be removed before discussions because of key constraints.
    $DB->delete_records('forum_discussion_subs', array('discussion' => $discussion->id));
    if (!$DB->delete_records("forum_discussions", array("id" => $discussion->id))) {
        $result = false;
    }

// Update completion state if we are tracking completion based on number of posts
    // But don't bother when deleting whole thing
    if (!$fulldelete) {
        $completion = new completion_info($course);
        if ($completion->is_enabled($cm) == COMPLETION_TRACKING_AUTOMATIC &&
           ($forum->completiondiscussions || $forum->completionreplies || $forum->completionposts)) {
            $completion->update_state($cm, COMPLETION_INCOMPLETE, $discussion->userid);
        }
    }

return $result;
}

/**
 * Deletes a single forum post.
 *
 * @global object
 * @param object $post Forum post object
 * @param mixed $children Whether to delete children. If false, returns false
 *   if there are any children (without deleting the post). If true,
 *   recursively deletes all children. If set to special value 'ignore', deletes
 *   post regardless of children (this is for use only when deleting all posts
 *   in a disussion).
 * @param object $course Course
 * @param object $cm Course-module
 * @param object $forum Forum
 * @param bool $skipcompletion True to skip updating completion state if it
 *   would otherwise be updated, i.e. when deleting entire forum anyway.
 * @return bool
 */
function forum_delete_post($post, $children, $course, $cm, $forum, $skipcompletion=false) {
    global $DB, $CFG, $USER;
    require_once($CFG->libdir.'/completionlib.php');

$context = context_module::instance($cm->id);

if ($children !== 'ignore' && ($childposts = $DB->get_records('forum_posts', array('parent'=>$post->id)))) {
       if ($children) {
           foreach ($childposts as $childpost) {
               forum_delete_post($childpost, true, $course, $cm, $forum, $skipcompletion);
           }
       } else {
           return false;
       }
    }

// Delete ratings.
    require_once($CFG->dirroot.'/rating/lib.php');
    $delopt = new stdClass;
    $delopt->contextid = $context->id;
    $delopt->component = 'mod_forum';
    $delopt->ratingarea = 'post';
    $delopt->itemid = $post->id;
    $rm = new rating_manager();
    $rm->delete_ratings($delopt);

// Delete attachments.
    $fs = get_file_storage();
    $fs->delete_area_files($context->id, 'mod_forum', 'attachment', $post->id);
    $fs->delete_area_files($context->id, 'mod_forum', 'post', $post->id);

// Delete cached RSS feeds.
    if (!empty($CFG->enablerssfeeds)) {
        require_once($CFG->dirroot.'/mod/forum/rsslib.php');
        forum_rss_delete_file($forum);
    }

if ($DB->delete_records("forum_posts", array("id" => $post->id))) {

forum_tp_delete_read_records(-1, $post->id);

// Just in case we are deleting the last post
        forum_discussion_update_last_post($post->discussion);

// Update completion state if we are tracking completion based on number of posts
        // But don't bother when deleting whole thing

if (!$skipcompletion) {
            $completion = new completion_info($course);
            if ($completion->is_enabled($cm) == COMPLETION_TRACKING_AUTOMATIC &&
               ($forum->completiondiscussions || $forum->completionreplies || $forum->completionposts)) {
                $completion->update_state($cm, COMPLETION_INCOMPLETE, $post->userid);
            }
        }

$params = array(
            'context' => $context,
            'objectid' => $post->id,
            'other' => array(
                'discussionid' => $post->discussion,
                'forumid' => $forum->id,
                'forumtype' => $forum->type,
            )
        );
        $post->deleted = 1;
        if ($post->userid !== $USER->id) {
            $params['relateduserid'] = $post->userid;
        }
        $event = \mod_forum\event\post_deleted::create($params);
        $event->add_record_snapshot('forum_posts', $post);
        $event->trigger();

return true;
    }
    return false;
}

/**
 * Sends post content to plagiarism plugin
 * @param object $post Forum post object
 * @param object $cm Course-module
 * @param string $name
 * @return bool
*/
function forum_trigger_content_uploaded_event($post, $cm, $name) {
    $context = context_module::instance($cm->id);
    $fs = get_file_storage();
    $files = $fs->get_area_files($context->id, 'mod_forum', 'attachment', $post->id, "timemodified", false);
    $params = array(
        'context' => $context,
        'objectid' => $post->id,
        'other' => array(
            'content' => $post->message,
            'pathnamehashes' => array_keys($files),
            'discussionid' => $post->discussion,
            'triggeredfrom' => $name,
        )
    );
    $event = \mod_forum\event\assessable_uploaded::create($params);
    $event->trigger();
    return true;
}

/**
 * Given a new post, subscribes or unsubscribes as appropriate.
 * Returns some text which describes what happened.
 *
 * @param object $fromform The submitted form
 * @param stdClass $forum The forum record
 * @param stdClass $discussion The forum discussion record
 * @return string
 */
function forum_post_subscription($fromform, $forum, $discussion) {
    global $USER;

if (\mod_forum\subscriptions::is_forcesubscribed($forum)) {
        return "";
    } else if (\mod_forum\subscriptions::subscription_disabled($forum)) {
        $subscribed = \mod_forum\subscriptions::is_subscribed($USER->id, $forum);
        if ($subscribed && !has_capability('moodle/course:manageactivities', context_course::instance($forum->course), $USER->id)) {
            // This user should not be subscribed to the forum.
            \mod_forum\subscriptions::unsubscribe_user($USER->id, $forum);
        }
        return "";
    }

$info = new stdClass();
    $info->name  = fullname($USER);
    $info->discussion = format_string($discussion->name);
    $info->forum = format_string($forum->name);

if (isset($fromform->discussionsubscribe) && $fromform->discussionsubscribe) {
        if ($result = \mod_forum\subscriptions::subscribe_user_to_discussion($USER->id, $discussion)) {
            return html_writer::tag('p', get_string('discussionnowsubscribed', 'forum', $info));
        }
    } else {
        if ($result = \mod_forum\subscriptions::unsubscribe_user_from_discussion($USER->id, $discussion)) {
            return html_writer::tag('p', get_string('discussionnownotsubscribed', 'forum', $info));
        }
    }

return '';
}

/**
 * Generate and return the subscribe or unsubscribe link for a forum.
 *
 * @param object $forum the forum. Fields used are $forum->id and $forum->forcesubscribe.
 * @param object $context the context object for this forum.
 * @param array $messages text used for the link in its various states
 *      (subscribed, unsubscribed, forcesubscribed or cantsubscribe).
 *      Any strings not passed in are taken from the $defaultmessages array
 *      at the top of the function.
 * @param bool $cantaccessagroup
 * @param bool $unused1
 * @param bool $backtoindex
 * @param array $unused2
 * @return string
 */
function forum_get_subscribe_link($forum, $context, $messages = array(), $cantaccessagroup = false, $unused1 = true,
    $backtoindex = false, $unused2 = null) {
    global $CFG, $USER, $PAGE, $OUTPUT;
    $defaultmessages = array(
        'subscribed' => get_string('unsubscribe', 'forum'),
        'unsubscribed' => get_string('subscribe', 'forum'),
        'cantaccessgroup' => get_string('no'),
        'forcesubscribed' => get_string('everyoneissubscribed', 'forum'),
        'cantsubscribe' => get_string('disallowsubscribe','forum')
    );
    $messages = $messages + $defaultmessages;

if (\mod_forum\subscriptions::is_forcesubscribed($forum)) {
        return $messages['forcesubscribed'];
    } else if (\mod_forum\subscriptions::subscription_disabled($forum) &&
            !has_capability('mod/forum:managesubscriptions', $context)) {
        return $messages['cantsubscribe'];
    } else if ($cantaccessagroup) {
        return $messages['cantaccessgroup'];
    } else {
        if (!is_enrolled($context, $USER, '', true)) {
            return '';
        }

$subscribed = \mod_forum\subscriptions::is_subscribed($USER->id, $forum);
        if ($subscribed) {
            $linktext = $messages['subscribed'];
            $linktitle = get_string('subscribestop', 'forum');
        } else {
            $linktext = $messages['unsubscribed'];
            $linktitle = get_string('subscribestart', 'forum');
        }

$options = array();
        if ($backtoindex) {
            $backtoindexlink = '&backtoindex=1';
            $options['backtoindex'] = 1;
        } else {
            $backtoindexlink = '';
        }

$options['id'] = $forum->id;
        $options['sesskey'] = sesskey();
        $url = new moodle_url('/mod/forum/subscribe.php', $options);
        return $OUTPUT->single_button($url, $linktext, 'get', array('title' => $linktitle));
    }
}

/**
 * Returns true if user created new discussion already.
 *
 * @param int $forumid  The forum to check for postings
 * @param int $userid   The user to check for postings
 * @param int $groupid  The group to restrict the check to
 * @return bool
 */
function forum_user_has_posted_discussion($forumid, $userid, $groupid = null) {
    global $CFG, $DB;

$sql = "SELECT 'x'
              FROM {forum_discussions} d, {forum_posts} p
             WHERE d.forum = ? AND p.discussion = d.id AND p.parent = 0 AND p.userid = ?";

$params = [$forumid, $userid];

if ($groupid) {
        $sql .= " AND d.groupid = ?";
        $params[] = $groupid;
    }

return $DB->record_exists_sql($sql, $params);
}

/**
 * @global object
 * @global object
 * @param int $forumid
 * @param int $userid
 * @return array
 */
function forum_discussions_user_has_posted_in($forumid, $userid) {
    global $CFG, $DB;

$haspostedsql = "SELECT d.id AS id,
                            d.*
                       FROM {forum_posts} p,
                            {forum_discussions} d
                      WHERE p.discussion = d.id
                        AND d.forum = ?
                        AND p.userid = ?";

return $DB->get_records_sql($haspostedsql, array($forumid, $userid));
}

/**
 * @global object
 * @global object
 * @param int $forumid
 * @param int $did
 * @param int $userid
 * @return bool
 */
function forum_user_has_posted($forumid, $did, $userid) {
    global $DB;

if (empty($did)) {
        // posted in any forum discussion?
        $sql = "SELECT 'x'
                  FROM {forum_posts} p
                  JOIN {forum_discussions} d ON d.id = p.discussion
                 WHERE p.userid = :userid AND d.forum = :forumid";
        return $DB->record_exists_sql($sql, array('forumid'=>$forumid,'userid'=>$userid));
    } else {
        return $DB->record_exists('forum_posts', array('discussion'=>$did,'userid'=>$userid));
    }
}

/**
 * Returns creation time of the first user's post in given discussion
 * @global object $DB
 * @param int $did Discussion id
 * @param int $userid User id
 * @return int|bool post creation time stamp or return false
 */
function forum_get_user_posted_time($did, $userid) {
    global $DB;

$posttime = $DB->get_field('forum_posts', 'MIN(created)', array('userid'=>$userid, 'discussion'=>$did));
    if (empty($posttime)) {
        return false;
    }
    return $posttime;
}

/**
 * @global object
 * @param object $forum
 * @param object $currentgroup
 * @param int $unused
 * @param object $cm
 * @param object $context
 * @return bool
 */
function forum_user_can_post_discussion($forum, $currentgroup=null, $unused=-1, $cm=NULL, $context=NULL) {
// $forum is an object
    global $USER;

// shortcut - guest and not-logged-in users can not post
    if (isguestuser() or !isloggedin()) {
        return false;
    }

if (!$cm) {
        debugging('missing cm', DEBUG_DEVELOPER);
        if (!$cm = get_coursemodule_from_instance('forum', $forum->id, $forum->course)) {
            print_error('invalidcoursemodule');
        }
    }

if (!$context) {
        $context = context_module::instance($cm->id);
    }

if (forum_is_cutoff_date_reached($forum)) {
        if (!has_capability('mod/forum:canoverridecutoff', $context)) {
            return false;
        }
    }

if ($currentgroup === null) {
        $currentgroup = groups_get_activity_group($cm);
    }

$groupmode = groups_get_activity_groupmode($cm);

if ($forum->type == 'news') {
        $capname = 'mod/forum:addnews';
    } else if ($forum->type == 'qanda') {
        $capname = 'mod/forum:addquestion';
    } else {
        $capname = 'mod/forum:startdiscussion';
    }

if (!has_capability($capname, $context)) {
        return false;
    }

if ($forum->type == 'single') {
        return false;
    }

if ($forum->type == 'eachuser') {
        if (forum_user_has_posted_discussion($forum->id, $USER->id, $currentgroup)) {
            return false;
        }
    }

if (!$groupmode or has_capability('moodle/site:accessallgroups', $context)) {
        return true;
    }

if ($currentgroup) {
        return groups_is_member($currentgroup);
    } else {
        // no group membership and no accessallgroups means no new discussions
        // reverted to 1.7 behaviour in 1.9+,  buggy in 1.8.0-1.9.0
        return false;
    }
}

/**
 * This function checks whether the user can reply to posts in a forum
 * discussion. Use forum_user_can_post_discussion() to check whether the user
 * can start discussions.
 *
 * @global object
 * @global object
 * @uses DEBUG_DEVELOPER
 * @uses CONTEXT_MODULE
 * @uses VISIBLEGROUPS
 * @param object $forum forum object
 * @param object $discussion
 * @param object $user
 * @param object $cm
 * @param object $course
 * @param object $context
 * @return bool
 */
function forum_user_can_post($forum, $discussion, $user=NULL, $cm=NULL, $course=NULL, $context=NULL) {
    global $USER, $DB;
    if (empty($user)) {
        $user = $USER;
    }

// shortcut - guest and not-logged-in users can not post
    if (isguestuser($user) or empty($user->id)) {
        return false;
    }

if (!isset($discussion->groupid)) {
        debugging('incorrect discussion parameter', DEBUG_DEVELOPER);
        return false;
    }

if (!$course) {
        debugging('missing course', DEBUG_DEVELOPER);
        if (!$course = $DB->get_record('course', array('id' => $forum->course))) {
            print_error('invalidcourseid');
        }
    }

if (!$context) {
        $context = context_module::instance($cm->id);
    }

if (forum_is_cutoff_date_reached($forum)) {
        if (!has_capability('mod/forum:canoverridecutoff', $context)) {
            return false;
        }
    }

// Check whether the discussion is locked.
    if (forum_discussion_is_locked($forum, $discussion)) {
        if (!has_capability('mod/forum:canoverridediscussionlock', $context)) {
            return false;
        }
    }

// normal users with temporary guest access can not post, suspended users can not post either
    if (!is_viewing($context, $user->id) and !is_enrolled($context, $user->id, '', true)) {
        return false;
    }

if ($forum->type == 'news') {
        $capname = 'mod/forum:replynews';
    } else {
        $capname = 'mod/forum:replypost';
    }

if (!has_capability($capname, $context, $user->id)) {
        return false;
    }

if (!$groupmode = groups_get_activity_groupmode($cm, $course)) {
        return true;
    }

if (has_capability('moodle/site:accessallgroups', $context)) {
        return true;
    }

if ($groupmode == VISIBLEGROUPS) {
        if ($discussion->groupid == -1) {
            // allow students to reply to all participants discussions - this was not possible in Moodle <1.8
            return true;
        }
        return groups_is_member($discussion->groupid);

