//From prototype.js                
var PeriodicalExecuter = new Class({
    // name: 'PeriodicalExecuter',
    initialize: function(callback, frequency) {
    
        this.callback = callback;
        this.frequency = frequency;
        this.currentlyExecuting = false;

        this.registerCallback();
    },

    registerCallback: function() {
    
        this.stop();
        this.timer = setInterval(this.onTimerEvent.bind(this), this.frequency * 1000);
        return this;
    },

    execute: function() {
    
        this.callback(this);
        return this;
    },

    stop: function() {
    
        if (!this.timer) return this;
        clearInterval(this.timer);
        this.timer = null;
        return this;
    },

    onTimerEvent: function() {
    
        if (!this.currentlyExecuting) {
        
            try {
            
                this.currentlyExecuting = true;
                this.execute();
            } finally {
            
                this.currentlyExecuting = false;
            }
        }
            
        return this;
    }
});

var CountDown = new Class({options: {

        date: null,
        onChange: $empty,
        onComplete: $empty
    },
    initialize: function (options) {
        this.setOptions(options);
    },
    setDate: function(date){
    	if(this.timer!=null){
    		this.timer.stop()
    	}
    	this.options.date = date;
    	this.start();
    },
    start: function(){
    	this.timer = new PeriodicalExecuter(this.update.bind(this), 1);
    },
    update: function () {
        var time = Math.floor((this.options.date.getTime() - new Date().getTime()) / 1000);
        
        if(time <= 0) time = 0;
        
        var stop = time == 0;
        
        var countdown = {days: Math.floor(time / (60 * 60 * 24)), 'time': time};
        
        time %= (60 * 60 * 24);
        
        countdown.hours = Math.floor(time / (60 * 60));
        time %= (60 * 60);
        countdown.minutes = Math.floor(time / 60);
        countdown.second = time % 60;
        
        this.fireEvent('onChange', countdown);
        
        if(stop) {
        
            this.timer.stop();
            this.fireEvent('onComplete');
        }
    },
    Implements: [Options, Events]
});