public function getUserId()
    {
        if (! is_null($this->userId)) {
            return $this->userId;
        }

        $rooms = $this->room->getRooms($this->getSender());

        foreach ($rooms as $room) {
            if (count($explode = explode(static::USER_PREFIX, $room)) === 2) {
                $this->userId = $explode[1];
            }
        }

        return $this->userId;
    }