water-management-system/mobile-app/lib/features/revenue/models/meter_reading_model.dart

/// 抄表记录模型
class MeterReadingModel {
  final String id;
  final String meterNo;
  final String userName;
  final String address;
  final double previousReading;
  final double? currentReading;
  final String status; // pending, completed, abnormal
  final DateTime readingDate;
  final String? reader;
  final String? remark;

  MeterReadingModel({
    required this.id,
    required this.meterNo,
    required this.userName,
    required this.address,
    required this.previousReading,
    this.currentReading,
    required this.status,
    required this.readingDate,
    this.reader,
    this.remark,
  });

  double? get usage =>
      currentReading != null ? currentReading! - previousReading : null;

  factory MeterReadingModel.fromJson(Map<String, dynamic> json) {
    return MeterReadingModel(
      id: json['id']?.toString() ?? '',
      meterNo: json['meterNo'] ?? '',
      userName: json['userName'] ?? '',
      address: json['address'] ?? '',
      previousReading: (json['previousReading'] ?? 0).toDouble(),
      currentReading: json['currentReading']?.toDouble(),
      status: json['status'] ?? 'pending',
      readingDate: DateTime.tryParse(json['readingDate'] ?? '') ?? DateTime.now(),
      reader: json['reader'],
      remark: json['remark'],
    );
  }

  Map<String, dynamic> toJson() {
    return {
      'id': id,
      'meterNo': meterNo,
      'userName': userName,
      'address': address,
      'previousReading': previousReading,
      'currentReading': currentReading,
      'status': status,
      'readingDate': readingDate.toIso8601String(),
      'reader': reader,
      'remark': remark,
    };
  }
}