/*
 * Simple inactivity detector.
 * When user is inactive for more then 60 sec it is detected 
 * Was written to prevent unnecessary ajax calls when user left 
 * our page open and went for lunch or 2 weeks holidays ;-) 
 * 
 * author Szymon Danielczyk danielczyk.szymon(remove this)@(remove that)gmail.com
 * 
 * Example of use:
 * At the begining when you loading your classes  
 * var detector = new IdleDetector(OPTIONS);
 * where:
 * OPTIONS.inactivityTimeInSec (optional)	- time of inactivity in second after detector set it state to isIdle=true
 * OPTIONS.idleCallback (optional) 		 	- callback function triggered when user is not active and detector detects idle
 * OPTIONS.backToActivityCallback (optional)- callback function triggered when user become active again 
 *  
 * than later in your code:
 * if(!detector.isIdle){
 *  	// do ajax request to your server 
 * }
 *  
 */

function IdleDetector(options){
	this.inactivityTimeInSec = 60; //default value
	this.backToActivityCallback = null;
	this.idleCallback = null;
	this.isIdle=false;
	this.idleTimeout = null;
	
	// overwrite options if provided
	if(options && options.inactivityTimeInSec){
		this.inactivityTimeInSec = options.inactivityTimeInSec;
	}
	if(options && options.idleCallback){
		this.idleCallback = options.idleCallback;
	}
	if(options && options.backToActivityCallback){
		this.backToActivityCallback = options.backToActivityCallback;
	}
	
	var THIS = this;
	document.onmousemove = function(e) {
		THIS.cancelIdle();
	};
	document.onmousedown = function(e) {
		THIS.cancelIdle();
	};
	document.onkeydown = function(e){
		THIS.cancelIdle();
	};
	this.cancelIdle();
}

IdleDetector.prototype.setIdle=function(){
	this.isIdle=true;
	if(this.idleCallback){
		this.idleCallback();
	}
};

IdleDetector.prototype.cancelIdle=function(){
	if(this.isIdle===true && this.backToActivityCallback){
		//set up isIdle to false before call callback
		this.isIdle=false;
		this.backToActivityCallback();
	}
	this.isIdle=false;
	clearTimeout(this.idleTimeout);
	var THIS = this;
	this.idleTimeout = setTimeout(function(THIS){THIS.setIdle();},THIS.inactivityTimeInSec*1000,THIS);
};