convert old core plugins to new model, re #814

Merge request studip/studip!440

1 files changed, 1385 insertions, 0 deletions

diff --git a/lib/classes/ForumEntry.php b/lib/classes/ForumEntry.php
new file mode 100644
index 0000000..bd62b08
--- /dev/null
+++ b/lib/classes/ForumEntry.php
@@ -0,0 +1,1385 @@
+<?php
+/**
+ * ForumEntry.php - Allows the retrieval and handling of forum-entrys
+ *
+ * This program 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.
+ *
+ * @author      Till Glöggler <tgloeggl@uos.de>
+ * @license     http://www.gnu.org/licenses/gpl-3.0.html GPL version 3
+ * @category    Stud.IP
+ */
+
+class ForumEntry  implements PrivacyObject
+{
+    const WITH_CHILDS = true;
+    const WITHOUT_CHILDS = false;
+    const THREAD_PREVIEW_LENGTH = 100;
+    const POSTINGS_PER_PAGE = 10;
+    const FEED_POSTINGS = 100;
+
+
+    /* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
+     * H   E   L   P   E   R   -   F   U   N   C   T   I   O   N   S *
+     * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */
+
+    /**
+     * is used for posting-preview. replaces all newlines with spaces
+     *
+     * @param string $text the text to work on
+     * @returns string
+     */
+    public static function br2space($text)
+    {
+        return str_replace("\n", ' ', str_replace("\r", '', $text));
+    }
+
+    /**
+     * remove the edit-html from a posting
+     *
+     * @param string $description the posting-content
+     * @return string the content stripped by the edit-mark
+     */
+    public static function killEdit($description)
+    {
+        // wurde schon mal editiert
+        if (preg_match('/^(.*)(<admin_msg.*?)$/s', $description, $match)) {
+            return $match[1];
+        }
+        return $description;
+    }
+
+    /**
+     * add the edit-html to a posting
+     *
+     * @param string $description the posting-content
+     * @return string the content with the edit-mark
+     */
+    public static function appendEdit($description)
+    {
+        $edit = "<admin_msg autor=\"" . addslashes(get_fullname()) . "\" chdate=\"" . time() . "\">";
+        return $description . $edit;
+    }
+
+    /**
+     * convert the edit-html to raw text
+     *
+     * @param string $description the posting-content
+     * @return string the content with the raw text version of the edit-mark
+     */
+    public static function parseEdit($description, $anonymous = false)
+    {
+        // TODO figure out if this function can be removed
+        //      has been replaced with getContentAsHTML in core code
+        $content = ForumEntry::killEdit($description);
+        $comment = ForumEntry::getEditComment($description, $anonymous);
+        return $content . ($comment ? "\n\n%%" . $comment .'%%' : '');
+    }
+
+    /**
+     * Get content with appended edit comment as HTML.
+     *
+     * @param string  $description  Database entry of forum entry's body.
+     * @param bool    $anonymous    True, if only root is allowed to see
+     *                              authors.
+     * @return string  Content and edit comment as HTML.
+     */
+    public static function getContentAsHtml($description, $anonymous = false)
+    {
+        $raw_content = ForumEntry::killEdit($description);
+
+        $comment = ForumEntry::getEditComment($description, $anonymous);
+        $content = formatReady($raw_content);
+
+        if ($comment) {
+            $content .= '<br><em>' . htmlReady($comment) . '</em>';
+        }
+
+        return $content;
+    }
+
+    /**
+     * Get author and time of an edited forum entry as a string.
+     *
+     * @param string  $description  Database entry of forum entry's body.
+     * @param bool    $anonymous    True, if only root is allowed to see
+     *                              authors.
+     * @return string  Author and time or empty string if not edited.
+     */
+    public static function getEditComment($description, $anonymous = false)
+    {
+        $info = ForumEntry::getEditInfo($description);
+        if ($info) {
+            $root = $GLOBALS['perm']->have_perm('root');
+            $author = ($anonymous && !$root) ? _('Anonym') : $info['author'];
+            $time = date('d.m.y - H:i', $info['time']);
+            return '[' . _('Zuletzt editiert von') . " $author - $time]";
+        }
+        return '';
+    }
+
+    /**
+     * Get author and time of an edited forum entry.
+     *
+     * @param string  $description  Database entry of forum entry's body.
+     * @return array    Associative array containing author and time.
+     *         boolean  False if edit tag was not found.
+     */
+    public static function getEditInfo($description) {
+        if (preg_match('/<admin_msg autor="([^"]*)" chdate="([^"]*)">\s*$/i', $description, $matches)) {
+            // wurde schon mal editiert
+            return ['author' => $matches[1], 'time' => $matches[2]];
+        }
+        return false;
+    }
+
+    /**
+     * Remove all quote blocks AND the quoted text from a forum post.
+     *
+     * @param String $string The string to remove the quote blocks from
+     * @return String the posting without the [quote]-blocks (not just tags!)
+     */
+    public static function removeQuotes($description)
+    {
+        if (Studip\Markup::isHtml($description)) {
+            // remove all blockquote tags
+            $dom = new DOMDocument();
+            $dom->loadHtml($description, LIBXML_HTML_NOIMPLIED | LIBXML_HTML_NODEFDTD);
+            $nodes = iterator_to_array($dom->getElementsByTagName('blockquote'));
+
+            foreach ($nodes as $node) {
+                $node->parentNode->removeChild($node);
+            }
+
+            return $dom->saveHTML();
+        } else {
+            $description = preg_replace('/\[quote(=.*)\].*\[\/quote\]/isU', '', $description);
+            $description = str_replace('[/quote]', '', $description);
+        }
+        return $description;
+    }
+
+
+    /**
+     * calls Stud.IP's kill_format and additionally removes any found smiley-tag
+     *
+     * @param string $text the text to parse
+     * @return string the text without format-tags and without smileys
+     */
+    public static function killFormat($text)
+    {
+        $text = kill_format($text);
+
+        // find stuff which is enclosed between to colons
+        preg_match('/' . SmileyFormat::REGEXP . '/U', $text, $matches);
+
+        // remove the match if it is a smiley
+        foreach ($matches as $match) {
+            if (Smiley::getByName($match) || Smiley::getByShort($match)) {
+                $text = str_replace($match, '', $text);
+            }
+        }
+
+        return $text;
+    }
+
+    /**
+     * returns the entry for the passed topic_id
+     *
+     * @param  string  $topic_id
+     * @return array   array('lft' => ..., 'rgt' => ..., seminar_id => ...)
