// 功能描述：购物车条目、并发版本和结算快照；版本：1.0.0。
import 'primary_models.dart';

/// 服务端购物车快照；revision 用于阻止过期操作覆盖其他设备的修改。
class CartItem {
  const CartItem({
    required this.product,
    required this.quantity,
    required this.selected,
    required this.available,
    required this.revision,
    this.specification = '',
  });
  final ProductSummary product;
  final int quantity;
  final bool selected, available;
  final String revision;
  final String specification;
  bool get purchasable => available && quantity > 0 && quantity <= product.stock;
  int get amount => product.price * quantity;

  factory CartItem.fromJson(Map<String, Object?> json, String Function(String) resolve) {
    final price = json['price_amount'], stock = json['stock_quantity'], quantity = json['quantity'];
    if (price is! int ||
        price < 0 ||
        stock is! int ||
        quantity is! int ||
        quantity < 0 ||
        quantity > 999 ||
        json['product_identity'] is! String ||
        (json['product_identity'] as String).isEmpty ||
        json['revision'] is! String ||
        json['selected'] is! bool ||
        json['available'] is! bool) {
      throw const FormatException('购物车数据异常');
    }
    return CartItem(
      product: ProductSummary(
        identity: json['product_identity'] as String,
        name: json['name'] as String? ?? '',
        price: price,
        stock: stock,
        imageUrl: resolve(json['image_url'] as String? ?? ''),
        category: json['category_name'] as String? ?? '',
      ),
      quantity: quantity,
      selected: json['selected'] as bool,
      available: json['available'] as bool,
      revision: json['revision'] as String,
      specification: json['specification'] as String? ?? '',
    );
  }
}