const YOUTUBE_VIDEO_ID = /^[A-Za-z0-9_-]{11}$/;
const YOUTUBE_HOSTS = new Set([
  "youtube.com",
  "www.youtube.com",
  "m.youtube.com",
  "music.youtube.com",
]);

export interface YouTubeVideo {
  videoId: string;
  watchUrl: string;
  embedUrl: string;
}

export function parseYouTubeUrl(value: string): YouTubeVideo | null {
  let url: URL;
  try {
    url = new URL(value);
  } catch {
    return null;
  }

  if (url.protocol !== "https:" && url.protocol !== "http:") return null;

  const hostname = url.hostname.toLowerCase();
  let videoId: string | null = null;

  if (hostname === "youtu.be") {
    videoId = url.pathname.split("/").filter(Boolean)[0] ?? null;
  } else if (YOUTUBE_HOSTS.has(hostname)) {
    if (url.pathname === "/watch") {
      videoId = url.searchParams.get("v");
    } else {
      const [kind, id] = url.pathname.split("/").filter(Boolean);
      if (["embed", "live", "shorts"].includes(kind)) videoId = id ?? null;
    }
  }

  if (!videoId || !YOUTUBE_VIDEO_ID.test(videoId)) return null;

  return {
    videoId,
    watchUrl: `https://www.youtube.com/watch?v=${videoId}`,
    embedUrl: `https://www.youtube-nocookie.com/embed/${videoId}`,
  };
}