+     *
+     * @throws Exception
+     */
+    public static function getConstraints($topic_id)
+    {
+        //very bad performance if topic_id is 0 or false
+        if (!$topic_id) return false;
+
+        // look up the range of postings
+        $range_stmt = DBManager::get()->prepare("SELECT *
+            FROM forum_entries WHERE topic_id = ?");
+        $range_stmt->execute([$topic_id]);
+        if (!$data = $range_stmt->fetch(PDO::FETCH_ASSOC)) {
+            return false;
+            // throw new Exception("Could not find entry with id >>$topic_id<< in forum_entries, " . __FILE__ . " on line " . __LINE__);
+        }
+
+        if ($data['depth'] == 1) {
+            $data['area'] = 1;
+        }
+
+        return $data;
+    }
+
+    /**
+     * return the topic_id of the parent element, false if there is none (ie the
+     * passed topic_id is already the upper-most node in the tree)
+     *
+     * @param string $topic_id the topic_id for which the parent shall be found
+     *
+     * @return string the topic_id of the parent element or false
+     */
+    public static function getParentTopicId($topic_id)
+    {
+        $path = ForumEntry::getPathToPosting($topic_id);
+        array_pop($path);
+        $data = array_pop($path);
+
+        return $data['id'] ?: false;
+    }
+
+
+    /**
+     * get the topic_ids of all childs of the passed topic including itself
+     *
+     * @param string $topic_id the topic_id to find the childs for
+     * @return array a list if topic_ids
+     */
+    public static function getChildTopicIds($topic_id)
+    {
+        $constraints = ForumEntry::getConstraints($topic_id);
+
+        $stmt = DBManager::get()->prepare("SELECT topic_id
+            FROM forum_entries WHERE lft >= ? AND rgt <= ?
+                AND seminar_id = ?");
+        $stmt->execute([$constraints['lft'], $constraints['rgt'], $constraints['seminar_id']]);
+
+        return $stmt->fetchAll(PDO::FETCH_COLUMN);
+    }
+
+    /* * * * * * * * * * * * * * * * * * * * * * * * * * * * *
+     * D   A   T   A   -   R   E   T   R   I   E   V   A   L *
+     * * * * * * * * * * * * * * * * * * * * * * * * * * * * */
+
+     /**
+      * get the page the passed posting is on
+      *
+      * @param  string  $topic_id
+      * @return  int
+      */
+    public static function getPostingPage($topic_id, $constraint = null)
+    {
+        if (!$constraint) {
+            $constraint = ForumEntry::getConstraints($topic_id);
+        }
+
+        // this calculation only works for postings
+        if ($constraint['depth'] <= 2) return ForumHelpers::getPage();
+
+        if ($parent_id = ForumEntry::getParentTopicId($topic_id)) {
+            $parent_constraint = ForumEntry::getConstraints($parent_id);
+
+            return ceil((($constraint['lft'] - $parent_constraint['lft'] + 3) / 2) / ForumEntry::POSTINGS_PER_PAGE);
+        }
+
+        return 0;
+    }
+
+    /**
+     * return the id for the oldest unread child-posting for the passed topic.
+     *
+     * @param string $parent_id
+     * @return string  id of oldest unread posting
+     */
+    public static function getLastUnread($parent_id)
+    {
+        $constraint = ForumEntry::getConstraints($parent_id);
+
+        // take users visitdate into account
+        $visitdate = ForumVisit::getLastVisit($constraint['seminar_id']);
+
+        // get the first unread entry
+        $stmt = DBManager::get()->prepare("SELECT * FROM forum_entries
+            WHERE lft > ? AND rgt < ? AND seminar_id = ?
+                AND mkdate >= ?
+            ORDER BY mkdate ASC LIMIT 1");
+        $stmt->execute([$constraint['lft'], $constraint['rgt'], $constraint['seminar_id'], $visitdate]);
+        $last_unread = $stmt->fetch(PDO::FETCH_ASSOC);
+
+        return $last_unread ? $last_unread['topic_id'] : null;
+    }
+
+    /**
+     * retrieve the the latest posting under $parent_id
+     * or false if the postings itself is the latest
+     *
+     * @param string $parent_id the node to lookup the childs in
+     * @return mixed the data for the latest postings or false
+     */
+    public static function getLatestPosting($parent_id)
+    {
+        $constraint = ForumEntry::getConstraints($parent_id);
+
+        // get last entry
+        $stmt = DBManager::get()->prepare("SELECT * FROM forum_entries
+            WHERE lft > ? AND rgt < ? AND seminar_id = ?
+            ORDER BY mkdate DESC LIMIT 1");
+        $stmt->execute([$constraint['lft'], $constraint['rgt'], $constraint['seminar_id']]);
+
+        if (!$data = $stmt->fetch(PDO::FETCH_ASSOC)) {
+            return false;
+        }
+
+        return $data;
+    }
+
+    /**
+     * returns a hashmap with arrays containing id and name with the entries
+     * which lead to the passed topic
+     *
+     * @param string $topic_id the topic to get the path for
+     *
+     * @return array
+     */
+    public static function getPathToPosting($topic_id)
+    {
+        $data = ForumEntry::getConstraints($topic_id);
+        $ret = [];
+
+        $stmt = DBManager::get()->prepare("SELECT * FROM forum_entries
+            WHERE lft <= ? AND rgt >= ? AND seminar_id = ? ORDER BY lft ASC");
+        $stmt->execute([$data['lft'], $data['rgt'], $data['seminar_id']]);
+
+        while ($data = $stmt->fetch(PDO::FETCH_ASSOC)) {
+            $ret[$data['topic_id']] = $data;
+            $ret[$data['topic_id']]['id'] = $data['topic_id'];
+        }
+
+        // set the name of the first entry to the name of the category the entry is in
+        if (sizeof($ret) > 1) {
+            reset($ret);
+            $tmp = array_slice($ret, 1, 1);
+            $area = array_pop($tmp);
+            $top  = current($ret);
+            $ret[$top['id']]['name'] = ForumCat::getCategoryNameForArea($area['id']) ?: _('Allgemein');
+        }
+
+        return $ret;
+    }
+
+    /**
+     * returns a hashmap where key is topic_id and value a posting-title from the
+     * entries which lead to the passed topic.
+     *
+     * WARNING: This function ommits postings with an empty title. For a full
+     * list please use ForumEntry::getPathToPosting()!
+     *
+     * @param string $topic_id the topic to get the path for
+     *
+     * @return array
+     */
+    public static function getFlatPathToPosting($topic_id)
+    {
+        // use only the part of the path until the thread, no posting title
+        $postings = array_slice(self::getPathToPosting($topic_id), 0, 3);
+
+        // var_dump($postings);
+
+        foreach ($postings as $post) {
+            if ($post['name']) {
+                $ret[$post['id']] = $post['name'];
+            }
+        }
+
+        return $ret;
+    }
+
+    /**
+     * fill the passed postings with additional data
+     *
+     * @param  array $postings
+     * @return array
+     */
+    public static function parseEntries($postings)
+    {
+        $posting_list = [];
+
+        // retrieve the postings
+        foreach ($postings as $data) {
+            // we throw away all formatting stuff, tags, etc, leaving the important bit of information
+            $desc_short = ForumEntry::br2space(ForumEntry::killFormat(strip_tags($data['content'])));
+            if (mb_strlen($desc_short) > (ForumEntry::THREAD_PREVIEW_LENGTH + 2)) {
+                $desc_short = mb_substr($desc_short, 0, ForumEntry::THREAD_PREVIEW_LENGTH) . '...';
+            } else {
+                $desc_short = $desc_short;
+            }
+
+            $posting_list[$data['topic_id']] = [
+                'author'          => $data['author'],
+                'topic_id'        => $data['topic_id'],
+                'name'            => formatReady($data['name']),
+                'name_raw'        => $data['name'],
+                'content'         => ForumEntry::getContentAsHtml($data['content'], $data['anonymous']),
+                'content_raw'     => ForumEntry::killEdit($data['content']),
+                'content_short'   => $desc_short,
+                'chdate'          => $data['chdate'],
+                'mkdate'          => $data['mkdate'],
+                'user_id'        => $data['user_id'],
+                'raw_title'       => $data['name'],
+                'raw_description' => ForumEntry::killEdit($data['content']),
+                'fav'             => ($data['fav'] == 'fav'),
+                'depth'           => $data['depth'],
+                'anonymous'       => $data['anonymous'],
+                'closed'          => $data['closed'],
+                'sticky'          => $data['sticky'],
+                'seminar_id'      => $data['seminar_id']
+            ];
+        } // retrieve the postings
+
+        return $posting_list;
+    }
+
+    /**
+     * Get all entries for the passed parent_id.