} else {
        //separate groups
        if ($discussion->groupid == -1) {
            return false;
        }
        return groups_is_member($discussion->groupid);
    }
}

/**
* Check to ensure a user can view a timed discussion.
*
* @param object $discussion
* @param object $user
* @param object $context
* @return boolean returns true if they can view post, false otherwise
*/
function forum_user_can_see_timed_discussion($discussion, $user, $context) {
    global $CFG;

// Check that the user can view a discussion that is normally hidden due to access times.
    if (!empty($CFG->forum_enabletimedposts)) {
        $time = time();
        if (($discussion->timestart != 0 && $discussion->timestart > $time)
            || ($discussion->timeend != 0 && $discussion->timeend < $time)) {
            if (!has_capability('mod/forum:viewhiddentimedposts', $context, $user->id)) {
                return false;
            }
        }
    }

return true;
}

/**
* Check to ensure a user can view a group discussion.
*
* @param object $discussion
* @param object $cm
* @param object $context
* @return boolean returns true if they can view post, false otherwise
*/
function forum_user_can_see_group_discussion($discussion, $cm, $context) {

// If it's a grouped discussion, make sure the user is a member.
    if ($discussion->groupid > 0) {
        $groupmode = groups_get_activity_groupmode($cm);
        if ($groupmode == SEPARATEGROUPS) {
            return groups_is_member($discussion->groupid) || has_capability('moodle/site:accessallgroups', $context);
        }
    }

return true;
}

/**
 * @global object
 * @global object
 * @uses DEBUG_DEVELOPER
 * @param object $forum
 * @param object $discussion
 * @param object $context
 * @param object $user
 * @return bool
 */
function forum_user_can_see_discussion($forum, $discussion, $context, $user=NULL) {
    global $USER, $DB;

if (empty($user) || empty($user->id)) {
        $user = $USER;
    }

// retrieve objects (yuk)
    if (is_numeric($forum)) {
        debugging('missing full forum', DEBUG_DEVELOPER);
        if (!$forum = $DB->get_record('forum',array('id'=>$forum))) {
            return false;
        }
    }
    if (is_numeric($discussion)) {
        debugging('missing full discussion', DEBUG_DEVELOPER);
        if (!$discussion = $DB->get_record('forum_discussions',array('id'=>$discussion))) {
            return false;
        }
    }
    if (!$cm = get_coursemodule_from_instance('forum', $forum->id, $forum->course)) {
        print_error('invalidcoursemodule');
    }

if (!has_capability('mod/forum:viewdiscussion', $context)) {
        return false;
    }

if (!forum_user_can_see_timed_discussion($discussion, $user, $context)) {
        return false;
    }

if (!forum_user_can_see_group_discussion($discussion, $cm, $context)) {
        return false;
    }

return true;
}

/**
 * Check whether a user can see the specified post.
 *
 * @param   \stdClass $forum The forum to chcek
 * @param   \stdClass $discussion The discussion the post is in
 * @param   \stdClass $post The post in question
 * @param   \stdClass $user The user to test - if not specified, the current user is checked.
 * @param   \stdClass $cm The Course Module that the forum is in (required).
 * @param   bool      $checkdeleted Whether to check the deleted flag on the post.
 * @return  bool
 */
function forum_user_can_see_post($forum, $discussion, $post, $user = null, $cm = null, $checkdeleted = true) {
    global $CFG, $USER, $DB;

if (is_numeric($discussion)) {
        debugging('missing full discussion', DEBUG_DEVELOPER);
        if (!$discussion = $DB->get_record('forum_discussions',array('id'=>$discussion))) {
            return false;
        }
    }
    if (is_numeric($post)) {
        debugging('missing full post', DEBUG_DEVELOPER);
        if (!$post = $DB->get_record('forum_posts',array('id'=>$post))) {
            return false;
        }
    }

if (!isset($post->id) && isset($post->parent)) {
        $post->id = $post->parent;
    }

if ($checkdeleted && !empty($post->deleted)) {
        return false;
    }

// Context used throughout function.
    $modcontext = context_module::instance($cm->id);

if (empty($user) || empty($user->id)) {
        $user = $USER;
    }

$canviewdiscussion = (isset($cm->cache) && !empty($cm->cache->caps['mod/forum:viewdiscussion']))
        || has_capability('mod/forum:viewdiscussion', $modcontext, $user->id);
    if (!$canviewdiscussion && !has_all_capabilities(array('moodle/user:viewdetails', 'moodle/user:readuserposts'), context_user::instance($post->userid))) {
        return false;
    }

if (!forum_post_is_visible_privately($post, $cm)) {
        return false;
    }

if (isset($cm->uservisible)) {
        if (!$cm->uservisible) {
            return false;
        }
    } else {
        if (!\core_availability\info_module::is_user_visible($cm, $user->id, false)) {
            return false;
        }
    }

if (!forum_user_can_see_timed_discussion($discussion, $user, $modcontext)) {
        return false;
    }

if (!forum_user_can_see_group_discussion($discussion, $cm, $modcontext)) {
        return false;
    }

if ($forum->type == 'qanda') {
        if (has_capability('mod/forum:viewqandawithoutposting', $modcontext, $user->id) || $post->userid == $user->id
                || (isset($discussion->firstpost) && $discussion->firstpost == $post->id)) {
            return true;
        }
        $firstpost = forum_get_firstpost_from_discussion($discussion->id);
        if ($firstpost->userid == $user->id) {
            return true;
        }
        $userfirstpost = forum_get_user_posted_time($discussion->id, $user->id);
        return (($userfirstpost !== false && (time() - $userfirstpost >= $CFG->maxeditingtime)));
    }
    return true;
}

/**
 * Returns all forum posts since a given time in specified forum.
 *
 * @todo Document this functions args
 * @global object
 * @global object
 * @global object
 * @global object
 */
function forum_get_recent_mod_activity(&$activities, &$index, $timestart, $courseid, $cmid, $userid=0, $groupid=0)  {
    global $CFG, $COURSE, $USER, $DB;

if ($COURSE->id == $courseid) {
        $course = $COURSE;
    } else {
        $course = $DB->get_record('course', array('id' => $courseid));
    }

$modinfo = get_fast_modinfo($course);

$cm = $modinfo->cms[$cmid];
    $params = array($timestart, $cm->instance);

if ($userid) {
        $userselect = "AND u.id = ?";
        $params[] = $userid;
    } else {
        $userselect = "";
    }

if ($groupid) {
        $groupselect = "AND d.groupid = ?";
        $params[] = $groupid;
    } else {
        $groupselect = "";
    }

$allnames = get_all_user_name_fields(true, 'u');
    if (!$posts = $DB->get_records_sql("SELECT p.*, f.type AS forumtype, d.forum, d.groupid,
                                              d.timestart, d.timeend, d.userid AS duserid,
                                              $allnames, u.email, u.picture, u.imagealt, u.email
                                         FROM {forum_posts} p
                                              JOIN {forum_discussions} d ON d.id = p.discussion
                                              JOIN {forum} f             ON f.id = d.forum
                                              JOIN {user} u              ON u.id = p.userid
                                        WHERE p.created > ? AND f.id = ?
                                              $userselect $groupselect
                                     ORDER BY p.id ASC", $params)) { // order by initial posting date
         return;
    }

$groupmode       = groups_get_activity_groupmode($cm, $course);
    $cm_context      = context_module::instance($cm->id);
    $viewhiddentimed = has_capability('mod/forum:viewhiddentimedposts', $cm_context);
    $accessallgroups = has_capability('moodle/site:accessallgroups', $cm_context);

$printposts = array();
    foreach ($posts as $post) {

if (!empty($CFG->forum_enabletimedposts) and $USER->id != $post->duserid
          and (($post->timestart > 0 and $post->timestart > time()) or ($post->timeend > 0 and $post->timeend < time()))) {
            if (!$viewhiddentimed) {
                continue;
            }
        }

if ($groupmode) {
            if ($post->groupid == -1 or $groupmode == VISIBLEGROUPS or $accessallgroups) {
                // oki (Open discussions have groupid -1)
            } else {
                // separate mode
                if (isguestuser()) {
                    // shortcut
                    continue;
                }

if (!in_array($post->groupid, $modinfo->get_groups($cm->groupingid))) {
                    continue;
                }
            }
        }

$printposts[] = $post;
    }

if (!$printposts) {
        return;
    }

$aname = format_string($cm->name,true);

foreach ($printposts as $post) {
        $tmpactivity = new stdClass();

$tmpactivity->type         = 'forum';
        $tmpactivity->cmid         = $cm->id;
        $tmpactivity->name         = $aname;
        $tmpactivity->sectionnum   = $cm->sectionnum;
        $tmpactivity->timestamp    = $post->modified;

$tmpactivity->content = new stdClass();
        $tmpactivity->content->id         = $post->id;
        $tmpactivity->content->discussion = $post->discussion;
        $tmpactivity->content->subject    = format_string($post->subject);
        $tmpactivity->content->parent     = $post->parent;
        $tmpactivity->content->forumtype  = $post->forumtype;

$tmpactivity->user = new stdClass();
        $additionalfields = array('id' => 'userid', 'picture', 'imagealt', 'email');
        $additionalfields = explode(',', user_picture::fields());
        $tmpactivity->user = username_load_fields_from_object($tmpactivity->user, $post, null, $additionalfields);
        $tmpactivity->user->id = $post->userid;

$activities[$index++] = $tmpactivity;
    }

return;
}

/**
 * Outputs the forum post indicated by $activity.
 *
 * @param object $activity      the activity object the forum resides in
 * @param int    $courseid      the id of the course the forum resides in
 * @param bool   $detail        not used, but required for compatibilty with other modules
 * @param int    $modnames      not used, but required for compatibilty with other modules
 * @param bool   $viewfullnames not used, but required for compatibilty with other modules
 */
function forum_print_recent_mod_activity($activity, $courseid, $detail, $modnames, $viewfullnames) {
    global $OUTPUT;

$content = $activity->content;
    if ($content->parent) {
        $class = 'reply';
    } else {
        $class = 'discussion';
    }

$tableoptions = [
        'border' => '0',
        'cellpadding' => '3',
        'cellspacing' => '0',
        'class' => 'forum-recent'
    ];
    $output = html_writer::start_tag('table', $tableoptions);
    $output .= html_writer::start_tag('tr');

$post = (object) ['parent' => $content->parent];
    $forum = (object) ['type' => $content->forumtype];
    $authorhidden = forum_is_author_hidden($post, $forum);

// Show user picture if author should not be hidden.
    if (!$authorhidden) {
        $pictureoptions = [
            'courseid' => $courseid,
            'link' => $authorhidden,
            'alttext' => $authorhidden,
        ];
        $picture = $OUTPUT->user_picture($activity->user, $pictureoptions);
        $output .= html_writer::tag('td', $picture, ['class' => 'userpicture', 'valign' => 'top']);
    }

// Discussion title and author.
    $output .= html_writer::start_tag('td', ['class' => $class]);
    if ($content->parent) {
        $class = 'title';
    } else {
        // Bold the title of new discussions so they stand out.
        $class = 'title bold';
    }

$output .= html_writer::start_div($class);
    if ($detail) {
        $aname = s($activity->name);
        $output .= $OUTPUT->image_icon('icon', $aname, $activity->type);
    }
    $discussionurl = new moodle_url('/mod/forum/discuss.php', ['d' => $content->discussion]);
    $discussionurl->set_anchor('p' . $activity->content->id);
    $output .= html_writer::link($discussionurl, $content->subject);
    $output .= html_writer::end_div();

$timestamp = userdate_htmltime($activity->timestamp);
    if ($authorhidden) {
        $authornamedate = $timestamp;
    } else {
        $fullname = fullname($activity->user, $viewfullnames);
        $userurl = new moodle_url('/user/view.php');
        $userurl->params(['id' => $activity->user->id, 'course' => $courseid]);
        $by = new stdClass();
        $by->name = html_writer::link($userurl, $fullname);
        $by->date = $timestamp;
        $authornamedate = get_string('bynameondate', 'forum', $by);
    }
    $output .= html_writer::div($authornamedate, 'user');
    $output .= html_writer::end_tag('td');
    $output .= html_writer::end_tag('tr');
    $output .= html_writer::end_tag('table');

echo $output;
}

/**
 * recursively sets the discussion field to $discussionid on $postid and all its children
 * used when pruning a post
 *
 * @global object
 * @param int $postid
 * @param int $discussionid
 * @return bool
 */
function forum_change_discussionid($postid, $discussionid) {
    global $DB;
    $DB->set_field('forum_posts', 'discussion', $discussionid, array('id' => $postid));
    if ($posts = $DB->get_records('forum_posts', array('parent' => $postid))) {
        foreach ($posts as $post) {
            forum_change_discussionid($post->id, $discussionid);
        }
    }
    return true;
}

/**
 * Prints the editing button on subscribers page
 *
 * @global object
 * @global object
 * @param int $courseid
 * @param int $forumid
 * @return string
 */
function forum_update_subscriptions_button($courseid, $forumid) {
    global $CFG, $USER;

if (!empty($USER->subscriptionsediting)) {
        $string = get_string('managesubscriptionsoff', 'forum');
        $edit = "off";
    } else {
        $string = get_string('managesubscriptionson', 'forum');
        $edit = "on";
    }

$subscribers = html_writer::start_tag('form', array('action' => $CFG->wwwroot . '/mod/forum/subscribers.php',
        'method' => 'get', 'class' => 'form-inline'));
    $subscribers .= html_writer::empty_tag('input', array('type' => 'submit', 'value' => $string,
        'class' => 'btn btn-secondary'));
    $subscribers .= html_writer::empty_tag('input', array('type' => 'hidden', 'name' => 'id', 'value' => $forumid));
    $subscribers .= html_writer::empty_tag('input', array('type' => 'hidden', 'name' => 'edit', 'value' => $edit));
    $subscribers .= html_writer::end_tag('form');

return $subscribers;
}

// Functions to do with read tracking.

