final stage 4 completed

README.md

@@ -20,7 +20,7 @@ rent out their cars and find customers.
 
 ## Project completion
 
-[//]: # (Project was completed on 14.05.23.)
+Project was completed on 18.08.23.
 
 ## Repository Contents
 
@@ -39,3 +39,7 @@ provided as bean. The CommandLineRunner uses a service to connect (query / inser
 
 17.08.23 Stage 3 completed. Add second entity `Car` with JPA-Repository and Service, connect it via `@ManyToOne` and
 `@JoinColumn` to the `Company`-table to generate a foreign key. Expand the menu structure (a bit weird requirements).
+
+17.08.23 Final Stage 4 completed. Third entity `Customer` was needed, that got its repository and service too. It has a 
+nullable `@OneToOne` connection to the `Car` entity. Used generic AbstractMenuController to reduce menu flow
+complexity. Also a JQL-`@Query` with `LEFT JOIN` was needed to query available cars without altering the tables. 

src/main/java/de/cofinpro/cars/controller/AbstractMenuController.java

@@ -0,0 +1,82 @@
+package de.cofinpro.cars.controller;
+
+
+import de.cofinpro.cars.io.ConsolePrinter;
+import de.cofinpro.cars.io.NamedItem;
+
+import java.util.List;
+import java.util.Scanner;
+
+/**
+ * Abstract controller class for menu looping over enum based menu actions, that takes the enum E as type parameter.
+ * Since this class provides methods for handling integer-choice based menus including the action loop and calling
+ * the menu item's action, new menus can be added very easily. The customization is done by abstract framework methods.
+ */
+abstract class AbstractMenuController<E extends Enum<E>> {
+
+    protected final ConsolePrinter printer;
+    protected final Scanner scanner;
+
+    protected AbstractMenuController(ConsolePrinter consolePrinter, Scanner scanner) {
+        this.printer = consolePrinter;
+        this.scanner = scanner;
+    }
+
+    /**
+     * abstract getter to implement in subclass.
+     * @return the menu text to display when prompting for a user choice
+     */
+    protected abstract String getMenuText();
+
+    /**
+     * abstract action getter for choice to implement in subclass.
+     * @param choice user's choice as enum constant of type parameter E
+     * @return the action to run for the user's choice
+     */
+    protected abstract Runnable getMenuAction(E choice);
+
+    /**
+     * abstract getter with which subclasses must tell this controller, which is the menu option to leave the menu
+     */
+    protected abstract E getExitChoice();
+
+    /**
+     * entry point method doing the menu loop and triggering the actions chosen.
+     */
+    public void run() {
+        var choice = getMenuChoice();
+        while (choice != getExitChoice()) {
+            getMenuAction(choice).run();
+            choice = getMenuChoice();
+        }
+    }
+
+    protected int chooseFromList(List<? extends NamedItem> items, String itemType) {
+        if (items.isEmpty()) {
+            printer.printInfo("The {} list is empty!\n", itemType);
+            return 0;
+        }
+        printItemsMenu(items, itemType);
+        var choice =  Integer.parseInt(scanner.nextLine());
+        printer.printInfo("");
+        return choice;
+    }
+
+    private void printItemsMenu(List<? extends NamedItem> items, String itemType) {
+        printer.printInfo("Choose a {}:", itemType);
+        printer.printEnumeratedList(items);
+        printer.printInfo("0. Back");
+    }
+
+    /**
+     * user interaction method, that displays the menu and prompts for the users integer choice.
+     * @return the choice as enum constant of the enum type parameter.
+     */
+    private E getMenuChoice() {
+        printer.printInfo(getMenuText());
+        var menuOptions = getExitChoice().getDeclaringClass().getEnumConstants();
+        var choice =  menuOptions[Integer.parseInt(scanner.nextLine())];
+        printer.printInfo("");
+        return choice;
+    }
+}

src/main/java/de/cofinpro/cars/controller/CompanyMenu.java

@@ -6,37 +6,42 @@
 import lombok.Setter;
 import org.springframework.stereotype.Controller;
 
+import java.util.Map;
 import java.util.Scanner;
 
 @Controller
-public class CompanyMenu {
+public class CompanyMenu extends AbstractMenuController<CompanyMenu.Choice> {
 
     private final CarService carService;
-    private final Scanner scanner;
-    private final ConsolePrinter printer;
     @Setter
     private Company company;
 
-    public CompanyMenu(CarService carService,
-                       Scanner scanner, 
-                       ConsolePrinter printer) {
+    public CompanyMenu(Scanner scanner,
+                       ConsolePrinter printer,
+                       CarService carService) {
+        super(printer, scanner);
         this.carService = carService;
-        this.scanner = scanner;
-        this.printer = printer;
     }
 