+     * Returns an array of the following structure:
+     * Array (
+     *     'list'  => Array (
+     *         'author'          =>
+     *         'topic_id'        =>
+     *         'name'            => formatReady()
+     *         'name_raw'        =>
+     *         'content'         => formatReady()
+     *         'content_raw'     =>
+     *         'content_short'   =>
+     *         'chdate'          =>
+     *         'mkdate'          =>
+     *         'user_id'        =>
+     *         'raw_title'       =>
+     *         'raw_description' =>
+     *         'fav'             =>
+     *         'depth'           =>
+     *         'sticky'          =>
+     *         'closed'          =>
+     *         'seminar_id'      =>
+     *     )
+     *     'count' =>
+     * )
+     *
+     * @param string $parent_id    id of parent-element to get entries for.
+     * @param boolean $with_childs  if true, the whole subtree is fetched
+     * @param string $add          for additional constraints in the WHERE-part of the query
+     * @param string $sort_order   can be ASC or DESC
+     * @param int $start        can be used for pagination, is used for the LIMIT-part of the query
+     * @param int $limit        number of entries to fetch, defaults to ForumEntry::POSTINGS_PER_PAGE
+     *
+     * @return array
+     *
+     * @throws Exception  if the retrieval failed, an Exception is thrown
+     */
+    public static function getEntries($parent_id, $with_childs = false, $add = '',
+        $sort_order = 'DESC', $start = 0, $limit = ForumEntry::POSTINGS_PER_PAGE)
+    {
+        $constraint = ForumEntry::getConstraints($parent_id);
+        $seminar_id = $constraint['seminar_id'];
+        $depth      = $constraint['depth'] + 1;
+
+        // count the entries and set correct page if necessary
+        if ($with_childs) {
+            $count_stmt = DBManager::get()->prepare("SELECT COUNT(*) FROM forum_entries
+                LEFT JOIN forum_favorites as ou ON (ou.topic_id = forum_entries.topic_id AND ou.user_id = ?)
+                WHERE (forum_entries.seminar_id = ?
+                    AND forum_entries.seminar_id != forum_entries.topic_id
+                    AND lft > ? AND rgt < ?) "
+                . ($depth > 2 ? " OR forum_entries.topic_id = ". DBManager::get()->quote($parent_id) : '')
+                . $add
+                . " ORDER BY forum_entries.mkdate $sort_order");
+            $count_stmt->execute([$GLOBALS['user']->id, $seminar_id, $constraint['lft'], $constraint['rgt']]);
+            $count = $count_stmt->fetchColumn();
+        } else {
+            $count_stmt = DBManager::get()->prepare("SELECT COUNT(*) FROM forum_entries
+                LEFT JOIN forum_favorites as ou ON (ou.topic_id = forum_entries.topic_id AND ou.user_id = ?)
+                WHERE ((depth = ? AND forum_entries.seminar_id = ?
+                    AND forum_entries.seminar_id != forum_entries.topic_id
+                    AND lft > ? AND rgt < ?) "
+                . ($depth > 2 ? " OR forum_entries.topic_id = ". DBManager::get()->quote($parent_id) : '')
+                . ') '. $add
+                . " ORDER BY forum_entries.mkdate $sort_order");
+            $count_stmt->execute([$GLOBALS['user']->id, $depth, $seminar_id, $constraint['lft'], $constraint['rgt']]);
+            $count = $count_stmt->fetchColumn();
+        }
+
+        // use the last page if the requested page does not exist
+        if ($start > $count) {
+            $page = ceil($count / ForumEntry::POSTINGS_PER_PAGE);
+            ForumHelpers::setPage($page);
+            $start = max(1, $page - 1) * ForumEntry::POSTINGS_PER_PAGE;
+        }
+
+        if ($with_childs) {
+            $stmt = DBManager::get()->prepare("SELECT forum_entries.*, IF(ou.topic_id IS NOT NULL, 'fav', NULL) as fav
+                    FROM forum_entries
+                LEFT JOIN forum_favorites as ou ON (ou.topic_id = forum_entries.topic_id AND ou.user_id = ?)
+                WHERE (forum_entries.seminar_id = ?
+                    AND forum_entries.seminar_id != forum_entries.topic_id
+                    AND lft > ? AND rgt < ?) "
+                . ($depth > 2 ? " OR forum_entries.topic_id = ". DBManager::get()->quote($parent_id) : '')
+                . $add
+                . " ORDER BY forum_entries.mkdate $sort_order"
+                . ($limit ? " LIMIT $start, $limit" : ''));
+            $stmt->execute([$GLOBALS['user']->id, $seminar_id, $constraint['lft'], $constraint['rgt']]);
+        } else {
+            $stmt = DBManager::get()->prepare("SELECT forum_entries.*, IF(ou.topic_id IS NOT NULL, 'fav', NULL) as fav
+                    FROM forum_entries
+                LEFT JOIN forum_favorites as ou ON (ou.topic_id = forum_entries.topic_id AND ou.user_id = ?)
+                WHERE ((depth = ? AND forum_entries.seminar_id = ?
+                    AND lft > ? AND rgt < ?) "
+                . ($depth > 2 ? " OR forum_entries.topic_id = ". DBManager::get()->quote($parent_id) : '')
+                . ') '. $add
+                . " ORDER BY forum_entries.mkdate $sort_order"
+                . ($limit ? " LIMIT $start, $limit" : ''));
+            $stmt->execute([$GLOBALS['user']->id, $depth, $seminar_id, $constraint['lft'], $constraint['rgt']]);
+        }
+
+        if (!$stmt) {
+            throw new Exception("Error while retrieving postings in " . __FILE__ . " on line " . __LINE__);
+        }
+
+        return ['list' => ForumEntry::parseEntries($stmt->fetchAll(PDO::FETCH_ASSOC)), 'count' => $count];
+    }
+
+
+    /**
+     * Takes a posting-array like the one generated by ForumEntry::getList()
+     * and adds the child-posting with the freshest creation-date to it.
