feat: implement delivery strategies

src/main/java/io/github/akadir/casestudy/delivery/Deliverable.java

@@ -0,0 +1,7 @@
+package io.github.akadir.casestudy.delivery;
+
+public interface Deliverable {
+    int getProductCount();
+
+    int getDeliveryCount();
+}

src/main/java/io/github/akadir/casestudy/delivery/strategy/DeliveryStrategy.java

@@ -0,0 +1,7 @@
+package io.github.akadir.casestudy.delivery.strategy;
+
+import io.github.akadir.casestudy.delivery.Deliverable;
+
+public interface DeliveryStrategy {
+    double calculateDeliveryCost(Deliverable deliverable);
+}

src/main/java/io/github/akadir/casestudy/delivery/strategy/FedexDelivery.java

@@ -0,0 +1,22 @@
+package io.github.akadir.casestudy.delivery.strategy;
+
+import io.github.akadir.casestudy.delivery.Deliverable;
+
+public class FedexDelivery implements DeliveryStrategy {
+    private final double costPerProduct;
+    private final double costPerDelivery;
+
+    public FedexDelivery(double costPerProduct, double costPerDelivery) {
+        this.costPerProduct = costPerProduct;
+        this.costPerDelivery = costPerDelivery;
+    }
+
+    @Override
+    public double calculateDeliveryCost(Deliverable deliverable) {
+        if (deliverable.getDeliveryCount() == 0) {
+            return 0;
+        } else {
+            return costPerDelivery * deliverable.getDeliveryCount() + costPerProduct * deliverable.getProductCount();
+        }
+    }
+}

src/main/java/io/github/akadir/casestudy/delivery/strategy/UPSDelivery.java

@@ -0,0 +1,22 @@
+package io.github.akadir.casestudy.delivery.strategy;
+
+import io.github.akadir.casestudy.delivery.Deliverable;
+
+public class UPSDelivery implements DeliveryStrategy {
+    private final double costPerProduct;
+    private final double costPerDelivery;
+
+    public UPSDelivery(double costPerProduct, double costPerDelivery) {
+        this.costPerProduct = costPerProduct;
+        this.costPerDelivery = costPerDelivery;
+    }
+
+    @Override
+    public double calculateDeliveryCost(Deliverable deliverable) {
+        if (deliverable.getDeliveryCount() == 0) {
+            return 0;
+        } else {
+            return costPerDelivery + deliverable.getProductCount() * costPerProduct;
+        }
+    }
+}

src/main/java/io/github/akadir/casestudy/shopping/model/ShoppingCart.java

@@ -1,13 +1,14 @@
 package io.github.akadir.casestudy.shopping.model;
 
+import io.github.akadir.casestudy.delivery.Deliverable;
 import io.github.akadir.casestudy.discount.campaign.base.Campaign;
 import io.github.akadir.casestudy.discount.coupon.base.Coupon;
 import io.github.akadir.casestudy.product.model.Product;
 
 import java.util.HashMap;
 import java.util.Map;
 
-public class ShoppingCart {
+public class ShoppingCart implements Deliverable {
     private final Map<Product, Integer> products;
     private Coupon appliedCoupon;
     private Campaign appliedCampaign;
@@ -49,4 +50,12 @@ public double getCartPrice() {
         return products.entrySet().stream()
                 .mapToDouble(e -> e.getKey().getPrice() * e.getValue()).sum();
     }
+
+    public int getDeliveryCount() {
+        return products.size();
+    }
+
+    public int getProductCount() {
+        return products.values().stream().mapToInt(a -> a).sum();
+    }
 }

src/main/java/io/github/akadir/casestudy/shopping/service/ShoppingCartService.java

@@ -3,6 +3,7 @@
 import io.github.akadir.casestudy.discount.campaign.base.Campaign;
 import io.github.akadir.casestudy.discount.coupon.base.Coupon;
 import io.github.akadir.casestudy.product.model.Product;
+import io.github.akadir.casestudy.shopping.model.ShoppingCart;
 
 import java.util.Map;
 
