class InvoiceItem {
  final int? id;
  final int? invoiceId;
  final int? productId;
  final String? sku;
  final String? hsnCode;

  final String? description;
  final double quantity;
  final double unitPrice;
  final double taxRate;
  final double discount;
  final double makingCharge;
  final double otherCharges;
  final double total;

  InvoiceItem({
    this.id,
    this.invoiceId,
    this.productId,
    this.hsnCode,
    this.sku,
    this.description,
    required this.quantity,
    required this.unitPrice,
    this.taxRate = 0.0,
    this.discount = 0.0,
    this.makingCharge = 0.0,
    this.otherCharges = 0.0,
    required this.total,
  });

  InvoiceItem copyWith({
    int? id,
    int? invoiceId,
    int? productId,
    String? hsnCode,
    String? sku,
    String? description,
    double? quantity,
    double? unitPrice,
    double? taxRate,
    double? discount,
    double? makingCharge,
    double? otherCharges,
    double? total,
  }) {
    return InvoiceItem(
      id: id ?? this.id,
      invoiceId: invoiceId ?? this.invoiceId,
      productId: productId ?? this.productId,
      hsnCode: hsnCode ?? this.hsnCode,
      sku: sku ?? this.sku,
      description: description ?? this.description,
      quantity: quantity ?? this.quantity,
      unitPrice: unitPrice ?? this.unitPrice,
      taxRate: taxRate ?? this.taxRate,
      discount: discount ?? this.discount,
      makingCharge: makingCharge ?? this.makingCharge,
      otherCharges: otherCharges ?? this.otherCharges,
      total: total ?? this.total,
    );
  }

  factory InvoiceItem.fromJson(Map<String, dynamic> json) {
    return InvoiceItem(
      id: json['id'],
      invoiceId: json['invoiceId'],
      productId: json['productId'],
      hsnCode: json['hsnCode'] ?? json['hsn_code'],
      sku: json['sku'],
      description: json['description'],
      quantity: json['quantity'].toDouble(),
      unitPrice: json['unitPrice'].toDouble(),
      taxRate: json['taxRate']?.toDouble() ?? 0.0,
      discount: json['discount']?.toDouble() ?? 0.0,
      makingCharge: json['makingCharge']?.toDouble() ?? 0.0,
      otherCharges: json['otherCharges']?.toDouble() ?? 0.0,
      total: json['total'].toDouble(),
    );
  }

  Map<String, dynamic> toJson() {
    final Map<String, dynamic> data = {};
    if (id != null) data['id'] = id;
    if (invoiceId != null) data['invoiceId'] = invoiceId;
    if (productId != null) data['productId'] = productId;
    if (hsnCode != null) data['hsnCode'] = hsnCode;
    if (sku != null) data['sku'] = sku;
    if (description != null) data['description'] = description;
    data['quantity'] = quantity;
    data['unitPrice'] = unitPrice;
    data['taxRate'] = taxRate;
    data['discount'] = discount;
    data['makingCharge'] = makingCharge;
    data['otherCharges'] = otherCharges;
    data['total'] = total;
    return data;
  }
}

class Invoice {
  final int? id;
  final int? customerId;
  final String invoiceNumber;
  final DateTime issueDate;
  final DateTime? dueDate;
  final double subtotal;
  final double taxTotal;
  final double discountTotal;
  final double totalAmount;
  final double amountPaid;
  final DateTime? nextPaymentDate;
  final String? paymentMethod;
  final int? paymentWalletId;
  final String status;
  final String? notes;
  final bool isEmi;
  final double? emiAmount;
  final String? emiCycle;
  final DateTime? emiStartDate;
  final List<InvoiceItem> items;
  final List<InvoicePayment>? payments;

  Invoice({
    this.id,
    this.customerId,
    required this.invoiceNumber,
    required this.issueDate,
    this.dueDate,
    required this.subtotal,
    this.taxTotal = 0.0,
    this.discountTotal = 0.0,
    required this.totalAmount,
    this.amountPaid = 0.0,
    this.nextPaymentDate,
    this.paymentMethod,
    this.paymentWalletId,
    this.status = 'DRAFT',
    this.notes,
    this.isEmi = false,
    this.emiAmount,
    this.emiCycle,
    this.emiStartDate,
    this.items = const [],
    this.payments,
  });

