Agora_Driver::mergeThread PHP Method

    public function mergeThread($thread_from, $message_id)
    {
        $sql = 'SELECT message_thread, parents FROM ' . $this->_threads_table . ' WHERE message_id = ?';
        try {
            $destination = $this->_db->selectOne($sql, array($message_id));
        } catch (Horde_Db_Exception $e) {
            throw new Agora_Exception($e->getMessage());
        }
        /* Merge to the top level */
        if ($destination['message_thread'] == 0) {
            $destination['message_thread'] = $message_id;
        }
        $sql = 'SELECT message_thread, parents, message_id FROM ' . $this->_threads_table . ' WHERE message_id = ? OR message_thread = ?';
        try {
            $children = $this->_db->select($sql, array($thread_from, $thread_from));
        } catch (Horde_Db_Exception $e) {
            throw new Agora_Exception($e->getMessage());
        }
        /* TODO: merging more than one message breaks parent/child relations,
         * also merging to deeper level than thread root doesn't work. */
        if (!empty($children)) {
            $sql = 'UPDATE ' . $this->_threads_table . ' SET message_thread = ?, parents = ? WHERE message_id = ?';
            foreach ($children as $i => $message) {
                $children[$i]['message_thread'] = $destination['message_thread'];
                if (!empty($destination['parents'])) {
                    $children[$i]['parents'] = $destination['parents'] . $message['parents'];
                } else {
                    $children[$i]['parents'] = ':' . $message_id;
                }
                try {
                    $this->_db->execute($sql, $children[$i]);
                } catch (Horde_Db_Exception $e) {
                    throw new Agora_Exception($e->getMessage());
                }
            }
        }
        $count = $this->countThreads($destination['message_thread']);
        $sql = 'UPDATE ' . $this->_threads_table . ' SET message_seq = ? WHERE message_id = ?';
        try {
            $this->_db->execute($sql, array($count, $destination['message_thread']));
        } catch (Horde_Db_Exception $e) {
            throw new Agora_Exception($e->getMessage());
        }
        /* Update last message */
        $this->_lastInForum($this->_forum_id);
        $this->_lastInThread($destination['message_thread']);
        $this->_forumSequence($this->_forum_id, 'thread', '-');
        /* Update cache */
        $this->_updateCacheState($destination['message_thread']);
    }