server.js

let http = require("http");
let express = require("express");
let bodyParser = require('body-parser');
let mongoose = require('mongoose');
let Fs = require('fs');
let pathFile = require("path");
let fse = require('fs-extra');
let busboy = require('connect-busboy');

let app = express();

app.use(bodyParser.urlencoded({extended: false}))


app.use(bodyParser.json());
app.use(busboy());
let env = require('./config/env');

require('./config/db')(mongoose, env);

let userCtrl = require('./controller/user');
let msgCtrl = require('./controller/message');

// Express CORS setup
app.use(function (req, res, next) {
    res.setHeader('Access-Control-Allow-Origin', 'http://localhost:4200');
    res.setHeader('Access-Control-Allow-Methods', 'GET, POST, OPTIONS, PUT, PATCH, DELETE');
    res.setHeader('Access-Control-Allow-Headers', 'X-Requested-With,content-type');
    res.setHeader('Access-Control-Allow-Credentials', true);
    next();
});

let server = app.listen(3000);

let io = require('socket.io').listen(server);

let path = __dirname + '/views/';
app.use(express.static(pathFile.join(__dirname, 'shared')));

let usersCollection = [];

// Express routes
app.set("view engine", "vash");

app.get("*", (req, res) => {
    res.render("index");
});

app.post("/listFriends", (req, res) => {
    let clonedArray = usersCollection.slice();
    let i = usersCollection.findIndex(x => x.id == req.body.userId);

    clonedArray.splice(i, 1);

    res.json(clonedArray);
});
app.post("/upload", (req, res) => {
    let folder = pathFile.join(__dirname, "./shared");

    fse.mkdirsSync(folder, {mode: 0o775});

    req.busboy.on("file", (fieldname, file, filename) => {
        let fstream = Fs.createWriteStream(pathFile.join(folder, filename), {mode: 0o775});

        file.pipe(fstream);

        fstream.on("close", function () {
            return res.status(200).json(filename);
        });
    });

    req.pipe(req.busboy);
});

// Socket.io operations
io.on('connection', (socket) => {
    userCtrl.getAll()
        .then((users) => {
            usersCollection = users;
            socket.on('join', (username) => {
                userCtrl.createUser(username, socket.id)
                    .then((newUser) => {
                        if (newUser.new) {
                            usersCollection.push({
                                id: newUser.user._id, // Assigning the socket ID as the user ID in this example
                                displayName: username.username,
                                status: 0, // ng-chat UserStatus.Online,
                                avatar: null,
                                _id: newUser.user._id,
                                socketId: socket.id,
                                interest: newUser.user.interest
                            });
                            socket.emit("generatedUserId", newUser.user._id);
                            socket.emit("friendsListChanged", usersCollection);
                            socket.broadcast.emit("friendsListChanged", usersCollection);
                        }
                        else {
                            usersCollection.forEach(function (one, i, all) {
                                if (one.displayName == username.username) {
                                    usersCollection[i].id = newUser.user._id;
                                    usersCollection[i].socketId = socket.id;
                                    usersCollection[i].status = 0;
                                }
                            });

                            socket.emit("generatedUserId", newUser.user._id);
                            socket.emit("friendsListChanged", usersCollection);
                            socket.broadcast.emit("friendsListChanged", usersCollection);
                        }
                    })
                socket.on('disconnect', () => {
                    userCtrl.updateUserInfo(socket.id)
                        .then((userOffline) => {
                            userCtrl.getAll()
                                .then((users) => {
                                    usersCollection = users;
                                    socket.emit("friendsListChanged", usersCollection);
                                    socket.broadcast.emit("friendsListChanged", usersCollection);
                                })
                        });

                });
            });
        });


    socket.on("sendMessage", (message) => {

        msgCtrl.create(message);
        userCtrl.find(message)
            .then((users) => {
                msgCtrl.getUserMsg(message)
                    .then((chats) => {
                        io.to(users[0][0].socketId).emit("messageReceived", chats);
                        io.to(users[1][0].socketId).emit("messageReceived", chats);
                    })
            });
    });
    socket.on("writeMessage", (message) =>{
        userCtrl.find(message)
            .then((users) => {
                io.to(users[1][0].socketId).emit("userWriteMsg", users[0][0]);
            });
    });

    socket.on("getChats", (message) => {
        userCtrl.find(message)
            .then((users) => {
                msgCtrl.getUserMsg(message)
                    .then((chats) => {
                        io.to(users[0][0].socketId).emit("messageReceived", chats);
                        io.to(users[1][0].socketId).emit("messageReceived", chats);
                    })
            });
    });
});