index.js

// required config

require("dotenv").config();
const express = require("express");
const app = express();
const cors = require("cors");
const mongoose = require("mongoose");
const { URL, PORT, FRONTEND_URL, JWT_SECRET } = require("./utils/config");
const cookieParser = require("cookie-parser");
const ws = require("ws");
const jwt = require("jsonwebtoken");
const Message = require("./models/messageModel");

// getting all routers
const userRouter = require("./routes/userRoutes");
const messageRouter = require("./routes/messageRoutes");

app.use(express.json());
app.use(cookieParser());
app.use(
  cors({
    credentials: true,
    origin: ["http://localhost:5173", "https://chat-app-suriya-k7.netlify.app"],
  })
);

mongoose.set("strictQuery", false);

mongoose
  .connect(URL)
  .then(() => {
    console.log("connected to Mongo DB");
  })
  .catch((err) => {
    console.error(err);
  });

app.get("/", (req, res) => {
  res.send("Welcome to Chat App");
});

app.use(userRouter);
app.use(messageRouter);

const server = app.listen(PORT, () => {
  console.log("server is running");
});

const wss = new ws.WebSocketServer({ server });

wss.on("connection", (connection, req) => {
  function notifyOnlineUser() {
    [...wss.clients].forEach((client) => {
      client.send(
        JSON.stringify({
          online: [...wss.clients].map((c) => ({
            userId: c.userId,
            username: c.username,
          })),
        })
      );
    });
  }

  connection.isAlive = true;

  connection.timer = setInterval(() => {
    connection.ping();
    connection.deathTimer = setTimeout(() => {
      connection.isAlive = false;
      clearInterval(connection.timer);
      connection.terminate();
      notifyOnlineUser();
    }, 1000);
  }, 5000);

  connection.on("pong", () => {
    clearTimeout(connection.deathTimer);
  });

  const cookies = req.headers.cookie;
  if (cookies) {
    const tokenCookieString = cookies
      .split(";")
      .find((str) => str.startsWith("token="));
    if (tokenCookieString) {
      const token = tokenCookieString.split("=")[1];
      if (token) {
        jwt.verify(token, JWT_SECRET, (err, userData) => {
          if (err) throw err;
          connection.userId = userData.userId;
          connection.username = userData.username;
        });
      }
    }
  }

  connection.on("message", async (message) => {
    const messageData = JSON.parse(message.toString());
    const { recipient, text, file } = messageData;
    if (recipient && (text || file)) {
      const messageDoc = await Message.create({
        sender: connection.userId,
        recipient,
        text,
        file,
      });

      [...wss.clients]
        .filter((c) => c.userId === recipient)
        .forEach((c) =>
          c.send(
            JSON.stringify({
              text,
              file,
              sender: connection.userId,
              recipient,
              _id: messageDoc._id,
            })
          )
        );
    }
  });

  notifyOnlineUser();
});