The task is completed

src/app.js

@@ -1 +1,33 @@
+/* eslint-disable no-console */
 'use strict';
+
+const { getBullsAndCows } = require('./bullsAndCows');
+const { generateNumber } = require('./generateNumber');
+const { terminal } = require('./terminal');
+const { isNumberValid } = require('./validateNumber');
+
+const generatedNumber = String(generateNumber());
+
+const startGame = () => {
+  terminal.question('Try to quess the number:\n', (enteredNumber) => {
+    if (!isNumberValid(enteredNumber)) {
+      console.log('Invalid number\n');
+      startGame();
+    } else {
+      const bullsAndCows = getBullsAndCows(generatedNumber, enteredNumber);
+      const bulls = bullsAndCows[0];
+      const cows = bullsAndCows[1];
+
+      console.log(`Bulls: ${bulls}, Cows: ${cows}\n`);
+
+      if (bulls === 4) {
+        console.log('Congratulations, you win!');
+        terminal.close();
+      } else {
+        startGame();
+      }
+    }
+  });
+};
+
+startGame();

src/bullsAndCows.js

@@ -0,0 +1,26 @@
+'use strict';
+
+const NUM_LENGTH = 4;
+
+module.exports.getBullsAndCows = (numberToGuess, enteredNumber) => {
+  const numberToGuessCopy = numberToGuess.split('');
+  const enteredNumberCopy = enteredNumber.split('');
+  let bullsCount = 0;
+  let cowsCount = 0;
+
+  for (let i = 0; i < NUM_LENGTH; i++) {
+    const isBull = enteredNumberCopy[0] === numberToGuessCopy[0];
+    const isCow = numberToGuess.includes(enteredNumberCopy[0]);
+
+    if (isBull) {
+      bullsCount++;
+    } else if (isCow) {
+      cowsCount++;
+    }
+
+    numberToGuessCopy.shift();
+    enteredNumberCopy.shift();
+  }
+
+  return [bullsCount, cowsCount];
+};

src/generateNumber.js

@@ -0,0 +1,17 @@
+'use strict';
+
+const NUM_LENGTH = 4;
+
+module.exports.generateNumber = () => {
+  const digitsArray = [];
+
+  while (digitsArray.length < NUM_LENGTH) {
+    const numToPush = Math.floor(Math.random() * 10);
+
+    if (!digitsArray.includes(numToPush)) {
+      digitsArray.push(numToPush);
+    }
+  }
+
+  return digitsArray.join('');
+};

src/terminal.js

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

src/validateNumber.js

@@ -0,0 +1,13 @@
+'use strict';
+
+const NUM_LENGTH = 4;
+
+module.exports.isNumberValid = (number) => {
+  for (let i = 1; i < NUM_LENGTH; i++) {
+    if (number[i] === number[i - 1]) {
+      return false;
+    }
+  }
+
+  return !isNaN(+number) && number.length === NUM_LENGTH;
+};