+     *
+     * @param array $postings
+     * @return array
+     */
+    public static function getLastPostings($postings)
+    {
+        foreach ($postings as $key => $posting) {
+
+            if ($data = ForumEntry::getLatestPosting($posting['topic_id'])) {
+                $last_posting['topic_id']      = $data['topic_id'];
+                $last_posting['date']          = $data['mkdate'];
+                $last_posting['user_id']       = $data['user_id'];
+                $last_posting['user_fullname'] = $data['author'];
+                $last_posting['username']      = get_username($data['user_id']);
+                $last_posting['anonymous']     = $data['anonymous'];
+
+                // we throw away all formatting stuff, tags, etc, so we have just the important bit of information
+                $text = strip_tags($data['name']);
+                $text = ForumEntry::br2space($text);
+                $text = ForumEntry::killFormat(ForumEntry::removeQuotes($text));
+
+                if (mb_strlen($text) > 42) {
+                    $text = mb_substr($text, 0, 40) . '...';
+                }
+
+                $last_posting['text'] = $text;
+            }
+
+            $postings[$key]['last_posting'] = $last_posting;
+            if (!$postings[$key]['last_unread']  = ForumEntry::getLastUnread($posting['topic_id'])) {
+                $postings[$key]['last_unread'] = $last_posting['topic_id'];
+            }
+            $postings[$key]['num_postings'] = ForumEntry::countEntries($posting['topic_id']);
+
+            unset($last_posting);
+        }
+
+        return $postings;
+    }
+
+    /**
+     * get a list of postings of a special type
+     *
+     * @param string $type one of 'area', 'list', 'postings', 'latest', 'favorites', 'dump', 'flat'
+     * @param string $parent_id the are to fetch from
+     * @return array array('list' => ..., 'count' => ...);
+     */
+    public static function getList($type, $parent_id)
+    {
+        $start = (ForumHelpers::getPage() - 1) * ForumEntry::POSTINGS_PER_PAGE;
+
+        switch ($type) {
+            case 'area':
+                $list = ForumEntry::getEntries($parent_id, ForumEntry::WITHOUT_CHILDS, '', 'DESC', 0, 1000);
+                $postings = $list['list'];
+
+                $postings = ForumEntry::getLastPostings($postings);
+                return ['list' => $postings, 'count' => $list['count']];
+
+                break;
+
+            case 'list':
+                $constraint = ForumEntry::getConstraints($parent_id);
+
+                // purpose of the following query is to retrieve the threads
+                // for an area ordered by the mkdate of their latest posting
+                $stmt = DBManager::get()->prepare("SELECT SQL_CALC_FOUND_ROWS
+                        fe.*, IF(ou.topic_id IS NOT NULL, 'fav', NULL) as fav
+                    FROM forum_entries AS fe
+                    LEFT JOIN forum_favorites as ou ON (ou.topic_id = fe.topic_id AND ou.user_id = :user_id)
+                    WHERE fe.seminar_id = :seminar_id AND fe.lft > :left
+                        AND fe.rgt < :right AND fe.depth = 2
+                    ORDER BY sticky DESC, latest_chdate DESC
+                    LIMIT $start, ". ForumEntry::POSTINGS_PER_PAGE);
+                $stmt->bindParam(':seminar_id', $constraint['seminar_id']);
+                $stmt->bindParam(':left', $constraint['lft'], PDO::PARAM_INT);
+                $stmt->bindParam(':right', $constraint['rgt'], PDO::PARAM_INT);
+                $stmt->bindParam(':user_id', $GLOBALS['user']->id);
+                $stmt->execute();
+
+                $postings = $stmt->fetchAll(PDO::FETCH_ASSOC);
+                $count = DBManager::get()->query("SELECT FOUND_ROWS()")->fetchColumn();
+                $postings = ForumEntry::parseEntries($postings);
+                $postings = ForumEntry::getLastPostings($postings);
+
+                return ['list' => $postings, 'count' => $count];
+                break;
+
+            case 'postings':
+                return ForumEntry::getEntries($parent_id, ForumEntry::WITH_CHILDS, '', 'ASC', $start);
+                break;
+
+            case 'newest':
+                $constraint = ForumEntry::getConstraints($parent_id);
+
+                // get postings
+                $stmt = DBManager::get()->prepare("SELECT forum_entries.*, IF(ou.topic_id IS NOT NULL, 'fav', NULL) as fav
+                    FROM forum_entries
+                    LEFT JOIN forum_favorites as ou ON (ou.topic_id = forum_entries.topic_id AND ou.user_id = :user_id)
+                    WHERE seminar_id = :seminar_id AND lft > :left
+                        AND rgt < :right AND (mkdate >= :mkdate OR chdate >= :mkdate)
+                    ORDER BY mkdate ASC
+                    LIMIT $start, ". ForumEntry::POSTINGS_PER_PAGE);
+
+                $stmt->bindParam(':seminar_id', $constraint['seminar_id']);
+                $stmt->bindParam(':left', $constraint['lft']);
+                $stmt->bindParam(':right', $constraint['rgt']);
+                $stmt->bindParam(':mkdate', ForumVisit::getLastVisit($constraint['seminar_id']));
+                $stmt->bindParam(':user_id', $GLOBALS['user']->id);
+                $stmt->execute();
+
+                $postings = $stmt->fetchAll(PDO::FETCH_ASSOC);
+
+                $postings = ForumEntry::parseEntries($postings);
+                // var_dump($postings);
+
+                // count found postings
+                $stmt_count = DBManager::get()->prepare("SELECT COUNT(*)
+                    FROM forum_entries
+                    WHERE seminar_id = :seminar_id AND lft > :left
+                        AND rgt < :right AND mkdate >= :mkdate
+                    ORDER BY mkdate ASC");
+
+                $stmt_count->bindParam(':seminar_id', $constraint['seminar_id']);
+                $stmt_count->bindParam(':left', $constraint['lft']);
+                $stmt_count->bindParam(':right', $constraint['rgt']);
+                $stmt_count->bindParam(':mkdate', ForumVisit::getLastVisit($constraint['seminar_id']));
+                $stmt_count->execute();
+
+
+                // return results
+                return ['list' => $postings, 'count' => $stmt_count->fetchColumn()];
+                break;
+
+            case 'latest':
+                return ForumEntry::getEntries($parent_id, ForumEntry::WITH_CHILDS, '', 'DESC', $start);
+                break;
+
+            case 'favorites':
+                $add = "AND ou.topic_id IS NOT NULL";
+                return ForumEntry::getEntries($parent_id, ForumEntry::WITH_CHILDS, $add, 'DESC', $start);
+                break;
+
+            case 'dump':
+                $constraint = ForumEntry::getConstraints($parent_id);
+                $seminar_id = $constraint['seminar_id'];
+                $depth      = $constraint['depth'] + 1;
+
+                $stmt = DBManager::get()->prepare("SELECT * FROM forum_entries
+                    WHERE (forum_entries.seminar_id = ?
