class Payment {
  final String id;
  final String childId;    // ← adicionado
  final String guardianId;
  final DateTime month;
  final double amount;
  final String status; // pending | paid | overdue
  final DateTime? paidAt;
  final String? receiptUrl;

  Payment({
    required this.id,
    required this.childId,
    required this.guardianId,
    required this.month,
    required this.amount,
    required this.status,
    this.paidAt,
    this.receiptUrl,
  });

  factory Payment.fromMap(Map<String, dynamic> map) => Payment(
    id:         map['id'] ?? '',
    childId:    map['child_id'] ?? '',
    guardianId: map['guardian_id'] ?? '',
    month:      DateTime.tryParse(map['month'] ?? '') ?? DateTime.now(),
    amount:     (map['amount'] ?? 0).toDouble(),
    status:     map['status'] ?? 'pending',
    paidAt:     map['paid_at'] != null ? DateTime.tryParse(map['paid_at']) : null,
    receiptUrl: map['receipt_url'],
  );

  Map<String, dynamic> toMap() => {
    'child_id':    childId,
    'guardian_id': guardianId,
    'month':       month.toIso8601String().split('T')[0],
    'amount':      amount,
    'status':      status,
    'paid_at':     paidAt?.toIso8601String(),
    'receipt_url': receiptUrl,
  };
}