import 'api_service.dart';
import 'content_policy.dart';

class HomeBanner {
  const HomeBanner._({
    required this.titleEn,
    required this.titleFa,
    required this.subtitleEn,
    required this.subtitleFa,
    required this.target,
    required this.isAdvertisement,
    this.image,
  });

  final String titleEn, titleFa, subtitleEn, subtitleFa;
  final Uri target;
  final Uri? image;
  final bool isAdvertisement;
  String title(bool persian) => persian ? titleFa : titleEn;
  String subtitle(bool persian) => persian ? subtitleFa : subtitleEn;

  static final telegram = HomeBanner._(
    titleEn: 'ReelBox updates',
    titleFa: 'تازه‌های ریل‌باکس',
    subtitleEn: 'Updates and announcements',
    subtitleFa: 'به‌روزرسانی‌ها و اطلاعیه‌ها',
    target: Uri.parse('https://t.me/ReelBoxApp'),
    isAdvertisement: false,
  );
}

/// Only configured advertisements are parsed. The official Telegram entry is
/// fixed in the client and can never be replaced or relabelled by server data.
List<HomeBanner> parseHomeBanners(dynamic raw) {
  final result = <HomeBanner>[HomeBanner.telegram];
  if (raw is! Map || raw['banners'] is! List) return result;
  for (final row in (raw['banners'] as List).take(20)) {
    if (result.length == 6) break;
    if (row is! Map) continue;
    final en = _label(row['title_en'], 80);
    final fa = _label(row['title_fa'] ?? row['title_en'], 80);
    final subtitleEn = _label(row['subtitle_en'] ?? '', 180);
    final subtitleFa = _label(
      row['subtitle_fa'] ?? row['subtitle_en'] ?? '',
      180,
    );
    final target = _https(row['target_url']);
    final imageValue = row['image_url'];
    final image = imageValue == null || imageValue == ''
        ? null
        : _https(imageValue);
    if (en == null ||
        en.isEmpty ||
        fa == null ||
        fa.isEmpty ||
        subtitleEn == null ||
        subtitleFa == null ||
        target == null ||
        (imageValue != null && imageValue != '' && image == null)) {
      continue;
    }
    result.add(
      HomeBanner._(
        titleEn: en,
        titleFa: fa,
        subtitleEn: subtitleEn,
        subtitleFa: subtitleFa,
        target: target,
        image: image,
        isAdvertisement: true,
      ),
    );
  }
  return List.unmodifiable(result);
}

String? _label(dynamic value, int limit) {
  if (value is! String ||
      value.length > limit ||
      RegExp(r'[\x00-\x1f\x7f\u202a-\u202e\u2066-\u2069]').hasMatch(value) ||
      !ContentPolicy.allowsText(value)) {
    return null;
  }
  return value.trim();
}

Uri? _https(dynamic value) {
  if (value is! String ||
      value.length > 2048 ||
      RegExp(r'[\x00-\x20\x7f\\]').hasMatch(value) ||
      RegExp(
        r'%(?![0-9a-fA-F]{2})|%(?:0[0-9a-f]|1[0-9a-f]|7f)',
        caseSensitive: false,
      ).hasMatch(value) ||
      !ContentPolicy.allowsUrl(value)) {
    return null;
  }
  try {
    final uri = Uri.parse(value);
    if (uri.scheme != 'https' ||
        uri.host.isEmpty ||
        uri.userInfo.isNotEmpty ||
        uri.port != 443 ||
        uri.host.length > 253 ||
        !uri.host
            .split('.')
            .every(
              (part) =>
                  RegExp(r'^[a-zA-Z0-9](?:[a-zA-Z0-9-]{0,61}[a-zA-Z0-9])?$')
                      .hasMatch(part),
            )) {
      return null;
    }
    return uri;
  } on FormatException {
    return null;
  }
}

/// Uses only the existing trusted metadata transport, never a config URL.
class HomeBannerService {
  const HomeBannerService(this.api);
  final ApiService api;
  Future<List<HomeBanner>> load() async {
    try {
      return parseHomeBanners(await api.get('banners/'));
    } catch (_) {
      // Announcements remain reachable when the metadata service is offline.
      return [HomeBanner.telegram];
    }
  }
}