+                        AND forum_entries.seminar_id != forum_entries.topic_id
+                        AND lft > ? AND rgt < ?) "
+                    . ($depth > 2 ? " OR forum_entries.topic_id = ". DBManager::get()->quote($parent_id) : '')
+                    . " ORDER BY forum_entries.lft ASC");
+                $stmt->execute([$seminar_id, $constraint['lft'], $constraint['rgt']]);
+
+                return ForumEntry::parseEntries($stmt->fetchAll(PDO::FETCH_ASSOC));
+                break;
+
+            case 'flat':
+                $constraint = ForumEntry::getConstraints($parent_id);
+
+                $stmt = DBManager::get()->prepare("SELECT SQL_CALC_FOUND_ROWS * FROM forum_entries
+                    WHERE lft > ? AND rgt < ? AND seminar_id = ? AND depth = ?
+                    ORDER BY name ASC");
+                $stmt->execute([$constraint['lft'], $constraint['rgt'], $constraint['seminar_id'], $constraint['depth'] + 1]);
+
+                $count = DBManager::get()->query("SELECT FOUND_ROWS()")->fetchColumn();
+
+                $posting_list = [];
+
+                // speed up things a bit by leaving out the formatReady fields
+                foreach ($stmt->fetchAll(PDO::FETCH_ASSOC) as $data) {
+                    // we throw away all formatting stuff, tags, etc, leaving the important bit of information
+                    $desc_short = ForumEntry::br2space(ForumEntry::killFormat(strip_tags($data['content'])));
+                    if (mb_strlen($desc_short) > (ForumEntry::THREAD_PREVIEW_LENGTH + 2)) {
+                        $desc_short = mb_substr($desc_short, 0, ForumEntry::THREAD_PREVIEW_LENGTH) . '...';
+                    } else {
+                        $desc_short = $desc_short;
+                    }
+                    $posting_list[$data['topic_id']] = [
+                        'author'          => $data['author'],
+                        'topic_id'        => $data['topic_id'],
+                        'name_raw'        => $data['name'],
+                        'content_raw'     => ForumEntry::killEdit($data['content']),
+                        'content_short'   => $desc_short,
+                        'chdate'          => $data['chdate'],
+                        'mkdate'          => $data['mkdate'],
+                        'user_id'         => $data['user_id'],
+                        'raw_title'       => $data['name'],
+                        'raw_description' => ForumEntry::killEdit($data['content']),
+                        'fav'             => ($data['fav'] == 'fav'),
+                        'depth'           => $data['depth'],
+                        'seminar_id'      => $data['seminar_id']
+                    ];
+                }
+
+                return ['list' => $posting_list, 'count' => $count];
+                break;
+
+            case 'depth_to_large':
+                $constraint = ForumEntry::getConstraints($parent_id);
+
+                $stmt = DBManager::get()->prepare("SELECT SQL_CALC_FOUND_ROWS * FROM forum_entries
+                    WHERE lft > ? AND rgt < ? AND seminar_id = ? AND depth > 3
+                    ORDER BY name ASC");
+                $stmt->execute([$constraint['lft'], $constraint['rgt'], $constraint['seminar_id']]);
+
+                $count = DBManager::get()->query("SELECT FOUND_ROWS()")->fetchColumn();
+
+                return ['list' => $stmt->fetchAll(PDO::FETCH_ASSOC), 'count' => $count];
+                break;
+        }
+    }
+
+    /**
+     * Get the latest forum entries for the passed entries childs
+     *
+     * @param string $parent_id
+     * @param int $start_date  timestamp
+     * @param int $end_date    timestamp
+     *
+     * @return array list of postings
+     */
+    public static function getLatestSince($parent_id, $start_date, $end_date)
+    {
+        $constraint = ForumEntry::getConstraints($parent_id);
+
+        $stmt = DBManager::get()->prepare("SELECT SQL_CALC_FOUND_ROWS * FROM forum_entries
+            WHERE lft > ? AND rgt < ? AND seminar_id = ?
+                AND mkdate BETWEEN ? AND ?
+            ORDER BY name ASC");
+        $stmt->execute([$constraint['lft'], $constraint['rgt'], $constraint['seminar_id'], $start_date, $end_date]);
+
+        return $stmt->fetchAll(PDO::FETCH_ASSOC);
+    }
+
+    /**
+     ** returns a list of postings for the passed search-term
+     *
+     * @param string $parent_id the area to search in (can be a whole seminar)
+     * @param string $_searchfor the term to search for
+     * @param array $options filter-options: search_title, search_content, search_author
+     * @return array array('list' => ..., 'count' => ...);
+     */
+    public static function getSearchResults($parent_id, $_searchfor, $options)
+    {
+        $start = (ForumHelpers::getPage() - 1) * ForumEntry::POSTINGS_PER_PAGE;
+
+        // if there are quoted parts, they should not be separated
+        $suchmuster = '/".*"/U';
+        preg_match_all($suchmuster, $_searchfor, $treffer);
+        array_walk($treffer[0], function(&$value) { $value = trim($value, '"'); });
+
+        // remove the quoted parts from $_searchfor
+        $_searchfor = trim(preg_replace($suchmuster, '', $_searchfor));
+
+        // split the searchstring $_searchfor at every space
+        $parts = explode(' ', $_searchfor);
+
+        foreach ($parts as $key => $val) {
+            if ($val == '') {
+                unset($parts[$key]);
+            }
+        }
+
+        if (!empty($parts)) {
+            $_searchfor = array_merge($parts, $treffer[0]);
+        } else  {
+            $_searchfor = $treffer[0];
+        }
+
+        // make an SQL-statement out of the searchstring
+        $search_string = [];
+        foreach ($_searchfor as $key => $val) {
+            if (!$val) {
+                unset($_searchfor[$key]);
+            } else {
+                $search_word = '%'. $val .'%';
+                $zw_search_string = [];
+                if ($options['search_title']) {
+                    $zw_search_string[] .= "name LIKE " . DBManager::get()->quote($search_word);
+                }
+
+                if ($options['search_content']) {
+                    $zw_search_string[] .= "content LIKE " . DBManager::get()->quote($search_word);
+                }
+
+                if ($options['search_author']) {
+                    $zw_search_string[] .= "author LIKE " . DBManager::get()->quote($search_word);
+                }
+
+                if (!empty($zw_search_string)) {
+                    $search_string[] = '(' . implode(' OR ', $zw_search_string) . ')';
+                }
+            }
+        }
+
+        if (!empty($search_string)) {
+            $add = "AND (" . implode(' AND ', $search_string) . ")";
+            return array_merge(
+                ['highlight' => $_searchfor],
+                ForumEntry::getEntries($parent_id, ForumEntry::WITH_CHILDS, $add, 'DESC', $start)
+            );
+        }
+
+        return ['num_postings' => 0, 'list' => []];
+    }
+
+    /**
+     * returns the entry for the passed topic_id
+     *
+     * @param string $topic_id
+     * @return array hash-array with the entries fields
+     */
+    public static function getEntry($topic_id)
+    {
+        return ForumEntry::getConstraints($topic_id);
+    }
+
+    /**
+     * Count the number of child-elements that the passed entry has and return it.
