update cart

lib/features/cart/domain/repositories/cart_repository.dart

@@ -0,0 +1,83 @@
+/// Domain Repository Interface: Cart Repository
+///
+/// Defines the contract for cart data operations.
+/// Implementation in data layer handles API and local storage.
+library;
+
+import 'package:worker/features/cart/domain/entities/cart_item.dart';
+
+/// Cart Repository Interface
+///
+/// Provides methods for managing shopping cart items:
+/// - Add items to cart
+/// - Remove items from cart
+/// - Get cart items
+/// - Update item quantities
+/// - Clear cart
+///
+/// Implementations should handle:
+/// - API-first strategy with local fallback
+/// - Offline queue for failed requests
+/// - Automatic sync when connection restored
+abstract class CartRepository {
+  /// Add items to cart
+  ///
+  /// [items] - List of cart items to add
+  /// [itemIds] - Product ERPNext item codes
+  /// [quantities] - Quantities for each item
+  /// [prices] - Unit prices for each item
+  ///
+  /// Returns list of cart items on success.
+  /// Throws exceptions on failure.
+  Future<List<CartItem>> addToCart({
+    required List<String> itemIds,
+    required List<double> quantities,
+    required List<double> prices,
+  });
+
+  /// Remove items from cart
+  ///
+  /// [itemIds] - Product ERPNext item codes to remove
+  ///
+  /// Returns true if successful, false otherwise.
+  /// Throws exceptions on failure.
+  Future<bool> removeFromCart({
+    required List<String> itemIds,
+  });
+
+  /// Get all cart items
+  ///
+  /// Returns list of cart items.
+  /// Throws exceptions on failure.
+  Future<List<CartItem>> getCartItems();
+
+  /// Update item quantity
+  ///
+  /// [itemId] - Product ERPNext item code
+  /// [quantity] - New quantity
+  /// [price] - Unit price
+  ///
+  /// Returns updated cart item list.
+  /// Throws exceptions on failure.
+  Future<List<CartItem>> updateQuantity({
+    required String itemId,
+    required double quantity,
+    required double price,
+  });
+
+  /// Clear all items from cart
+  ///
+  /// Returns true if successful, false otherwise.
+  /// Throws exceptions on failure.
+  Future<bool> clearCart();
+
+  /// Get total cart value
+  ///
+  /// Returns total amount of all items in cart.
+  Future<double> getCartTotal();
+
+  /// Get total cart item count
+  ///
+  /// Returns total number of items (sum of quantities).
+  Future<int> getCartItemCount();
+}