export async function extractListId(url: string): Promise<string> {
  let resolved = url;

  if (url.includes("goo.gl/") || url.includes("maps.app")) {
    resolved = await followRedirects(url);
  }

  const placelistMatch = /\/maps\/placelists\/list\/([^/?#]+)/.exec(resolved);
  if (placelistMatch?.[1]) {
    return placelistMatch[1];
  }

  const decoded = decodeURIComponent(resolved);
  const dataMatch = /!2s([^!&?#\s]+)/.exec(decoded);
  if (dataMatch?.[1]) {
    return dataMatch[1];
  }

  throw new Error(`Could not extract list ID from URL: ${url}`);
}

async function followRedirects(url: string, maxHops = 10): Promise<string> {
  let current = url;

  for (let i = 0; i < maxHops; i++) {
    const response = await fetch(current, { redirect: "manual" });
    await response.body?.cancel();
    const location = response.headers.get("location");

    if (!location) {
      return response.url || current;
    }

    current = location.startsWith("/")
      ? new URL(location, current).href
      : location;
  }

  return current;
}