Add stock capabilities

src/main/java/org/example/Shop.java

@@ -1,17 +1,21 @@
 package org.example;
 
+import java.util.HashMap;
 import java.util.List;
+import java.util.Set;
 
 public class Shop {
 
-    List<Product> products;
+    HashMap<Product, Integer> products;
     ShoppingCart cart = new ShoppingCart();
 
-    public Shop(List<Product> products) {
+    public Shop(HashMap<Product, Integer> products) {
         this.products = products;
     }
 
     public void addProductToCart(Product product) {
+        int currentQuantity = cart.getProductQuantity(product);
+        if (currentQuantity < getStock(product))
             cart.addProduct(product);
     }
 
@@ -20,11 +24,16 @@ public class Shop {
     }
 
     public void setProductQuantityInCart(Product product, int quantity) {
+        if (quantity <= getStock(product))
             cart.setProductQuantity(product, quantity);
     }
 
+    public int getStock(Product product) {
+        return products.getOrDefault(product, 0);
+    }
+
     public Product getProductById(int id) {
-        for (Product product : products) {
+        for (Product product : products.keySet()) {
             if (product.id == id) {
                 return product;
             }
@@ -32,6 +41,14 @@ public class Shop {
         return null;
     }
 
+    public List<Product> getProductList() {
+        return products.keySet().stream().toList();
+    }
+
+    public HashMap<Product, Integer> getCart() {
+        return cart.products;
+    }
+
     public Order checkout() {
         Order order = cart.toOrder();
         cart.clearProducts();