server.js

require('dotenv').config();
const express = require('express');
const cors = require('cors');
const cookieParser = require('cookie-parser');
const SpotifyWebApi = require('spotify-web-api-node');

const app = express();
app.use(express.static(__dirname + '/public'))
    .use(cors())
    .use(cookieParser());

const credentials = {
    clientId: process.env.SPOTIPY_CLIENT_ID,
    clientSecret: process.env.SPOTIPY_CLIENT_SECRET,
    redirectUri: process.env.SPOTIPY_REDIRECT_URI
};

app.get('/login', (req, res) => {
    const spotifyApi = new SpotifyWebApi(credentials);
    const scopes = ['user-read-private', 'user-read-email', 'user-read-currently-playing', 'user-read-playback-state'];

    // Create the authorization URL
    const authorizeURL = spotifyApi.createAuthorizeURL(scopes, 'some-state');
    res.redirect(authorizeURL);
});

app.get('/callback', (req, res) => {
    const code = req.query.code || null;
    const spotifyApi = new SpotifyWebApi(credentials);

    spotifyApi.authorizationCodeGrant(code).then(
        function (data) {
            console.log('The token expires in ' + data.body['expires_in']);
            console.log('The access token is ' + data.body['access_token']);
            console.log('The refresh token is ' + data.body['refresh_token']);

            // Redirect to the frontend with the tokens
            res.redirect(`http://127.0.0.1:5173/?access_token=${data.body['access_token']}&refresh_token=${data.body['refresh_token']}`);
        },
        function (err) {
            console.log('Something went wrong!', err);
            res.redirect(`http://127.0.0.1:5173/?error=invalid_token`);
        }
    );
});

app.get('/refresh_token', (req, res) => {
    const refresh_token = req.query.refresh_token;
    const spotifyApi = new SpotifyWebApi({
        ...credentials,
        refreshToken: refresh_token
    });

    spotifyApi.refreshAccessToken().then(
        function (data) {
            res.json({
                access_token: data.body['access_token'],
                expires_in: data.body['expires_in']
            });
        },
        function (err) {
            console.log('Could not refresh access token', err);
            res.status(400).send('Could not refresh access token');
        }
    );
});

const PORT = 8888;
app.listen(PORT, () => {
    console.log(`Server listening on port ${PORT}`);
});