/**
 * Mark posts as read.
 *
 * @global object
 * @global object
 * @param object $user object
 * @param array $postids array of post ids
 * @return boolean success
 */
function forum_tp_mark_posts_read($user, $postids) {
    global $CFG, $DB;

if (!forum_tp_can_track_forums(false, $user)) {
        return true;
    }

$status = true;

$now = time();
    $cutoffdate = $now - ($CFG->forum_oldpostdays * 24 * 3600);

if (empty($postids)) {
        return true;

} else if (count($postids) > 200) {
        while ($part = array_splice($postids, 0, 200)) {
            $status = forum_tp_mark_posts_read($user, $part) && $status;
        }
        return $status;
    }

list($usql, $postidparams) = $DB->get_in_or_equal($postids, SQL_PARAMS_NAMED, 'postid');

$insertparams = array(
        'userid1' => $user->id,
        'userid2' => $user->id,
        'userid3' => $user->id,
        'firstread' => $now,
        'lastread' => $now,
        'cutoffdate' => $cutoffdate,
    );
    $params = array_merge($postidparams, $insertparams);

if ($CFG->forum_allowforcedreadtracking) {
        $trackingsql = "AND (f.trackingtype = ".FORUM_TRACKING_FORCED."
                        OR (f.trackingtype = ".FORUM_TRACKING_OPTIONAL." AND tf.id IS NULL))";
    } else {
        $trackingsql = "AND ((f.trackingtype = ".FORUM_TRACKING_OPTIONAL."  OR f.trackingtype = ".FORUM_TRACKING_FORCED.")
                            AND tf.id IS NULL)";
    }

// First insert any new entries.
    $sql = "INSERT INTO {forum_read} (userid, postid, discussionid, forumid, firstread, lastread)

SELECT :userid1, p.id, p.discussion, d.forum, :firstread, :lastread
                FROM {forum_posts} p
                    JOIN {forum_discussions} d       ON d.id = p.discussion
                    JOIN {forum} f                   ON f.id = d.forum
                    LEFT JOIN {forum_track_prefs} tf ON (tf.userid = :userid2 AND tf.forumid = f.id)
                    LEFT JOIN {forum_read} fr        ON (
                            fr.userid = :userid3
                        AND fr.postid = p.id
                        AND fr.discussionid = d.id
                        AND fr.forumid = f.id
                    )
                WHERE p.id $usql
                    AND p.modified >= :cutoffdate
                    $trackingsql
                    AND fr.id IS NULL";

$status = $DB->execute($sql, $params) && $status;

// Then update all records.
    $updateparams = array(
        'userid' => $user->id,
        'lastread' => $now,
    );
    $params = array_merge($postidparams, $updateparams);
    $status = $DB->set_field_select('forum_read', 'lastread', $now, '
                userid      =  :userid
            AND lastread    <> :lastread
            AND postid      ' . $usql,
            $params) && $status;

return $status;
}

/**
 * Mark post as read.
 * @global object
 * @global object
 * @param int $userid
 * @param int $postid
 */
function forum_tp_add_read_record($userid, $postid) {
    global $CFG, $DB;

$now = time();
    $cutoffdate = $now - ($CFG->forum_oldpostdays * 24 * 3600);

if (!$DB->record_exists('forum_read', array('userid' => $userid, 'postid' => $postid))) {
        $sql = "INSERT INTO {forum_read} (userid, postid, discussionid, forumid, firstread, lastread)

SELECT ?, p.id, p.discussion, d.forum, ?, ?
                  FROM {forum_posts} p
                       JOIN {forum_discussions} d ON d.id = p.discussion
                 WHERE p.id = ? AND p.modified >= ?";
        return $DB->execute($sql, array($userid, $now, $now, $postid, $cutoffdate));

} else {
        $sql = "UPDATE {forum_read}
                   SET lastread = ?
                 WHERE userid = ? AND postid = ?";
        return $DB->execute($sql, array($now, $userid, $userid));
    }
}

/**
 * If its an old post, do nothing. If the record exists, the maintenance will clear it up later.
 *
 * @param   int     $userid The ID of the user to mark posts read for.
 * @param   object  $post   The post record for the post to mark as read.
 * @param   mixed   $unused
 * @return bool
 */
function forum_tp_mark_post_read($userid, $post, $unused = null) {
    if (!forum_tp_is_post_old($post)) {
        return forum_tp_add_read_record($userid, $post->id);
    } else {
        return true;
    }
}

/**
 * Marks a whole forum as read, for a given user
 *
 * @global object
 * @global object
 * @param object $user
 * @param int $forumid
 * @param int|bool $groupid
 * @return bool
 */
function forum_tp_mark_forum_read($user, $forumid, $groupid=false) {
    global $CFG, $DB;

$cutoffdate = time() - ($CFG->forum_oldpostdays*24*60*60);

$groupsel = "";
    $params = array($user->id, $forumid, $cutoffdate);

if ($groupid !== false) {
        $groupsel = " AND (d.groupid = ? OR d.groupid = -1)";
        $params[] = $groupid;
    }

$sql = "SELECT p.id
              FROM {forum_posts} p
                   LEFT JOIN {forum_discussions} d ON d.id = p.discussion
                   LEFT JOIN {forum_read} r        ON (r.postid = p.id AND r.userid = ?)
             WHERE d.forum = ?
                   AND p.modified >= ? AND r.id is NULL
                   $groupsel";

if ($posts = $DB->get_records_sql($sql, $params)) {
        $postids = array_keys($posts);
        return forum_tp_mark_posts_read($user, $postids);
    }

return true;
}

/**
 * Marks a whole discussion as read, for a given user
 *
 * @global object
 * @global object
 * @param object $user
 * @param int $discussionid
 * @return bool
 */
function forum_tp_mark_discussion_read($user, $discussionid) {
    global $CFG, $DB;

$cutoffdate = time() - ($CFG->forum_oldpostdays*24*60*60);

$sql = "SELECT p.id
              FROM {forum_posts} p
                   LEFT JOIN {forum_read} r ON (r.postid = p.id AND r.userid = ?)
             WHERE p.discussion = ?
                   AND p.modified >= ? AND r.id is NULL";

if ($posts = $DB->get_records_sql($sql, array($user->id, $discussionid, $cutoffdate))) {
        $postids = array_keys($posts);
        return forum_tp_mark_posts_read($user, $postids);
    }

return true;
}

/**
 * @global object
 * @param int $userid
 * @param object $post
 */
function forum_tp_is_post_read($userid, $post) {
    global $DB;
    return (forum_tp_is_post_old($post) ||
            $DB->record_exists('forum_read', array('userid' => $userid, 'postid' => $post->id)));
}

/**
 * @global object
 * @param object $post
 * @param int $time Defautls to time()
 */
function forum_tp_is_post_old($post, $time=null) {
    global $CFG;

if (is_null($time)) {
        $time = time();
    }
    return ($post->modified < ($time - ($CFG->forum_oldpostdays * 24 * 3600)));
}

/**
 * Returns the count of records for the provided user and course.
 * Please note that group access is ignored!
 *
 * @global object
 * @global object
 * @param int $userid
 * @param int $courseid
 * @return array
 */
function forum_tp_get_course_unread_posts($userid, $courseid) {
    global $CFG, $DB;

$now = floor(time() / 60) * 60; // DB cache friendliness.
    $cutoffdate = $now - ($CFG->forum_oldpostdays * 24 * 60 * 60);
    $params = array($userid, $userid, $courseid, $cutoffdate, $userid);

if (!empty($CFG->forum_enabletimedposts)) {
        $timedsql = "AND d.timestart < ? AND (d.timeend = 0 OR d.timeend > ?)";
        $params[] = $now;
        $params[] = $now;
    } else {
        $timedsql = "";
    }

if ($CFG->forum_allowforcedreadtracking) {
        $trackingsql = "AND (f.trackingtype = ".FORUM_TRACKING_FORCED."
                            OR (f.trackingtype = ".FORUM_TRACKING_OPTIONAL." AND tf.id IS NULL
                                AND (SELECT trackforums FROM {user} WHERE id = ?) = 1))";
    } else {
        $trackingsql = "AND ((f.trackingtype = ".FORUM_TRACKING_OPTIONAL." OR f.trackingtype = ".FORUM_TRACKING_FORCED.")
                            AND tf.id IS NULL
                            AND (SELECT trackforums FROM {user} WHERE id = ?) = 1)";
    }

$sql = "SELECT f.id, COUNT(p.id) AS unread
              FROM {forum_posts} p
                   JOIN {forum_discussions} d       ON d.id = p.discussion
                   JOIN {forum} f                   ON f.id = d.forum
                   JOIN {course} c                  ON c.id = f.course
                   LEFT JOIN {forum_read} r         ON (r.postid = p.id AND r.userid = ?)
                   LEFT JOIN {forum_track_prefs} tf ON (tf.userid = ? AND tf.forumid = f.id)
             WHERE f.course = ?
                   AND p.modified >= ? AND r.id is NULL
                   $trackingsql
                   $timedsql
          GROUP BY f.id";

if ($return = $DB->get_records_sql($sql, $params)) {
        return $return;
    }

return array();
}

/**
 * Returns the count of records for the provided user and forum and [optionally] group.
 *
 * @global object
 * @global object
 * @global object
 * @param object $cm
 * @param object $course
 * @param bool   $resetreadcache optional, true to reset the function static $readcache var
 * @return int
 */
function forum_tp_count_forum_unread_posts($cm, $course, $resetreadcache = false) {
    global $CFG, $USER, $DB;

static $readcache = array();

if ($resetreadcache) {
        $readcache = array();
    }

$forumid = $cm->instance;

if (!isset($readcache[$course->id])) {
        $readcache[$course->id] = array();
        if ($counts = forum_tp_get_course_unread_posts($USER->id, $course->id)) {
            foreach ($counts as $count) {
                $readcache[$course->id][$count->id] = $count->unread;
            }
        }
    }

if (empty($readcache[$course->id][$forumid])) {
        // no need to check group mode ;-)
        return 0;
    }

$groupmode = groups_get_activity_groupmode($cm, $course);

if ($groupmode != SEPARATEGROUPS) {
        return $readcache[$course->id][$forumid];
    }

if (has_capability('moodle/site:accessallgroups', context_module::instance($cm->id))) {
        return $readcache[$course->id][$forumid];
    }

require_once($CFG->dirroot.'/course/lib.php');

$modinfo = get_fast_modinfo($course);

$mygroups = $modinfo->get_groups($cm->groupingid);

// add all groups posts
    $mygroups[-1] = -1;

list ($groups_sql, $groups_params) = $DB->get_in_or_equal($mygroups);

$now = floor(time() / 60) * 60; // DB Cache friendliness.
    $cutoffdate = $now - ($CFG->forum_oldpostdays*24*60*60);
    $params = array($USER->id, $forumid, $cutoffdate);

$params = array_merge($params, $groups_params);

$sql = "SELECT COUNT(p.id)
              FROM {forum_posts} p
                   JOIN {forum_discussions} d ON p.discussion = d.id
                   LEFT JOIN {forum_read} r   ON (r.postid = p.id AND r.userid = ?)
             WHERE d.forum = ?
                   AND p.modified >= ? AND r.id is NULL
                   $timedsql
                   AND d.groupid $groups_sql";

return $DB->get_field_sql($sql, $params);
}

/**
 * Deletes read records for the specified index. At least one parameter must be specified.
 *
 * @global object
 * @param int $userid
 * @param int $postid
 * @param int $discussionid
 * @param int $forumid
 * @return bool
 */
function forum_tp_delete_read_records($userid=-1, $postid=-1, $discussionid=-1, $forumid=-1) {
    global $DB;
    $params = array();

$select = '';
    if ($userid > -1) {
        if ($select != '') $select .= ' AND ';
        $select .= 'userid = ?';
        $params[] = $userid;
    }
    if ($postid > -1) {
        if ($select != '') $select .= ' AND ';
        $select .= 'postid = ?';
        $params[] = $postid;
    }
    if ($discussionid > -1) {
        if ($select != '') $select .= ' AND ';
        $select .= 'discussionid = ?';
        $params[] = $discussionid;
    }
    if ($forumid > -1) {
        if ($select != '') $select .= ' AND ';
        $select .= 'forumid = ?';
        $params[] = $forumid;
    }
    if ($select == '') {
        return false;
    }
    else {
        return $DB->delete_records_select('forum_read', $select, $params);
    }
}
/**
 * Get a list of forums not tracked by the user.
 *
 * @global object
 * @global object
 * @param int $userid The id of the user to use.
 * @param int $courseid The id of the course being checked.
 * @return mixed An array indexed by forum id, or false.
 */
function forum_tp_get_untracked_forums($userid, $courseid) {
    global $CFG, $DB;

if ($CFG->forum_allowforcedreadtracking) {
        $trackingsql = "AND (f.trackingtype = ".FORUM_TRACKING_OFF."
                            OR (f.trackingtype = ".FORUM_TRACKING_OPTIONAL." AND (ft.id IS NOT NULL
                                OR (SELECT trackforums FROM {user} WHERE id = ?) = 0)))";
    } else {
        $trackingsql = "AND (f.trackingtype = ".FORUM_TRACKING_OFF."
                            OR ((f.trackingtype = ".FORUM_TRACKING_OPTIONAL." OR f.trackingtype = ".FORUM_TRACKING_FORCED.")
                                AND (ft.id IS NOT NULL
                                    OR (SELECT trackforums FROM {user} WHERE id = ?) = 0)))";
    }

$sql = "SELECT f.id
              FROM {forum} f
                   LEFT JOIN {forum_track_prefs} ft ON (ft.forumid = f.id AND ft.userid = ?)
             WHERE f.course = ?
                   $trackingsql";

if ($forums = $DB->get_records_sql($sql, array($userid, $courseid, $userid))) {
        foreach ($forums as $forum) {
            $forums[$forum->id] = $forum;
        }
        return $forums;

} else {
        return array();
    }
}

/**
 * Determine if a user can track forums and optionally a particular forum.
 * Checks the site settings, the user settings and the forum settings (if
 * requested).
 *
 * @global object
 * @global object
 * @global object
 * @param mixed $forum The forum object to test, or the int id (optional).
 * @param mixed $userid The user object to check for (optional).
 * @return boolean
 */
function forum_tp_can_track_forums($forum=false, $user=false) {
    global $USER, $CFG, $DB;

// if possible, avoid expensive
    // queries
    if (empty($CFG->forum_trackreadposts)) {
        return false;
    }

if ($user === false) {
        $user = $USER;
    }

if (isguestuser($user) or empty($user->id)) {
        return false;
    }

if ($forum === false) {
        if ($CFG->forum_allowforcedreadtracking) {
            // Since we can force tracking, assume yes without a specific forum.
            return true;
        } else {
            return (bool)$user->trackforums;
        }
    }

// Work toward always passing an object...
    if (is_numeric($forum)) {
        debugging('Better use proper forum object.', DEBUG_DEVELOPER);
        $forum = $DB->get_record('forum', array('id' => $forum), '', 'id,trackingtype');
    }

$forumallows = ($forum->trackingtype == FORUM_TRACKING_OPTIONAL);
    $forumforced = ($forum->trackingtype == FORUM_TRACKING_FORCED);

if ($CFG->forum_allowforcedreadtracking) {
        // If we allow forcing, then forced forums takes procidence over user setting.
        return ($forumforced || ($forumallows  && (!empty($user->trackforums) && (bool)$user->trackforums)));
    } else {
        // If we don't allow forcing, user setting trumps.
        return ($forumforced || $forumallows)  && !empty($user->trackforums);
    }
}

