class AppRelease {
  final String id;
  final String versionName;
  final int buildNumber;
  final String downloadUrl;
  final String releaseNotes;
  final String? sha256;
  final int? fileSize;
  final DateTime? publishedAt;

  const AppRelease({
    required this.id,
    required this.versionName,
    required this.buildNumber,
    required this.downloadUrl,
    required this.releaseNotes,
    required this.sha256,
    required this.fileSize,
    required this.publishedAt,
  });

  factory AppRelease.fromJson(Map<String, dynamic> json) {
    final id = json['id']?.toString().trim() ?? '';
    final versionName = json['versionName']?.toString().trim() ?? '';
    final buildNumber = (json['buildNumber'] as num?)?.toInt() ?? -1;
    final downloadUrl = json['downloadUrl']?.toString().trim() ?? '';
    if (id.isEmpty ||
        versionName.isEmpty ||
        buildNumber < 0 ||
        downloadUrl.isEmpty) {
      throw const FormatException('更新服务返回了不完整的版本信息');
    }
    return AppRelease(
      id: id,
      versionName: versionName,
      buildNumber: buildNumber,
      downloadUrl: downloadUrl,
      releaseNotes: json['releaseNotes']?.toString().trim() ?? '',
      sha256: json['sha256']?.toString().trim().nullIfEmpty,
      fileSize: (json['fileSize'] as num?)?.toInt(),
      publishedAt: DateTime.tryParse(json['publishedAt']?.toString() ?? ''),
    );
  }
}

class UpdateCheckResponse {
  final bool hasUpdate;
  final bool forceUpdate;
  final AppRelease? release;

  const UpdateCheckResponse({
    required this.hasUpdate,
    required this.forceUpdate,
    required this.release,
  });

  factory UpdateCheckResponse.fromJson(Map<String, dynamic> json) {
    final releaseJson = json['release'];
    final release = releaseJson is Map
        ? AppRelease.fromJson(Map<String, dynamic>.from(releaseJson))
        : null;
    final hasUpdate = json['hasUpdate'] == true;
    if (hasUpdate && release == null) {
      throw const FormatException('更新服务未返回目标版本');
    }
    return UpdateCheckResponse(
      hasUpdate: hasUpdate,
      forceUpdate: json['forceUpdate'] == true,
      release: release,
    );
  }
}

extension on String {
  String? get nullIfEmpty => isEmpty ? null : this;
}

class UpdatePolicy {
  UpdatePolicy._();

  static AppRelease? availableRelease(
    UpdateCheckResponse response, {
    required int currentBuild,
  }) {
    final release = response.release;
    if (!response.hasUpdate || release == null) return null;
    return release.buildNumber > currentBuild ? release : null;
  }

  static bool shouldPresent({
    required AppRelease release,
    required bool forced,
    required bool manual,
    required String? ignoredReleaseId,
  }) {
    if (forced || manual) return true;
    return ignoredReleaseId != release.id;
  }
}