Refactor code structure for improved readability and maintainability

lib/youtube.ts

@@ -0,0 +1,47 @@
+const SUPPORTED_HOSTS = new Set([
+  "youtube.com",
+  "m.youtube.com",
+  "youtu.be",
+  "youtube-nocookie.com",
+]);
+
+const VIDEO_ID_REGEX = /^[a-zA-Z0-9_-]{11}$/;
+
+function normalizeHost(hostname: string) {
+  return hostname.toLowerCase().replace(/^www\./, "");
+}
+
+function fromPathSegments(pathname: string) {
+  const segments = pathname.split("/").filter(Boolean);
+  if (!segments.length) return null;
+
+  if (segments[0] === "watch") return null;
+  if (segments[0] === "shorts" && segments[1]) return segments[1];
+  if (segments[0] === "embed" && segments[1]) return segments[1];
+
+  return segments[0];
+}
+
+export function getYoutubeVideoId(link: string) {
+  try {
+    const url = new URL(link);
+    const host = normalizeHost(url.hostname);
+
+    if (!SUPPORTED_HOSTS.has(host)) return null;
+
+    const videoId = host === "youtu.be" ? fromPathSegments(url.pathname) : url.searchParams.get("v") ?? fromPathSegments(url.pathname);
+    if (!videoId || !VIDEO_ID_REGEX.test(videoId)) return null;
+
+    return videoId;
+  } catch {
+    return null;
+  }
+}
+
+export function getYoutubeEmbedUrl(link: string) {
+  const videoId = getYoutubeVideoId(link);
+  if (!videoId) return null;
+
+  // Use privacy-enhanced mode to reduce cross-site cookie noise in modern browsers.
+  return `https://www.youtube-nocookie.com/embed/${videoId}?rel=0&modestbranding=1`;
+}