  factory Invoice.fromJson(Map<String, dynamic> json) {
    return Invoice(
      id: json['id'],
      customerId: json['customerId'],
      invoiceNumber: json['invoiceNumber'],
      issueDate: DateTime.parse(json['issueDate']),
      dueDate: json['dueDate'] != null ? DateTime.parse(json['dueDate']) : null,
      subtotal: json['subtotal'].toDouble(),
      taxTotal: json['taxTotal']?.toDouble() ?? 0.0,
      discountTotal: json['discountTotal']?.toDouble() ?? 0.0,
      totalAmount: json['totalAmount'].toDouble(),
      amountPaid: json['amountPaid']?.toDouble() ?? 0.0,
      nextPaymentDate: json['nextPaymentDate'] != null ? DateTime.parse(json['nextPaymentDate']) : null,
      paymentMethod: json['paymentMethod'],
      paymentWalletId: json['paymentWalletId'],
      status: json['status'] ?? 'DRAFT',
      notes: json['notes'],
      isEmi: json['isEmi'] ?? false,
      emiAmount: json['emiAmount']?.toDouble(),
      emiCycle: json['emiCycle'],
      emiStartDate: json['emiStartDate'] != null ? DateTime.parse(json['emiStartDate']) : null,
      items: json['items'] != null ? (json['items'] as List).map((i) => InvoiceItem.fromJson(i)).toList() : [],
      payments: json['payments'] != null ? (json['payments'] as List).map((i) => InvoicePayment.fromJson(i)).toList() : null,
    );
  }

  Map<String, dynamic> toJson() {
    final Map<String, dynamic> data = {};
    if (id != null) data['id'] = id;
    if (customerId != null) data['customerId'] = customerId;
    data['invoiceNumber'] = invoiceNumber;
    data['issueDate'] = issueDate.toIso8601String().split('T')[0];
    if (dueDate != null) data['dueDate'] = dueDate!.toIso8601String().split('T')[0];
    data['subtotal'] = subtotal;
    data['taxTotal'] = taxTotal;
    data['discountTotal'] = discountTotal;
    data['totalAmount'] = totalAmount;
    if (amountPaid > 0) data['amountPaid'] = amountPaid;
    if (nextPaymentDate != null) data['nextPaymentDate'] = nextPaymentDate!.toIso8601String().split('T')[0];
    if (paymentMethod != null) data['paymentMethod'] = paymentMethod;
    if (paymentWalletId != null) data['paymentWalletId'] = paymentWalletId;
    data['status'] = status;
    if (notes != null) data['notes'] = notes;
    data['isEmi'] = isEmi;
    if (emiAmount != null) data['emiAmount'] = emiAmount;
    if (emiCycle != null) data['emiCycle'] = emiCycle;
    if (emiStartDate != null) data['emiStartDate'] = emiStartDate!.toIso8601String().split('T')[0];
    data['items'] = items.map((i) => i.toJson()).toList();
    if (payments != null) data['payments'] = payments!.map((i) => i.toJson()).toList();
    return data;
  }
}

class InvoicePayment {
  final int? id;
  final int? invoiceId;
  final double amount;
  final DateTime? paymentDate;
  final String paymentMethod;
  final int? emiInstallmentNumber;
  final int? walletId;

  InvoicePayment({
    this.id,
    this.invoiceId,
    required this.amount,
    this.paymentDate,
    required this.paymentMethod,
    this.emiInstallmentNumber,
    this.walletId,
  });

  factory InvoicePayment.fromJson(Map<String, dynamic> json) {
    return InvoicePayment(
      id: json['id'],
      invoiceId: json['invoiceId'],
      amount: json['amount'].toDouble(),
      paymentDate: json['paymentDate'] != null ? DateTime.parse(json['paymentDate']) : null,
      paymentMethod: json['paymentMethod'] ?? 'Cash',
      emiInstallmentNumber: json['emiInstallmentNumber'],
      walletId: json['walletId'],
    );
  }

  Map<String, dynamic> toJson() {
    final Map<String, dynamic> data = {};
    if (id != null) data['id'] = id;
    if (invoiceId != null) data['invoiceId'] = invoiceId;
    data['amount'] = amount;
    if (paymentDate != null) data['paymentDate'] = paymentDate!.toIso8601String().split('T')[0];
    data['paymentMethod'] = paymentMethod;
    if (emiInstallmentNumber != null) data['emiInstallmentNumber'] = emiInstallmentNumber;
    if (walletId != null) data['walletId'] = walletId;
    return data;
  }
}