added solution

src/app.js

@@ -1 +1,18 @@
+/* eslint-disable no-console */
 'use strict';
+
+const generateRandomNumber = require('./generateRandomNumber');
+const handlePlayRound = require('./handlePlayRound');
+
+const handlePlayGame = () => {
+  const programNumber = generateRandomNumber();
+
+  handlePlayRound(programNumber);
+
+  console.log(
+    'Welcome to the Bulls and Cows game!',
+    'Try to guess the 4-digit number with unique digits:',
+  );
+};
+
+handlePlayGame();

src/generateRandomNumber.js

@@ -0,0 +1,22 @@
+'use strict';
+
+const NUMBER_LENGTH = 4;
+const MAX_RANGE_VALUE = 10;
+
+function generateRandomNumber() {
+  const usedDigits = new Set();
+  let result = '';
+
+  while (usedDigits.size < NUMBER_LENGTH) {
+    const randomDigit = Math.floor(Math.random() * MAX_RANGE_VALUE);
+
+    if (!usedDigits.has(randomDigit)) {
+      usedDigits.add(randomDigit);
+      result += randomDigit;
+    }
+  }
+
+  return result;
+}
+
+module.exports = generateRandomNumber;

src/getBullsAndCows.js

@@ -0,0 +1,21 @@
+'use strict';
+
+const getBullsAndCows = (programNumber, userNumber) => {
+  let bulls = 0;
+  let cows = 0;
+
+  for (let i = 0; i < programNumber.length; i++) {
+    if (userNumber[i] === programNumber[i]) {
+      bulls++;
+    } else if (programNumber.includes(userNumber[i])) {
+      cows++;
+    }
+  }
+
+  return {
+    bulls,
+    cows,
+  };
+};
+
+module.exports = getBullsAndCows;

src/handlePlayRound.js

@@ -0,0 +1,38 @@
+/* eslint-disable no-console */
+'use strict';
+
+const getBullsAndCows = require('./getBullsAndCows');
+const validateInput = require('./validateInput');
+const inputAndOutputOperations = require('./inputAndOutputOperations');
+
+const handlePlayRound = (programNumber) => {
+  inputAndOutputOperations.question('', (userNumber) => {
+    const isInputValid = validateInput(userNumber);
+    const result = getBullsAndCows(programNumber, userNumber);
+
+    if (!isInputValid) {
+      console.log('Please enter a valid 4-digit number with unique digits.');
+      handlePlayRound(programNumber);
+
+      return;
+    }
+
+    if (result.bulls === 4) {
+      console.log(`Congratulations! You guessed the ${programNumber}!`);
+
+      inputAndOutputOperations.close();
+    } else {
+      console.log(
+        `The result is ${result.bulls} ${
+          result.bulls === 1 ? 'bull' : 'bulls'
+        } and ${result.cows} ${
+          result.cows === 1 ? 'cow' : 'cows'
+        }.\nEnter your guess: `,
+      );
+
+      handlePlayRound(programNumber);
+    }
+  });
+};
+
+module.exports = handlePlayRound;

src/inputAndOutputOperations.js

@@ -0,0 +1,10 @@
+'use strict';
+
+const readline = require('readline');
+
+const inputAndOutputOperations = readline.createInterface({
+  input: process.stdin,
+  output: process.stdout,
+});
+
+module.exports = inputAndOutputOperations;

src/validateInput.js

@@ -0,0 +1,7 @@
+'use strict';
+
+const validateInput = (input) => {
+  return /^\d{4}$/.test(input) && new Set(input).size === 4;
+};
+
+module.exports = validateInput;