server.js

const express = require("express");
const app = express();

// OLD VERSION taught in the course.
// const server = require("http").Server(app);
// const io = require("socket.io")(server);

// LATEST VERSION Socket io @4.4.1
const { createServer } = require("http");
const { Server } = require("socket.io");
const httpServer = createServer(app);
const io = new Server(httpServer, {
  /* options */
});

const next = require("next");
const dev = process.env.NODE_ENV !== "production";
const nextApp = next({ dev });
const handle = nextApp.getRequestHandler();
require("dotenv").config({ path: "./config.env" });

const connectDb = require("./utilsServer/connectDb");
connectDb();

app.use(express.json());

const PORT = process.env.PORT || 3000;
const {
  addUser,
  removeUser,
  findConnectedUser
} = require("./utilsServer/roomActions");
const {
  loadMessages,
  sendMsg,
  setMsgToUnread,
  deleteMsg
} = require("./utilsServer/messageActions");

const { likeOrUnlikePost } = require("./utilsServer/likeOrUnlikePost");

io.on("connection", socket => {
  socket.on("join", async ({ userId }) => {
    const users = await addUser(userId, socket.id);
    console.log(users);

    setInterval(() => {
      socket.emit("connectedUsers", {
        users: users.filter(user => user.userId !== userId)
      });
    }, 10000);
  });

  socket.on("likePost", async ({ postId, userId, like }) => {
    const { success, name, profilePicUrl, username, postByUserId, error } =
      await likeOrUnlikePost(postId, userId, like);

    if (success) {
      socket.emit("postLiked");

      if (postByUserId !== userId) {
        const receiverSocket = findConnectedUser(postByUserId);

        if (receiverSocket && like) {
          // WHEN YOU WANT TO SEND DATA TO ONE PARTICULAR CLIENT
          io.to(receiverSocket.socketId).emit("newNotificationReceived", {
            name,
            profilePicUrl,
            username,
            postId
          });
        }
      }
    }
  });

  socket.on("loadMessages", async ({ userId, messagesWith }) => {
    const { chat, error } = await loadMessages(userId, messagesWith);

    !error ? socket.emit("messagesLoaded", { chat }) : socket.emit("noChatFound");
  });

  socket.on("sendNewMsg", async ({ userId, msgSendToUserId, msg }) => {
    const { newMsg, error } = await sendMsg(userId, msgSendToUserId, msg);
    const receiverSocket = findConnectedUser(msgSendToUserId);

    if (receiverSocket) {
      // WHEN YOU WANT TO SEND MESSAGE TO A PARTICULAR SOCKET
      io.to(receiverSocket.socketId).emit("newMsgReceived", { newMsg });
    }
    //
    else {
      await setMsgToUnread(msgSendToUserId);
    }

    !error && socket.emit("msgSent", { newMsg });
  });

  socket.on("deleteMsg", async ({ userId, messagesWith, messageId }) => {
    const { success } = await deleteMsg(userId, messagesWith, messageId);

    if (success) socket.emit("msgDeleted");
  });

  socket.on("sendMsgFromNotification", async ({ userId, msgSendToUserId, msg }) => {
    const { newMsg, error } = await sendMsg(userId, msgSendToUserId, msg);
    const receiverSocket = findConnectedUser(msgSendToUserId);

    if (receiverSocket) {
      // WHEN YOU WANT TO SEND MESSAGE TO A PARTICULAR SOCKET
      io.to(receiverSocket.socketId).emit("newMsgReceived", { newMsg });
    }
    //
    else {
      await setMsgToUnread(msgSendToUserId);
    }

    !error && socket.emit("msgSentFromNotification");
  });

  socket.on("disconnect", () => removeUser(socket.id));
});

nextApp.prepare().then(() => {
  app.use("/api/signup", require("./api/signup"));
  app.use("/api/auth", require("./api/auth"));
  app.use("/api/search", require("./api/search"));
  app.use("/api/posts", require("./api/posts"));
  app.use("/api/profile", require("./api/profile"));
  app.use("/api/notifications", require("./api/notifications"));
  app.use("/api/chats", require("./api/chats"));
  app.use("/api/reset", require("./api/reset"));

  app.all("*", (req, res) => handle(req, res));

  httpServer.listen(PORT, err => {
    if (err) throw err;
    console.log("Express server running");
  });
});