+     *
+     * @param string $parent_id
+     *
+     * @return int  the number of child entries for the passed entry
+     */
+    public static function countEntries($parent_id)
+    {
+        $data = ForumEntry::getConstraints($parent_id);
+        return max((($data['rgt'] - $data['lft'] - 1) / 2) + 1, 0);
+    }
+
+    /**
+    * Count the number of postings in a given course and return it.
+    *
+    * @param string $course_id the id of the given course
+    *
+    * @return int the number of postings in the course
+    */
+    public static function countPostings($course_id)
+    {
+        $stmt = DBManager::get()->prepare("SELECT COUNT(*) FROM forum_entries
+            WHERE seminar_id = ? AND depth >= 2");
+        $stmt->execute([$course_id]);
+
+        return $stmt->fetchColumn(0);
+    }
+
+    /**
+     * Count all entries the passed user has ever written and return the result
+     *
+     * @staticvar type $entries
+     *
+     * @param string $user_id
+     *
+     * @return int  number of entries user has ever written
+     */
+    public static function countUserEntries($user_id, $seminar_id = null)
+    {
+        static $entries;
+
+        if (!$entries[$user_id]) {
+            $stmt = DBManager::get()->prepare("SELECT COUNT(*)
+                FROM forum_entries
+                WHERE user_id = ? AND seminar_id = IFNULL(?, seminar_id)");
+            $stmt->execute([$user_id, $seminar_id]);
+
+            $entries[$user_id] = $stmt->fetchColumn();
+        }
+
+        return $entries[$user_id];
+    }
+
+    /* * * * * * * * * * * * * * * * * * * * * * * * * * * * *
+     *   D   A   T   A   -   C   R   E   A   T   I   O   N   *
+     * * * * * * * * * * * * * * * * * * * * * * * * * * * * */
+
+    /**
+     * insert a node into the table
+     *
+     * @param array $data an array containing the following fields:
+     *     topic_id     the id of the new topic
+     *     seminar_id   the id of the seminar to add the topic to
+     *     user_id      the id of the user who created the topic
+     *     name         the title of the entry
+     *     content      the content of the entry
+     *     author       the author's name as a plaintext string
+     *     author_host  ip-address of creator
+     * @param string $parent_id the node to add the topic to
+     *
+     * @return void
+     */
+    public static function insert($data, $parent_id)
+    {
+        $constraint = ForumEntry::getConstraints($parent_id);
+
+        // #TODO: Zusammenfassen in eine Transaktion!!!
+        DBManager::get()->exec('UPDATE forum_entries SET lft = lft + 2
+            WHERE lft > '. $constraint['rgt'] ." AND seminar_id = '". $constraint['seminar_id'] ."'");
+        DBManager::get()->exec('UPDATE forum_entries SET rgt = rgt + 2
+            WHERE rgt >= '. $constraint['rgt'] ." AND seminar_id = '". $constraint['seminar_id'] ."'");
+
+        $stmt = DBManager::get()->prepare("INSERT INTO forum_entries
+            (topic_id, seminar_id, user_id, name, content, mkdate, latest_chdate,
+                chdate, author, author_host, lft, rgt, depth, anonymous)
+            VALUES (? ,?, ?, ?, ?, UNIX_TIMESTAMP(), UNIX_TIMESTAMP(), UNIX_TIMESTAMP(), ?, ?, ?, ?, ?, ?)");
+        $stmt->execute([$data['topic_id'], $data['seminar_id'], $data['user_id'],
+            $data['name'], transformBeforeSave($data['content']), $data['author'], $data['author_host'],
+            $constraint['rgt'], $constraint['rgt'] + 1, $constraint['depth'] + 1, $data['anonymous'] ? : 0]);
+
+        // update "latest_chdate" for easier sorting of actual threads
+        DBManager::get()->exec("UPDATE forum_entries SET latest_chdate = UNIX_TIMESTAMP()
+            WHERE topic_id = '" . $constraint['topic_id'] . "'");
+
+        NotificationCenter::postNotification('ForumAfterInsert', $data['topic_id'], $data);
+    }
+
+
+    /**
+     * update the passed topic
+     *
+     * @param string $topic_id the id of the topic to update
+     * @param string $name the new name
+     * @param string $content the new content
+     *
+     * @return void
+     */
+    public static function update($topic_id, $name, $content)
+    {
+        $post = ForumEntry::getConstraints($topic_id);
+
+        if (time() - $post['mkdate'] > 5 * 60) {
+            $content = ForumEntry::appendEdit($content);
+        }
+
+        $stmt = DBManager::get()->prepare("UPDATE forum_entries
+            SET name = ?, content = ?, chdate = UNIX_TIMESTAMP(), latest_chdate = UNIX_TIMESTAMP()
+            WHERE topic_id = ?");
+        $stmt->execute([$name, transformBeforeSave($content), $topic_id]);
+
+        // update "latest_chdate" for easier sorting of actual threads
+        $parent_id = ForumEntry::getParentTopicId($topic_id);
+        DBManager::get()->exec("UPDATE forum_entries SET latest_chdate = UNIX_TIMESTAMP()
+            WHERE topic_id = '" . $parent_id . "'");
+
+        $post['name']    = $name;
+        $post['content'] = $content;
+
+        NotificationCenter::postNotification('ForumAfterUpdate', $topic_id, $post);
+    }
+
+    /**
+     * delete an entry and all his descendants from the mptt-table
+     *
+     * @param string $topic_id the id of the entry to delete
+     *
+     * @return void
+     */
+    public static function delete($topic_id)
+    {
+        $post   = ForumEntry::getConstraints($topic_id);
+        $parent = ForumEntry::getConstraints(ForumEntry::getParentTopicId($topic_id));
+
+        NotificationCenter::postNotification('ForumBeforeDelete', $topic_id, $post);
+
+        // #TODO: Zusammenfassen in eine Transaktion!!!
+        // get all entry-ids to delete them from the category-reference-table
+        $stmt = DBManager::get()->prepare("SELECT topic_id FROM forum_entries
+            WHERE seminar_id = ? AND lft >= ? AND rgt <= ? AND depth = 1");
+        $stmt->execute([$post['seminar_id'], $post['lft'], $post['rgt']]);
+        $ids = $stmt->fetchAll(PDO::FETCH_COLUMN);
+
+        if ($ids != false && !is_array($ids)) $ids = [$ids];
+
+        if (!empty($ids)) {
+            $stmt = DBManager::get()->prepare("DELETE FROM forum_categories_entries
+                WHERE topic_id IN (:ids)");
+            $stmt->bindParam(':ids', $ids, StudipPDO::PARAM_ARRAY);
+            $stmt->execute();
+        }
+
+        // delete all entries
+        $stmt = DBManager::get()->prepare("DELETE FROM forum_entries
+            WHERE seminar_id = ? AND lft >= ? AND rgt <= ?");
+
+        $stmt->execute([$post['seminar_id'], $post['lft'], $post['rgt']]);
+
+        // update lft and rgt
+        $diff = $post['rgt'] - $post['lft'] + 1;
+        $stmt = DBManager::get()->prepare("UPDATE forum_entries SET lft = lft - $diff
+            WHERE lft > ? AND seminar_id = ?");
+        $stmt->execute([$post['rgt'], $post['seminar_id']]);
+
+        $stmt = DBManager::get()->prepare("UPDATE forum_entries SET rgt = rgt - $diff
+            WHERE rgt > ? AND seminar_id = ?");
+        $stmt->execute([$post['rgt'], $post['seminar_id']]);
+
+
+        // set the latest_chdate to the latest child's chdate
+        $stmt = DBManager::get()->prepare("SELECT chdate FROM forum_entries
+            WHERE lft > ? AND rgt < ? AND seminar_id = ?
