// This section where we create our varaibles and assign them default values is typically called the 'initialization'

var currentTime;                //what time is it now?
var timeChange;                 //save changes in time every frame after the timer starts
var previousTime=currentTime;   //save previous time every frame
var countTime=20*1000;          //1 minute= seconds * milliseconds per second
var timeLeft=countTime;         //our timer is at 100%
var timerStart=false;           //another variable to control the timer on/off
var state=0;

animation.stop();               //animation stays stopped until the timer starts

function update(e)
{
    //getTime() method returns the number of milliseconds since midnight January 1, 1970, universal time, for the specified Date object.
    //Use this method to represent a specific instant in time when comparing two or more Date objects.
    currentTime= new Date().getTime();

    timeChange=currentTime-previousTime;    // How much time has passed since last frame?
    previousTime=currentTime;               // save currentTime value into previousTime variable


    if(timerStart)
    {
        timeLeft=timeLeft-timeChange;       // update the time remaining

        //convert timeLeft value to seconds and minutes
        //Math.floor returns the closest integer that is less than or equal to the specified number or expression.
        var seconds=Math.floor(timeLeft/1000%60);
        var minutes=Math.floor(timeLeft/1000/60);

        //display secondes and minutes in separate textboxes
        minutesText.text=minutes.toString();
        secondsText.text=seconds.toString();

        //visualize by applying the percentage of timeLeft to properties of an intstance or to frame number of an animation movie clip.
        box.scaleY=timeLeft/countTime;
        var frameNum=Math.round(animation.totalFrames*(1-timeLeft/countTime));
        animation.gotoAndStop(frameNum);
    }

    if(timeLeft<=0)
    {
        timerStart=false;                               //stop the timer
        box.scaleY=0;                                   //stop reducing the box size
        animation.gotoAndStop(animation.totalFrames);   //stop the animation play
        minutesText.text='0';
        secondsText.text='0';

    }
}

function startTimer(e)
{
    timerStart=true;
    if(var state=0)
    {
        timeStart=true;
    }
    else
    {
        timerStart=true;
        animation.gotoAndStop(animation.first);
        secondsText.text='20';
        timeLeft=(20*1000);
        box.scaleY=1;
        var state=0;
    }
}

function pauseTimer(e)
{
    timerStart=false;
    var state=0;
}

function stopTimer(e)
{
    timerStart=true;
    animation.gotoAndStop(animation.totalFrames);
    secondsText.text='0';
    timeLeft=0;
    var state=1;
}

function resetTimer(e)
{
    timerStart=false;
    animation.gotoAndStop(animation.first);
    secondsText.text='20';
    timeLeft=(20*1000);
    box.scaleY=1;
    var state=0;

}

addEventListener('enterFrame', update);
startBtn.addEventListener('mouseDown', startTimer);
pauseBtn.addEventListener('mouseDown', pauseTimer);
resetBtn.addEventListener('mouseDown', resetTimer);
stopBtn.addEventListener('mouseDown', stopTimer);