public static function parseUserNick($userId = null, $onEmpty = 'guest'): ?string
    {
        if (!Any::isInt($userId)) {
            return \App::$Security->strip_tags($onEmpty);
        }

        // try to find user active record as object
        $identity = App::$User->identity($userId);
        if (!$identity) {
            return \App::$Security->strip_tags($onEmpty);
        }

        // return user nickname from profile
        return $identity->profile->getNickname();
    }