flutter_ecommerce_portal/lib/services/cart_service.dart

import 'package:flutter/foundation.dart';

import '../models/cart_item.dart';
import '../models/product.dart';

class CartService extends ChangeNotifier {
  final List<CartItem> _items = [];

  List<CartItem> get items => List.unmodifiable(_items);

  int get totalItems => _items.fold(0, (sum, item) => sum + item.quantity);

  double get totalPrice =>
      _items.fold(0.0, (sum, item) => sum + item.lineTotal);

  void addProduct(Product product) {
    final index = _items.indexWhere((item) => item.product.id == product.id);
    if (index == -1) {
      _items.add(CartItem(product: product));
    } else {
      _items[index].quantity += 1;
    }
    notifyListeners();
  }

  void removeProduct(String productId) {
    _items.removeWhere((item) => item.product.id == productId);
    notifyListeners();
  }

  void updateQuantity(String productId, int quantity) {
    if (quantity < 1) return;
    final index = _items.indexWhere((item) => item.product.id == productId);
    if (index == -1) return;
    _items[index].quantity = quantity;
    notifyListeners();
  }

  void clear() {
    _items.clear();
    notifyListeners();
  }
}