Solution

src/app.js

@@ -1,3 +1,62 @@
 'use strict';
+/* eslint-disable no-console */
 
-// 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 guessNumber = generateRandomNumber();
+let count = 0;
+
+function playGame(question = '') {
+  terminal.question(question, (userInput) => {
+    if (!checkIsValidUserInput(userInput)) {
+      console.log(
+        'It is not valid number! Input the 4 dight number, without duplicates!',
+      );
+      playGame('Try again!');
+    } else {
+      count++;
+
+      const result = getBullsAndCows(userInput, guessNumber);
+
+      console.log(result, '(Try', count, ')');
+
+      if (result.bulls === 4) {
+        console.log(
+          'Congratulation!!! You win!!! Number is...  ',
+          guessNumber,
+          ` [From ${count} try!]`,
+        );
+        terminal.close();
+      } else {
+        const { bulls, cows } = result;
+
+        if (bulls === 0 && cows === 0) {
+          playGame('Dont worry, it happens...');
+        }
+
+        if (bulls === 1 || cows === 1) {
+          playGame('You are on the right track!');
+        }
+
+        if (
+          bulls === 2 ||
+          bulls === 3 ||
+          cows === 2 ||
+          cows === 3 ||
+          cows === 4
+        ) {
+          playGame('So close... Come on!');
+        }
+      }
+    }
+  });
+}
+
+console.log('Lets play the game "Bulls and Cows"!!!');
+console.log('Input the 4 dight number');
+playGame();

src/modules/checkIsValidUserInput.js

@@ -9,7 +9,18 @@
  * @return {boolean} - True if the user input is valid, false otherwise
  */
 function checkIsValidUserInput(userInput) {
-  /* Write your code here */
+  const is4digitNumber = userInput.length === 4;
+  const isAllAreNumbers = userInput.split('').every((x) => /^[0-9]$/.test(x));
+  const isNotStartZero = userInput[0] !== '0';
+  const isNotDuplicates = userInput
+    .split('')
+    .every((x, _, arr) => arr.indexOf(x) === arr.lastIndexOf(x));
+
+  if (is4digitNumber && isAllAreNumbers && isNotStartZero && isNotDuplicates) {
+    return true;
+  } else {
+    return false;
+  }
 }
 
 module.exports = {

src/modules/generateRandomNumber.js

@@ -8,6 +8,19 @@
  */
 function generateRandomNumber() {
   /* Write your code here */
+  const availableNums = [1, 2, 3, 4, 5, 6, 7, 8, 9];
+  const result = [];
+
+  const getRandomN = () => Math.floor(Math.random() * availableNums.length);
+
+  result.push(availableNums.splice(getRandomN(), 1)[0]);
+  availableNums.unshift(0);
+
+  while (result.length < 4) {
+    result.push(availableNums.splice(getRandomN(), 1)[0]);
+  }
+
+  return Number(result.join(''));
 }
 
 module.exports = {

src/modules/getBullsAndCows.js

@@ -13,7 +13,22 @@
  * Example: { bulls: 1, cows: 2 }
  */
 function getBullsAndCows(userInput, numberToGuess) {
-  /* Write your code here */
+  const userInputArr = userInput.toString().split('');
+  const numberToGuessArr = numberToGuess.toString().split('');
+  const result = {
+    bulls: 0,
+    cows: 0,
+  };
+
+  userInputArr.forEach((el, i) => {
+    if (el === numberToGuessArr[i]) {
+      result.bulls++;
+    } else if (numberToGuessArr.includes(el)) {
+      result.cows++;
+    }
+  });
+
+  return result;
 }
 
 module.exports = {