index.js

require('dotenv').config();
const express = require('express');
const session = require('express-session');
const passport = require('passport');
const DiscordStrategy = require('passport-discord').Strategy;

const app = express();

const ALLOWED_IDS = (process.env.ALLOWED_IDS || "").split(",");

app.use(session({
    secret: process.env.SESSION_SECRET,
    resave: false,
    saveUninitialized: false,
    cookie: { maxAge: 24 * 60 * 60 * 1000, httpOnly: true } 
}));

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

passport.serializeUser((user, done) => done(null, user));
passport.deserializeUser((obj, done) => done(null, obj));

passport.use(new DiscordStrategy({
    clientID: process.env.DISCORD_CLIENT_ID,
    clientSecret: process.env.DISCORD_CLIENT_SECRET,
    callbackURL: process.env.DISCORD_CALLBACK_URL,
    scope: ['identify']
}, (accessToken, refreshToken, profile, done) => {
    return done(null, profile);
}));

app.get('/verify', (req, res) => {
    if (req.isAuthenticated() && ALLOWED_IDS.includes(req.user.id)) {
        return res.sendStatus(200);
    }
    return res.sendStatus(401); 
});

app.get('/auth/login', passport.authenticate('discord'));

app.get('/auth/discord/callback', 
    passport.authenticate('discord', { failureRedirect: '/' }),
    (req, res) => {
        res.redirect('/');
    }
);

app.listen(process.env.PORT || 3000, () => console.log('Auth Gatekeeper Running on Port ' + (process.env.PORT || 3000)));