// Spotify OAuth logic
const client_id = '5ed07e2a23384be495efff4d463aba54';
const redirect_uri = window.location.origin + window.location.pathname;
const scope = 'user-read-private user-read-email user-read-playback-state user-modify-playback-state user-read-currently-playing';

function loginWithSpotify() {
    const code_verifier = generateCodeVerifier();
    localStorage.setItem('code_verifier', code_verifier);
    generateCodeChallenge(code_verifier).then(code_challenge => {
        const params = new URLSearchParams({
            response_type: 'code',
            client_id,
            scope,
            redirect_uri,
            code_challenge_method: 'S256',
            code_challenge
        });
        window.location = 'https://accounts.spotify.com/authorize?' + params.toString();
    });
}

async function handleRedirect() {
    const params = new URLSearchParams(window.location.search);
    const code = params.get('code');
    if (!code) return null;

    const code_verifier = localStorage.getItem('code_verifier');
    const body = new URLSearchParams({
        client_id,
        grant_type: 'authorization_code',
        code,
        redirect_uri,
        code_verifier
    });

    const response = await fetch('https://accounts.spotify.com/api/token', {
        method: 'POST',
        headers: { 'Content-Type': 'application/x-www-form-urlencoded' },
        body
    });
    const data = await response.json();
    if (data.access_token) {
        window.history.replaceState({}, document.title, window.location.pathname);
        localStorage.removeItem('code_verifier');
        localStorage.setItem('access_token', data.access_token);
        return data.access_token;
    } else {
        showError('Error: ' + JSON.stringify(data, null, 2));
        return null;
    }
}