solution

src/app.js

@@ -1,3 +1,41 @@
+/* eslint-disable no-console */
 '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 rl = readline.createInterface({
+  input: process.stdin,
+  output: process.stdout,
+});
+
+const numberToGuess = generateRandomNumber().toString();
+
+function askUserForGuess() {
+  rl.question('Enter your guess: ', (userInput) => {
+    if (!checkIsValidUserInput(userInput)) {
+      console.log(
+        'Invalid input. Please enter a 4-digit number without duplicates.',
+      );
+      askUserForGuess();
+
+      return;
+    }
+
+    const result = getBullsAndCows(userInput, numberToGuess);
+
+    console.log(`Bulls: ${result.bulls}, Cows: ${result.cows}`);
+
+    if (result.bulls === 4) {
+      console.log('Congratulations! You guessed the number.');
+      rl.close();
+    } else {
+      askUserForGuess();
+    }
+  });
+}
+
+askUserForGuess();

src/modules/checkIsValidUserInput.js

@@ -8,8 +8,35 @@
  * @param {string} userInput - The user input
  * @return {boolean} - True if the user input is valid, false otherwise
  */
+
+function hasRepeatingdigits(numStr) {
+  for (let i = 0; i < numStr.length; i++) {
+    if (numStr.substring(i + 1).includes(numStr[i])) {
+      return true;
+    }
+  }
+
+  return false;
+}
+
 function checkIsValidUserInput(userInput) {
-  /* Write your code here */
+  // if (
+  //   userInput.length !== 4 ||
+  //   parseFloat(userInput[0]) === 0 ||
+  //   hasRepeatingdigits(userInput)
+  // ) {
+  //   return false;
+  // }
+
+  if (!/^\d{4}$/.test(userInput)) {
+    return false;
+  }
+
+  if (userInput[0] === '0' || hasRepeatingdigits(userInput)) {
+    return false;
+  }
+
+  return true;
 }
 
 module.exports = {

src/modules/generateRandomNumber.js

@@ -6,8 +6,28 @@
  *
  * @return {number} A random 4-digit number
  */
+const LENGTH = 4;
+
+function generateDigit() {
+  return Math.floor(Math.random() * 10);
+}
+
 function generateRandomNumber() {
-  /* Write your code here */
+  let strNum = '';
+
+  while (strNum.length < LENGTH) {
+    const digit = generateDigit().toString();
+
+    if (strNum.length === 0 && digit === '0') {
+      continue;
+    }
+
+    if (!strNum.includes(digit)) {
+      strNum += digit;
+    }
+  }
+
+  return parseFloat(strNum);
 }
 
 module.exports = {

src/modules/getBullsAndCows.js

@@ -12,8 +12,25 @@
  * @return {object} An object containing the number of bulls and cows.
  * Example: { bulls: 1, cows: 2 }
  */
+
 function getBullsAndCows(userInput, numberToGuess) {
-  /* Write your code here */
+  const bullsAndCows = {
+    bulls: 0,
+    cows: 0,
+  };
+
+  const strToGuess = `${numberToGuess}`;
+  const strInput = `${userInput}`;
+
+  for (let i = 0; i < strInput.length; i++) {
+    if (strInput[i] === strToGuess[i]) {
+      bullsAndCows.bulls += 1;
+    } else if (strToGuess.includes(strInput[i])) {
+      bullsAndCows.cows += 1;
+    }
+  }
+
+  return bullsAndCows;
 }
 
 module.exports = {