Develop

src/app.js

@@ -1,3 +1,42 @@
 '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();
+let isFirstAttempt = true;
+const print = (message) => terminal.write(message + '\n');
+
+const askQuestion = () => {
+  const prompt = isFirstAttempt
+    ? `I generated a number of 4 different digits. Please, guess a number :)\n`
+    : 'Your guess:\n';
+
+  terminal.question(prompt, (userInput) => {
+    isFirstAttempt = false;
+
+    if (!checkIsValidUserInput(userInput)) {
+      print('Your input is invalid, please, try again :)');
+
+      return askQuestion();
+    }
+
+    const { bulls, cows } = getBullsAndCows(userInput, numberToGuess);
+
+    print(`bulls: ${bulls}, cows: ${cows}\n`);
+
+    if (bulls === 4) {
+      print('Congratulations!');
+
+      return terminal.close();
+    }
+
+    askQuestion();
+  });
+};
+
+askQuestion();

src/modules/checkIsValidUserInput.js

@@ -9,7 +9,31 @@
  * @return {boolean} - True if the user input is valid, false otherwise
  */
 function checkIsValidUserInput(userInput) {
-  /* Write your code here */
+  if (isNaN(+userInput)) {
+    return false;
+  }
+
+  if (userInput.length !== 4) {
+    return false;
+  }
+
+  if (userInput[0] === '0') {
+    return false;
+  }
+
+  for (let i = 0; i < userInput.length; i++) {
+    for (let j = 0; j < userInput.length; j++) {
+      if (i === j) {
+        continue;
+      }
+
+      if (userInput[i] === userInput[j]) {
+        return false;
+      }
+    }
+  }
+
+  return true;
 }
 
 module.exports = {

src/modules/generateRandomNumber.js

@@ -7,7 +7,21 @@
  * @return {number} A random 4-digit number
  */
 function generateRandomNumber() {
-  /* Write your code here */
+  let resultStr = '';
+
+  while (resultStr.length < 4) {
+    const randomDigitStr = String(Math.floor(Math.random() * 10));
+
+    if (resultStr.length === 0) {
+      if (randomDigitStr !== '0') {
+        resultStr += randomDigitStr;
+      }
+    } else if (!resultStr.includes(randomDigitStr)) {
+      resultStr += randomDigitStr;
+    }
+  }
+
+  return +resultStr;
 }
 
 module.exports = {

src/modules/getBullsAndCows.js

@@ -13,7 +13,25 @@
  * Example: { bulls: 1, cows: 2 }
  */
 function getBullsAndCows(userInput, numberToGuess) {
-  /* Write your code here */
+  const numberToGuessStr = String(numberToGuess);
+  const userInputStr = String(userInput);
+  const numberToGuessStrArr = numberToGuessStr.split('');
+  const userInputStrArr = userInputStr.split('');
+
+  const result = {
+    bulls: 0,
+    cows: 0,
+  };
+
+  for (let i = 0; i < userInputStrArr.length; i++) {
+    if (userInputStrArr[i] === numberToGuessStrArr[i]) {
+      result.bulls++;
+    } else if (numberToGuessStr.includes(userInputStrArr[i])) {
+      result.cows++;
+    }
+  }
+
+  return result;
 }
 
 module.exports = {