/**
 * Tells whether a specific forum is tracked by the user. A user can optionally
 * be specified. If not specified, the current user is assumed.
 *
 * @global object
 * @global object
 * @global object
 * @param mixed $forum If int, the id of the forum being checked; if object, the forum object
 * @param int $userid The id of the user being checked (optional).
 * @return boolean
 */
function forum_tp_is_tracked($forum, $user=false) {
    global $USER, $CFG, $DB;

if ($user === false) {
        $user = $USER;
    }

if (isguestuser($user) or empty($user->id)) {
        return false;
    }

$cache = cache::make('mod_forum', 'forum_is_tracked');
    $forumid = is_numeric($forum) ? $forum : $forum->id;
    $key = $forumid . '_' . $user->id;
    if ($cachedvalue = $cache->get($key)) {
        return $cachedvalue == 'tracked';
    }

if (!forum_tp_can_track_forums($forum, $user)) {
        return false;
    }

$forumallows = ($forum->trackingtype == FORUM_TRACKING_OPTIONAL);
    $forumforced = ($forum->trackingtype == FORUM_TRACKING_FORCED);
    $userpref = $DB->get_record('forum_track_prefs', array('userid' => $user->id, 'forumid' => $forum->id));

if ($CFG->forum_allowforcedreadtracking) {
        $istracked = $forumforced || ($forumallows && $userpref === false);
    } else {
        $istracked = ($forumallows || $forumforced) && $userpref === false;
    }

// We have to store a string here because the cache API returns false
    // when it can't find the key which would be confused with our legitimate
    // false value. *sigh*.
    $cache->set($key, $istracked ? 'tracked' : 'not');

return $istracked;
}

/**
 * @global object
 * @global object
 * @param int $forumid
 * @param int $userid
 */
function forum_tp_start_tracking($forumid, $userid=false) {
    global $USER, $DB;

if ($userid === false) {
        $userid = $USER->id;
    }

return $DB->delete_records('forum_track_prefs', array('userid' => $userid, 'forumid' => $forumid));
}

/**
 * @global object
 * @global object
 * @param int $forumid
 * @param int $userid
 */
function forum_tp_stop_tracking($forumid, $userid=false) {
    global $USER, $DB;

if ($userid === false) {
        $userid = $USER->id;
    }

if (!$DB->record_exists('forum_track_prefs', array('userid' => $userid, 'forumid' => $forumid))) {
        $track_prefs = new stdClass();
        $track_prefs->userid = $userid;
        $track_prefs->forumid = $forumid;
        $DB->insert_record('forum_track_prefs', $track_prefs);
    }

return forum_tp_delete_read_records($userid, -1, -1, $forumid);
}

/**
 * Clean old records from the forum_read table.
 * @global object
 * @global object
 * @return void
 */
function forum_tp_clean_read_records() {
    global $CFG, $DB;

if (!isset($CFG->forum_oldpostdays)) {
        return;
    }
// Look for records older than the cutoffdate that are still in the forum_read table.
    $cutoffdate = time() - ($CFG->forum_oldpostdays*24*60*60);

//first get the oldest tracking present - we need tis to speedup the next delete query
    $sql = "SELECT MIN(fp.modified) AS first
              FROM {forum_posts} fp
                   JOIN {forum_read} fr ON fr.postid=fp.id";
    if (!$first = $DB->get_field_sql($sql)) {
        // nothing to delete;
        return;
    }

// now delete old tracking info
    $sql = "DELETE
              FROM {forum_read}
             WHERE postid IN (SELECT fp.id
                                FROM {forum_posts} fp
                               WHERE fp.modified >= ? AND fp.modified < ?)";
    $DB->execute($sql, array($first, $cutoffdate));
}

/**
 * Sets the last post for a given discussion
 *
 * @global object
 * @global object
 * @param into $discussionid
 * @return bool|int
 **/
function forum_discussion_update_last_post($discussionid) {
    global $CFG, $DB;

// Check the given discussion exists
    if (!$DB->record_exists('forum_discussions', array('id' => $discussionid))) {
        return false;
    }

// Use SQL to find the last post for this discussion
    $sql = "SELECT id, userid, modified
              FROM {forum_posts}
             WHERE discussion=?
             ORDER BY modified DESC";

// Lets go find the last post
    if (($lastposts = $DB->get_records_sql($sql, array($discussionid), 0, 1))) {
        $lastpost = reset($lastposts);
        $discussionobject = new stdClass();
        $discussionobject->id           = $discussionid;
        $discussionobject->usermodified = $lastpost->userid;
        $discussionobject->timemodified = $lastpost->modified;
        $DB->update_record('forum_discussions', $discussionobject);
        return $lastpost->id;
    }

// To get here either we couldn't find a post for the discussion (weird)
// or we couldn't update the discussion record (weird x2)
    return false;
}

/**
 * List the actions that correspond to a view of this module.
 * This is used by the participation report.
 *
 * Note: This is not used by new logging system. Event with
 *       crud = 'r' and edulevel = LEVEL_PARTICIPATING will
 *       be considered as view action.
 *
 * @return array
 */
function forum_get_view_actions() {
    return array('view discussion', 'search', 'forum', 'forums', 'subscribers', 'view forum');
}

/**
 * List the options for forum subscription modes.
 * This is used by the settings page and by the mod_form page.
 *
 * @return array
 */
function forum_get_subscriptionmode_options() {
    $options = array();
    $options[FORUM_CHOOSESUBSCRIBE] = get_string('subscriptionoptional', 'forum');
    $options[FORUM_FORCESUBSCRIBE] = get_string('subscriptionforced', 'forum');
    $options[FORUM_INITIALSUBSCRIBE] = get_string('subscriptionauto', 'forum');
    $options[FORUM_DISALLOWSUBSCRIBE] = get_string('subscriptiondisabled', 'forum');
    return $options;
}

/**
 * List the actions that correspond to a post of this module.
 * This is used by the participation report.
 *
 * Note: This is not used by new logging system. Event with
 *       crud = ('c' || 'u' || 'd') and edulevel = LEVEL_PARTICIPATING
 *       will be considered as post action.
 *
 * @return array
 */
function forum_get_post_actions() {
    return array('add discussion','add post','delete discussion','delete post','move discussion','prune post','update post');
}

/**
 * Returns a warning object if a user has reached the number of posts equal to
 * the warning/blocking setting, or false if there is no warning to show.
 *
 * @param int|stdClass $forum the forum id or the forum object
 * @param stdClass $cm the course module
 * @return stdClass|bool returns an object with the warning information, else
 *         returns false if no warning is required.
 */
function forum_check_throttling($forum, $cm = null) {
    global $CFG, $DB, $USER;

if (is_numeric($forum)) {
        $forum = $DB->get_record('forum', array('id' => $forum), '*', MUST_EXIST);
    }

if (!is_object($forum)) {
        return false; // This is broken.
    }

if (!$cm) {
        $cm = get_coursemodule_from_instance('forum', $forum->id, $forum->course, false, MUST_EXIST);
    }

if (empty($forum->blockafter)) {
        return false;
    }

if (empty($forum->blockperiod)) {
        return false;
    }

$modcontext = context_module::instance($cm->id);
    if (has_capability('mod/forum:postwithoutthrottling', $modcontext)) {
        return false;
    }

// Get the number of posts in the last period we care about.
    $timenow = time();
    $timeafter = $timenow - $forum->blockperiod;
    $numposts = $DB->count_records_sql('SELECT COUNT(p.id) FROM {forum_posts} p
                                        JOIN {forum_discussions} d
                                        ON p.discussion = d.id WHERE d.forum = ?
                                        AND p.userid = ? AND p.created > ?', array($forum->id, $USER->id, $timeafter));

$a = new stdClass();
    $a->blockafter = $forum->blockafter;
    $a->numposts = $numposts;
    $a->blockperiod = get_string('secondstotime'.$forum->blockperiod);

if ($forum->blockafter <= $numposts) {
        $warning = new stdClass();
        $warning->canpost = false;
        $warning->errorcode = 'forumblockingtoomanyposts';
        $warning->module = 'error';
        $warning->additional = $a;
        $warning->link = $CFG->wwwroot . '/mod/forum/view.php?f=' . $forum->id;

return $warning;
    }

if ($forum->warnafter <= $numposts) {
        $warning = new stdClass();
        $warning->canpost = true;
        $warning->errorcode = 'forumblockingalmosttoomanyposts';
        $warning->module = 'forum';
        $warning->additional = $a;
        $warning->link = null;

return $warning;
    }
}

/**
 * Throws an error if the user is no longer allowed to post due to having reached
 * or exceeded the number of posts specified in 'Post threshold for blocking'
 * setting.
 *
 * @since Moodle 2.5
 * @param stdClass $thresholdwarning the warning information returned
 *        from the function forum_check_throttling.
 */
function forum_check_blocking_threshold($thresholdwarning) {
    if (!empty($thresholdwarning) && !$thresholdwarning->canpost) {
        print_error($thresholdwarning->errorcode,
                    $thresholdwarning->module,
                    $thresholdwarning->link,
                    $thresholdwarning->additional);
    }
}

/**
 * Removes all grades from gradebook
 *
 * @global object
 * @global object
 * @param int $courseid
 * @param string $type optional
 */
function forum_reset_gradebook($courseid, $type='') {
    global $CFG, $DB;

$wheresql = '';
    $params = array($courseid);
    if ($type) {
        $wheresql = "AND f.type=?";
        $params[] = $type;
    }

$sql = "SELECT f.*, cm.idnumber as cmidnumber, f.course as courseid
              FROM {forum} f, {course_modules} cm, {modules} m
             WHERE m.name='forum' AND m.id=cm.module AND cm.instance=f.id AND f.course=? $wheresql";

if ($forums = $DB->get_records_sql($sql, $params)) {
        foreach ($forums as $forum) {
            forum_grade_item_update($forum, 'reset');
        }
    }
}

/**
 * This function is used by the reset_course_userdata function in moodlelib.
 * This function will remove all posts from the specified forum
 * and clean up any related data.
 *
 * @global object
 * @global object
 * @param $data the data submitted from the reset course.
 * @return array status array
 */
function forum_reset_userdata($data) {
    global $CFG, $DB;
    require_once($CFG->dirroot.'/rating/lib.php');

$componentstr = get_string('modulenameplural', 'forum');
    $status = array();

$params = array($data->courseid);

$removeposts = false;
    $typesql     = "";
    if (!empty($data->reset_forum_all)) {
        $removeposts = true;
        $typesstr    = get_string('resetforumsall', 'forum');
        $types       = array();
    } else if (!empty($data->reset_forum_types)){
        $removeposts = true;
        $types       = array();
        $sqltypes    = array();
        $forum_types_all = forum_get_forum_types_all();
        foreach ($data->reset_forum_types as $type) {
            if (!array_key_exists($type, $forum_types_all)) {
                continue;
            }
            $types[] = $forum_types_all[$type];
            $sqltypes[] = $type;
        }
        if (!empty($sqltypes)) {
            list($typesql, $typeparams) = $DB->get_in_or_equal($sqltypes);
            $typesql = " AND f.type " . $typesql;
            $params = array_merge($params, $typeparams);
        }
        $typesstr = get_string('resetforums', 'forum').': '.implode(', ', $types);
    }
    $alldiscussionssql = "SELECT fd.id
                            FROM {forum_discussions} fd, {forum} f
                           WHERE f.course=? AND f.id=fd.forum";

$allforumssql      = "SELECT f.id
                            FROM {forum} f
                           WHERE f.course=?";

$allpostssql       = "SELECT fp.id
                            FROM {forum_posts} fp, {forum_discussions} fd, {forum} f
                           WHERE f.course=? AND f.id=fd.forum AND fd.id=fp.discussion";

$forumssql = $forums = $rm = null;

// Check if we need to get additional data.
    if ($removeposts || !empty($data->reset_forum_ratings) || !empty($data->reset_forum_tags)) {
        // Set this up if we have to remove ratings.
        $rm = new rating_manager();
        $ratingdeloptions = new stdClass;
        $ratingdeloptions->component = 'mod_forum';
        $ratingdeloptions->ratingarea = 'post';

// Get the forums for actions that require it.
        $forumssql = "$allforumssql $typesql";
        $forums = $DB->get_records_sql($forumssql, $params);
    }

if ($removeposts) {
        $discussionssql = "$alldiscussionssql $typesql";
        $postssql       = "$allpostssql $typesql";

// now get rid of all attachments
        $fs = get_file_storage();
        if ($forums) {
            foreach ($forums as $forumid=>$unused) {
                if (!$cm = get_coursemodule_from_instance('forum', $forumid)) {
                    continue;
                }
                $context = context_module::instance($cm->id);
                $fs->delete_area_files($context->id, 'mod_forum', 'attachment');
                $fs->delete_area_files($context->id, 'mod_forum', 'post');

//remove ratings
                $ratingdeloptions->contextid = $context->id;
                $rm->delete_ratings($ratingdeloptions);

core_tag_tag::delete_instances('mod_forum', null, $context->id);
            }
        }

// first delete all read flags
        $DB->delete_records_select('forum_read', "forumid IN ($forumssql)", $params);

// remove tracking prefs
        $DB->delete_records_select('forum_track_prefs', "forumid IN ($forumssql)", $params);

// remove posts from queue
        $DB->delete_records_select('forum_queue', "discussionid IN ($discussionssql)", $params);

// all posts - initial posts must be kept in single simple discussion forums
        $DB->delete_records_select('forum_posts', "discussion IN ($discussionssql) AND parent <> 0", $params); // first all children
        $DB->delete_records_select('forum_posts', "discussion IN ($discussionssql AND f.type <> 'single') AND parent = 0", $params); // now the initial posts for non single simple

// finally all discussions except single simple forums
        $DB->delete_records_select('forum_discussions', "forum IN ($forumssql AND f.type <> 'single')", $params);

// remove all grades from gradebook
        if (empty($data->reset_gradebook_grades)) {
            if (empty($types)) {
                forum_reset_gradebook($data->courseid);
            } else {
                foreach ($types as $type) {
                    forum_reset_gradebook($data->courseid, $type);
                }
            }
        }

$status[] = array('component'=>$componentstr, 'item'=>$typesstr, 'error'=>false);
    }

// remove all ratings in this course's forums
    if (!empty($data->reset_forum_ratings)) {
        if ($forums) {
            foreach ($forums as $forumid=>$unused) {
                if (!$cm = get_coursemodule_from_instance('forum', $forumid)) {
                    continue;
                }
                $context = context_module::instance($cm->id);

//remove ratings
                $ratingdeloptions->contextid = $context->id;
                $rm->delete_ratings($ratingdeloptions);
            }
        }

// remove all grades from gradebook
        if (empty($data->reset_gradebook_grades)) {
            forum_reset_gradebook($data->courseid);
        }
    }

// Remove all the tags.
    if (!empty($data->reset_forum_tags)) {
        if ($forums) {
            foreach ($forums as $forumid => $unused) {
                if (!$cm = get_coursemodule_from_instance('forum', $forumid)) {
                    continue;
                }

