impl solution

src/app.js

@@ -1,3 +1,36 @@
 'use strict';
 
-// Write your code here
+const readline = require('readline');
+const { log } = require('console');
+const { generateRandomNumber } = require('./modules/generateRandomNumber.js');
+const { checkIsValidUserInput } = require('./modules/checkIsValidUserInput.js');
+const { getBullsAndCows } = require('./modules/getBullsAndCows.js');
+
+const terminal = readline.createInterface(process.stdin, process.stdout);
+
+const chooseNumber = () =>
+  terminal.question('Enter the 4-digit unique number: ', (input) => {
+    const generatedNumber = generateRandomNumber();
+    const isValidInput = checkIsValidUserInput(input);
+
+    if (!isValidInput) {
+      log('Invalid input. Try again.');
+      chooseNumber();
+
+      return;
+    }
+
+    if (input === generatedNumber) {
+      log('Congratulations! You won!');
+      terminal.close();
+
+      return;
+    }
+
+    const { bulls, cows } = getBullsAndCows(input, generatedNumber);
+
+    log(`Your result is: Bulls - ${bulls}, Cows - ${cows}`);
+    chooseNumber();
+  });
+
+chooseNumber();

src/modules/checkIsValidUserInput.js

@@ -9,7 +9,19 @@
  * @return {boolean} - True if the user input is valid, false otherwise
  */
 function checkIsValidUserInput(userInput) {
-  /* Write your code here */
+  const userInputArray = userInput.split('');
+  const isNumeric = userInputArray.every((item) => !isNaN(item));
+
+  if (
+    userInputArray.length !== 4 ||
+    userInputArray[0] === '0' ||
+    new Set(userInputArray).size !== 4 ||
+    !isNumeric
+  ) {
+    return false;
+  }
+
+  return true;
 }
 
 module.exports = {

src/modules/generateRandomNumber.js

@@ -7,9 +7,26 @@
  * @return {number} A random 4-digit number
  */
 function generateRandomNumber() {
-  /* Write your code here */
+  let { number, numberArray } = getRandomNumAndArray();
+
+  while (new Set(numberArray).size !== 4) {
+    const { number: numberRegen, numberArray: numberArrayRegen } =
+      getRandomNumAndArray();
+
+    number = numberRegen;
+    numberArray = numberArrayRegen;
+  }
+
+  return number;
 }
 
+const getRandomNumAndArray = () => {
+  const number = Math.floor(1000 + Math.random() * 9000);
+  const numberArray = number.toString().split('');
+
+  return { number, numberArray };
+};
+
 module.exports = {
   generateRandomNumber,
 };

src/modules/getBullsAndCows.js

@@ -13,7 +13,20 @@
  * Example: { bulls: 1, cows: 2 }
  */
 function getBullsAndCows(userInput, numberToGuess) {
-  /* Write your code here */
+  const userInputArray = userInput.toString().split('');
+  const numberToGuessArray = numberToGuess.toString().split('');
+  let bulls = 0;
+  let cows = 0;
+
+  for (let i = 0; i < userInputArray.length; i++) {
+    if (userInputArray[i] === numberToGuessArray[i]) {
+      bulls++;
+    } else if (numberToGuessArray.includes(userInputArray[i])) {
+      cows++;
+    }
+  }
+
+  return { bulls, cows };
 }
 
 module.exports = {