app.js

const inquirer = require('inquirer');

//Declare robot X, Y, and Direction variables.
let robotXCoordinate;
let robotYCoordinate;
let robotDirection;

//The following is the direction of the robot is facing, converted as numerical number to be used later. 
let direction = {
    'NORTH'   : 1,
    'EAST'    : 2,
    'SOUTH'   : 3,
    'WEST'    : 4  
};

//This function returns the textual direction, based on the numerial direction, as per the 'direction' object. 
function getKeyByValue(object, value) {
  return Object.keys(object).find(key => object[key] === value);
}



//************************************************************************************************************************************************
//**********************************************************Questions Prompts*********************************************************************

const initialQuestion = [
    { type: 'input', 
    name: 'confirmPlacement', 
    message: 'Please type "PLACE" to start',
    validate: function (input) {
        // Declare function as asynchronous, and save the done callback
        var done = this.async();
    
        // Do async stuff
        setTimeout(function() {
          if (input.toUpperCase().trim() !== 'PLACE') {
            // Pass the return value in the done callback
            done('You need to type "PLACE" to start.');
            return;
          }
          // Pass the return value in the done callback
          done(null, true);
        }, 0);
      }
    },
];

const secondQuestion = [{
  type: 'input',
  name: 'confirmCoor',
  message: 'Type the placement coordinate in X,Y,F format.',
}];

const thirdQuestions = [{
  type: 'input',
  name: 'response',
  message: 'What do you want to do: PLACE/MOVE/LEFT/RIGHT/REPORT ?',
}];



//*************************************************************************************************************************************************
//****************************************************Command Line Questions & Response************************************************************

//'question1' will prompt user to type 'PLACE' 
const question1 = () => {
    inquirer
        .prompt(initialQuestion)
        .then(answers => {
            question2();
        });

};

//'question2' prompt user for robot X,Y,F coordinate. Then user will be directed to 'question3' function.
const question2 = () => {
    inquirer
        .prompt(secondQuestion)
        .then(answers => {
            let placementCoor = answers.confirmCoor.split(',');
            robotXCoordinate = Number(placementCoor[0].trim());
            robotYCoordinate = Number(placementCoor[1].trim());
            let robotTextDirection = String(placementCoor[2].toUpperCase().trim());
            
            //Check if input coordinates is one of the following number. Otherwise show error to user.
            if (![0,1,2,3,4,5].includes(robotXCoordinate) || ![0,1,2,3,4,5].includes(robotYCoordinate)){
                console.log('Invalid coordinate input. Coordinate must be between 0 to 5.');
                question1();
            } 
            
            //Check if input direction is one of the following direction. Otherwise show error to user.
            else if (!["NORTH", "EAST", "SOUTH", "WEST"].includes(robotTextDirection)){
                console.log('Invalid direction input. Direction must be either NORTH, EAST, SOUTH, or WEST.');
                question1();
            }
            
            else {
                //Assign numerial direction according to 'direction' object.
                robotDirection = direction[robotTextDirection];
                
                question3();
            }
            
        });
    
};

//'question3' will prompt user for the following command: PLACE, MOVE, LEFT, RIGHT, REPORT. 
const question3 = () => {
    inquirer
        .prompt(thirdQuestions)
        .then(answers => {
            //Sanitize user's input to upper case and remove all whitespace.
            let sanitizedAnswer = answers.response.toUpperCase().trim();
            
            //Run this code block if user types 'MOVE'. Then add or minus their coordinate, according to their direction. 
            //If robot is at the edge of table, don't take any action, and show error to user.
            if (sanitizedAnswer === 'MOVE'){
                
                if (robotDirection === 1){
                   
                    if (robotYCoordinate === 5){
                        console.log('Invalid movement. Robot will fall down the table.');
                    } else {  robotYCoordinate++ }
                    
                } else if (robotDirection === 2){
                    
                    if (robotXCoordinate === 5){
                        console.log('Invalid movement. Robot will fall down the table.');
                    } else {  robotXCoordinate++ }
                    
                } else if (robotDirection === 3){
                    
                    if (robotYCoordinate === 0){
                        console.log('Invalid movement. Robot will fall down the table.');
                    } else { robotYCoordinate-- }
                    
                } else if (robotDirection === 4){
                    
                    if (robotXCoordinate === 0){
                        console.log('Invalid movement. Robot will fall down the table.');
                    } else { robotXCoordinate-- }
                    
                }
                
                question3();
            }
            
            //Run this code block if user types 'LEFT'. Then move the robot direction's to left side, by minus 1 to their numerical direction. 
            //If the number is 1, directly assign it to 4 without minus the number.
            else if (sanitizedAnswer === 'LEFT'){
                
                if (robotDirection === 1){
                    robotDirection = 4;
                } else { robotDirection-- }
                
                question3();
            }
            
            //Run this code block if user types 'RIGHT'. Then move the robot direction's to right side, by adding 1 to their numerical direction. 
            //If the number is 4, directly assign it to 41 without adding the number.
            else if (sanitizedAnswer === 'RIGHT'){
                
                if (robotDirection === 4){
                    robotDirection = 1;
                } else { robotDirection++ }
                
                question3();
            }
            
            //Run this code block if user types 'REPORT'. Then report back the robot coordinate in the console. 
            else if (sanitizedAnswer === 'REPORT'){
                
                let robotTextDirection = getKeyByValue(direction, robotDirection);
                console.log(`The robot's coordinate is (${robotXCoordinate}, ${robotYCoordinate}, ${robotTextDirection}).`);
                
                question3();
                
            }
            
            //Run this code block if user types 'PLACE'. The application will start again from the beginning. 
            else if (sanitizedAnswer === 'PLACE'){
                
                question2();
                
            }
            
            //Check if sanitized answer satisfy one of the answer options above. Otherwise show an error to user.
            else {
                console.log('Invalid input. Please try again.');
                question3();
            }
        });
        
};

//Run the first 'question1' function at start of application.
question1();