tasks.js

var fs = require('fs');

const fileName = process.argv[2] || 'tasks.json';

var fileContents

if (fs.existsSync(fileName)) {
  fileContents = fs.readFileSync(fileName, 'utf8');
} else {
  fs.writeFileSync(fileName, "[]")
  fileContents = fs.readFileSync(fileName, 'utf8');
}

const tasks = JSON.parse(fileContents);


const { title } = require('process');
const { finished } = require('stream');
const { isUndefined } = require('util');
/**
 * Starts the application
 * This is the function that is run when the app starts
 * 
 * It prints a welcome line, and then a line with "----",
 * then nothing.
 *  
 * @param  {string} name the name of the app
 * @returns {void}
 */
function startApp(name){
  process.stdin.resume();
  process.stdin.setEncoding('utf8');
  process.stdin.on('data', onDataReceived);
  console.log(`Welcome to ${name}'s application!`)
  console.log("----------************----------")
}


/**
 * Decides what to do depending on the data that was received
 * This function receives the input sent by the user.
 * 
 * For example, if the user entered 
 * ```
 * node tasks.js batata
 * ```
 * 
 * The text received would be "batata"
 * This function  then directs to other functions
 * 
 * @param  {string} text data typed by the user
 * @returns {void}
 */
function onDataReceived(text) {

  text = text.replace("\n", " ").trim().split(" ");
 // const first = text[0];
 if (text[0] === 'quit'|| text[0] === 'exit') {
  quit();
}
else if(text[0] === 'hello'){
  hello(text);
}
else if(text[0] === 'help'){
  help();
}
else if(text[0] === 'list'){
  list()
}
else if(text[0] === 'add'){

      text.shift();
      let x=text.join(" ");
      add(x, false);
}
else if(text[0] === 'remove'){
 
  remove(text);
}
else if(text[0] === 'edit' || text[0] === 'Edit'){
  let i= text[1]
  text.shift()
  text.shift()
  let newText = text.join(" ");
   edit(i, newText);
  
}

else if(text[0] === 'check'){
  text.shift();
  text.join(" ");
  check(text);
}
else if(text[0] === 'uncheck'){
  text.shift();
  
  unCheck(text);
}


else{
  unknownCommand(text[0]);
 }
}


/**
 * prints "unknown command"
 * This function is supposed to run when all other commands have failed
 *
 * @param  {string} c the text received
 * @returns {void}
 */
function unknownCommand(c){
  console.log('unknown command: "'+ c.trim() +'"')
}

function hello(x){
  if(x[1]===undefined){
   console.log("hello!");}
  else {
     console.log('hello ' + x[1] + '!')}
}






// // var tasks =
// var tasks =[{ task : "woke up " ,done : false},
// { task : "open laptop " ,done : false},{ task : "open VS code " ,done : false},{ task : "work on your assignment" ,done : false}]

function list(){

for(let i= 0; i<tasks.length ; i++) {
  const taski =tasks[i]
  let tasksCheck = "[ ]";
  if (taski.done){
    tasksCheck = "[✓]";
  }
  console.log(`${i + 1}:${tasksCheck}  ${taski.task} `);

};

}


//add function
function add(task ,done){
if (!task && !done) {
  console.log('Error! there is No task added ');
  
} else {
  tasks.push({task ,done});
  console.log(`Added ${task} to the list`);
  var data = JSON.stringify(tasks, null, 2);
    fs.writeFileSync(fileName, data, finished);
}
}

//remove function 

function remove(x) {
  if (x == 'remove' ) {
     let num=tasks.pop();
     console.log(num);
    }
  else if(x[1] === "1"){
    let num1=tasks.slice(0,1);
     console.log(num1);
    }
  else if(x[1] === '2'){
    let num2=tasks.slice(1,2);
     console.log(num2);
    }
    else if(x[1] === '3'){
      let num3=tasks.slice(2,3);
       console.log(num3);
      }
      else if(x[1] === '4'){
        let num4=tasks.slice(3,4);
         console.log(num4);
        }
        else if(x[1] === '5'){
          let num5=tasks.slice(4,5);
           console.log(num5);
          }
  else{

      console.log(tasks);
    } 
  }



//edit function
function edit(i, newText){
if(!i && !newText){
console.log('Error: add the new text')
}
else if (i >= 0 && i < tasks.length) {
  tasks[i-1].task = newText

}
}


//check function 
  function check(index) {

    if (!index) {
      console.log("Error: no task index provided");
    }else{
        tasks[index-1].done = true;
        var data = JSON.stringify(tasks, null, 2);
         fs.writeFileSync(fileName, data, finished);
    }  
  }


  
  function unCheck(index) {
    if (!index ) {
      console.log("Error: no task index provided");
    }else{
        tasks[index-1].done = false;
        var data = JSON.stringify(tasks, null, 2);
        fs.writeFileSync(fileName, data, finished);
    }  
  }
  

  /**
   * help Function => it lists all the possible commands 
   *
   * @returns {void}
   */

  function help(){
    console.log('\n-hello : hello!'+'\n-hello x : hello x! =>this command put "!"after the string containing two word'+'\n-quit or exit => it exit from the program'+'\n-help => help command ,this command lists the possible command in program'+'\n-list => it list all the task'+'\n-add => it add task to the list'+'\n-remove => remove the last element from the list '+ '\n-remove 1 => it remove the first item in the list'+'\n-remove 2 => it remove the second item in the list'+ '\n-remove 3 => it remove the third item in the list'+ '\n-edit x newText => this command edit the task at specific index'+'\n check 1  => it will check the task at id :1'+'\n-uncheck 1 =>this command uncheck the task at id :1 ')
   
  }


/**
 * Exits the application
 *
 * @returns {void}
 */
function quit(){
  console.log('Quitting now, goodbye!')
  process.exit();
}

// The following line starts the application
startApp("Bodour Almalki")