fix: added totp to spotify autoplay endpoint (#21)

Fixes: #20

Author: olliedean

build/functions/autoPlay.js

@@ -1,5 +1,6 @@
 const undici = require('undici');
 const { JSDOM } = require('jsdom');
+const crypto = require('crypto');
 
 async function scAutoPlay(url) {
     const res = await undici.fetch(`${url}/recommended`);
@@ -28,7 +29,39 @@ async function scAutoPlay(url) {
 }
 
 async function spAutoPlay(track_id) {
-    const data = await undici.fetch("https://open.spotify.com/get_access_token?reason=transport&productType=embed");
+    const TOTP_SECRET = new Uint8Array([53,53,48,55,49,52,53,56,53,51,52,56,55,52,57,57,53,57,50,50,52,56,54,51,48,51,50,57,51,52,55]);
+
+    const hmac = crypto.createHmac('sha1', TOTP_SECRET);
+
+    function generateTotp() {
+        const counter = Math.floor(Date.now() / 30000);
+        const counterBuffer = Buffer.alloc(8);
+        counterBuffer.writeBigInt64BE(BigInt(counter));
+        
+        hmac.update(counterBuffer);
+        const hmacResult = hmac.digest();
+        
+        const offset = hmacResult[hmacResult.length - 1] & 15;
+        const truncatedValue = 
+            ((hmacResult[offset] & 127) << 24) |
+            ((hmacResult[offset + 1] & 255) << 16) |
+            ((hmacResult[offset + 2] & 255) << 8) |
+            (hmacResult[offset + 3] & 255);
+        
+        const totp = (truncatedValue % 1000000).toString().padStart(6, '0');
+        return [totp, counter * 30000];
+    }
+
+    const [totp, timestamp] = generateTotp();
+    const params = {
+        "reason": "transport",
+        "productType": "embed",
+        "totp": totp,
+        "totpVer": 5,
+        "ts": timestamp,
+    }
+
+    const data = await undici.fetch("https://open.spotify.com/get_access_token?" + new URLSearchParams(params).toString());
 
     const body = await data.json();
 
@@ -44,4 +77,4 @@ async function spAutoPlay(track_id) {
     return json.tracks[Math.floor(Math.random() * json.tracks.length)].id
 }
 
-module.exports = { scAutoPlay, spAutoPlay };
+module.exports = { scAutoPlay, spAutoPlay };