express-template/src/auth.ts

import 'dotenv/config';
import { Router } from 'express';

import mongoose from 'mongoose';
import passport from 'passport';
import { Strategy as GoogleStrategy } from 'passport-google-oauth20';

interface UserInterface {
	username: string;
	googleId: string;
}
const UserSchema: mongoose.Schema<UserInterface> = new mongoose.Schema({
	username: String,
	googleId: String,
});

export const User = mongoose.model('User', UserSchema);

passport.use(
	new GoogleStrategy(
		{
			clientID: process.env.GOOGLE_CLIENT_ID!,
			clientSecret: process.env.GOOGLE_CLIENT_SECRET!,
			callbackURL: process.env.GOOGLE_CALLBACK!,
		},
		async (accessToken: any, refreshToken: any, profile: any, cb) => {
			User.findOne({ googleId: profile.id! }, async (err: any, user: any) => {
				if (err) {
					console.log('happens');
					return cb(err);
				}
				if (!user) {
					await User.create({
						username: profile.displayName,
						googleId: profile.id,
					});
				}
				return cb(err, user);
			});
		}
	)
);

export const authRouter = Router();

passport.serializeUser((user: any, done) => {
	done(null, user);
});

passport.deserializeUser((user: any, done) => {
	done(null, user);
});

authRouter.get(
	'/google',
	passport.authenticate('google', { scope: ['profile'] })
);

authRouter.get(
	'/google/callback',
	passport.authenticate('google'),
	(req, res) => {
		res.redirect('/');
	}
);

authRouter.get('/logout', (req, res) => {
	req.logout();
	res.redirect((req.query['redirect'] as string) || '/');
});