String fileNameFromUrl(String url, {String defaultName = 'ecard.pdf'}) {
  try {
    final segment = Uri.parse(url).pathSegments.lastWhere(
          (s) => s.isNotEmpty,
          orElse: () => '',
        );
    if (segment.contains('.')) return Uri.decodeComponent(segment);
  } catch (_) {}
  return defaultName;
}