Refactor project structure: add Engine class and move games to separate package

Author: Antojkv

app/src/main/java/hexlet/code/App.java

@@ -1,30 +1,41 @@
 package hexlet.code;
 
+import hexlet.code.games.Calculator;
+import hexlet.code.games.Even;
+
 import java.util.Scanner;
 
-public class App {
+class App {
     public static void main(String[] args) {
         System.out.println("Please enter the game number and press Enter.");
-
-        Scanner scanner = new Scanner(System.in);
         System.out.println("1 - Greet");
         System.out.println("2 - Even");
+        System.out.println("3 - Calculator");
         System.out.println("0 - Exit");
+
+        Scanner scanner = new Scanner(System.in);
         String digit = scanner.next();
         System.out.println("Your choice: " + digit);
 
-        if (digit.equals("1")) {
-            System.out.println("Welcome to the Brain Games!");
-            Cli.greetUser();
-        } else if (digit.equals("0")) {
-            System.out.println("Goodbye!");
-        } else if (digit.equals("2")) {
-            System.out.println("Welcome to the Brain Games!");
-            String userName = Cli.greetUser();
-            Even.generateNumber(userName);
-        } else {
-            System.out.println("Invalid choice");
+        switch (digit) {
+            case "1":
+                System.out.println("Welcome to the Brain Games!");
+                Cli.greetUser();
+                break;
+            case "2":
+                Even.startGame();
+                break;
+            case "3":
+                Calculator.startGame();
+                break;
+            case "0":
+                System.out.println("Goodbye!");
+                break;
+            default:
+                System.out.println("Invalid choice");
+                break;
         }
+
         scanner.close();
     }
 }

app/src/main/java/hexlet/code/Engine.java

@@ -0,0 +1,36 @@
+package hexlet.code;
+
+import java.util.Scanner;
+
+public class Engine {
+    private static final int ROUNDS = 3;
+    private static final Scanner SCANNER = new Scanner(System.in);
+
+    public static int getRoundsCount() {
+        return ROUNDS;
+    }
+
+    public static void run(String description, String[][] data) {
+        System.out.println("Welcome to the Brain Games!");
+        String userName = Cli.greetUser();
+        System.out.println(description);
+
+        for (int i = 0; i < ROUNDS; i++) {
+            String question = data[i][0];
+            String correctAnswer = data[i][1];
+
+            System.out.println("Question: " + question);
+            System.out.print("Your answer: ");
+            String answer = SCANNER.next();
+
+            if (answer.equalsIgnoreCase(correctAnswer)) {
+                System.out.println("Correct!");
+            } else {
+                System.out.println("'" + answer + "' is wrong answer ;(. Correct answer was '" + correctAnswer + "'.");
+                System.out.println("Let's try again, " + userName + "!");
+                return;
+            }
+        }
+        System.out.println("Congratulations, " + userName + "!");
+    }
+}

app/src/main/java/hexlet/code/Even.java

@@ -0,0 +1,44 @@
+package hexlet.code.games;
+
+import hexlet.code.Engine;
+
+import java.security.SecureRandom;
+
+public class Calculator {
+    private static final String DESCRIPTION = "What is the result of the expression?";
+    private static final char[] OPERATORS = {'+', '-', '*'};
+
+    public static int calculate(int operand1, int operand2, char operator) {
+        switch (operator) {
+            case '+':
+                return operand1 + operand2;
+            case '-':
+                return operand1 - operand2;
+            case '*':
+                return operand1 * operand2;
+            default:
+                return 0;
+        }
+    }
+
+    public static void startGame() {
+        String[][] data = new String[Engine.getRoundsCount()][2];
+        SecureRandom random = new SecureRandom();
+
+        for (int i = 0; i < Engine.getRoundsCount(); i++) {
+            int number1 = random.nextInt(100) + 1;
+            int number2 = random.nextInt(100) + 1;
+            char operator = OPERATORS[random.nextInt(OPERATORS.length)];
+
+            String question = number1 + " " + operator + " " + number2;
+            String correctAnswer = String.valueOf(calculate(number1, number2, operator));
+
+            data[i][0] = question;
+            data[i][1] = correctAnswer;
+        }
+
+        Engine.run(DESCRIPTION, data);
+    }
+}
+
+

app/src/main/java/hexlet/code/games/Calculator.java

@@ -0,0 +1,30 @@
+package hexlet.code.games;
+import hexlet.code.Engine;
+
+import java.security.SecureRandom;
+
+public class Even {
+    private static final String DESCRIPTION = "Answer 'yes' if the number is even, otherwise answer 'no'.";
+
+
+    private static boolean isEven(int number) {
+        return number % 2 == 0;
+    }
+    public static void startGame() {
+        String[][] data = new String[Engine.getRoundsCount()][2];
+        SecureRandom random = new SecureRandom();
+
+        for (int i = 0; i < Engine.getRoundsCount(); i++) {
+            int number = random.nextInt(100) + 1;
+            String question = String.valueOf(number);
+            String correctAnswer = isEven(number) ? "yes" : "no";
+
+            data[i][0] = question;
+            data[i][1] = correctAnswer;
+        }
+
+        Engine.run(DESCRIPTION, data);
+    }
+
+
+}