server.js

const express = require("express");

const authRouter = require('./routes/auth-routes');
const profileRouter = require('./routes/profile-routes');
const librarianRouter = require('./routes/librarian');
const userRouter = require('./routes/user');
const homerouter = require('./routes/home');

const LocalStrategy = require('passport-local').Strategy;
const customStrategy = require('./config/custom-strategy');
const passportSetup = require('./config/passport-setup');
const keys2 = require('./config/keys');
const passport = require('passport');
const domain = require('./routes/domain');
const cors = require("cors");
const ejs = require("ejs");
const mysql = require('mysql');
const cookieSession = require('cookie-session');
const flash = require('connect-flash');
const jobs = require('./scheduledJobs')
var keys = require('./keys.js');
const Mail = require("nodemailer/lib/mailer");
require("dotenv").config();

const app = express();
app.use(cors());
const port = process.env.PORT || 5000;

app.use(cookieSession({
    maxAge: 24 * 60 * 60 * 1000,
    keys: [keys.sessionKey]
}))

app.use(passport.initialize());
app.use(passport.session());
app.use(flash());

app.use(express.urlencoded({ extended: true }))

app.use(express.json())

app.use(function (req, res, next) {
    res.header('Cache-Control', 'private, no-cache, no-store, must-revalidate');
    res.header('Expires', '-1');
    res.header('Pragma', 'no-cache');
    next();
});
app.use(express.json());
app.set('view engine', 'ejs');

app.use(express.static('views'));
app.set('views', __dirname + '/views');

var db_config;
// Local Host
if (domain.href == 'http://localhost:5000/') {
    db_config = {
        multipleStatements: true,
        host: 'localhost',
        user: 'vaibhav',
        password: 'password',
        database: 'mydb',
        port: 3306
    };
} else {

    // ClearDB
    var db_config = {
        multipleStatements: true,
        host: keys.db_host,
        user: keys.db_user,
        password: keys.db_password,
        database: keys.db_name,
        port: 3306
    };
}
// Another DB 
// var db_config = {
//     multipleStatements: true,
//     host: keys.db_host2,
//     user: keys.db_user2,
//     password: keys.db_password2,
//     database: keys.db_name2,
//     port: 3306
// };

function handleDisconnect() {
    console.log('1. connecting to db:');
    connection = mysql.createConnection(db_config); // Recreate the connection, since
    // the old one cannot be reused.

    connection.connect(function (err) {              	// The server is either down
        if (err) {                                     // or restarting (takes a while sometimes).
            console.log('2. error when connecting to db:', err);
            setTimeout(handleDisconnect, 1000); // We introduce a delay before attempting to reconnect,
        }                                     	// to avoid a hot loop, and to allow our node script to
    });                                     	// process asynchronous requests in the meantime.
    // If you're also serving http, display a 503 error.
    connection.on('error', function (err) {
        console.log('3. db error', err);
        if (err.code === 'PROTOCOL_CONNECTION_LOST') { 	// Connection to the MySQL server is usually
            handleDisconnect();                      	// lost due to either server restart, or a
        } else {                                      	// connnection idle timeout (the wait_timeout
            throw err;                                  // server variable configures this)
        }
    });
}

handleDisconnect();

const cquery = async (sql, req, res) => {
    return new Promise((resolve, reject) => {
        connection.query(sql, (err, result) => {
            if (err) throw err;
            resolve(result);
        })
    }
    )
}

const auth = (req, res, next) => {
    if (req.user) {
        next();
    } else {
        res.redirect('/auth/login');
    }
}

app.use("/", homerouter);
app.use('/auth', authRouter);
app.use('/profile', auth, profileRouter);
app.use('/librarian', auth, librarianRouter);
app.use('/user', auth, userRouter);
app.listen(port, () => {
    console.log("Server is running at port : ", port);
});