$context = context_module::instance($cm->id);
                core_tag_tag::delete_instances('mod_forum', null, $context->id);
            }
        }

$status[] = array('component' => $componentstr, 'item' => get_string('tagsdeleted', 'forum'), 'error' => false);
    }

// remove all digest settings unconditionally - even for users still enrolled in course.
    if (!empty($data->reset_forum_digests)) {
        $DB->delete_records_select('forum_digests', "forum IN ($allforumssql)", $params);
        $status[] = array('component' => $componentstr, 'item' => get_string('resetdigests', 'forum'), 'error' => false);
    }

// remove all subscriptions unconditionally - even for users still enrolled in course
    if (!empty($data->reset_forum_subscriptions)) {
        $DB->delete_records_select('forum_subscriptions', "forum IN ($allforumssql)", $params);
        $DB->delete_records_select('forum_discussion_subs', "forum IN ($allforumssql)", $params);
        $status[] = array('component' => $componentstr, 'item' => get_string('resetsubscriptions', 'forum'), 'error' => false);
    }

// remove all tracking prefs unconditionally - even for users still enrolled in course
    if (!empty($data->reset_forum_track_prefs)) {
        $DB->delete_records_select('forum_track_prefs', "forumid IN ($allforumssql)", $params);
        $status[] = array('component'=>$componentstr, 'item'=>get_string('resettrackprefs','forum'), 'error'=>false);
    }

/// updating dates - shift may be negative too
    if ($data->timeshift) {
        // Any changes to the list of dates that needs to be rolled should be same during course restore and course reset.
        // See MDL-9367.
        shift_course_mod_dates('forum', array('assesstimestart', 'assesstimefinish'), $data->timeshift, $data->courseid);
        $status[] = array('component'=>$componentstr, 'item'=>get_string('datechanged'), 'error'=>false);
    }

return $status;
}

/**
 * Called by course/reset.php
 *
 * @param $mform form passed by reference
 */
function forum_reset_course_form_definition(&$mform) {
    $mform->addElement('header', 'forumheader', get_string('modulenameplural', 'forum'));

$mform->addElement('checkbox', 'reset_forum_all', get_string('resetforumsall','forum'));

$mform->addElement('select', 'reset_forum_types', get_string('resetforums', 'forum'), forum_get_forum_types_all(), array('multiple' => 'multiple'));
    $mform->setAdvanced('reset_forum_types');
    $mform->disabledIf('reset_forum_types', 'reset_forum_all', 'checked');

$mform->addElement('checkbox', 'reset_forum_digests', get_string('resetdigests','forum'));
    $mform->setAdvanced('reset_forum_digests');

$mform->addElement('checkbox', 'reset_forum_subscriptions', get_string('resetsubscriptions','forum'));
    $mform->setAdvanced('reset_forum_subscriptions');

$mform->addElement('checkbox', 'reset_forum_track_prefs', get_string('resettrackprefs','forum'));
    $mform->setAdvanced('reset_forum_track_prefs');
    $mform->disabledIf('reset_forum_track_prefs', 'reset_forum_all', 'checked');

$mform->addElement('checkbox', 'reset_forum_ratings', get_string('deleteallratings'));
    $mform->disabledIf('reset_forum_ratings', 'reset_forum_all', 'checked');

$mform->addElement('checkbox', 'reset_forum_tags', get_string('removeallforumtags', 'forum'));
    $mform->disabledIf('reset_forum_tags', 'reset_forum_all', 'checked');
}

/**
 * Course reset form defaults.
 * @return array
 */
function forum_reset_course_form_defaults($course) {
    return array('reset_forum_all'=>1, 'reset_forum_digests' => 0, 'reset_forum_subscriptions'=>0, 'reset_forum_track_prefs'=>0, 'reset_forum_ratings'=>1);
}

/**
 * Returns array of forum layout modes
 *
 * @return array
 */
function forum_get_layout_modes() {
    return array (FORUM_MODE_FLATOLDEST => get_string('modeflatoldestfirst', 'forum'),
                  FORUM_MODE_FLATNEWEST => get_string('modeflatnewestfirst', 'forum'),
                  FORUM_MODE_THREADED   => get_string('modethreaded', 'forum'),
                  FORUM_MODE_NESTED     => get_string('modenested', 'forum'));
}

/**
 * Returns array of forum types chooseable on the forum editing form
 *
 * @return array
 */
function forum_get_forum_types() {
    return array ('general'  => get_string('generalforum', 'forum'),
                  'eachuser' => get_string('eachuserforum', 'forum'),
                  'single'   => get_string('singleforum', 'forum'),
                  'qanda'    => get_string('qandaforum', 'forum'),
                  'blog'     => get_string('blogforum', 'forum'));
}

/**
 * Returns array of all forum layout modes
 *
 * @return array
 */
function forum_get_forum_types_all() {
    return array ('news'     => get_string('namenews','forum'),
                  'social'   => get_string('namesocial','forum'),
                  'general'  => get_string('generalforum', 'forum'),
                  'eachuser' => get_string('eachuserforum', 'forum'),
                  'single'   => get_string('singleforum', 'forum'),
                  'qanda'    => get_string('qandaforum', 'forum'),
                  'blog'     => get_string('blogforum', 'forum'));
}

/**
 * Returns all other caps used in module
 *
 * @return array
 */
function forum_get_extra_capabilities() {
    return ['moodle/rating:view', 'moodle/rating:viewany', 'moodle/rating:viewall', 'moodle/rating:rate'];
}

/**
 * Adds module specific settings to the settings block
 *
 * @param settings_navigation $settings The settings navigation object
 * @param navigation_node $forumnode The node to add module settings to
 */
function forum_extend_settings_navigation(settings_navigation $settingsnav, navigation_node $forumnode) {
    global $USER, $PAGE, $CFG, $DB, $OUTPUT;

$forumobject = $DB->get_record("forum", array("id" => $PAGE->cm->instance));
    if (empty($PAGE->cm->context)) {
        $PAGE->cm->context = context_module::instance($PAGE->cm->instance);
    }

$params = $PAGE->url->params();
    if (!empty($params['d'])) {
        $discussionid = $params['d'];
    }

// for some actions you need to be enrolled, beiing admin is not enough sometimes here
    $enrolled = is_enrolled($PAGE->cm->context, $USER, '', false);
    $activeenrolled = is_enrolled($PAGE->cm->context, $USER, '', true);

$canmanage  = has_capability('mod/forum:managesubscriptions', $PAGE->cm->context);
    $subscriptionmode = \mod_forum\subscriptions::get_subscription_mode($forumobject);
    $cansubscribe = $activeenrolled && !\mod_forum\subscriptions::is_forcesubscribed($forumobject) &&
            (!\mod_forum\subscriptions::subscription_disabled($forumobject) || $canmanage);

if ($canmanage) {
        $mode = $forumnode->add(get_string('subscriptionmode', 'forum'), null, navigation_node::TYPE_CONTAINER);
        $mode->add_class('subscriptionmode');

$allowchoice = $mode->add(get_string('subscriptionoptional', 'forum'), new moodle_url('/mod/forum/subscribe.php', array('id'=>$forumobject->id, 'mode'=>FORUM_CHOOSESUBSCRIBE, 'sesskey'=>sesskey())), navigation_node::TYPE_SETTING);
        $forceforever = $mode->add(get_string("subscriptionforced", "forum"), new moodle_url('/mod/forum/subscribe.php', array('id'=>$forumobject->id, 'mode'=>FORUM_FORCESUBSCRIBE, 'sesskey'=>sesskey())), navigation_node::TYPE_SETTING);
        $forceinitially = $mode->add(get_string("subscriptionauto", "forum"), new moodle_url('/mod/forum/subscribe.php', array('id'=>$forumobject->id, 'mode'=>FORUM_INITIALSUBSCRIBE, 'sesskey'=>sesskey())), navigation_node::TYPE_SETTING);
        $disallowchoice = $mode->add(get_string('subscriptiondisabled', 'forum'), new moodle_url('/mod/forum/subscribe.php', array('id'=>$forumobject->id, 'mode'=>FORUM_DISALLOWSUBSCRIBE, 'sesskey'=>sesskey())), navigation_node::TYPE_SETTING);

switch ($subscriptionmode) {
            case FORUM_CHOOSESUBSCRIBE : // 0
                $allowchoice->action = null;
                $allowchoice->add_class('activesetting');
                $allowchoice->icon = new pix_icon('t/selected', '', 'mod_forum');
                break;
            case FORUM_FORCESUBSCRIBE : // 1
                $forceforever->action = null;
                $forceforever->add_class('activesetting');
                $forceforever->icon = new pix_icon('t/selected', '', 'mod_forum');
                break;
            case FORUM_INITIALSUBSCRIBE : // 2
                $forceinitially->action = null;
                $forceinitially->add_class('activesetting');
                $forceinitially->icon = new pix_icon('t/selected', '', 'mod_forum');
                break;
            case FORUM_DISALLOWSUBSCRIBE : // 3
                $disallowchoice->action = null;
                $disallowchoice->add_class('activesetting');
                $disallowchoice->icon = new pix_icon('t/selected', '', 'mod_forum');
                break;
        }

} else if ($activeenrolled) {

switch ($subscriptionmode) {
            case FORUM_CHOOSESUBSCRIBE : // 0
                $notenode = $forumnode->add(get_string('subscriptionoptional', 'forum'));
                break;
            case FORUM_FORCESUBSCRIBE : // 1
                $notenode = $forumnode->add(get_string('subscriptionforced', 'forum'));
                break;
            case FORUM_INITIALSUBSCRIBE : // 2
                $notenode = $forumnode->add(get_string('subscriptionauto', 'forum'));
                break;
            case FORUM_DISALLOWSUBSCRIBE : // 3
                $notenode = $forumnode->add(get_string('subscriptiondisabled', 'forum'));
                break;
        }
    }

if ($cansubscribe) {
        if (\mod_forum\subscriptions::is_subscribed($USER->id, $forumobject, null, $PAGE->cm)) {
            $linktext = get_string('unsubscribe', 'forum');
        } else {
            $linktext = get_string('subscribe', 'forum');
        }
        $url = new moodle_url('/mod/forum/subscribe.php', array('id'=>$forumobject->id, 'sesskey'=>sesskey()));
        $forumnode->add($linktext, $url, navigation_node::TYPE_SETTING);

if (isset($discussionid)) {
            if (\mod_forum\subscriptions::is_subscribed($USER->id, $forumobject, $discussionid, $PAGE->cm)) {
                $linktext = get_string('unsubscribediscussion', 'forum');
            } else {
                $linktext = get_string('subscribediscussion', 'forum');
            }
            $url = new moodle_url('/mod/forum/subscribe.php', array(
                    'id' => $forumobject->id,
                    'sesskey' => sesskey(),
                    'd' => $discussionid,
                    'returnurl' => $PAGE->url->out(),
                ));
            $forumnode->add($linktext, $url, navigation_node::TYPE_SETTING);
        }
    }

if (has_capability('mod/forum:viewsubscribers', $PAGE->cm->context)){
        $url = new moodle_url('/mod/forum/subscribers.php', array('id'=>$forumobject->id));
        $forumnode->add(get_string('showsubscribers', 'forum'), $url, navigation_node::TYPE_SETTING);
    }

if ($enrolled && forum_tp_can_track_forums($forumobject)) { // keep tracking info for users with suspended enrolments
        if ($forumobject->trackingtype == FORUM_TRACKING_OPTIONAL
                || ((!$CFG->forum_allowforcedreadtracking) && $forumobject->trackingtype == FORUM_TRACKING_FORCED)) {
            if (forum_tp_is_tracked($forumobject)) {
                $linktext = get_string('notrackforum', 'forum');
            } else {
                $linktext = get_string('trackforum', 'forum');
            }
            $url = new moodle_url('/mod/forum/settracking.php', array(
                    'id' => $forumobject->id,
                    'sesskey' => sesskey(),
                ));
            $forumnode->add($linktext, $url, navigation_node::TYPE_SETTING);
        }
    }

if (!isloggedin() && $PAGE->course->id == SITEID) {
        $userid = guest_user()->id;
    } else {
        $userid = $USER->id;
    }

$hascourseaccess = ($PAGE->course->id == SITEID) || can_access_course($PAGE->course, $userid);
    $enablerssfeeds = !empty($CFG->enablerssfeeds) && !empty($CFG->forum_enablerssfeeds);

if ($enablerssfeeds && $forumobject->rsstype && $forumobject->rssarticles && $hascourseaccess) {

if (!function_exists('rss_get_url')) {
            require_once("$CFG->libdir/rsslib.php");
        }

if ($forumobject->rsstype == 1) {
            $string = get_string('rsssubscriberssdiscussions','forum');
        } else {
            $string = get_string('rsssubscriberssposts','forum');
        }

$url = new moodle_url(rss_get_url($PAGE->cm->context->id, $userid, "mod_forum", $forumobject->id));
        $forumnode->add($string, $url, settings_navigation::TYPE_SETTING, null, null, new pix_icon('i/rss', ''));
    }
}

/**
 * Adds information about unread messages, that is only required for the course view page (and
 * similar), to the course-module object.
 * @param cm_info $cm Course-module object
 */
function forum_cm_info_view(cm_info $cm) {
    global $CFG;

if (forum_tp_can_track_forums()) {
        if ($unread = forum_tp_count_forum_unread_posts($cm, $cm->get_course())) {
            $out = '<span class="unread"> <a href="' . $cm->url . '#unread">';
            if ($unread == 1) {
                $out .= get_string('unreadpostsone', 'forum');
            } else {
                $out .= get_string('unreadpostsnumber', 'forum', $unread);
            }
            $out .= '</a></span>';
            $cm->set_after_link($out);
        }
    }
}

/**
 * Return a list of page types
 * @param string $pagetype current page type
 * @param stdClass $parentcontext Block's parent context
 * @param stdClass $currentcontext Current context of block
 */
function forum_page_type_list($pagetype, $parentcontext, $currentcontext) {
    $forum_pagetype = array(
        'mod-forum-*'=>get_string('page-mod-forum-x', 'forum'),
        'mod-forum-view'=>get_string('page-mod-forum-view', 'forum'),
        'mod-forum-discuss'=>get_string('page-mod-forum-discuss', 'forum')
    );
    return $forum_pagetype;
}

/**
 * Gets all of the courses where the provided user has posted in a forum.
 *
 * @global moodle_database $DB The database connection
 * @param stdClass $user The user who's posts we are looking for
 * @param bool $discussionsonly If true only look for discussions started by the user
 * @param bool $includecontexts If set to trye contexts for the courses will be preloaded
 * @param int $limitfrom The offset of records to return
 * @param int $limitnum The number of records to return
 * @return array An array of courses
 */
function forum_get_courses_user_posted_in($user, $discussionsonly = false, $includecontexts = true, $limitfrom = null, $limitnum = null) {
    global $DB;

