/**
 * 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;
  }

  // Extract the clean upload path
  let uploadPath = '';
  if (trimmed.startsWith('/api/uploads/')) {
    uploadPath = trimmed.replace(/^\/api\/uploads\//, '');
  } else if (trimmed.startsWith('/api/media/')) {
    uploadPath = trimmed.replace(/^\/api\/media\//, '');
  } else if (trimmed.startsWith('/uploads/')) {
    uploadPath = trimmed.replace(/^\/uploads\//, '');
  } else if (trimmed.startsWith('uploads/')) {
    uploadPath = trimmed.replace(/^uploads\//, '');
  } else if (trimmed.startsWith('/media/')) {
    uploadPath = trimmed.replace(/^\/media\//, '');
  } else if (trimmed.startsWith('media/')) {
    uploadPath = trimmed.replace(/^media\//, '');
  } else {
    const uploadsMatch = trimmed.match(/^https?:\/\/[^/]+\/uploads\/(.+)$/i);
    if (uploadsMatch && uploadsMatch[1]) {
      uploadPath = uploadsMatch[1];
    }
  }

  if (uploadPath) {
    const isStage = typeof window !== 'undefined' && window.location.hostname.includes('stage');
    const isDev = process.env.NODE_ENV === 'development';
    const backendBase = process.env.NEXT_PUBLIC_API_URL?.replace(/\/api\/?$/, '') ||
      (isDev ? 'http://localhost:4400' : isStage ? 'https://stageapi.canina.ir' : 'https://api.canina.ir');
    return `${backendBase}/uploads/${uploadPath}`;
  }

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