@@ -24,5 +25,7 @@ public interface ShoppingCartService {
 
     double getDiscounts();
 
+    ShoppingCart getShoppingCart();
+
     Map<Product, Integer> getProducts();
 }

src/main/java/io/github/akadir/casestudy/shopping/service/impl/ConcreteShoppingCartServiceImpl.java

@@ -3,8 +3,8 @@
 import io.github.akadir.casestudy.discount.campaign.base.Campaign;
 import io.github.akadir.casestudy.discount.coupon.base.Coupon;
 import io.github.akadir.casestudy.product.model.Product;
-import io.github.akadir.casestudy.shopping.service.ShoppingCartService;
 import io.github.akadir.casestudy.shopping.model.ShoppingCart;
+import io.github.akadir.casestudy.shopping.service.ShoppingCartService;
 import io.github.akadir.casestudy.shopping.validator.CartEventValidator;
 import io.github.akadir.casestudy.shopping.validator.impl.AmountValidator;
 import io.github.akadir.casestudy.shopping.validator.impl.ProductValidator;
@@ -173,6 +173,11 @@ public double getDiscounts() {
         return shoppingCart.getDiscount();
     }
 
+    @Override
+    public ShoppingCart getShoppingCart() {
+        return shoppingCart;
+    }
+
     public Map<Product, Integer> getProducts() {
         return Collections.unmodifiableMap(shoppingCart.getProducts());
     }

src/test/java/io/github/akadir/casestudy/delivery/strategy/FedexDeliveryTest.java

@@ -0,0 +1,79 @@
+package io.github.akadir.casestudy.delivery.strategy;
+
+import io.github.akadir.casestudy.delivery.Deliverable;
+import io.github.akadir.casestudy.delivery.strategy.DeliveryStrategy;
+import io.github.akadir.casestudy.delivery.strategy.FedexDelivery;
+import io.github.akadir.casestudy.product.model.Category;
+import io.github.akadir.casestudy.product.model.Product;
+import io.github.akadir.casestudy.shopping.service.ShoppingCartService;
+import io.github.akadir.casestudy.shopping.service.impl.ConcreteShoppingCartServiceImpl;
+import org.junit.Before;
+import org.junit.Test;
+
+import java.util.HashMap;
+import java.util.Map;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+public class FedexDeliveryTest {
+    private ShoppingCartService shoppingCartService;
+
+    @Before
+    public void init() {
+        shoppingCartService = new ConcreteShoppingCartServiceImpl();
+    }
+
+    @Test
+    public void whenUPSDeliveryCostCalculatedWithNonEmptyProductCartThenExpectCorrectCost() {
+        Category category = new Category("Accessories");
+        Product product = new Product("bag", 50, category);
+
+        shoppingCartService.addProduct(product);
+
+        double costPerDelivery = 3;
+        double costPerProduct = 1;
+
+        DeliveryStrategy deliveryStrategy = new FedexDelivery(costPerProduct, costPerDelivery);
+
+        Map<Product, Integer> productsBackup = new HashMap<>(shoppingCartService.getProducts());
+
+        Deliverable deliverable = shoppingCartService.getShoppingCart();
+
+        assertThat(deliveryStrategy.calculateDeliveryCost(deliverable))
+                .as("Delivery cost should be correct")
+                .isEqualTo(costPerDelivery + costPerProduct);
+
+        assertThat(shoppingCartService.getProducts())
+                .as("Shopping cart should not be modified in delivery cost calculation")
+                .isEqualTo(productsBackup);
+
+        Product anotherProduct = new Product("back bag", 100, category);
+
+        shoppingCartService.addProduct(anotherProduct, 2);
+
+        productsBackup = new HashMap<>(shoppingCartService.getProducts());
+
+        assertThat(deliveryStrategy.calculateDeliveryCost(deliverable))
+                .as("Delivery cost should be correct")
+                .isEqualTo((costPerDelivery * deliverable.getDeliveryCount()) + (costPerProduct * deliverable.getProductCount()));
+
+        assertThat(shoppingCartService.getProducts())
+                .as("Shopping cart should not be modified in delivery cost calculation")
+                .isEqualTo(productsBackup);
+    }
+
+    @Test
+    public void whenUPSDeliveryCostCalculatedWithEmptyCartThenExpectZeroCost() {
+        DeliveryStrategy deliveryStrategy = new FedexDelivery(1, 3);
+
+        Map<Product, Integer> productsBackup = new HashMap<>(shoppingCartService.getProducts());
+
+        assertThat(deliveryStrategy.calculateDeliveryCost(shoppingCartService.getShoppingCart()))
+                .as("Delivery cost should be zero for empty cart")
+                .isZero();
+
+        assertThat(shoppingCartService.getProducts())
+                .as("Shopping cart should not be modified in delivery cost calculation")
+                .isEqualTo(productsBackup);
+    }
+}

