server.js

/**
 * @summary server use passport express mysql sequelize socket.io
 */
const express = require('express');

const app = express();
const bp = require('body-parser');
const passport = require('passport');
const async = require('async');
const session = require('express-session');
const { user } = require('./db');
const Investment = require('./db').investment;
const spending = require('./db').spendings;
const { reminder } = require('./db');
const response = require('./utils-module/response');
const GoogleStrategy = require('passport-google-oauth').OAuth2Strategy;

// Use the GoogleStrategy within Passport.
//   Strategies in Passport require a `verify` function, which accept
//   credentials (in this case, an accessToken, refreshToken, and Google
//   profile), and invoke a callback with a user object.
passport.use(new GoogleStrategy({
    clientID: 'CLIENT_ID',
    clientSecret: 'CLIENT_SECRET',
    callbackURL: "http://localhost:3100/google/callback"
},
    function (accessToken, refreshToken, profile, done) {
        user.findOne({ 'email': profile.email }).then(user => {

            if (!user) {

                let newUser = {
                    username: profile.displayName,
                    email: profile.emails[0].value,
                };

                // Creating a new user if not exist
                user.create(newUser).then(user => {
                    return done(null, user);
                }).catch(error => {
                    return done(error, null);
                });
            }
            else {
                return done(null, user);
            }
        });
    }
));

// To locate the config folder by default it searches for .env here it is .env.example

// Sample ENV properties are loaded here in reallife scenario this would be populated by the environment property of machine running the app server

require('dotenv').config({ path: `${process.cwd()}/.env.example` });

app.use('/', express.static(`${__dirname}/Public_static`));
app.use(bp.urlencoded({ extended: true }));
app.use(bp.json());

app.use(
    session({ secret: 'keyboard cat', resave: true, saveUninitialized: true })
); // session secret

// Passport Authentication Implementation

require('./config/passport.js');

app.use(passport.initialize());

app.use(passport.session()); // persistent login sessions

// Sign up Implementation

app.post('/signup', (req, res, next) => {
    passport.authenticate('local-signup', function (err, user, info) {
        if (err) {
            return response.responseWriter(res, 500, info);
        }
        if (!user) {
            return response.responseWriter(res, 400, info);
        }

        return response.responseWriter(res, 200, user);
    })(req, res, next);
});

// Login value is sent to

app.post('/login', (req, res, next) => {
    passport.authenticate('local-signin', function (err, user, info) {
        if (err) {
            return response.responseWriter(res, 500, info);
        }
        if (!user) {
            return response.responseWriter(res, 400, info);
        }

        return response.responseWriter(res, 200, user);
    })(req, res, next);
});

// GET /auth/google
//   Use passport.authenticate() as route middleware to authenticate the
//   request.  The first step in Google authentication will involve
//   redirecting the user to google.com.  After authorization, Google
//   will redirect the user back to this application at /auth/google/callback
app.get('/google', (req, res, next) => {
    passport.authenticate('google', { scope: ['profile', 'email'] })(req, res, next);
});

// GET /auth/google/callback
//   Use passport.authenticate() as route middleware to authenticate the
//   request.  If authentication fails, the user will be redirected back to the
//   login page.  Otherwise, the primary route function function will be called,
//   which, in this example, will redirect the user to the home page.
app.get('/google/callback', (req, res, next) => {
    passport.authenticate('google', { failureRedirect: '/login' })(req, res, next)
},
    function (req, res) {

        // Redirecting to /main URL after successful lgon
        res.redirect('http://localhost:3100/main.html');
    });

app.use('/', require('./routes/index'));

app.listen(3100, function () {
    console.log('Server started on http://localhost:3100');
});