brief-20/backend/src/modules/websockets/websockets.gateway.ts

import {
  WebSocketGateway,
  WebSocketServer,
  SubscribeMessage,
  OnGatewayConnection,
  OnGatewayDisconnect,
  OnGatewayInit,
} from '@nestjs/websockets';
import { Logger } from '@nestjs/common';
import { Server, Socket } from 'socket.io';

/**
 * WebSocketsGateway
 * 
 * This gateway handles all WebSocket connections and events.
 * It implements the events specified in the specifications:
 * - project:updated
 * - project:collaboratorAdded
 * - group:created
 * - group:updated
 * - group:personAdded
 * - group:personRemoved
 * - notification:new
 */
@WebSocketGateway({
  cors: {
    origin: process.env.FRONTEND_URL || 'http://localhost:3001',
    credentials: true,
  },
})
export class WebSocketsGateway
  implements OnGatewayInit, OnGatewayConnection, OnGatewayDisconnect {
  
  @WebSocketServer() server: Server;
  
  private logger = new Logger('WebSocketsGateway');
  private connectedClients = new Map<string, string>(); // socketId -> userId

  /**
   * After gateway initialization
   */
  afterInit(server: Server) {
    this.logger.log('WebSocket Gateway initialized');
  }

  /**
   * Handle new client connections
   */
  handleConnection(client: Socket, ...args: any[]) {
    const userId = client.handshake.query.userId as string;
    
    if (userId) {
      this.connectedClients.set(client.id, userId);
      client.join(`user:${userId}`);
      this.logger.log(`Client connected: ${client.id}, User ID: ${userId}`);
    } else {
      this.logger.warn(`Client connected without user ID: ${client.id}`);
    }
  }

  /**
   * Handle client disconnections
   */
  handleDisconnect(client: Socket) {
    this.connectedClients.delete(client.id);
    this.logger.log(`Client disconnected: ${client.id}`);
  }

  /**
   * Join a project room to receive project-specific events
   */
  @SubscribeMessage('project:join')
  handleJoinProject(client: Socket, projectId: string) {
    client.join(`project:${projectId}`);
    this.logger.log(`Client ${client.id} joined project room: ${projectId}`);
    return { success: true };
  }

  /**
   * Leave a project room
   */
  @SubscribeMessage('project:leave')
  handleLeaveProject(client: Socket, projectId: string) {
    client.leave(`project:${projectId}`);
    this.logger.log(`Client ${client.id} left project room: ${projectId}`);
    return { success: true };
  }

  /**
   * Emit project updated event
   */
  emitProjectUpdated(projectId: string, data: any) {
    this.server.to(`project:${projectId}`).emit('project:updated', data);
    this.logger.log(`Emitted project:updated for project ${projectId}`);
  }

  /**
   * Emit collaborator added event
   */
  emitCollaboratorAdded(projectId: string, data: any) {
    this.server.to(`project:${projectId}`).emit('project:collaboratorAdded', data);
    this.logger.log(`Emitted project:collaboratorAdded for project ${projectId}`);
  }

  /**
   * Emit group created event
   */
  emitGroupCreated(projectId: string, data: any) {
    this.server.to(`project:${projectId}`).emit('group:created', data);
    this.logger.log(`Emitted group:created for project ${projectId}`);
  }

  /**
   * Emit group updated event
   */
  emitGroupUpdated(projectId: string, data: any) {
    this.server.to(`project:${projectId}`).emit('group:updated', data);
    this.logger.log(`Emitted group:updated for project ${projectId}`);
  }

  /**
   * Emit person added to group event
   */
  emitPersonAddedToGroup(projectId: string, data: any) {
    this.server.to(`project:${projectId}`).emit('group:personAdded', data);
    this.logger.log(`Emitted group:personAdded for project ${projectId}`);
  }

  /**
   * Emit person removed from group event
   */
  emitPersonRemovedFromGroup(projectId: string, data: any) {
    this.server.to(`project:${projectId}`).emit('group:personRemoved', data);
    this.logger.log(`Emitted group:personRemoved for project ${projectId}`);
  }

  /**
   * Emit notification to a specific user
   */
  emitNotification(userId: string, data: any) {
    this.server.to(`user:${userId}`).emit('notification:new', data);
    this.logger.log(`Emitted notification:new for user ${userId}`);
  }

  /**
   * Emit notification to all users in a project
   */
  emitProjectNotification(projectId: string, data: any) {
    this.server.to(`project:${projectId}`).emit('notification:new', data);
    this.logger.log(`Emitted notification:new for project ${projectId}`);
  }
}