feat: Implementation of session facade design pattern #1278 (#3121)

* implementation of session facade #1278 * minor change * readme updated * addressed the comments regarding changing lists to maps and adding maven assembly plugin --------- Co-authored-by: Ilkka Seppälä <iluwatar@users.noreply.github.com>
2026-05-16 14:59:21 +00:00 · 2025-01-11 17:45:01 +02:00
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+/*
+ * This project is licensed under the MIT license. Module model-view-viewmodel is using ZK framework licensed under LGPL (see lgpl-3.0.txt).
+ *
+ * The MIT License
+ * Copyright © 2014-2022 Ilkka Seppälä
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+
+package com.iluwatar.sessionfacade;
+
+/**
+ * The main entry point of the application that demonstrates the usage
+ * of the ShoppingFacade to manage the shopping process using the Session Facade pattern.
+ * This class serves as a client that interacts with the simplified
+ * interface provided by the ShoppingFacade, which encapsulates
+ * complex interactions with the underlying business services.
+ * The ShoppingFacade acts as a session bean that coordinates the communication
+ * between multiple services, hiding their complexity and providing a single, unified API.
+ */
+public class App {
+  /**
+   * The entry point of the application.
+   * This method demonstrates how the ShoppingFacade, acting as a Session Facade, is used to:
+   * - Add items to the shopping cart
+   * - Process a payment
+   * - Place the order
+   * The session facade manages the communication between the individual services
+   * and simplifies the interactions for the client.
+   *
+   * @param args the input arguments
+   */
+  public static void main(String[] args) {
+    ShoppingFacade shoppingFacade = new ShoppingFacade();
+
+    // Adding items to the shopping cart
+    shoppingFacade.addToCart(1);
+    shoppingFacade.addToCart(2);
+
+    // Processing the payment with the chosen method
+    shoppingFacade.processPayment("cash");
+
+    // Finalizing the order
+    shoppingFacade.order();
+  }
+}
@@ -0,0 +1,87 @@
+/*
+ * This project is licensed under the MIT license. Module model-view-viewmodel is using ZK framework licensed under LGPL (see lgpl-3.0.txt).
+ *
+ * The MIT License
+ * Copyright © 2014-2022 Ilkka Seppälä
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+
+package com.iluwatar.sessionfacade;
+
+
+import java.util.Map;
+import lombok.Getter;
+import lombok.extern.slf4j.Slf4j;
+
+/**
+ * The type Cart service.
+ * Represents the cart entity, has add to cart and remove from cart methods
+ */
+@Slf4j
+public class CartService {
+  /**
+   * -- GETTER --
+   *  Gets cart.
+   */
+  @Getter
+  private final Map<Integer, Product> cart;
+  private final Map<Integer, Product> productCatalog;
+
+  /**
+   * Instantiates a new Cart service.
+   *
+   * @param cart           the cart
+   * @param productCatalog the product catalog
+   */
+  public CartService(Map<Integer, Product> cart, Map<Integer, Product> productCatalog) {
+    this.cart = cart;
+    this.productCatalog = productCatalog;
+  }
+
+  /**
+   * Add to cart.
+   *
+   * @param productId the product id
+   */
+  public void addToCart(int productId) {
+    Product product = productCatalog.get(productId);
+    if (product != null) {
+      cart.put(productId, product);
+      LOGGER.info("{} successfully added to the cart", product);
+    } else {
+      LOGGER.info("No product is found in catalog with id {}", productId);
+    }
+  }
+
+  /**
+   * Remove from cart.
+   *
+   * @param productId the product id
+   */
+  public void removeFromCart(int productId) {
+    Product product = cart.remove(productId); // Remove product from cart
+    if (product != null) {
+      LOGGER.info("{} successfully removed from the cart", product);
+    } else {
+      LOGGER.info("No product is found in cart with id {}", productId);
+    }
+  }
+
+}
@@ -0,0 +1,83 @@
+/*
+ * This project is licensed under the MIT license. Module model-view-viewmodel is using ZK framework licensed under LGPL (see lgpl-3.0.txt).
