/**
  * Internal method. Queries for a number of forums, including additional
  * data about unread posts etc. Returns the database result.
  * @param array $cmids If specified, array of course-module IDs of desired
  *   forums
  * @param object $course If specified, course object
  * @param int $userid User ID, 0 = current user
  * @param int $unread Type of unread data to obtain (UNREAD_xx constant).
  * @param array $groups Array of group IDs to which the given user belongs
  *   (may be null if unread data not required)
  * @param array $aagforums Array of forums in which the user has
  *   'access all groups' (may be null if unread data not required)
  * @param array $viewhiddenforums Array of forums in which the user has
  *   'view hidden discussions' (may be null if unread data not required)
  * @return array Array of row objects
  */
 private static function query_forums($cmids = array(), $course = null, $userid, $unread, $groups, $aagforums, $viewhiddenforums)
 {
     global $CFG, $USER;
     if (!count($cmids) && !$course) {
         throw new forum_exception("forum::query_forums requires course id or cmids");
     }
     if (count($cmids)) {
         $conditions = "cm.id " . forum_utils::in_or_equals($cmids);
     } else {
         $conditions = "f.course = {$course->id}";
     }
     $singleforum = count($cmids) == 1 ? reset($cmids) : false;
     $inviewhiddenforums = forum_utils::in_or_equals($viewhiddenforums);
     // This array of additional results is used later if combining
     // standard results with single-forum calls.
     $plusresult = array();
     // For read tracking, we get a count of total number of posts in
     // forum, and total number of read posts in the forum (this
     // is so we can display the number of UNread posts, but the query
     // works that way around because it will return 0 if no read
     // information is stored).
     if ($unread != self::UNREAD_NONE && forum::enabled_read_tracking()) {
         // Work out when unread status ends
         $endtime = time() - $CFG->forumng_readafterdays * 24 * 3600;
         if (!$userid) {
             $userid = $USER->id;
         }
         $ingroups = forum_utils::in_or_equals($groups);
         $inaagforums = forum_utils::in_or_equals($aagforums);
         $restrictionsql = '';
         if ($singleforum) {
             // If it is for a single forum, get the restriction from the
             // forum type
             $forum = forum::get_from_cmid($singleforum, forum::CLONE_DIRECT);
             $type = $forum->get_type();
             if ($type->has_unread_restriction()) {
                 $value = $type->get_unread_restriction_sql($forum);
                 if ($value) {
                     $restrictionsql = 'AND ' . $value;
                 }
             }
         } else {
             // When it is not for a single forum, we can only group together
             // results for types that do not place restrictions on the
             // unread count.
             $modinfo = self::get_modinfo_special($course, $cmids);
             $okayids = array();
             if (array_key_exists('forumng', $modinfo->instances)) {
                 foreach ($modinfo->instances['forumng'] as $info) {
                     if (count($cmids) && !in_array($info->id, $cmids)) {
                         continue;
                     }
                     $type = self::get_type_from_modinfo_info($info);
                     if (forum_type::get_new($type)->has_unread_restriction()) {
                         // This one's a problem! Do it individually
                         $problemresults = self::query_forums(array($info->id), null, $userid, $unread, $groups, $aagforums, $viewhiddenforums);
                         foreach ($problemresults as $problemresult) {
                             $plusresult[$problemresult->f_id] = $problemresult;
                         }
                     } else {
                         $okayids[] = $info->id;
                     }
                 }
             }
             if (count($okayids) == 0) {
                 // There are no 'normal' forums, so return result so far
                 // after sorting it
                 uasort($plusresult, 'forum::sort_forum_result');
                 return $plusresult;
             } else {
                 // Fall through to normal calculation, but change conditions
                 // to include only the 'normal' forums
                 $conditions .= " AND cm.id " . forum_utils::in_or_equals($okayids);
             }
         }
         // NOTE fpfirst is used only by forum types, not here
         $now = time();
         $sharedquerypart = "\nFROM\n    {$CFG->prefix}forumng_discussions fd\n    INNER JOIN {$CFG->prefix}forumng_posts fplast ON fd.lastpostid = fplast.id\n    INNER JOIN {$CFG->prefix}forumng_posts fpfirst ON fd.postid = fpfirst.id\n    LEFT JOIN {$CFG->prefix}forumng_read fr ON fd.id = fr.discussionid AND fr.userid={$userid}\nWHERE\n    fd.forumid=f.id AND fplast.modified>{$endtime}\n    AND (\n        (fd.groupid IS NULL)\n        OR (fd.groupid {$ingroups})\n        OR cm.groupmode=" . VISIBLEGROUPS . "\n        OR (fd.forumid {$inaagforums})\n    )\n    AND fd.deleted=0\n    AND (\n        ((fd.timestart=0 OR fd.timestart <= {$now})\n        AND (fd.timeend=0 OR fd.timeend > {$now}))\n        OR (fd.forumid {$inviewhiddenforums})\n    )\n    AND ((fplast.edituserid IS NOT NULL AND fplast.edituserid<>{$userid})\n        OR fplast.userid<>{$userid})\n    AND (fr.time IS NULL OR fplast.modified>fr.time)\n    {$restrictionsql}";
         // Note: There is an unusual case in which this number can
         // be inaccurate. It is to do with ignoring messages the user
         // posted. We consider a discussion as 'not unread' if the last
         // message is by current user. In actual fact, a discussion could
         // contain unread messages if messages were posted by other users
         // after this user viewed the forum last, but before they posted
         // their reply. Since this should be an infrequent occurrence I
         // believe this behaviour is acceptable.