+            ORDER BY chdate DESC LIMIT 1");
+        $stmt->execute([$parent['lft'], $parent['rgt'], $parent['seminar_id']]);
+        $chdate = $stmt->fetchColumn();
+
+        $stmt_insert = DBManager::get()->prepare("UPDATE forum_entries
+            SET chdate = ? WHERE topic_id = ?");
+        if ($chdate) {
+            $stmt_insert->execute([$chdate, $parent['topic_id']]);
+        } else {
+            $stmt_insert->execute([$parent['chdate'], $parent['topic_id']]);
+        }
+    }
+
+    /**
+     * move the passed topic to the passed area
+     *
+     * @param string $topic_id the topic to move
+     * @param string $destination the area_id where the topic is moved to
+     *
+     * @return void
+     */
+    public static function move($topic_id, $destination)
+    {
+        // #TODO: Zusammenfassen in eine Transaktion!!!
+        $constraints = ForumEntry::getConstraints($topic_id);
+
+        // move the affected entries "outside" the tree
+        $stmt = DBManager::get()->prepare("UPDATE forum_entries
+            SET lft = lft * -1, rgt = rgt * -1
+            WHERE seminar_id = ? AND lft >= ? AND rgt <= ?");
+        $stmt->execute([$constraints['seminar_id'], $constraints['lft'], $constraints['rgt']]);
+
+        // update the lft and rgt values of the parent to reflect the "deletion"
+        $diff = $constraints['rgt'] - $constraints['lft'] + 1;
+        $stmt = DBManager::get()->prepare("UPDATE forum_entries SET lft = lft - ?
+            WHERE lft > ? AND seminar_id = ?");
+        $stmt->execute([$diff, $constraints['rgt'], $constraints['seminar_id']]);
+
+        $stmt = DBManager::get()->prepare("UPDATE forum_entries SET rgt = rgt - ?
+            WHERE rgt > ? AND seminar_id = ?");
+        $stmt->execute([$diff, $constraints['rgt'], $constraints['seminar_id']]);
+
+        // make some space by updating the lft and rgt values of the target node
+        $constraints_destination = ForumEntry::getConstraints($destination);
+        $size = $constraints['rgt'] - $constraints['lft'] + 1;
+
+        $stmt = DBManager::get()->prepare("UPDATE forum_entries SET lft = lft + ?
+            WHERE lft > ? AND seminar_id = ?");
+        $stmt->execute([$size, $constraints_destination['rgt'], $constraints_destination['seminar_id']]);
+
+        $stmt = DBManager::get()->prepare("UPDATE forum_entries SET rgt = rgt + ?
+            WHERE rgt >= ? AND seminar_id = ?");
+        $stmt->execute([$size, $constraints_destination['rgt'], $constraints_destination['seminar_id']]);
+
+        //move the entries from "outside" the tree to the target node
+        $constraints_destination = ForumEntry::getConstraints($destination);
+
+
+        // update the depth to reflect the new position in the tree
+        // determine if we need to add, subtract or even do nothing to/from the depth
+        $depth_mod = $constraints_destination['depth'] - $constraints['depth'] + 1;
+
+        $stmt = DBManager::get()->prepare("UPDATE forum_entries
+            SET depth = depth + ?
+            WHERE seminar_id = ? AND lft < 0");
+        $stmt->execute([$depth_mod, $constraints_destination['seminar_id']]);
+
+        // if the depth is larger than 3, fix it
+        $stmt = DBManager::get()->prepare("UPDATE forum_entries
+            SET depth = 3
+            WHERE seminar_id = ? AND depth > 3 AND lft < 0");
+        $stmt->execute([$constraints_destination['seminar_id']]);
+
+        // move the tree to its destination
+        $diff = ($constraints_destination['rgt'] - ($constraints['rgt'] - $constraints['lft'])) - 1 - $constraints['lft'];
+
+        $stmt = DBManager::get()->prepare("UPDATE forum_entries
+            SET lft = (lft * -1) + ?, rgt = (rgt * -1) + ?
+            WHERE seminar_id = ? AND lft < 0");
+        $stmt->execute([$diff, $diff, $constraints_destination['seminar_id']]);
+
+        if ($depth_mod != 0) {
+            self::fix_ordering($topic_id);
+        }
+    }
+
+    private static function fix_ordering($parent_id)
+    {
+        $db = DBManager::get();
+
+        $entry = ForumEntry::getConstraints($parent_id);
+
+        $stmt= $db->prepare('SELECT topic_id FROM forum_entries
+                               WHERE lft > ? AND rgt < ? AND depth = 3
+                                    AND seminar_id = ?
+                               ORDER BY mkdate');
+
+        $stmt->execute([$entry['lft'], $entry['rgt'], $entry['seminar_id']]);
+
+        $lft = $entry['lft'] + 1;
+        $rgt = $lft + 1;
+
+        $inner_stmt = $db->prepare("UPDATE forum_entries SET lft=?, rgt=?
