// 功能描述：定义用气统计的服务端事实模型；版本：1.0.0。

class UsagePoint {
  const UsagePoint({required this.date, required this.usage});
  final DateTime date;
  final double usage;

  factory UsagePoint.fromJson(Map<String, Object?> json) => UsagePoint(
    date: DateTime.parse(json['date'] as String),
    usage: (json['usage'] as num).toDouble(),
  );
}

class UsageComposition {
  const UsageComposition({required this.breakfast, required this.lunch, required this.dinner});
  final double breakfast, lunch, dinner;

  factory UsageComposition.fromJson(Map<String, Object?> json) => UsageComposition(
    breakfast: (json['breakfast'] as num? ?? 0).toDouble(),
    lunch: (json['lunch'] as num? ?? 0).toDouble(),
    dinner: (json['dinner'] as num? ?? 0).toDouble(),
  );
}

class UsageStatistics {
  const UsageStatistics({
    required this.available,
    required this.deviceIdentity,
    required this.deviceName,
    required this.deviceCode,
    required this.period,
    required this.periodStart,
    required this.periodEnd,
    required this.unit,
    required this.points,
    required this.totalUsage,
    required this.averageUsage,
    required this.composition,
    required this.source,
    required this.calcVersion,
    required this.updatedAt,
    required this.unavailableReason,
  });

  final bool available;
  final String deviceIdentity, deviceName, deviceCode, period, unit;
  final DateTime periodStart, periodEnd;
  final List<UsagePoint> points;
  final double totalUsage, averageUsage;
  final UsageComposition composition;
  final String source, calcVersion, unavailableReason;
  final DateTime? updatedAt;

  factory UsageStatistics.fromJson(Map<String, Object?> json) {
    final device = json['device'] as Map<String, Object?>? ?? const {};
    final composition = json['composition'] as Map<String, Object?>? ?? const {};
    return UsageStatistics(
      available: json['available'] == true,
      deviceIdentity: device['identity'] as String? ?? '',
      deviceName: device['name'] as String? ?? '',
      deviceCode: device['code'] as String? ?? '',
      period: json['period'] as String? ?? 'month',
      periodStart: DateTime.parse(json['period_start'] as String),
      periodEnd: DateTime.parse(json['period_end'] as String),
      unit: json['unit'] as String? ?? 'kg',
      points: (json['points'] as List<Object?>? ?? const [])
          .map((item) => UsagePoint.fromJson(item as Map<String, Object?>))
          .toList(),
      totalUsage: (json['total_usage'] as num? ?? 0).toDouble(),
      averageUsage: (json['average_usage'] as num? ?? 0).toDouble(),
      composition: UsageComposition.fromJson(composition),
      source: json['source'] as String? ?? '',
      calcVersion: json['calc_version'] as String? ?? '',
      updatedAt: DateTime.tryParse(json['updated_at']?.toString() ?? '')?.toLocal(),
      unavailableReason: json['unavailable_reason'] as String? ?? '',
    );
  }
}