solution

src/app.js

@@ -1,3 +1,33 @@
 'use strict';
 
-// Write your code here
+const readline = require('readline');
+const { checkIsValidUserInput } = require('./modules/checkIsValidUserInput');
+const { generateRandomNumber } = require('./modules/generateRandomNumber');
+const { getBullsAndCows } = require('./modules/getBullsAndCows');
+
+const terminal = readline.createInterface(process.stdin, process.stdout);
+const numberToGuess = generateRandomNumber();
+
+function guess() {
+  terminal.question('Enter 4 different numbers: ', (data) => {
+    if (checkIsValidUserInput(data)) {
+      // eslint-disable-next-line no-console
+      console.log(getBullsAndCows(+data, +numberToGuess));
+    } else {
+      // eslint-disable-next-line no-console
+      console.log('Invalid input. Please enter 4 different numbers: ');
+    }
+
+    if (+data === numberToGuess) {
+      // eslint-disable-next-line no-console
+      console.log('You are a winner');
+      terminal.close();
+
+      return;
+    }
+
+    return guess();
+  });
+}
+
+guess();

src/modules/checkIsValidUserInput.js

@@ -10,6 +10,26 @@
  */
 function checkIsValidUserInput(userInput) {
   /* Write your code here */
+
+  if (userInput.length !== 4 || Number(userInput[0]) === 0) {
+    return false;
+  }
+
+  const amount = {};
+
+  for (let i = 0; i < userInput.length; i++) {
+    if (isNaN(Number(userInput[i]))) {
+      return false;
+    }
+
+    if (!amount[userInput[i]]) {
+      amount[userInput[i]] = 1;
+    } else {
+      return false;
+    }
+  }
+
+  return true;
 }
 
 module.exports = {

src/modules/generateRandomNumber.js

@@ -8,6 +8,28 @@
  */
 function generateRandomNumber() {
   /* Write your code here */
+  const numberToGuess = [];
+
+  for (let i = 0; i < 4; ) {
+    const min = 0;
+    const max = 9;
+
+    const randmonNumber = Math.floor(Math.random() * (max - min + 1) + min);
+
+    if (!numberToGuess.includes(randmonNumber)) {
+      i++;
+
+      numberToGuess.push(randmonNumber);
+    }
+
+    continue;
+  }
+
+  if (numberToGuess[0] === 0) {
+    return generateRandomNumber();
+  }
+
+  return Number(numberToGuess.join(''));
 }
 
 module.exports = {

src/modules/getBullsAndCows.js

@@ -14,6 +14,21 @@
  */
 function getBullsAndCows(userInput, numberToGuess) {
   /* Write your code here */
+  let bulls = 0;
+  let cows = 0;
+
+  const input = String(userInput);
+  const guess = String(numberToGuess);
+
+  for (let i = 0; i < input.length; i++) {
+    if (input[i] === guess[i]) {
+      bulls++;
+    } else if (input.includes(guess[i])) {
+      cows++;
+    }
+  }
+
+  return { bulls, cows };
 }
 
 module.exports = {