Support variant-aware cart lines

src/app/services/cart.service.ts

@@ -5,6 +5,8 @@ import { normalizeDeliveryOption, normalizeOptionalNumber } from '../utils/norma
 import { environment } from '../../environments/environment';
 import type { } from '../types/telegram.types';
 
+type CartVariant = { colour?: string; size?: string; price?: number; currency?: string };
+
 @Injectable({
   providedIn: 'root'
 })
@@ -187,16 +189,30 @@ export class CartService {
     return false;
   }
 
-  addItem(itemID: number, quantity: number = 1, variant?: { colour?: string; size?: string; price?: number; currency?: string }): void {
+  private normalizeVariantSize(size?: string): string {
+    return size && size.toLowerCase() !== 'default' ? size : '';
+  }
+
+  private isSameCartLine(item: CartItem, itemID: number, variant?: CartVariant): boolean {
+    return item.itemID === itemID
+      && (item.colour ?? '') === (variant?.colour ?? '')
+      && this.normalizeVariantSize(item.size) === this.normalizeVariantSize(variant?.size);
+  }
+
+  private findCartLineIndex(itemID: number, variant?: CartVariant): number {
+    return this.cartItems().findIndex(item => this.isSameCartLine(item, itemID, variant));
+  }
+
+  addItem(itemID: number, quantity: number = 1, variant?: CartVariant): void {
     // Prevent duplicate API calls for same item
     if (this.addingItems.has(itemID)) return;
     
     const currentItems = this.cartItems();
-    const existingItem = currentItems.find(i => i.itemID === itemID);
+    const existingItem = currentItems.find(i => this.isSameCartLine(i, itemID, variant));
     
     if (existingItem) {
       // Item exists, increase quantity
-      this.updateQuantity(itemID, existingItem.quantity + quantity);
+      this.updateQuantity(itemID, existingItem.quantity + quantity, variant);
     } else {
       // Get item details from API and add to cart
       this.addingItems.add(itemID);
@@ -226,15 +242,15 @@ export class CartService {
     }
   }
 
-  updateQuantity(itemID: number, quantity: number): void {
+  updateQuantity(itemID: number, quantity: number, variant?: CartVariant): void {
     if (quantity <= 0) {
-      this.removeItem(itemID);
+      this.removeItem(itemID, variant);
       return;
     }
     
     const currentItems = this.cartItems();
     const updatedItems = currentItems.map(item =>
-      item.itemID === itemID ? { ...item, quantity } : item
+      this.isSameCartLine(item, itemID, variant) ? { ...item, quantity } : item
     );
     this.cartItems.set(updatedItems);
   }
@@ -261,8 +277,19 @@ export class CartService {
     this.cartItems.set(updatedItems);
   }
 
-  removeItem(itemID: number): void {
-    this.removeItems([itemID]);
+  removeItem(itemID: number, variant?: CartVariant): void {
+    if (!variant) {
+      this.removeItems([itemID]);
+      return;
+    }
+
+    const lineIndex = this.findCartLineIndex(itemID, variant);
+    if (lineIndex === -1) {
+      return;
+    }
+
+    const updatedItems = this.cartItems().filter((_item, index) => index !== lineIndex);
+    this.cartItems.set(updatedItems);
   }
 
   clearCart(): void {