         if ($unread == self::UNREAD_BINARY && ($CFG->dbtype == 'postgres7' || $CFG->dbtype == 'mysql')) {
             // Query to get 0/1 unread discussions count
             $readtracking = "\n(SELECT\n    COUNT(1)\nFROM (\n    SELECT\n        1\n    {$sharedquerypart}\n    LIMIT 1) innerquery\n) AS f_hasunreaddiscussions";
         } else {
             // Query to get full unread discussions count
             $readtracking = "\n(SELECT\n    COUNT(1)\n{$sharedquerypart}\n) AS f_numunreaddiscussions";
         }
     } else {
         $readtracking = "NULL AS numreadposts, NULL AS timeread";
     }
     $now = time();
     $orderby = "LOWER(f.name)";
     // Main query. This retrieves:
     // - Full forum fields
     // - Basic course-module and course data (not whole tables)
     // - Discussion count
     // - Unread data, if enabled
     // - User subscription data
     $rs = get_recordset_sql($sql = "\nSELECT\n    " . forum_utils::select_forum_fields('f') . ",\n    " . forum_utils::select_course_module_fields('cm') . ",\n    " . forum_utils::select_course_fields('c') . ",\n    (SELECT COUNT(1)\n        FROM {$CFG->prefix}forumng_discussions cfd\n        WHERE cfd.forumid=f.id AND cfd.deleted=0\n        AND (\n            ((cfd.timestart=0 OR cfd.timestart <= {$now})\n            AND (cfd.timeend=0 OR cfd.timeend > {$now}))\n            OR (cfd.forumid {$inviewhiddenforums})\n        )\n        ) AS f_numdiscussions,\n    {$readtracking}\nFROM\n    {$CFG->prefix}forumng f\n    INNER JOIN {$CFG->prefix}course_modules cm ON cm.instance=f.id\n        AND cm.module=(SELECT id from {$CFG->prefix}modules WHERE name='forumng')\n    INNER JOIN {$CFG->prefix}course c ON c.id=f.course\nWHERE\n    {$conditions}\nORDER BY\n    {$orderby}");
     if (!$rs) {
         throw new forum_exception("Failed to retrieve forums");
     }
     $result = recordset_to_array($rs);
     rs_close($rs);
     if (count($plusresult) > 0) {
         foreach ($plusresult as $key => $value) {
             $result[$key] = $value;
         }
         uasort($result, 'forum::sort_forum_result');
     }
     return $result;
 }
 /**
  * @return bool True if read tracking is enabled for this discussion
  *   (it is not too old, and read tracking is turned on globally)
  */
 public function is_read_tracked()
 {
     $this->check_full();
     return forum::enabled_read_tracking() && $this->discussionfields->timemodified >= forum::get_read_tracking_deadline();
 }
 /**
  * Splits this post to become a new discussion
  * @param $newsubject
  * @param bool $log True to log action
  * @return int ID of new discussion
  */
 function split($newsubject, $log = true)
 {
     global $CFG;
     $this->require_children();
     // Begin a transaction
     forum_utils::start_transaction();
     $olddiscussion = $this->get_discussion();
     // Create new discussion
     $newest = null;
     $this->find_newest_child($newest);
     $newdiscussionid = $olddiscussion->clone_for_split($this->get_id(), $newest->get_id());
     // Update all child posts
     $list = array();
     $this->list_child_ids($list);
     unset($list[0]);
     // Don't include this post itself
     if (count($list) > 0) {
         $inorequals = forum_utils::in_or_equals($list);
         forum_utils::execute_sql("\nUPDATE\n    {$CFG->prefix}forumng_posts\nSET\n    discussionid = {$newdiscussionid}\nWHERE\n    id {$inorequals}");
     }
     // Update this post
     $changes = new stdClass();
     $changes->id = $this->get_id();
     $changes->subject = addslashes($newsubject);
     $changes->parentpostid = null;
     //When split the post, reset the important to 0 so that it is not highlighted.
     $changes->important = 0;
     // Note don't update modified time, or it makes this post unread,
     // which isn't very helpful
     $changes->discussionid = $newdiscussionid;
     forum_utils::update_record('forumng_posts', $changes);
     // Update read data if relevant
     if (forum::enabled_read_tracking() && $newest->get_modified() >= forum::get_read_tracking_deadline()) {
         $rs = forum_utils::get_recordset_sql("\nSELECT\n    userid, time\nFROM\n    {$CFG->prefix}forumng_read\nWHERE\n    discussionid = " . $olddiscussion->get_id() . "\n    AND time >= " . $this->get_created());
         while ($rec = rs_fetch_next_record($rs)) {
             $rec->discussionid = $newdiscussionid;
             forum_utils::insert_record('forumng_read', $rec);
         }
         rs_close($rs);
     }
     $olddiscussion->possible_lastpost_change();
     // Move attachments
     $olddiscussionfolder = $olddiscussion->get_attachment_folder();
     $newdiscussionfolder = $olddiscussion->get_attachment_folder(0, 0, $newdiscussionid);
     if (is_dir($olddiscussionfolder)) {
         // Put this post back on the list
         $list[0] = $this->get_id();
         // Loop through all posts; move attachments if present
         $madenewfolder = false;
         foreach ($list as $id) {
             $oldfolder = $olddiscussionfolder . '/' . $id;
             $newfolder = $newdiscussionfolder . '/' . $id;
             if (is_dir($oldfolder)) {
                 if (!$madenewfolder) {
                     check_dir_exists($newfolder, true, true);
                     $madenewfolder = true;
                 }
                 forum_utils::rename($oldfolder, $newfolder);
             }
         }
     }
     if ($log) {
         $this->log('split post');
     }
     forum_utils::finish_transaction();
     $this->get_discussion()->uncache();
     // If discussion-based completion is turned on, this may enable someone
     // to complete
     if ($this->get_forum()->get_completion_discussions()) {
         $this->update_completion(true);
     }
     return $newdiscussionid;
 }