countdown.js

const secondsInaMinute = 60;
const minutes_25 = secondsInaMinute * 25;
const minutes_50 = secondsInaMinute * 50;
const minutes_10 = secondsInaMinute * 10;
const seconds_10 = 10; //for testing

let interval;
let isPaused = true;
let countdownWasStarted = false;
let pomodoroDuration = minutes_50; //by default
let timeLeftInSeconds = 0;

// Button Handlers
function updateDuration() {
  //The pomodoro duration is by default 50, but we can change to 25!
  if(pomodoroDuration == minutes_50 ) {
    pomodoroDuration = minutes_25;
  } else if(pomodoroDuration == minutes_25) {
    pomodoroDuration = minutes_10;
  } else {
    pomodoroDuration = minutes_50;
  }

  timeLeftInSeconds = pomodoroDuration
  updateTimeString()
}

function playPauseCountdown() {
  isPaused = !isPaused

  updatePlayPauseButton();

  if(!countdownWasStarted) {
    //This function could be called after initiating the timer,
    //so we need to differentiate when its start vs pause vs resume
    resetCountdown()
    updateTimeString()
  }

  countdownWasStarted = true

  if(isPaused) {
    stopCountdown()
  } else {
    // Update the count down every 1 second
    interval = setInterval(updateCountdown, 1000);
  }
}

function restartCountdown() {
  //When we reset the countdown, stop the interval and reset things back to normal
  stopCountdown()
  resetCountdown()

  isPaused = true
  updatePlayPauseButton()
  updateTimeString()
}

// Biz Logic
function updateCountdown() {
  if(isPaused) {
    return
  }

  timeLeftInSeconds--;

  updateTimeString();

  if(timeLeftInSeconds == 0) {
    playYoScott()
    stopCountdown()
    isPaused = true
    updatePlayPauseButton()
  }
}

function pauseCountdown() {
  isPaused = !isPaused;
}

function stopCountdown() {
  clearInterval(interval)
}

function resetCountdown() {
  isPaused = false
  timeLeftInSeconds = pomodoroDuration
}

// View Updates
function updatePlayPauseButton() {
  let playPauseImageSrc;
  if(isPaused) {
    playPauseImageSrc = "icons8-play-50.png"
  } else {
    playPauseImageSrc = "icons8-pause-32.png"
  }
  document.getElementById("playPause").src = playPauseImageSrc;
}

function updateTimeString() {
  let minutes = Math.floor(timeLeftInSeconds / secondsInaMinute);
  let seconds = timeLeftInSeconds % secondsInaMinute;

  if(seconds < 10) {
    secondsString = "0" + seconds
  } else {
    secondsString = seconds
  }

  // Output the result in an element with id="demo"
  document.getElementById("countdown").innerHTML = minutes + ":" + secondsString;
}

function playYoScott() {
  var yoScottAudio = document.getElementById("yoScottAudio");
  yoScottAudio.play();

  document.getElementById("countdown").innerHTML = "DONE";
}