add solution

src/app.js

@@ -1,3 +1,34 @@
 '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 randomNum = generateRandomNumber();
+
+function askForNumber() {
+  terminal.question('Enter a number of 4 different digits ', (digits) => {
+    if (checkIsValidUserInput(digits)) {
+      const result = getBullsAndCows(digits, randomNum);
+
+      process.stdout.write(`Result: ${JSON.stringify(result)}\n`);
+
+      if (result.bulls === 4) {
+        terminal.close();
+        process.stdout.write(`You guessed all numbers. Game is over!`);
+      } else {
+        askForNumber();
+      }
+    } else {
+      process.stdout.write(
+        `You entered incorrect numbers. Please try again.\n`,
+      );
+      askForNumber();
+    }
+  });
+}
+
+askForNumber();

src/modules/checkIsValidUserInput.js

@@ -9,7 +9,24 @@
  * @return {boolean} - True if the user input is valid, false otherwise
  */
 function checkIsValidUserInput(userInput) {
-  /* Write your code here */
+  const userInputArr = userInput.split('').map((el) => Number(el));
+  const allowedLength = 4;
+  let isValid = true;
+
+  if (
+    userInputArr.length !== allowedLength ||
+    new Set(userInputArr).size !== allowedLength
+  ) {
+    return false;
+  }
+
+  userInputArr.forEach((el, i, arr) => {
+    if (isNaN(el) || arr[0] === 0) {
+      isValid = false;
+    }
+  });
+
+  return isValid;
 }
 
 module.exports = {

src/modules/generateRandomNumber.js

@@ -6,8 +6,19 @@
  *
  * @return {number} A random 4-digit number
  */
+
+const getRandomNum = () => {
+  return Math.floor(Math.random() * 9000) + 1000;
+};
+
 function generateRandomNumber() {
-  /* Write your code here */
+  let res;
+
+  do {
+    res = getRandomNum();
+  } while (new Set(String(res).split('')).size !== 4);
+
+  return res;
 }
 
 module.exports = {

src/modules/getBullsAndCows.js

@@ -12,8 +12,31 @@
  * @return {object} An object containing the number of bulls and cows.
  * Example: { bulls: 1, cows: 2 }
  */
+
+const createArrFromNum = (num) => {
+  return String(num)
+    .split('')
+    .map((el) => Number(el));
+};
+
 function getBullsAndCows(userInput, numberToGuess) {
-  /* Write your code here */
+  const userInputArr = createArrFromNum(userInput);
+  const numberToGuessArr = createArrFromNum(numberToGuess);
+
+  const result = {
+    bulls: 0,
+    cows: 0,
+  };
+
+  userInputArr.forEach((item, index) => {
+    if (item === numberToGuessArr[index]) {
+      result.bulls++;
+    } else if (numberToGuessArr.includes(item)) {
+      result.cows++;
+    }
+  });
+
+  return result;
 }
 
 module.exports = {