WebSockets & Real-Time

// Server: Socket.io
import { Server } from 'socket.io';
import { createServer } from 'http';

const httpServer = createServer(app);
const io = new Server(httpServer, {
  cors: { origin: 'http://localhost:3000', methods: ['GET', 'POST'] }
});

io.on('connection', (socket) => {
  console.log('User connected:', socket.id);

  // Join a room
  socket.on('join-room', (roomId) => {
    socket.join(roomId);
  });

  // Handle message
  socket.on('send-message', (data) => {
    io.to(data.roomId).emit('new-message', data);
  });

  socket.on('disconnect', () => {
    console.log('User disconnected:', socket.id);
  });
});

// Client: React
import { useEffect, useRef } from 'react';
import { io, Socket } from 'socket.io-client';

function ChatRoom({ roomId }) {
  const socketRef = useRef<Socket>();
  useEffect(() => {
    socketRef.current = io('http://localhost:3001');
    socketRef.current.emit('join-room', roomId);
    socketRef.current.on('new-message', handleMessage);
    return () => { socketRef.current?.disconnect(); }; // cleanup!
  }, [roomId]);
}

// server — real-time order updates
import { Server } from 'socket.io';

const io = new Server(httpServer);

// Middleware for auth on socket connection
io.use(async (socket, next) => {
  const token = socket.handshake.auth.token;
  try {
    const user = await verifyToken(token);
    socket.data.user = user;
    next();
  } catch {
    next(new Error('Authentication error'));
  }
});

io.on('connection', (socket) => {
  const userId = socket.data.user.id;

  // Each user gets their own room
  socket.join(`user:${userId}`);

  console.log(`User ${userId} connected for order tracking`);
});

// Call from your order service when status changes
export function notifyOrderUpdate(userId: string, order: Order) {
  io.to(`user:${userId}`).emit('order:updated', {
    orderId: order.id,
    status: order.status,
    estimatedDelivery: order.estimatedDelivery,
    trackingUrl: order.trackingUrl,
  });
}

// Usage in order processing
async function updateOrderStatus(orderId: string, status: string) {
  const order = await db.orders.update({ where: { id: orderId }, data: { status } });
  notifyOrderUpdate(order.userId, order); // push to user's browser!
  return order;
}