signin.js

1	const clientId = '6c4c04a3751b4e409ddad7d71aad9949';
2	const scope = 'user-library-read user-modify-playback-state user-read-playback-state';
3	const prematureRefreshSeconds = 60 * 5; // 5 minutes before expiration
4
5	function getSpotifyRedirectURL() {
6	// If the current hostname is 'localhost'
7	if (window.location.hostname === 'localhost') {
8	return 'http://localhost:5500/public/index.html';
9	} else if (window.location.hostname === '127.0.0.1') {
10	return 'http://127.0.0.1:5500/public/index.html';
11	} else {
12	return 'https://pavelsafronov.gitlab.io/hawk/index.html';
13	}
14	}
15
16	async function signOut() {
17	localStorage.removeItem('access_token');
18	localStorage.removeItem('refresh_token');
19	localStorage.removeItem('expires_at');
20	await deleteDb();
21	window.location = getSpotifyRedirectURL();
22	}
23
24	async function signIn() {
25	let codeVerifier = generateRandomString(128);
26	const codeChallenge = await generateCodeChallenge(codeVerifier)
27	let state = generateRandomString(16);
28
29	localStorage.setItem('code_verifier', codeVerifier);
30
31	const redirectUrl = getSpotifyRedirectURL();
32	let args = new URLSearchParams({
33	response_type: 'code',
34	client_id: clientId,
35	scope: scope,
36	redirect_uri: redirectUrl,
37	state: state,
38	code_challenge_method: 'S256',
39	code_challenge: codeChallenge
40	});
41
42	window.location = 'https://accounts.spotify.com/authorize?' + args;
43	}
44
45	async function getToken(code) {
46	let codeVerifier = localStorage.getItem('code_verifier');
47
48	const redirectUrl = getSpotifyRedirectURL();
49	let body = new URLSearchParams({
50	grant_type: 'authorization_code',
51	code: code,
52	redirect_uri: redirectUrl,
53	client_id: clientId,
54	code_verifier: codeVerifier
55	});
56
57	try {
58	const response = await fetch('https://accounts.spotify.com/api/token', {
59	method: 'POST',
60	headers: {
61	'Content-Type': 'application/x-www-form-urlencoded'
62	},
63	body: body
64	});
65	if (!response.ok) {
66	console.error('HTTP status ' + response.status);
67	throw new Error('HTTP status ' + response.status);
68	}
69	const data = await response.json();
70	const expiresInSeconds = data.expires_in;
71	localStorage.setItem('access_token', data.access_token);
72	localStorage.setItem('refresh_token', data.refresh_token);
73	localStorage.setItem('expires_at', Date.now() + expiresInSeconds * 1000);
74	} catch (error) {
75	console.error('Error:', error);
76	}
77	}
78
79	function generateRandomString(length) {
80	let text = '';
81	let possible = 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789';
82
83	for (let i = 0; i < length; i++) {
84	text += possible.charAt(Math.floor(Math.random() * possible.length));
85	}
86	return text;
87	}
88
89	async function generateCodeChallenge(codeVerifier) {
90	function base64encode(string) {
91	return btoa(String.fromCharCode.apply(null, new Uint8Array(string)))
92	.replace(/\+/g, '-')
93	.replace(/\//g, '_')
94	.replace(/=+$/, '');
95	}
96
97	const encoder = new TextEncoder();
98	const data = encoder.encode(codeVerifier);
99	const digest = await window.crypto.subtle.digest('SHA-256', data);
100
101	return base64encode(digest);
102	}
103
104	async function getAccessToken() {
105	let accessToken = localStorage.getItem('access_token');
106	if (!accessToken) {
107	throw 'No access token found';
108	}
109
110	const expiresAtText = localStorage.getItem('expires_at');
111	if (!expiresAtText) {
112	throw 'No expiration found';
113	}
114	const expiresAt = parseInt(expiresAtText);
115	const shouldRefresh = Date.now() > expiresAt - prematureRefreshSeconds * 1000;
116	if (shouldRefresh) {
117	console.log('Refreshing access token');
118	accessToken = await refreshToken();
119	}
120
121	return accessToken;
122	}
123
124	async function refreshToken() {
125	const refreshToken = localStorage.getItem('refresh_token');
126	if (!refreshToken) {
127	throw 'No refresh token found';
128	}
129
130	let body = new URLSearchParams({
131	grant_type: 'refresh_token',
132	refresh_token: refreshToken,
133	client_id: clientId
134	});
135
136	const response = await fetch('https://accounts.spotify.com/api/token', {
137	method: 'POST',
138	headers: {
139	'Content-Type': 'application/x-www-form-urlencoded'
140	},
141	body: body,
142	});
143	if (!response.ok) {
144	console.error('HTTP status ' + response.status);
145	throw new Error('HTTP status ' + response.status);
146	}
147	const data = await response.json();
148	const expiresInSeconds = data.expires_in;
149	localStorage.setItem('access_token', data.access_token);
150	localStorage.setItem('refresh_token', data.refresh_token);
151	localStorage.setItem('expires_at', Date.now() + expiresInSeconds * 1000);
152	return data.access_token;
153	}