src/test/java/io/github/akadir/casestudy/delivery/strategy/UPSDeliveryTest.java

@@ -0,0 +1,78 @@
+package io.github.akadir.casestudy.delivery.strategy;
+
+import io.github.akadir.casestudy.delivery.strategy.DeliveryStrategy;
+import io.github.akadir.casestudy.delivery.strategy.UPSDelivery;
+import io.github.akadir.casestudy.product.model.Category;
+import io.github.akadir.casestudy.product.model.Product;
+import io.github.akadir.casestudy.shopping.service.ShoppingCartService;
+import io.github.akadir.casestudy.shopping.service.impl.ConcreteShoppingCartServiceImpl;
+import org.junit.Before;
+import org.junit.Test;
+
+import java.util.HashMap;
+import java.util.Map;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+public class UPSDeliveryTest {
+
+    private ShoppingCartService shoppingCartService;
+
+    @Before
+    public void init() {
+        shoppingCartService = new ConcreteShoppingCartServiceImpl();
+    }
+
+    @Test
+    public void whenUPSDeliveryCostCalculatedWithNonEmptyProductCartThenExpectCorrectCost() {
+        Category category = new Category("Accessories");
+        Product product = new Product("bag", 50, category);
+
+        shoppingCartService.addProduct(product);
+
+        double costPerDelivery = 3;
+        double costPerProduct = 1;
+
+        DeliveryStrategy deliveryStrategy = new UPSDelivery(costPerProduct, costPerDelivery);
+
+        Map<Product, Integer> productsBackup = new HashMap<>(shoppingCartService.getProducts());
+
+        assertThat(deliveryStrategy.calculateDeliveryCost(shoppingCartService.getShoppingCart()))
+                .as("Delivery cost should be correct")
+                .isEqualTo(costPerDelivery + costPerProduct);
+
+        assertThat(shoppingCartService.getProducts())
+                .as("Shopping cart should not be modified in delivery cost calculation")
+                .isEqualTo(productsBackup);
+
+        Product anotherProduct = new Product("back bag", 100, category);
+
+        shoppingCartService.addProduct(anotherProduct, 2);
+
+        productsBackup = new HashMap<>(shoppingCartService.getProducts());
+
+        assertThat(deliveryStrategy.calculateDeliveryCost(shoppingCartService.getShoppingCart()))
+                .as("Delivery cost should be correct")
+                .isEqualTo(costPerDelivery + 3 * costPerProduct);
+
+        assertThat(shoppingCartService.getProducts())
+                .as("Shopping cart should not be modified in delivery cost calculation")
+                .isEqualTo(productsBackup);
+
+    }
+
+    @Test
+    public void whenUPSDeliveryCostCalculatedWithEmptyCartThenExpectZeroCost() {
+        DeliveryStrategy deliveryStrategy = new UPSDelivery(1, 3);
+
+        Map<Product, Integer> productsBackup = new HashMap<>(shoppingCartService.getProducts());
+
+        assertThat(deliveryStrategy.calculateDeliveryCost(shoppingCartService.getShoppingCart()))
+                .as("Delivery cost should be zero for empty cart")
+                .isZero();
+
+        assertThat(shoppingCartService.getProducts())
+                .as("Shopping cart should not be modified in delivery cost calculation")
+                .isEqualTo(productsBackup);
+    }
+}