/**
 * Normalizes any media/upload URL to use the local frontend Next.js media proxy (/api/uploads/...)
 * instead of directly exposing or calling backend domains (api.canina.ir, etc.).
 *
 * Benefits:
 * 1. Leverages Next.js server caching and optimization.
 * 2. Hides internal backend URLs and avoids ugly direct backend domain calls.
 * 3. Supports HTTP Range requests for seamless video/audio seeking and streaming.
 */
export function getMediaUrl(url?: string | null): string {
  if (!url) return '';
  const trimmed = url.trim();
  if (!trimmed) return '';

  // Data URLs or blob URLs stay as-is
  if (trimmed.startsWith('data:') || trimmed.startsWith('blob:')) {
    return trimmed;
  }

  // If already proxied via /api/uploads/ or /api/media/
  if (trimmed.startsWith('/api/uploads/') || trimmed.startsWith('/api/media/')) {
    return trimmed;
  }

  // If relative path starting with /uploads/
  if (trimmed.startsWith('/uploads/')) {
    return `/api/uploads/${trimmed.replace(/^\/uploads\//, '')}`;
  }

  // If relative path starting with uploads/
  if (trimmed.startsWith('uploads/')) {
    return `/api/uploads/${trimmed.replace(/^uploads\//, '')}`;
  }

  // If relative path starting with /media/ or media/
  if (trimmed.startsWith('/media/')) {
    return `/api/uploads/${trimmed.replace(/^\/media\//, '')}`;
  }
  if (trimmed.startsWith('media/')) {
    return `/api/uploads/${trimmed.replace(/^media\//, '')}`;
  }

  // If full backend URL containing /uploads/ (e.g. http://localhost:4001/uploads/..., https://api.canina.ir/uploads/...)
  const uploadsMatch = trimmed.match(/^https?:\/\/[^/]+\/uploads\/(.+)$/i);
  if (uploadsMatch && uploadsMatch[1]) {
    return `/api/uploads/${uploadsMatch[1]}`;
  }

  // External URLs (like unsplash, cdn, youtube, aparat) stay as-is
  return trimmed;
}