+ *
+ * The MIT License
+ * Copyright © 2014-2022 Ilkka Seppälä
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+
+package com.iluwatar.sessionfacade;
+
+import java.util.Map;
+import lombok.extern.slf4j.Slf4j;
+
+/**
+ * The OrderService class is responsible for finalizing a customer's order.
+ * It includes a method to calculate the total cost of the order, which follows
+ * the information expert principle from GRASP by assigning the responsibility
+ * of total calculation to this service.
+ * Additionally, it provides a method to complete the order, which empties the
+ * client's shopping cart once the order is finalized.
+ */
+@Slf4j
+public class OrderService {
+  private final Map<Integer, Product> cart;
+
+  /**
+   * Instantiates a new Order service.
+   *
+   * @param cart the cart
+   */
+  public OrderService(Map<Integer, Product> cart) {
+    this.cart = cart;
+  }
+
+  /**
+   * Order.
+   */
+  public void order() {
+    Double total = getTotal();
+    if (!this.cart.isEmpty()) {
+      LOGGER.info("Client has chosen to order {} with total {}", cart,
+          String.format("%.2f", total));
+      this.completeOrder();
+    } else {
+      LOGGER.info("Client's shopping cart is empty");
+    }
+  }
+
+  /**
+   * Gets total.
+   *
+   * @return the total
+   */
+  public double getTotal() {
+    final double[] total = {0.0};
+    this.cart.forEach((key, product) -> total[0] += product.price());
+    return total[0];
+  }
+
+  /**
+   * Complete order.
+   */
+  public void completeOrder() {
+    this.cart.clear();
+  }
+}
@@ -0,0 +1,75 @@
+/*
+ * This project is licensed under the MIT license. Module model-view-viewmodel is using ZK framework licensed under LGPL (see lgpl-3.0.txt).
+ *
+ * The MIT License
+ * Copyright © 2014-2022 Ilkka Seppälä
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+
+package com.iluwatar.sessionfacade;
+
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+/**
+ * The PaymentService class is responsible for handling the selection and processing
+ * of different payment methods. It provides functionality to select a payment method
+ * (cash or credit card) and process the corresponding payment option. The class uses
+ * logging to inform the client of the selected payment method.
+ * It includes methods to:
+ * - Select the payment method based on the client's choice.
+ * - Process cash payments through the `cashPayment()` method.
+ * - Process credit card payments through the `creditCardPayment()` method.
+ */
+public class PaymentService {
+  /**
+   * The constant LOGGER.
+   */
+  public static Logger LOGGER = LoggerFactory.getLogger(PaymentService.class);
+
+  /**
+   * Select payment method.
+   *
+   * @param method the method
+   */
+  public void selectPaymentMethod(String method) {
+    if (method.equals("cash")) {
+      cashPayment();
+    } else if (method.equals("credit")) {
+      creditCardPayment();
+    } else {
+      LOGGER.info("Unspecified payment method type");
+    }
+  }
+
+  /**
+   * Cash payment.
+   */
+  public void cashPayment() {
+    LOGGER.info("Client have chosen cash payment option");
+  }
+
+  /**
+   * Credit card payment.
+   */
+  public void creditCardPayment() {
+    LOGGER.info("Client have chosen credit card payment option");
+  }
+}
@@ -0,0 +1,38 @@
+/*
+ * This project is licensed under the MIT license. Module model-view-viewmodel is using ZK framework licensed under LGPL (see lgpl-3.0.txt).
+ *
+ * The MIT License
+ * Copyright © 2014-2022 Ilkka Seppälä
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+
+package com.iluwatar.sessionfacade;
+
+/**
+ * The type Product.
+ */
+public record Product(int id, String name, double price, String description) {
+  @Override
+  public String toString() {
+    return "ID: " + id + "\nName: " + name + "\nPrice: $" + price + "\nDescription: " + description;
+  }
+}
+
+
@@ -0,0 +1,60 @@
+/*
+ * This project is licensed under the MIT license. Module model-view-viewmodel is using ZK framework licensed under LGPL (see lgpl-3.0.txt).
+ *
+ * The MIT License
+ * Copyright © 2014-2022 Ilkka Seppälä
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+
+package com.iluwatar.sessionfacade;
+
+import java.util.Map;
+
+/**
+ * The type ProductCatalogService.
