update Utils.js

lib/Utils.js

@@ -1 +1,42 @@
-//
+'use strict';
+
+const Crypto = require('crypto');
+const UserAgent = require('user-agents');
+
+function generateSidAuth (sid) {
+  const youtube = 'https://www.youtube.com';
+  const timestamp = Math.floor(new Date().getTime() / 1000);
+  const input = [timestamp, sid, youtube].join(' ');
+ 
+  let hash = Crypto.createHash('sha1');
+  let data = hash.update(input, 'utf-8');
+  let gen_hash = data.digest('hex');
+ 
+  return ['SAPISIDHASH', [timestamp, gen_hash].join('_')].join(' ');
+}
+
+function encodeId (id) {
+  return encodeURI(new Buffer.from(``+id+`*`).toString('base64').replace('==', '')+'BQBw==');
+}
+
+function getRandomUserAgent (type) {
+  switch (type) {
+    case 'mobile':
+      return new UserAgent(/Android/).data;
+    case 'desktop':
+      return new UserAgent({ deviceCategory: 'desktop' }).data;
+    default:
+  }
+}
+
+function getStringBetweenStrings (data, start_string, end_string) {
+  const regex = new RegExp(`${escapeStringRegexp(start_string)}(.*?)${escapeStringRegexp(end_string)}`, "s");
+  const match = data.match(regex);
+  return match ? match[1] : undefined;
+}
+
+function escapeStringRegexp(string) {
+  return string.replace(/[|\\{}()[\]^$+*?.]/g, "\\$&").replace(/-/g, "\\x2d");
+}
+
+module.exports = { generateSidAuth, encodeId, getRandomUserAgent, getStringBetweenStrings };