// If we are only after discussions we need only look at the forum_discussions
    // table and join to the userid there. If we are looking for posts then we need
    // to join to the forum_posts table.
    if (!$discussionsonly) {
        $subquery = "(SELECT DISTINCT fd.course
                         FROM {forum_discussions} fd
                         JOIN {forum_posts} fp ON fp.discussion = fd.id
                        WHERE fp.userid = :userid )";
    } else {
        $subquery= "(SELECT DISTINCT fd.course
                         FROM {forum_discussions} fd
                        WHERE fd.userid = :userid )";
    }

$params = array('userid' => $user->id);

// Join to the context table so that we can preload contexts if required.
    if ($includecontexts) {
        $ctxselect = ', ' . context_helper::get_preload_record_columns_sql('ctx');
        $ctxjoin = "LEFT JOIN {context} ctx ON (ctx.instanceid = c.id AND ctx.contextlevel = :contextlevel)";
        $params['contextlevel'] = CONTEXT_COURSE;
    } else {
        $ctxselect = '';
        $ctxjoin = '';
    }

// Now we need to get all of the courses to search.
    // All courses where the user has posted within a forum will be returned.
    $sql = "SELECT c.* $ctxselect
            FROM {course} c
            $ctxjoin
            WHERE c.id IN ($subquery)";
    $courses = $DB->get_records_sql($sql, $params, $limitfrom, $limitnum);
    if ($includecontexts) {
        array_map('context_helper::preload_from_record', $courses);
    }
    return $courses;
}

/**
 * Gets all of the forums a user has posted in for one or more courses.
 *
 * @global moodle_database $DB
 * @param stdClass $user
 * @param array $courseids An array of courseids to search or if not provided
 *                       all courses the user has posted within
 * @param bool $discussionsonly If true then only forums where the user has started
 *                       a discussion will be returned.
 * @param int $limitfrom The offset of records to return
 * @param int $limitnum The number of records to return
 * @return array An array of forums the user has posted within in the provided courses
 */
function forum_get_forums_user_posted_in($user, array $courseids = null, $discussionsonly = false, $limitfrom = null, $limitnum = null) {
    global $DB;

if (!is_null($courseids)) {
        list($coursewhere, $params) = $DB->get_in_or_equal($courseids, SQL_PARAMS_NAMED, 'courseid');
        $coursewhere = ' AND f.course '.$coursewhere;
    } else {
        $coursewhere = '';
        $params = array();
    }
    $params['userid'] = $user->id;
    $params['forum'] = 'forum';

if ($discussionsonly) {
        $join = 'JOIN {forum_discussions} ff ON ff.forum = f.id';
    } else {
        $join = 'JOIN {forum_discussions} fd ON fd.forum = f.id
                 JOIN {forum_posts} ff ON ff.discussion = fd.id';
    }

$sql = "SELECT f.*, cm.id AS cmid
              FROM {forum} f
              JOIN {course_modules} cm ON cm.instance = f.id
              JOIN {modules} m ON m.id = cm.module
              JOIN (
                  SELECT f.id
                    FROM {forum} f
                    {$join}
                   WHERE ff.userid = :userid
                GROUP BY f.id
                   ) j ON j.id = f.id
             WHERE m.name = :forum
                 {$coursewhere}";

$courseforums = $DB->get_records_sql($sql, $params, $limitfrom, $limitnum);
    return $courseforums;
}

/**
 * Returns posts made by the selected user in the requested courses.
 *
 * This method can be used to return all of the posts made by the requested user
 * within the given courses.
 * For each course the access of the current user and requested user is checked
 * and then for each post access to the post and forum is checked as well.
 *
 * This function is safe to use with usercapabilities.
 *
 * @global moodle_database $DB
 * @param stdClass $user The user whose posts we want to get
 * @param array $courses The courses to search
 * @param bool $musthaveaccess If set to true errors will be thrown if the user
 *                             cannot access one or more of the courses to search
 * @param bool $discussionsonly If set to true only discussion starting posts
 *                              will be returned.
 * @param int $limitfrom The offset of records to return
 * @param int $limitnum The number of records to return
 * @return stdClass An object the following properties
 *               ->totalcount: the total number of posts made by the requested user
 *                             that the current user can see.
 *               ->courses: An array of courses the current user can see that the
 *                          requested user has posted in.
 *               ->forums: An array of forums relating to the posts returned in the
 *                         property below.
 *               ->posts: An array containing the posts to show for this request.
 */
function forum_get_posts_by_user($user, array $courses, $musthaveaccess = false, $discussionsonly = false, $limitfrom = 0, $limitnum = 50) {
    global $DB, $USER, $CFG;

$return = new stdClass;
    $return->totalcount = 0;    // The total number of posts that the current user is able to view
    $return->courses = array(); // The courses the current user can access
    $return->forums = array();  // The forums that the current user can access that contain posts
    $return->posts = array();   // The posts to display

// First up a small sanity check. If there are no courses to check we can
    // return immediately, there is obviously nothing to search.
    if (empty($courses)) {
        return $return;
    }

// A couple of quick setups
    $isloggedin = isloggedin();
    $isguestuser = $isloggedin && isguestuser();
    $iscurrentuser = $isloggedin && $USER->id == $user->id;

// Checkout whether or not the current user has capabilities over the requested
    // user and if so they have the capabilities required to view the requested
    // users content.
    $usercontext = context_user::instance($user->id, MUST_EXIST);
    $hascapsonuser = !$iscurrentuser && $DB->record_exists('role_assignments', array('userid' => $USER->id, 'contextid' => $usercontext->id));
    $hascapsonuser = $hascapsonuser && has_all_capabilities(array('moodle/user:viewdetails', 'moodle/user:readuserposts'), $usercontext);

// Before we actually search each course we need to check the user's access to the
    // course. If the user doesn't have the appropraite access then we either throw an
    // error if a particular course was requested or we just skip over the course.
    foreach ($courses as $course) {
        $coursecontext = context_course::instance($course->id, MUST_EXIST);
        if ($iscurrentuser || $hascapsonuser) {
            // If it is the current user, or the current user has capabilities to the
            // requested user then all we need to do is check the requested users
            // current access to the course.
            // Note: There is no need to check group access or anything of the like
            // as either the current user is the requested user, or has granted
            // capabilities on the requested user. Either way they can see what the
            // requested user posted, although its VERY unlikely in the `parent` situation
            // that the current user will be able to view the posts in context.
            if (!is_viewing($coursecontext, $user) && !is_enrolled($coursecontext, $user)) {
                // Need to have full access to a course to see the rest of own info
                if ($musthaveaccess) {
                    print_error('errorenrolmentrequired', 'forum');
                }
                continue;
            }
        } else {
            // Check whether the current user is enrolled or has access to view the course
            // if they don't we immediately have a problem.
            if (!can_access_course($course)) {
                if ($musthaveaccess) {
                    print_error('errorenrolmentrequired', 'forum');
                }
                continue;
            }

// If groups are in use and enforced throughout the course then make sure
            // we can meet in at least one course level group.
            // Note that we check if either the current user or the requested user have
            // the capability to access all groups. This is because with that capability
            // a user in group A could post in the group B forum. Grrrr.
            if (groups_get_course_groupmode($course) == SEPARATEGROUPS && $course->groupmodeforce
              && !has_capability('moodle/site:accessallgroups', $coursecontext) && !has_capability('moodle/site:accessallgroups', $coursecontext, $user->id)) {
                // If its the guest user to bad... the guest user cannot access groups
                if (!$isloggedin or $isguestuser) {
                    // do not use require_login() here because we might have already used require_login($course)
                    if ($musthaveaccess) {
                        redirect(get_login_url());
                    }
                    continue;
                }
                // Get the groups of the current user
                $mygroups = array_keys(groups_get_all_groups($course->id, $USER->id, $course->defaultgroupingid, 'g.id, g.name'));
                // Get the groups the requested user is a member of
                $usergroups = array_keys(groups_get_all_groups($course->id, $user->id, $course->defaultgroupingid, 'g.id, g.name'));
                // Check whether they are members of the same group. If they are great.
                $intersect = array_intersect($mygroups, $usergroups);
                if (empty($intersect)) {
                    // But they're not... if it was a specific course throw an error otherwise
                    // just skip this course so that it is not searched.
                    if ($musthaveaccess) {
                        print_error("groupnotamember", '', $CFG->wwwroot."/course/view.php?id=$course->id");
                    }
                    continue;
                }
            }
        }
        // Woo hoo we got this far which means the current user can search this
        // this course for the requested user. Although this is only the course accessibility
        // handling that is complete, the forum accessibility tests are yet to come.
        $return->courses[$course->id] = $course;
    }
    // No longer beed $courses array - lose it not it may be big
    unset($courses);

// Make sure that we have some courses to search
    if (empty($return->courses)) {
        // If we don't have any courses to search then the reality is that the current
        // user doesn't have access to any courses is which the requested user has posted.
        // Although we do know at this point that the requested user has posts.
        if ($musthaveaccess) {
            print_error('permissiondenied');
        } else {
            return $return;
        }
    }

// Next step: Collect all of the forums that we will want to search.
    // It is important to note that this step isn't actually about searching, it is
    // about determining which forums we can search by testing accessibility.
    $forums = forum_get_forums_user_posted_in($user, array_keys($return->courses), $discussionsonly);

// Will be used to build the where conditions for the search
    $forumsearchwhere = array();
    // Will be used to store the where condition params for the search
    $forumsearchparams = array();
    // Will record forums where the user can freely access everything
    $forumsearchfullaccess = array();
    // DB caching friendly
    $now = floor(time() / 60) * 60;
    // For each course to search we want to find the forums the user has posted in
    // and providing the current user can access the forum create a search condition
    // for the forum to get the requested users posts.
    foreach ($return->courses as $course) {
        // Now we need to get the forums
        $modinfo = get_fast_modinfo($course);
        if (empty($modinfo->instances['forum'])) {
            // hmmm, no forums? well at least its easy... skip!
            continue;
        }
        // Iterate
        foreach ($modinfo->get_instances_of('forum') as $forumid => $cm) {
            if (!$cm->uservisible or !isset($forums[$forumid])) {
                continue;
            }
            // Get the forum in question
            $forum = $forums[$forumid];

// This is needed for functionality later on in the forum code. It is converted to an object
            // because the cm_info is readonly from 2.6. This is a dirty hack because some other parts of the
            // code were expecting an writeable object. See {@link forum_print_post()}.
            $forum->cm = new stdClass();
            foreach ($cm as $key => $value) {
                $forum->cm->$key = $value;
            }

// Check that either the current user can view the forum, or that the
            // current user has capabilities over the requested user and the requested
            // user can view the discussion
            if (!has_capability('mod/forum:viewdiscussion', $cm->context) && !($hascapsonuser && has_capability('mod/forum:viewdiscussion', $cm->context, $user->id))) {
                continue;
            }

// This will contain forum specific where clauses
            $forumsearchselect = array();
            if (!$iscurrentuser && !$hascapsonuser) {
                // Make sure we check group access
                if (groups_get_activity_groupmode($cm, $course) == SEPARATEGROUPS and !has_capability('moodle/site:accessallgroups', $cm->context)) {
                    $groups = $modinfo->get_groups($cm->groupingid);
                    $groups[] = -1;
                    list($groupid_sql, $groupid_params) = $DB->get_in_or_equal($groups, SQL_PARAMS_NAMED, 'grps'.$forumid.'_');
                    $forumsearchparams = array_merge($forumsearchparams, $groupid_params);
                    $forumsearchselect[] = "d.groupid $groupid_sql";
                }

// hidden timed discussions
                if (!empty($CFG->forum_enabletimedposts) && !has_capability('mod/forum:viewhiddentimedposts', $cm->context)) {
                    $forumsearchselect[] = "(d.userid = :userid{$forumid} OR (d.timestart < :timestart{$forumid} AND (d.timeend = 0 OR d.timeend > :timeend{$forumid})))";
                    $forumsearchparams['userid'.$forumid] = $user->id;
                    $forumsearchparams['timestart'.$forumid] = $now;
                    $forumsearchparams['timeend'.$forumid] = $now;
                }

// qanda access
                if ($forum->type == 'qanda' && !has_capability('mod/forum:viewqandawithoutposting', $cm->context)) {
                    // We need to check whether the user has posted in the qanda forum.
                    $discussionspostedin = forum_discussions_user_has_posted_in($forum->id, $user->id);
                    if (!empty($discussionspostedin)) {
                        $forumonlydiscussions = array();  // Holds discussion ids for the discussions the user is allowed to see in this forum.
                        foreach ($discussionspostedin as $d) {
                            $forumonlydiscussions[] = $d->id;
                        }
                        list($discussionid_sql, $discussionid_params) = $DB->get_in_or_equal($forumonlydiscussions, SQL_PARAMS_NAMED, 'qanda'.$forumid.'_');
                        $forumsearchparams = array_merge($forumsearchparams, $discussionid_params);
                        $forumsearchselect[] = "(d.id $discussionid_sql OR p.parent = 0)";
                    } else {
                        $forumsearchselect[] = "p.parent = 0";
                    }

}

if (count($forumsearchselect) > 0) {
                    $forumsearchwhere[] = "(d.forum = :forum{$forumid} AND ".implode(" AND ", $forumsearchselect).")";
                    $forumsearchparams['forum'.$forumid] = $forumid;
                } else {
                    $forumsearchfullaccess[] = $forumid;
                }
            } else {
                // The current user/parent can see all of their own posts
                $forumsearchfullaccess[] = $forumid;
            }
        }
    }

// If we dont have any search conditions, and we don't have any forums where
    // the user has full access then we just return the default.
    if (empty($forumsearchwhere) && empty($forumsearchfullaccess)) {
        return $return;
    }

// Prepare a where condition for the full access forums.
    if (count($forumsearchfullaccess) > 0) {
        list($fullidsql, $fullidparams) = $DB->get_in_or_equal($forumsearchfullaccess, SQL_PARAMS_NAMED, 'fula');
        $forumsearchparams = array_merge($forumsearchparams, $fullidparams);
        $forumsearchwhere[] = "(d.forum $fullidsql)";
    }

// Prepare SQL to both count and search.
    // We alias user.id to useridx because we forum_posts already has a userid field and not aliasing this would break
    // oracle and mssql.
    $userfields = user_picture::fields('u', null, 'useridx');
    $countsql = 'SELECT COUNT(*) ';
    $selectsql = 'SELECT p.*, d.forum, d.name AS discussionname, '.$userfields.' ';
    $wheresql = implode(" OR ", $forumsearchwhere);

if ($discussionsonly) {
        if ($wheresql == '') {
            $wheresql = 'p.parent = 0';
        } else {
            $wheresql = 'p.parent = 0 AND ('.$wheresql.')';
        }
    }

$sql = "FROM {forum_posts} p
            JOIN {forum_discussions} d ON d.id = p.discussion
            JOIN {user} u ON u.id = p.userid
           WHERE ($wheresql)
             AND p.userid = :userid ";
    $orderby = "ORDER BY p.modified DESC";
    $forumsearchparams['userid'] = $user->id;