+ * This class manages a catalog of products. It holds a map of products,
+ * where each product is identified by a unique ID. The class
+ * provides functionality to access and manage the products in the catalog.
+ */
+public class ProductCatalogService {
+
+  private final Map<Integer, Product> products;
+
+  /**
+   * Instantiates a new ProductCatalogService.
+   *
+   * @param products the map of products to be used by this service
+   */
+  public ProductCatalogService(Map<Integer, Product> products) {
+    this.products = products;
+  }
+
+  // Additional methods to interact with products can be added here, for example:
+
+  /**
+   * Retrieves a product by its ID.
+   *
+   * @param id the product ID
+   * @return the product corresponding to the ID
+   */
+  public Product getProductById(int id) {
+    return products.get(id);
+  }
+}
@@ -0,0 +1,126 @@
+/*
+ * This project is licensed under the MIT license. Module model-view-viewmodel is using ZK framework licensed under LGPL (see lgpl-3.0.txt).
+ *
+ * The MIT License
+ * Copyright © 2014-2022 Ilkka Seppälä
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+
+package com.iluwatar.sessionfacade;
+
+import java.util.HashMap;
+import java.util.Map;
+import lombok.extern.slf4j.Slf4j;
+
+
+/**
+ * The ShoppingFacade class provides a simplified interface for clients to interact with the shopping system.
+ * It acts as a facade to handle operations related to a shopping cart, order processing, and payment.
+ * Responsibilities:
+ * - Add products to the shopping cart.
+ * - Remove products from the shopping cart.
+ * - Retrieve the current shopping cart.
+ * - Finalize an order by calling the order service.
+ * - Check if a payment is required based on the order total.
+ * - Process payment using different payment methods (e.g., cash, credit card).
+ * The ShoppingFacade class delegates operations to the following services:
+ * - CartService: Manages the cart and product catalog.
+ * - OrderService: Handles the order finalization process and calculation of the total.
+ * - PaymentService: Handles the payment processing based on the selected payment method.
+ */
+@Slf4j
+public class ShoppingFacade {
+  private final CartService cartService;
+  private final OrderService orderService;
+  private final PaymentService paymentService;
+
+  /**
+   * Instantiates a new Shopping facade.
+   */
+  public ShoppingFacade() {
+    Map<Integer, Product> productCatalog = new HashMap<>();
+    productCatalog.put(1, new Product(1, "Wireless Mouse", 25.99, "Ergonomic wireless mouse with USB receiver."));
+    productCatalog.put(2, new Product(2, "Gaming Keyboard", 79.99, "RGB mechanical gaming keyboard with programmable keys."));
+    Map<Integer, Product> cart = new HashMap<>();
+    cartService = new CartService(cart, productCatalog);
+    orderService = new OrderService(cart);
+    paymentService = new PaymentService();
+  }
+
+  /**
+   * Gets cart.
+   *
+   * @return the cart
+   */
+  public Map<Integer, Product> getCart() {
+    return this.cartService.getCart();
+  }
+
+  /**
+   * Add to cart.
+   *
+   * @param productId the product id
+   */
+  public void addToCart(int productId) {
+    this.cartService.addToCart(productId);
+  }
+
+  /**
+   * Remove from cart.
+   *
+   * @param productId the product id
+   */
+  public void removeFromCart(int productId) {
+    this.cartService.removeFromCart(productId);
+  }
+
+  /**
+   * Order.
+   */
+  public void order() {
+    this.orderService.order();
+  }
+
+  /**
+   * Is payment required boolean.
+   *
+   * @return the boolean
+   */
+  public Boolean isPaymentRequired() {
+    double total = this.orderService.getTotal();
+    if (total == 0.0) {
+      LOGGER.info("No payment required");
+      return false;
+    }
+    return true;
+  }
+
+  /**
+   * Process payment.
+   *
+   * @param method the method
+   */
+  public void processPayment(String method) {
+    Boolean isPaymentRequired = isPaymentRequired();
+    if (Boolean.TRUE.equals(isPaymentRequired)) {
+      paymentService.selectPaymentMethod(method);
+    }
+  }
+}