[Nest.js] websocket 클라이언트로 ack 보내기

export class ChatMessageGateway
  implements OnGatewayConnection, OnGatewayDisconnect
{
  constructor(
    @Inject(CHAT_ROOM_REPOSITORY_DI_TOKEN)
    private readonly chatRoomRepository: ChatRoomRepositoryPort,
    @Inject(APP_JWT_SERVICE_DI_TOKEN)
    private readonly appJwtService: AppJwtServicePort,
    @Inject(WINSTON_MODULE_NEST_PROVIDER)
    private readonly logger: Logger,
    private readonly commandBus: CommandBus,
  ) {}

  @WebSocketServer()
  server: Server;

  async handleConnection(socket: SocketWithUserDto) {
    ...
  }

  async handleDisconnect(socket: SocketWithUserDto) {
    ...
  }

  @UsePipes(customValidationPipe)
  @UseFilters(SocketCatchHttpExceptionFilter)
  @SubscribeMessage('enter_chat_room')
  async enterChat(
    @MessageBody() data: EnterChatDto,
    @ConnectedSocket() socket: SocketWithUserDto,
  ) {
    const { roomId } = data;

    const chatRoom = await this.chatRoomRepository.findOneById(roomId);

    if (isNil(chatRoom)) {
      this.logger.error(
        `[Socket] enter_chat_room failed: Room ${roomId} does not exist`,
      );
      throw new WsException('Does not exist room');
    }

    socket.join(String(roomId));

    this.logger.log(`[Socket] User ${socket.user.sub} joined room ${roomId}`);
  }

  @UsePipes(customValidationPipe)
  @UseFilters(SocketCatchHttpExceptionFilter)
  @SubscribeMessage('send_message')
  async sendMessage(
    @MessageBody() data: CreateChatMessageDto,
    @ConnectedSocket() socket: SocketWithUserDto,
  ) {
    const { roomId, message, blogPostUrl } = data;
    const { sub: userId } = socket.user;

    this.logger.log(
      `[Socket] Received message from ${userId} in room ${roomId}: ${message}`,
    );

    const command = new CreateChatMessageCommand({
      roomId: BigInt(roomId),
      userId: BigInt(userId),
      message,
      blogPostUrl,
    });

    this.logger.log(
      `[Socket] Sending message from ${userId} in room ${roomId}: ${message}, ${blogPostUrl}`,
    );

    await this.commandBus.execute<CreateChatMessageCommand, void>(command);

    socket
      .to(String(roomId))
      .emit('receive_message', { senderId: userId, message, blogPostUrl });

    this.logger.log(
      `[Socket] Message emitted to room ${roomId} from ${userId}`,
    );
  }
}