+            WHERE topic_id = ?");
+        while ($topic_id = $stmt->fetchColumn()) {
+            $inner_stmt->execute([$lft, $rgt, $topic_id]);
+
+            $lft += 2;
+            $rgt += 2;
+        }
+    }
+
+    /**
+     * close the passed topic
+     *
+     * @param string $topic_id the topic to close
+     *
+     * @return void
+     */
+    public static function close($topic_id)
+    {
+        // close all entries belonging to the topic
+        $stmt = DBManager::get()->prepare("UPDATE forum_entries
+            SET closed = 1
+            WHERE topic_id = ?");
+        $stmt->execute([$topic_id]);
+    }
+
+    /**
+     * open the passed topic
+     *
+     * @param string $topic_id the topic to open
+     *
+     * @return void
+     */
+    public static function open($topic_id)
+    {
+        // open all entries belonging to the topic
+        $stmt = DBManager::get()->prepare("UPDATE forum_entries
+            SET closed = 0
+            WHERE topic_id = ?");
+        $stmt->execute([$topic_id]);
+    }
+
+    /**
+     * make the passed topic sticky
+     *
+     * @param string $topic_id the topic to make sticky
+     *
+     * @return void
+     */
+    public static function sticky($topic_id)
+    {
+        // open all entries belonging to the topic
+        $stmt = DBManager::get()->prepare("UPDATE forum_entries
+            SET sticky = 1
+            WHERE topic_id = ?");
+        $stmt->execute([$topic_id]);
+    }
+
+    /**
+     * make the passed topic unsticky
+     *
+     * @param string $topic_id the topic to make unsticky
+     *
+     * @return void
+     */
+    public static function unsticky($topic_id)
+    {
+        // open all entries belonging to the topic
+        $stmt = DBManager::get()->prepare("UPDATE forum_entries
+            SET sticky = 0
+            WHERE topic_id = ?");
+        $stmt->execute([$topic_id]);
+    }
+
+    /**
+     * check, if the default root-node for this seminar exists and make sure
+     * the default category exists as well
+     *
+     * @param string $seminar_id
+     *
+     * @return void
+     */
+    public static function checkRootEntry($seminar_id)
+    {
+        setTempLanguage();
+
+        // check, if the root entry in the topic tree exists
+        $stmt = DBManager::get()->prepare("SELECT COUNT(*) FROM forum_entries
+            WHERE topic_id = ? AND seminar_id = ?");
+        $stmt->execute([$seminar_id, $seminar_id]);
+        if ($stmt->fetchColumn() == 0) {
+            $stmt = DBManager::get()->prepare("INSERT INTO forum_entries
+                (topic_id, seminar_id, name, mkdate, chdate, lft, rgt, depth)
+                VALUES (?, ?, 'Übersicht', UNIX_TIMESTAMP(), UNIX_TIMESTAMP(), 0, 1, 0)");
+            $stmt->execute([$seminar_id, $seminar_id]);
+        }
+
+
+        // make sure, that the category "Allgemein" exists
+        $stmt = DBManager::get()->prepare("INSERT IGNORE INTO forum_categories
+            (category_id, seminar_id, entry_name) VALUES (?, ?, ?)");
+        $stmt->execute([$seminar_id, $seminar_id, _('Allgemein')]);
+
+        // make sure that the default area "Allgemeine Diskussionen" exists, if there is nothing else present
+        $stmt = DBManager::get()->prepare("SELECT COUNT(*) FROM forum_entries
+            WHERE seminar_id = ? AND depth = 1");
+        $stmt->execute([$seminar_id]);
+
+        // add default area
+        if ($stmt->fetchColumn() == 0) {
+            $data = [
+                'topic_id'    => md5(uniqid()),
+                'seminar_id'  => $seminar_id,
+                'user_id'     => '',
+                'name'        => _('Allgemeine Diskussion'),
+                'content'     => _('Hier ist Raum für allgemeine Diskussionen'),
+                'author'      => '',
+                'author_host' => ''
+            ];
+            ForumEntry::insert($data, $seminar_id);
+        }
+
+        restoreLanguage();
+    }
+
+    /**
+     * returns the ten most active seminars
+     *
+     * @return array
+     */
+    public static function getTopTenSeminars()
+    {
+        return DBManager::get()->query("SELECT a.seminar_id, b.name AS display,
+            count( a.seminar_id ) AS count FROM forum_entries a
+            INNER JOIN seminare b USING ( seminar_id )
+            WHERE b.visible = 1
+            AND a.mkdate > UNIX_TIMESTAMP( NOW( ) - INTERVAL 2 WEEK )
+            GROUP BY a.seminar_id
+            ORDER BY count DESC
+            LIMIT 10")->fetchAll(PDO::FETCH_ASSOC);
+    }
+
+    /**
+     * count all entries that exists in the whole installation and return it.
+     *
+     * @return int
+     */
+    public static function countAllEntries()
+    {
+        return count_table_rows('forum_entries');
+    }
+
+    /**
+     * updates the user-entries and replaces the old user-id by the new one
+     *
+     * @param string $user_from
+     * @param string $user_to
+     */
+    public static function migrateUser($user_from, $user_to)
+    {
+        $stmt = DBManager::get()->prepare("UPDATE forum_entries SET user_id = ? WHERE user_id = ?");
+        $stmt->execute([$user_to, $user_from]);
+
+        $stmt = DBManager::get()->prepare("UPDATE IGNORE forum_favorites SET user_id = ? WHERE user_id = ?");
+        $stmt->execute([$user_to, $user_from]);
+
+        $stmt = DBManager::get()->prepare("UPDATE IGNORE forum_visits SET user_id = ? WHERE user_id = ?");
+        $stmt->execute([$user_to, $user_from]);
+
+        $stmt = DBManager::get()->prepare("UPDATE IGNORE forum_likes SET user_id = ? WHERE user_id = ?");
+        $stmt->execute([$user_to, $user_from]);
+
+        $stmt = DBManager::get()->prepare("UPDATE IGNORE forum_abo_users SET user_id = ? WHERE user_id = ?");
+        $stmt->execute([$user_to, $user_from]);
+    }
+
+    /**
+     * returns the complete seminar or only the passed sub-tree as a html-string
+     *
+     * @param string $seminar_id
+     *
+     * @return string
+     */
+    public static function getDump($seminar_id, $parent_id = null)
+    {
+        $seminar_name = get_object_name($seminar_id, 'sem');
+        $content = '<h1>'. _('Forum') .': '  . $seminar_name['name'] .'</h1>';
+        $data = ForumEntry::getList('dump', $parent_id ?: $seminar_id);
+
+        foreach ($data as $entry) {
+            if ($entry['depth'] == 1) {
+                $content .= '<h2>'. _('Bereich') .': '. $entry['name'] .'</h2>';
+                $content .= $entry['content'] .'<br><br>';
+            } else if ($entry['depth'] == 2) {
+                $content .= '<h3 style="margin-bottom: 0px;">'. _('Thema') .': '. $entry['name'] .'</h3>';
+                $content .= '<i>' . sprintf(_('erstellt von %s am %s'), htmlReady($entry['author']),
+                    strftime('%A %d. %B %Y, %H:%M', (int)$entry['mkdate'])) . '</i><br>';
+                $content .= $entry['content'] .'<br><br>';
+            } else if ($entry['depth'] == 3) {
+                $content .= '<b>'.$entry['name'] .'</b><br>';
+                $content .= '<i>' . sprintf(_('erstellt von %s am %s'), htmlReady($entry['author']),
+                    strftime('%A %d. %B %Y, %H:%M', (int)$entry['mkdate'])) . '</i><br>';
+                $content .= $entry['content'] .'<hr><br>';
+            }
+        }
+
+        return $content;
+    }
+
+    public static function isClosed($topic_id)
+    {
+        foreach(ForumEntry::getPathToPosting($topic_id) as $entry) {
+            if ($entry['closed']) {
+                return true;
+            }
+        }
+
+        return false;
+    }
+
+    /**
+     * Export available data of a given user into a storage object
+     * (an instance of the StoredUserData class) for that user.
+     *
+     * @param StoredUserData $storage object to store data into
+     */
+    public static function exportUserData(StoredUserData $storage)
+    {
+        $field_data = DBManager::get()->fetchAll("SELECT * FROM forum_entries WHERE user_id = ?", [$storage->user_id]);
+        if ($field_data) {
+            $storage->addTabularData(_('Forum Einträge'), 'forum_entries', $field_data);
+        }
+    }
+
+}