passportConfig.js

const User = require('./user');
const bcrypt = require('bcryptjs');
const localStrategy = require('passport-local').Strategy;

module.exports = function(passport) {
    passport.use(
        new localStrategy(( username, password, done ) => {
            User.findOne({ username: username }, ( err, user ) => {
                if(err)
                    throw err;
                if(!user)
                    return done(null, false);
                bcrypt.compare(password, user.password, ( err, result ) => {
                    if(err) throw err;
                    if(result === true){
                        return done(null, user);
                    } else {
                        return done(null, false);
                    }
                });
            });
        })
    );

    passport.serializeUser((user, cb) => {
        cb(null, user.id)
    });

    passport.deserializeUser((id, cb) => {
        User.findOne({ _id: id }, (err, user) => {
            const userInformation = {
                username: user.username,
            };
            cb(err, userInformation);
        });
    });
};