// Set the total number posts made by the requested user that the current user can see
    $return->totalcount = $DB->count_records_sql($countsql.$sql, $forumsearchparams);
    // Set the collection of posts that has been requested
    $return->posts = $DB->get_records_sql($selectsql.$sql.$orderby, $forumsearchparams, $limitfrom, $limitnum);

// We need to build an array of forums for which posts will be displayed.
    // We do this here to save the caller needing to retrieve them themselves before
    // printing these forums posts. Given we have the forums already there is
    // practically no overhead here.
    foreach ($return->posts as $post) {
        if (!array_key_exists($post->forum, $return->forums)) {
            $return->forums[$post->forum] = $forums[$post->forum];
        }
    }

return $return;
}

/**
 * Set the per-forum maildigest option for the specified user.
 *
 * @param stdClass $forum The forum to set the option for.
 * @param int $maildigest The maildigest option.
 * @param stdClass $user The user object. This defaults to the global $USER object.
 * @throws invalid_digest_setting thrown if an invalid maildigest option is provided.
 */
function forum_set_user_maildigest($forum, $maildigest, $user = null) {
    global $DB, $USER;

if (is_number($forum)) {
        $forum = $DB->get_record('forum', array('id' => $forum));
    }

if ($user === null) {
        $user = $USER;
    }

$course  = $DB->get_record('course', array('id' => $forum->course), '*', MUST_EXIST);
    $cm      = get_coursemodule_from_instance('forum', $forum->id, $course->id, false, MUST_EXIST);
    $context = context_module::instance($cm->id);

// User must be allowed to see this forum.
    require_capability('mod/forum:viewdiscussion', $context, $user->id);

// Validate the maildigest setting.
    $digestoptions = forum_get_user_digest_options($user);

if (!isset($digestoptions[$maildigest])) {
        throw new moodle_exception('invaliddigestsetting', 'mod_forum');
    }

// Attempt to retrieve any existing forum digest record.
    $subscription = $DB->get_record('forum_digests', array(
        'userid' => $user->id,
        'forum' => $forum->id,
    ));

// Create or Update the existing maildigest setting.
    if ($subscription) {
        if ($maildigest == -1) {
            $DB->delete_records('forum_digests', array('forum' => $forum->id, 'userid' => $user->id));
        } else if ($maildigest !== $subscription->maildigest) {
            // Only update the maildigest setting if it's changed.

$subscription->maildigest = $maildigest;
            $DB->update_record('forum_digests', $subscription);
        }
    } else {
        if ($maildigest != -1) {
            // Only insert the maildigest setting if it's non-default.

$subscription = new stdClass();
            $subscription->forum = $forum->id;
            $subscription->userid = $user->id;
            $subscription->maildigest = $maildigest;
            $subscription->id = $DB->insert_record('forum_digests', $subscription);
        }
    }
}

/**
 * Determine the maildigest setting for the specified user against the
 * specified forum.
 *
 * @param Array $digests An array of forums and user digest settings.
 * @param stdClass $user The user object containing the id and maildigest default.
 * @param int $forumid The ID of the forum to check.
 * @return int The calculated maildigest setting for this user and forum.
 */
function forum_get_user_maildigest_bulk($digests, $user, $forumid) {
    if (isset($digests[$forumid]) && isset($digests[$forumid][$user->id])) {
        $maildigest = $digests[$forumid][$user->id];
        if ($maildigest === -1) {
            $maildigest = $user->maildigest;
        }
    } else {
        $maildigest = $user->maildigest;
    }
    return $maildigest;
}

/**
 * Retrieve the list of available user digest options.
 *
 * @param stdClass $user The user object. This defaults to the global $USER object.
 * @return array The mapping of values to digest options.
 */
function forum_get_user_digest_options($user = null) {
    global $USER;

// Revert to the global user object.
    if ($user === null) {
        $user = $USER;
    }

$digestoptions = array();
    $digestoptions['0']  = get_string('emaildigestoffshort', 'mod_forum');
    $digestoptions['1']  = get_string('emaildigestcompleteshort', 'mod_forum');
    $digestoptions['2']  = get_string('emaildigestsubjectsshort', 'mod_forum');

// We need to add the default digest option at the end - it relies on
    // the contents of the existing values.
    $digestoptions['-1'] = get_string('emaildigestdefault', 'mod_forum',
            $digestoptions[$user->maildigest]);

// Resort the options to be in a sensible order.
    ksort($digestoptions);

return $digestoptions;
}

/**
 * Determine the current context if one was not already specified.
 *
 * If a context of type context_module is specified, it is immediately
 * returned and not checked.
 *
 * @param int $forumid The ID of the forum
 * @param context_module $context The current context.
 * @return context_module The context determined
 */
function forum_get_context($forumid, $context = null) {
    global $PAGE;

if (!$context || !($context instanceof context_module)) {
        // Find out forum context. First try to take current page context to save on DB query.
        if ($PAGE->cm && $PAGE->cm->modname === 'forum' && $PAGE->cm->instance == $forumid
                && $PAGE->context->contextlevel == CONTEXT_MODULE && $PAGE->context->instanceid == $PAGE->cm->id) {
            $context = $PAGE->context;
        } else {
            $cm = get_coursemodule_from_instance('forum', $forumid);
            $context = \context_module::instance($cm->id);
        }
    }

return $context;
}

/**
 * Mark the activity completed (if required) and trigger the course_module_viewed event.
 *
 * @param  stdClass $forum   forum object
 * @param  stdClass $course  course object
 * @param  stdClass $cm      course module object
 * @param  stdClass $context context object
 * @since Moodle 2.9
 */
function forum_view($forum, $course, $cm, $context) {

// Completion.
    $completion = new completion_info($course);
    $completion->set_module_viewed($cm);

// Trigger course_module_viewed event.

$params = array(
        'context' => $context,
        'objectid' => $forum->id
    );

$event = \mod_forum\event\course_module_viewed::create($params);
    $event->add_record_snapshot('course_modules', $cm);
    $event->add_record_snapshot('course', $course);
    $event->add_record_snapshot('forum', $forum);
    $event->trigger();
}

/**
 * Trigger the discussion viewed event
 *
 * @param  stdClass $modcontext module context object
 * @param  stdClass $forum      forum object
 * @param  stdClass $discussion discussion object
 * @since Moodle 2.9
 */
function forum_discussion_view($modcontext, $forum, $discussion) {
    $params = array(
        'context' => $modcontext,
        'objectid' => $discussion->id,
    );

$event = \mod_forum\event\discussion_viewed::create($params);
    $event->add_record_snapshot('forum_discussions', $discussion);
    $event->add_record_snapshot('forum', $forum);
    $event->trigger();
}

/**
 * Set the discussion to pinned and trigger the discussion pinned event
 *
 * @param  stdClass $modcontext module context object
 * @param  stdClass $forum      forum object
 * @param  stdClass $discussion discussion object
 * @since Moodle 3.1
 */
function forum_discussion_pin($modcontext, $forum, $discussion) {
    global $DB;

$DB->set_field('forum_discussions', 'pinned', FORUM_DISCUSSION_PINNED, array('id' => $discussion->id));

$params = array(
        'context' => $modcontext,
        'objectid' => $discussion->id,
        'other' => array('forumid' => $forum->id)
    );

$event = \mod_forum\event\discussion_pinned::create($params);
    $event->add_record_snapshot('forum_discussions', $discussion);
    $event->trigger();
}

/**
 * Set discussion to unpinned and trigger the discussion unpin event
 *
 * @param  stdClass $modcontext module context object
 * @param  stdClass $forum      forum object
 * @param  stdClass $discussion discussion object
 * @since Moodle 3.1
 */
function forum_discussion_unpin($modcontext, $forum, $discussion) {
    global $DB;

$DB->set_field('forum_discussions', 'pinned', FORUM_DISCUSSION_UNPINNED, array('id' => $discussion->id));

$params = array(
        'context' => $modcontext,
        'objectid' => $discussion->id,
        'other' => array('forumid' => $forum->id)
    );

$event = \mod_forum\event\discussion_unpinned::create($params);
    $event->add_record_snapshot('forum_discussions', $discussion);
    $event->trigger();
}

/**
 * Add nodes to myprofile page.
 *
 * @param \core_user\output\myprofile\tree $tree Tree object
 * @param stdClass $user user object
 * @param bool $iscurrentuser
 * @param stdClass $course Course object
 *
 * @return bool
 */
function mod_forum_myprofile_navigation(core_user\output\myprofile\tree $tree, $user, $iscurrentuser, $course) {
    if (isguestuser($user)) {
        // The guest user cannot post, so it is not possible to view any posts.
        // May as well just bail aggressively here.
        return false;
    }
    $postsurl = new moodle_url('/mod/forum/user.php', array('id' => $user->id));
    if (!empty($course)) {
        $postsurl->param('course', $course->id);
    }
    $string = get_string('forumposts', 'mod_forum');
    $node = new core_user\output\myprofile\node('miscellaneous', 'forumposts', $string, null, $postsurl);
    $tree->add_node($node);

$discussionssurl = new moodle_url('/mod/forum/user.php', array('id' => $user->id, 'mode' => 'discussions'));
    if (!empty($course)) {
        $discussionssurl->param('course', $course->id);
    }
    $string = get_string('myprofileotherdis', 'mod_forum');
    $node = new core_user\output\myprofile\node('miscellaneous', 'forumdiscussions', $string, null,
        $discussionssurl);
    $tree->add_node($node);

return true;
}

/**
 * Checks whether the author's name and picture for a given post should be hidden or not.
 *
 * @param object $post The forum post.
 * @param object $forum The forum object.
 * @return bool
 * @throws coding_exception
 */
function forum_is_author_hidden($post, $forum) {
    if (!isset($post->parent)) {
        throw new coding_exception('$post->parent must be set.');
    }
    if (!isset($forum->type)) {
        throw new coding_exception('$forum->type must be set.');
    }
    if ($forum->type === 'single' && empty($post->parent)) {
        return true;
    }
    return false;
}

/**
 * Manage inplace editable saves.
 *
 * @param   string      $itemtype       The type of item.
 * @param   int         $itemid         The ID of the item.
 * @param   mixed       $newvalue       The new value
 * @return  string
 */
function mod_forum_inplace_editable($itemtype, $itemid, $newvalue) {
    global $DB, $PAGE;

if ($itemtype === 'digestoptions') {
        // The itemid is the forumid.
        $forum   = $DB->get_record('forum', array('id' => $itemid), '*', MUST_EXIST);
        $course  = $DB->get_record('course', array('id' => $forum->course), '*', MUST_EXIST);
        $cm      = get_coursemodule_from_instance('forum', $forum->id, $course->id, false, MUST_EXIST);
        $context = context_module::instance($cm->id);

$PAGE->set_context($context);
        require_login($course, false, $cm);
        forum_set_user_maildigest($forum, $newvalue);

$renderer = $PAGE->get_renderer('mod_forum');
        return $renderer->render_digest_options($forum, $newvalue);
    }
}

/**
 * Determine whether the specified forum's cutoff date is reached.
 *
 * @param stdClass $forum The forum
 * @return bool
 */
function forum_is_cutoff_date_reached($forum) {
    $entityfactory = \mod_forum\local\container::get_entity_factory();
    $coursemoduleinfo = get_fast_modinfo($forum->course);
    $cminfo = $coursemoduleinfo->instances['forum'][$forum->id];
    $forumentity = $entityfactory->get_forum_from_stdclass(
            $forum,
            context_module::instance($cminfo->id),
            $cminfo->get_course_module_record(),
            $cminfo->get_course()
    );

return $forumentity->is_cutoff_date_reached();
}

/**
 * Determine whether the specified forum's due date is reached.
 *
 * @param stdClass $forum The forum
 * @return bool
 */
function forum_is_due_date_reached($forum) {
    $entityfactory = \mod_forum\local\container::get_entity_factory();
    $coursemoduleinfo = get_fast_modinfo($forum->course);
    $cminfo = $coursemoduleinfo->instances['forum'][$forum->id];
    $forumentity = $entityfactory->get_forum_from_stdclass(
            $forum,
            context_module::instance($cminfo->id),
            $cminfo->get_course_module_record(),
            $cminfo->get_course()
    );

return $forumentity->is_due_date_reached();
}

/**
 * Determine whether the specified discussion is time-locked.
 *
 * @param   stdClass    $forum          The forum that the discussion belongs to
 * @param   stdClass    $discussion     The discussion to test
 * @return  bool
 */
function forum_discussion_is_locked($forum, $discussion) {
    $entityfactory = \mod_forum\local\container::get_entity_factory();
    $coursemoduleinfo = get_fast_modinfo($forum->course);
    $cminfo = $coursemoduleinfo->instances['forum'][$forum->id];
    $forumentity = $entityfactory->get_forum_from_stdclass(
        $forum,
        context_module::instance($cminfo->id),
        $cminfo->get_course_module_record(),
        $cminfo->get_course()
    );
    $discussionentity = $entityfactory->get_discussion_from_stdclass($discussion);

return $forumentity->is_discussion_locked($discussionentity);
}

/**
 * Check if the module has any update that affects the current user since a given time.
 *
 * @param  cm_info $cm course module data
 * @param  int $from the time to check updates from
 * @param  array $filter  if we need to check only specific updates
 * @return stdClass an object with the different type of areas indicating if they were updated or not
 * @since Moodle 3.2
 */
function forum_check_updates_since(cm_info $cm, $from, $filter = array()) {

$context = $cm->context;
    $updates = new stdClass();
    if (!has_capability('mod/forum:viewdiscussion', $context)) {
        return $updates;
    }

$updates = course_check_module_updates_since($cm, $from, array(), $filter);

// Check if there are new discussions in the forum.
    $updates->discussions = (object) array('updated' => false);
    $discussions = forum_get_discussions($cm, '', false, -1, -1, true, -1, 0, FORUM_POSTS_ALL_USER_GROUPS, $from);
    if (!empty($discussions)) {
        $updates->discussions->updated = true;
        $updates->discussions->itemids = array_keys($discussions);
    }

return $updates;
}

/**
 * Check if the user can create attachments in a forum.
 * @param  stdClass $forum   forum object
 * @param  stdClass $context context object
 * @return bool true if the user can create attachments, false otherwise
 * @since  Moodle 3.3
 */
function forum_can_create_attachment($forum, $context) {
    // If maxbytes == 1 it means no attachments at all.
    if (empty($forum->maxattachments) || $forum->maxbytes == 1 ||
            !has_capability('mod/forum:createattachment', $context)) {
        return false;
    }
    return true;
}

/**
 * Get icon mapping for font-awesome.
 *
 * @return  array
 */
function mod_forum_get_fontawesome_icon_map() {
    return [
        'mod_forum:i/pinned' => 'fa-map-pin',
        'mod_forum:t/selected' => 'fa-check',
        'mod_forum:t/subscribed' => 'fa-envelope-o',
        'mod_forum:t/unsubscribed' => 'fa-envelope-open-o',
        'mod_forum:t/star' => 'fa-star',
    ];
}

