first commit

src/lib/asyncHandler.js

@@ -0,0 +1,3 @@
+module.exports = function asyncHandler(fn) {
+  return (req, res, next) => Promise.resolve(fn(req, res, next)).catch(next);
+};

src/lib/youtube.js

@@ -0,0 +1,28 @@
+const YOUTUBE_HOSTS = new Set(['youtube.com', 'www.youtube.com', 'youtu.be', 'm.youtube.com']);
+
+function extractVideoId(url) {
+  let parsed;
+  try {
+    parsed = new URL(url);
+  } catch {
+    return null;
+  }
+  if (!YOUTUBE_HOSTS.has(parsed.hostname)) return null;
+
+  if (parsed.hostname === 'youtu.be') {
+    return parsed.pathname.slice(1) || null;
+  }
+  if (parsed.pathname === '/watch') {
+    return parsed.searchParams.get('v');
+  }
+  if (parsed.pathname.startsWith('/embed/')) {
+    return parsed.pathname.split('/embed/')[1] || null;
+  }
+  return null;
+}
+
+function isValidYoutubeUrl(url) {
+  return extractVideoId(url) !== null;
+}
+
+module.exports = { extractVideoId, isValidYoutubeUrl };