acp_forums::move_forum PHP Method

    function move_forum($from_id, $to_id)
    {
        global $db, $user, $phpbb_dispatcher;
        $errors = array();
        // Check if we want to move to a parent with link type
        if ($to_id > 0) {
            $to_data = $this->get_forum_info($to_id);
            if ($to_data['forum_type'] == FORUM_LINK) {
                $errors[] = $user->lang['PARENT_IS_LINK_FORUM'];
            }
        }
        /**
         * Event when we move all children of one forum to another
         *
         * This event may be triggered, when a forum is deleted
         *
         * @event core.acp_manage_forums_move_children
         * @var	int		from_id		If of the current parent forum
         * @var	int		to_id		If of the new parent forum
         * @var	array	errors		Array of errors, should be strings and not
         *							language key.
         * @since 3.1.0-a1
         */
        $vars = array('from_id', 'to_id', 'errors');
        extract($phpbb_dispatcher->trigger_event('core.acp_manage_forums_move_children', compact($vars)));
        // Return if there were errors
        if (!empty($errors)) {
            return $errors;
        }
        $moved_forums = get_forum_branch($from_id, 'children', 'descending');
        $from_data = $moved_forums[0];
        $diff = sizeof($moved_forums) * 2;
        $moved_ids = array();
        for ($i = 0, $size = sizeof($moved_forums); $i < $size; ++$i) {
            $moved_ids[] = $moved_forums[$i]['forum_id'];
        }
        // Resync parents
        $sql = 'UPDATE ' . FORUMS_TABLE . "\n\t\t\tSET right_id = right_id - {$diff}, forum_parents = ''\n\t\t\tWHERE left_id < " . $from_data['right_id'] . "\n\t\t\t\tAND right_id > " . $from_data['right_id'];
        $db->sql_query($sql);
        // Resync righthand side of tree
        $sql = 'UPDATE ' . FORUMS_TABLE . "\n\t\t\tSET left_id = left_id - {$diff}, right_id = right_id - {$diff}, forum_parents = ''\n\t\t\tWHERE left_id > " . $from_data['right_id'];
        $db->sql_query($sql);
        if ($to_id > 0) {
            // Retrieve $to_data again, it may have been changed...
            $to_data = $this->get_forum_info($to_id);
            // Resync new parents
            $sql = 'UPDATE ' . FORUMS_TABLE . "\n\t\t\t\tSET right_id = right_id + {$diff}, forum_parents = ''\n\t\t\t\tWHERE " . $to_data['right_id'] . ' BETWEEN left_id AND right_id
					AND ' . $db->sql_in_set('forum_id', $moved_ids, true);
            $db->sql_query($sql);
            // Resync the righthand side of the tree
            $sql = 'UPDATE ' . FORUMS_TABLE . "\n\t\t\t\tSET left_id = left_id + {$diff}, right_id = right_id + {$diff}, forum_parents = ''\n\t\t\t\tWHERE left_id > " . $to_data['right_id'] . '
					AND ' . $db->sql_in_set('forum_id', $moved_ids, true);
            $db->sql_query($sql);
            // Resync moved branch
            $to_data['right_id'] += $diff;
            if ($to_data['right_id'] > $from_data['right_id']) {
                $diff = '+ ' . ($to_data['right_id'] - $from_data['right_id'] - 1);
            } else {
                $diff = '- ' . abs($to_data['right_id'] - $from_data['right_id'] - 1);
            }
        } else {
            $sql = 'SELECT MAX(right_id) AS right_id
				FROM ' . FORUMS_TABLE . '
				WHERE ' . $db->sql_in_set('forum_id', $moved_ids, true);
            $result = $db->sql_query($sql);
            $row = $db->sql_fetchrow($result);
            $db->sql_freeresult($result);
            $diff = '+ ' . ($row['right_id'] - $from_data['left_id'] + 1);
        }
        $sql = 'UPDATE ' . FORUMS_TABLE . "\n\t\t\tSET left_id = left_id {$diff}, right_id = right_id {$diff}, forum_parents = ''\n\t\t\tWHERE " . $db->sql_in_set('forum_id', $moved_ids);
        $db->sql_query($sql);
        return $errors;
    }