backend/src/services/socketService.js

const jwt = require('jsonwebtoken');
const User = require('../models/User');

// Socket authentication middleware
const authenticateSocket = async (socket, next) => {
  try {
    const token = socket.handshake.auth.token;
    if (!token) {
      return next(new Error('Authentication error'));
    }

    const decoded = jwt.verify(token, process.env.JWT_SECRET);
    const user = await User.findById(decoded.userId);
    
    if (!user) {
      return next(new Error('User not found'));
    }

    socket.userId = user._id.toString();
    socket.user = user;
    next();
  } catch (error) {
    next(new Error('Authentication error'));
  }
};

const initializeSocket = (io) => {
  // Authentication middleware
  io.use(authenticateSocket);

  io.on('connection', (socket) => {
    console.log(`User ${socket.user.username} connected`);

    // Join user to their personal room
    socket.join(`user_${socket.userId}`);

    // Handle typing events
    socket.on('typing', (data) => {
      socket.to(`user_${socket.userId}`).emit('userTyping', {
        conversationId: data.conversationId,
        isTyping: data.isTyping
      });
    });

    // Handle disconnection
    socket.on('disconnect', () => {
      console.log(`User ${socket.user.username} disconnected`);
    });

    // Update user's last seen
    socket.user.lastSeen = new Date();
    socket.user.save().catch(console.error);
  });

  return io;
};

module.exports = {
  initializeSocket
};