/**
 * Callback function that determines whether an action event should be showing its item count
 * based on the event type and the item count.
 *
 * @param calendar_event $event The calendar event.
 * @param int $itemcount The item count associated with the action event.
 * @return bool
 */
function mod_forum_core_calendar_event_action_shows_item_count(calendar_event $event, $itemcount = 0) {
    // Always show item count for forums if item count is greater than 1.
    // If only one action is required than it is obvious and we don't show it for other modules.
    return $itemcount > 1;
}

/**
 * This function receives a calendar event and returns the action associated with it, or null if there is none.
 *
 * This is used by block_myoverview in order to display the event appropriately. If null is returned then the event
 * is not displayed on the block.
 *
 * @param calendar_event $event
 * @param \core_calendar\action_factory $factory
 * @param int $userid User id to use for all capability checks, etc. Set to 0 for current user (default).
 * @return \core_calendar\local\event\entities\action_interface|null
 */
function mod_forum_core_calendar_provide_event_action(calendar_event $event,
                                                      \core_calendar\action_factory $factory,
                                                      int $userid = 0) {
    global $DB, $USER;

if (!$userid) {
        $userid = $USER->id;
    }

$cm = get_fast_modinfo($event->courseid, $userid)->instances['forum'][$event->instance];

if (!$cm->uservisible) {
        // The module is not visible to the user for any reason.
        return null;
    }

$context = context_module::instance($cm->id);

if (!has_capability('mod/forum:viewdiscussion', $context, $userid)) {
        return null;
    }

$completion = new \completion_info($cm->get_course());

$completiondata = $completion->get_data($cm, false, $userid);

if ($completiondata->completionstate != COMPLETION_INCOMPLETE) {
        return null;
    }

// Get action itemcount.
    $itemcount = 0;
    $forum = $DB->get_record('forum', array('id' => $cm->instance));
    $postcountsql = "
                SELECT
                    COUNT(1)
                  FROM
                    {forum_posts} fp
                    INNER JOIN {forum_discussions} fd ON fp.discussion=fd.id
                 WHERE
                    fp.userid=:userid AND fd.forum=:forumid";
    $postcountparams = array('userid' => $userid, 'forumid' => $forum->id);

if ($forum->completiondiscussions) {
        $count = $DB->count_records('forum_discussions', array('forum' => $forum->id, 'userid' => $userid));
        $itemcount += ($forum->completiondiscussions >= $count) ? ($forum->completiondiscussions - $count) : 0;
    }

if ($forum->completionreplies) {
        $count = $DB->get_field_sql( $postcountsql.' AND fp.parent<>0', $postcountparams);
        $itemcount += ($forum->completionreplies >= $count) ? ($forum->completionreplies - $count) : 0;
    }

if ($forum->completionposts) {
        $count = $DB->get_field_sql($postcountsql, $postcountparams);
        $itemcount += ($forum->completionposts >= $count) ? ($forum->completionposts - $count) : 0;
    }

// Well there is always atleast one actionable item (view forum, etc).
    $itemcount = $itemcount > 0 ? $itemcount : 1;

return $factory->create_instance(
        get_string('view'),
        new \moodle_url('/mod/forum/view.php', ['id' => $cm->id]),
        $itemcount,
        true
    );
}

/**
 * Add a get_coursemodule_info function in case any forum type wants to add 'extra' information
 * for the course (see resource).
 *
 * Given a course_module object, this function returns any "extra" information that may be needed
 * when printing this activity in a course listing.  See get_array_of_activities() in course/lib.php.
 *
 * @param stdClass $coursemodule The coursemodule object (record).
 * @return cached_cm_info An object on information that the courses
 *                        will know about (most noticeably, an icon).
 */
function forum_get_coursemodule_info($coursemodule) {
    global $DB;

$dbparams = ['id' => $coursemodule->instance];
    $fields = 'id, name, intro, introformat, completionposts, completiondiscussions, completionreplies';
    if (!$forum = $DB->get_record('forum', $dbparams, $fields)) {
        return false;
    }

$result = new cached_cm_info();
    $result->name = $forum->name;

if ($coursemodule->showdescription) {
        // Convert intro to html. Do not filter cached version, filters run at display time.
        $result->content = format_module_intro('forum', $forum, $coursemodule->id, false);
    }

// Populate the custom completion rules as key => value pairs, but only if the completion mode is 'automatic'.
    if ($coursemodule->completion == COMPLETION_TRACKING_AUTOMATIC) {
        $result->customdata['customcompletionrules']['completiondiscussions'] = $forum->completiondiscussions;
        $result->customdata['customcompletionrules']['completionreplies'] = $forum->completionreplies;
        $result->customdata['customcompletionrules']['completionposts'] = $forum->completionposts;
    }

return $result;
}

/**
 * Callback which returns human-readable strings describing the active completion custom rules for the module instance.
 *
 * @param cm_info|stdClass $cm object with fields ->completion and ->customdata['customcompletionrules']
 * @return array $descriptions the array of descriptions for the custom rules.
 */
function mod_forum_get_completion_active_rule_descriptions($cm) {
    // Values will be present in cm_info, and we assume these are up to date.
    if (empty($cm->customdata['customcompletionrules'])
        || $cm->completion != COMPLETION_TRACKING_AUTOMATIC) {
        return [];
    }

$descriptions = [];
    foreach ($cm->customdata['customcompletionrules'] as $key => $val) {
        switch ($key) {
            case 'completiondiscussions':
                if (!empty($val)) {
                    $descriptions[] = get_string('completiondiscussionsdesc', 'forum', $val);
                }
                break;
            case 'completionreplies':
                if (!empty($val)) {
                    $descriptions[] = get_string('completionrepliesdesc', 'forum', $val);
                }
                break;
            case 'completionposts':
                if (!empty($val)) {
                    $descriptions[] = get_string('completionpostsdesc', 'forum', $val);
                }
                break;
            default:
                break;
        }
    }
    return $descriptions;
}

/**
 * Check whether the forum post is a private reply visible to this user.
 *
 * @param   stdClass    $post   The post to check.
 * @param   cm_info     $cm     The context module instance.
 * @return  bool                Whether the post is visible in terms of private reply configuration.
 */
function forum_post_is_visible_privately($post, $cm) {
    global $USER;

if (!empty($post->privatereplyto)) {
        // Allow the user to see the private reply if:
        // * they hold the permission;
        // * they are the author; or
        // * they are the intended recipient.
        $cansee = false;
        $cansee = $cansee || ($post->userid == $USER->id);
        $cansee = $cansee || ($post->privatereplyto == $USER->id);
        $cansee = $cansee || has_capability('mod/forum:readprivatereplies', context_module::instance($cm->id));
        return $cansee;
    }

return true;
}

/**
 * Check whether the user can reply privately to the parent post.
 *
 * @param   \context_module $context
 * @param   \stdClass   $parent
 * @return  bool
 */
function forum_user_can_reply_privately(\context_module $context, \stdClass $parent) : bool {
    if ($parent->privatereplyto) {
        // You cannot reply privately to a post which is, itself, a private reply.
        return false;
    }

return has_capability('mod/forum:postprivatereply', $context);
}

/**
 * This function calculates the minimum and maximum cutoff values for the timestart of
 * the given event.
 *
 * It will return an array with two values, the first being the minimum cutoff value and
 * the second being the maximum cutoff value. Either or both values can be null, which
 * indicates there is no minimum or maximum, respectively.
 *
 * If a cutoff is required then the function must return an array containing the cutoff
 * timestamp and error string to display to the user if the cutoff value is violated.
 *
 * A minimum and maximum cutoff return value will look like:
 * [
 *     [1505704373, 'The date must be after this date'],
 *     [1506741172, 'The date must be before this date']
 * ]
 *
 * @param calendar_event $event The calendar event to get the time range for
 * @param stdClass $forum The module instance to get the range from
 * @return array Returns an array with min and max date.
 */
function mod_forum_core_calendar_get_valid_event_timestart_range(\calendar_event $event, \stdClass $forum) {
    global $CFG;

require_once($CFG->dirroot . '/mod/forum/locallib.php');

$mindate = null;
    $maxdate = null;

if ($event->eventtype == FORUM_EVENT_TYPE_DUE) {
        if (!empty($forum->cutoffdate)) {
            $maxdate = [
                $forum->cutoffdate,
                get_string('cutoffdatevalidation', 'forum'),
            ];
        }
    }

return [$mindate, $maxdate];
}

/**
 * This function will update the forum module according to the
 * event that has been modified.
 *
 * It will set the timeclose value of the forum instance
 * according to the type of event provided.
 *
 * @throws \moodle_exception
 * @param \calendar_event $event
 * @param stdClass $forum The module instance to get the range from
 */
function mod_forum_core_calendar_event_timestart_updated(\calendar_event $event, \stdClass $forum) {
    global $CFG, $DB;

require_once($CFG->dirroot . '/mod/forum/locallib.php');

if ($event->eventtype != FORUM_EVENT_TYPE_DUE) {
        return;
    }

$courseid = $event->courseid;
    $modulename = $event->modulename;
    $instanceid = $event->instance;

// Something weird going on. The event is for a different module so
    // we should ignore it.
    if ($modulename != 'forum') {
        return;
    }

if ($forum->id != $instanceid) {
        return;
    }

$coursemodule = get_fast_modinfo($courseid)->instances[$modulename][$instanceid];
    $context = context_module::instance($coursemodule->id);

// The user does not have the capability to modify this activity.
    if (!has_capability('moodle/course:manageactivities', $context)) {
        return;
    }

if ($event->eventtype == FORUM_EVENT_TYPE_DUE) {
        if ($forum->duedate != $event->timestart) {
            $forum->duedate = $event->timestart;
            $forum->timemodified = time();
            // Persist the instance changes.
            $DB->update_record('forum', $forum);
            $event = \core\event\course_module_updated::create_from_cm($coursemodule, $context);
            $event->trigger();
        }
    }
}

/**
 * Fetch the data used to display the discussions on the current page.
 *
 * @param   \mod_forum\local\entities\forum  $forum The forum entity
 * @param   stdClass                         $user The user to render for
 * @param   int[]|null                       $groupid The group to render
 * @param   int|null                         $sortorder The sort order to use when selecting the discussions in the list
 * @param   int|null                         $pageno The zero-indexed page number to use
 * @param   int|null                         $pagesize The number of discussions to show on the page
 * @return  array                            The data to use for display
 */
function mod_forum_get_discussion_summaries(\mod_forum\local\entities\forum $forum, stdClass $user, ?int $groupid, ?int $sortorder,
        ?int $pageno = 0, ?int $pagesize = 0) {

$vaultfactory = mod_forum\local\container::get_vault_factory();
    $discussionvault = $vaultfactory->get_discussions_in_forum_vault();
    $managerfactory = mod_forum\local\container::get_manager_factory();
    $capabilitymanager = $managerfactory->get_capability_manager($forum);

$groupids = mod_forum_get_groups_from_groupid($forum, $user, $groupid);

if (null === $groupids) {
        return $discussions = $discussionvault->get_from_forum_id(
            $forum->get_id(),
            $capabilitymanager->can_view_hidden_posts($user),
            $user->id,
            $sortorder,
            $pagesize,
            $pageno * $pagesize);
    } else {
        return $discussions = $discussionvault->get_from_forum_id_and_group_id(
            $forum->get_id(),
            $groupids,
            $capabilitymanager->can_view_hidden_posts($user),
            $user->id,
            $sortorder,
            $pagesize,
            $pageno * $pagesize);
    }
}

/**
 * Get a count of all discussions in a forum.
 *
 * @param   \mod_forum\local\entities\forum  $forum The forum entity
 * @param   stdClass                         $user The user to render for
 * @param   int                              $groupid The group to render
 * @return  int                              The number of discussions in a forum
 */
function mod_forum_count_all_discussions(\mod_forum\local\entities\forum $forum, stdClass $user, ?int $groupid) {

$managerfactory = mod_forum\local\container::get_manager_factory();
    $capabilitymanager = $managerfactory->get_capability_manager($forum);
    $vaultfactory = mod_forum\local\container::get_vault_factory();
    $discussionvault = $vaultfactory->get_discussions_in_forum_vault();

$groupids = mod_forum_get_groups_from_groupid($forum, $user, $groupid);

if (null === $groupids) {
        return $discussionvault->get_total_discussion_count_from_forum_id(
            $forum->get_id(),
            $capabilitymanager->can_view_hidden_posts($user),
            $user->id);
    } else {
        return $discussionvault->get_total_discussion_count_from_forum_id_and_group_id(
            $forum->get_id(),
            $groupids,
            $capabilitymanager->can_view_hidden_posts($user),
            $user->id);
    }
}

/**
 * Get the list of groups to show based on the current user and requested groupid.
 *
 * @param   \mod_forum\local\entities\forum  $forum The forum entity
 * @param   stdClass                         $user The user viewing
 * @param   int                              $groupid The groupid requested
 * @return  array                            The list of groups to show
 */
function mod_forum_get_groups_from_groupid(\mod_forum\local\entities\forum $forum, stdClass $user, ?int $groupid) : ?array {

$effectivegroupmode = $forum->get_effective_group_mode();
    if (empty($effectivegroupmode)) {
        // This forum is not in a group mode. Show all posts always.
        return null;
    }

if (null == $groupid) {
        $managerfactory = mod_forum\local\container::get_manager_factory();
        $capabilitymanager = $managerfactory->get_capability_manager($forum);
        // No group was specified.
        $showallgroups = (VISIBLEGROUPS == $effectivegroupmode);
        $showallgroups = $showallgroups || $capabilitymanager->can_access_all_groups($user);
        if ($showallgroups) {
            // Return null to show all groups.
            return null;
        } else {
            // No group was specified. Only show the users current groups.
            return array_keys(
                groups_get_all_groups(
                    $forum->get_course_id(),
                    $user->id,
                    $forum->get_course_module_record()->groupingid
                )
            );
        }
    } else {
        // A group was specified. Just show that group.
        return [$groupid];
    }
}

/**
 * Return a list of all the user preferences used by mod_forum.
 *
 * @return array
 */
function mod_forum_user_preferences() {
    $vaultfactory = \mod_forum\local\container::get_vault_factory();
    $discussionlistvault = $vaultfactory->get_discussions_in_forum_vault();

$preferences = array();
    $preferences['forum_discussionlistsortorder'] = array(
        'null' => NULL_NOT_ALLOWED,
        'default' => $discussionlistvault::SORTORDER_LASTPOST_DESC,
        'type' => PARAM_INT,
        'choices' => array(
            $discussionlistvault::SORTORDER_LASTPOST_DESC,
            $discussionlistvault::SORTORDER_LASTPOST_ASC,
            $discussionlistvault::SORTORDER_CREATED_DESC,
            $discussionlistvault::SORTORDER_CREATED_ASC,
            $discussionlistvault::SORTORDER_REPLIES_DESC,
            $discussionlistvault::SORTORDER_REPLIES_ASC
        )
    );

return $preferences;
}