-    public void run() {
-        printMenu();
-        var choice = Integer.parseInt(scanner.nextLine());
-        while (choice != 0) {
-            switch (choice) {
-                case 1 -> listCars();
-                case 2 -> createCar();
-                default -> throw new IllegalStateException("invalid choice");
-            }
-            printMenu();
-            choice = Integer.parseInt(scanner.nextLine());
-        }
+    @Override
+    protected String getMenuText() {
+        return """
+                1. Car list
+                2. Create a car
+                0. Back""";
+    }
+
+    @Override
+    protected Runnable getMenuAction(Choice choice) {
+        return Map.<Choice, Runnable>of(
+                Choice.LIST_CARS, this::listCars,
+                Choice.CREATE_CAR, this::createCar
+        ).get(choice);
+    }
+
+    @Override
+    protected Choice getExitChoice() {
+        return Choice.EXIT;
     }
 
     private void createCar() {
@@ -47,15 +52,14 @@ private void createCar() {
     }
 
     private void listCars() {
-        var cars = carService.listCars(company.getId());
+        var cars = carService.getCars(company.getId());
         printer.printCarList(cars);
+        printer.printInfo("");
     }
 
-    private void printMenu() {
-        printer.printInfo("""
-                1. Car list
-                2. Create a car
-                0. Back
-                """);
+    protected enum Choice {
+        EXIT,
+        LIST_CARS,
+        CREATE_CAR
     }
 }

src/main/java/de/cofinpro/cars/controller/CustomerMenu.java

@@ -0,0 +1,102 @@
+package de.cofinpro.cars.controller;
+
+import de.cofinpro.cars.io.ConsolePrinter;
+import de.cofinpro.cars.persistence.Customer;
+import de.cofinpro.cars.service.CarService;
+import de.cofinpro.cars.service.CompanyService;
+import de.cofinpro.cars.service.CustomerService;
+import lombok.Setter;
+import org.springframework.stereotype.Controller;
+
+import java.util.Map;
+import java.util.Objects;
+import java.util.Scanner;
+
+@Controller
+public class CustomerMenu extends AbstractMenuController<CustomerMenu.Choice> {
+
+    public static final String NO_CAR_RENT = "You didn't rent a car!\n";
+    private final CustomerService customerService;
+    private final CompanyService companyService;
+    private final CarService carService;
+    @Setter
+    private Customer customer;
+
+    protected CustomerMenu(ConsolePrinter consolePrinter,
+                           Scanner scanner,
+                           CustomerService customerService,
+                           CompanyService companyService,
+                           CarService carService) {
+        super(consolePrinter, scanner);
+        this.customerService = customerService;
+        this.companyService = companyService;
+        this.carService = carService;
+    }
+
+    @Override
+    protected String getMenuText() {
+        return """
+        1. Rent a car
+        2. Return a rented car
+        3. My rented car
+        0. Back""";
+    }
+
+    @Override
+    protected Runnable getMenuAction(Choice choice) {
+        return Map.<Choice, Runnable>of(
+                Choice.RENT, this::rentCar,
+                Choice.RETURN, this::returnCar,
+                Choice.SHOW, this::showCar
+        ).get(choice);
+    }
+
+    @Override
+    protected Choice getExitChoice() {
+        return Choice.EXIT;
+    }
+
+    private void rentCar() {
+        if (Objects.nonNull(customer.getRentedCar())) {
+            printer.printInfo("You've already rented a car!\n");
+            return;
+        }
+        var companies = companyService.getCompanies();
+        var index = chooseFromList(companies, "company");
+        var companySelected = companies.get(index - 1);
+        var cars = carService.getAvailableCars(companySelected.getId());
+        index = chooseFromList(cars, "car");
+        if (index > 0) {
+            var car = cars.get(index - 1);
+            customerService.rentCar(customer, car);
+            printer.printInfo("You rented '{}'\n", car.getName());
+        }
+    }
+
+    private void returnCar() {
+        if (Objects.isNull(customer.getRentedCar())) {
+            printer.printInfo(NO_CAR_RENT);
+            return;
+        }
+        customerService.returnCar(customer);
+        printer.printInfo("You've returned a rented car!\n");
+    }
+
+    private void showCar() {
+        if (Objects.isNull(customer.getRentedCar())) {
+            printer.printInfo(NO_CAR_RENT);
+            return;
+        }
+        printer.printInfo("Your rented car:");
+        printer.printInfo(customer.getRentedCar().getName());
+        printer.printInfo("Company:");
+        printer.printInfo("{}\n", customer.getRentedCar().getCompany().getName());
+    }
+
+    protected enum Choice {
+        EXIT,
+        RENT,
+        RETURN,
+        SHOW
+    }
+}