/**
 * Converts a direct R2 public URL to a same-origin proxy URL.
 * Used in API responses so <img> tags load via /api/img instead of
 * pub-xxx.r2.dev (which returns 503 for cross-origin sub-resource requests
 * due to Cloudflare Bot Management on the r2.dev domain).
 */

function getR2BaseUrl() {
  const pub = process.env.R2_PUBLIC_URL;
  const id = process.env.R2_ACCOUNT_ID;
  return pub || `https://pub-${id}.r2.dev`;
}

export function toProxyUrl(r2Url: string | null | undefined): string | null {
  if (!r2Url) return null;
  const base = getR2BaseUrl();
  if (r2Url.startsWith(base + "/")) {
    const key = r2Url.slice(base.length + 1);
    return `/api/img?key=${encodeURIComponent(key)}`;
  }
  return r2Url;
}