const TRACKING_QUERY_KEYS = new Set([
  'fbclid',
  'gclid',
  'dclid',
  'msclkid',
  'mc_cid',
  'mc_eid',
]);

export function removeTrackingParameters(url: URL): void {
  for (const key of Array.from(url.searchParams.keys())) {
    const normalized = key.toLowerCase();
    if (normalized === 'atx' || normalized.startsWith('utm_') || TRACKING_QUERY_KEYS.has(normalized)) {
      url.searchParams.delete(key);
    }
  }
}

/** Direct, tracking-free HTTPS WooCommerce PDP URL with the selected variation. */
export function buildWooCommerceProductUrl(
  productUrl: string | undefined,
  variationId?: string | null,
  variationSelections?: Record<string, Record<string, string>>
): string | null {
  if (!productUrl) return null;
  try {
    const url = new URL(productUrl);
    if (url.protocol !== 'https:') return null;
    url.hash = '';
    removeTrackingParameters(url);
    url.searchParams.delete('variation_id');
    for (const key of Array.from(url.searchParams.keys())) {
      if (key.toLowerCase().startsWith('attribute_')) url.searchParams.delete(key);
    }
    if (variationId && /^\d+$/.test(String(variationId))) {
      url.searchParams.set('variation_id', String(variationId));
      const selected = variationSelections?.[String(variationId)] ?? {};
      for (const [name, value] of Object.entries(selected)) {
        const key = name.startsWith('attribute_') ? name : `attribute_${name}`;
        if (/^attribute_[a-z0-9_-]+$/i.test(key) && typeof value === 'string' && value) {
          url.searchParams.set(key, value);
        }
      }
    }
    return url.toString();
  } catch {
    return null;
  }
}