var Core = {};

//W3C DOM2 events model
if (document.addEventListener){
	Core.addEventListener = function(target, type, listener){
		target.addEventListener(type, listener, false);
	};
	
	Core.removeEventListener = function(target, type, listener){
		target.removeEventListener(type, listener, false);
	};
	
	Core.preventDefault = function(event){
		event.preventDefault();
	};
	
	Core.stopPropagation = function(event){
		event.stopPropagation();
	};
}

//IE Events Model
else if (document.attachEvent){
	Core.addEventListener = function(target, type, listener)
	{
		if (Core._findListener(target,type,listener) != -1)	return;
			
		var listener2 = function(){
			var event = window.event;
			
			if (Function.prototype.call){
				listener.call(target,event);
			}else{
				target._currentListener = listener;
				target._currentListener(event);
				target._currentListener = null;
			}
		};
		target.attachEvent("on"+type,listener2);
		
		var listenerRecord ={
			target:target,
			type:type,
			listener:listener,
			listener2:listener2
		};
		var targetDocument = target.document || target;
		var targetWindow = targetDocument.parentWindow;
		var listenerId = "1" + Core._listenerCounter++;
		if(!targetWindow._allListeners) targetWindow._allListeners = {};
		targetWindow._allListeners[listenerId] = listenerRecord;
		if(!target._listeners) target._listeners = [];
		target._listeners[target._listeners.length] = listenerId;
		
		if (!targetWindow._unloadListenerAdded){
			targetWindow._unloadListenerAdded = true;
			targetWindow.attachEvent("onunload", Core._removeAllListeners);
		}
	};
	
	Core.removeEventListener = function(target, type, listener){
		var listenerIndex = Core._findListener(target,type,listener);
		if(listenerIndex == -1) return;
		
		var targetDocument 	= target.document || target;
		var targetWindow	= targetDocument.parentWindow;
		
		var listenerId = target._listeners[listenerIndex];
		var listenerRecord = targetWindow._allListeners[listenerId];
		
		target.detachEvent("on" + type, listenerRecord.listener2);
		target._listeners.splice(listenerIndex, 1);
		
		delete targetWindow._allListeners[listenerId];
	};
	
	Core.preventDefault = function(event){
		event.returnValue = false;
	};
	
	Core.stopPropagation = function(event){
		event.cancelBubble = true;
	};
	
	Core._findListener = function(target,type,listener){
		var listeners = target._listeners;
		if (!listeners) return -1;
		
		var targetDocument 	= target.document || target;
		var targetWindow	= targetDocument.parentWindow;
		
		for (var i = listeners.length - 1; i >= 0; i--)
		{
			var listenerId = listeners[i];
			
			var listenerRecord = targetWindow._allListeners[listenerId];
			
			if (listenerRecord.type == type && listenerRecord.listener == listener)
			{
				return i;
			}
		}
		return -1;

	};
	
	Core._removeAllListeners = function(){
		var targetWindow = this;
		for (id in targetWindow._allListeners)
		{
			var listenerRecord = targetWindow._allListeners[id];
			listenerRecord.target.detachEvent("on" + listenerRecord.type, listenerRecord.listener2);
			delete targetWindow._allListeners[id];
		}
	};
	Core._listenerCounter = 0;
}

Core.addClass = function(target,theClass){
	if(!Core.hasClass(target, theClass)){
		if(target.className == ""){
			target.className = theClass;
		}else{
			target.className += " " + theClass;
		}
	}
};

Core.getElementsByClass = function(theClass,target){
	var node = (typeof(target)=='undefined'? document : target);
	var elementArray = [];
	if (node.all){
		elementArray = node.all;
	}else{
		elementArray = node.getElementsByTagName("*");
	}
	var matchedArray 	= [];
	var pattern			= new RegExp("(^| )" + theClass + "( |$)");
	for (var i=0; i < elementArray.length; i++){
		if (pattern.test(elementArray[i].className)){
			matchedArray[matchedArray.length] = elementArray[i];		
		}
	}
	return matchedArray;
};

Core.hasClass = function(target,theClass){
	var pattern	= new RegExp("(^| )" + theClass + "( |$)");
	
	if (pattern.test(target.className))
	{
		return true;
	}
	
	return false;
};

Core.removeClass = function(target,theClass){
	var pattern	= new RegExp("(^| )" + theClass + "( |$)");
	
	target.className = target.className.replace(pattern, "$1");
	target.className = target.className.replace(/ $/, "");
};

Core.getComputedStyle = function(element, styleProperty){
	var computedStyle= null;
	
	if (typeof element.currentStyle != "undefined")
	{
		computedStyle = element.currentStyle;
	}
	else
	{
		computedStyle = document.defaultView.getComputedStyle(element, null);
	}
	
	return computedStyle[styleProperty];
};

Core.getViewportSize = function(debug){
	debug = (typeof(debug)=='undefined'? false: true);
	var debugmsg = '';
	var size = [0,0];
	if(window.innerWidth && window.innerHeight){
		debugmsg = 'innerWidth+innerHeight';
		size = [ window.innerWidth, window.innerHeight ];
	} else {
		if (typeof document.documentElement != 'undefined' && typeof document.documentElement.clientWidth != 'undefined' && document.documentElement.clientWidth != 0){
			size = [document.documentElement.clientWidth, document.documentElement.clientHeight];
			debugmsg='documentelement clientwidth';
		} else {
			size = [document.getElementsByTagName('body')[0].clientWidth,document.getElementsByTagName('body')[0].clientHeight];
			debugmsg='document body clientWidth';
		};
	};
	if(debug === true)
	{
		alert('vp wdth = '+ size[0] + "\n"+ 'vp height = '+ size[1] + "\n\nmethod used = " + debugmsg);
	}
	return size;
};
Core.getViewportOffset = function(debug){
	debug = (typeof(debug)=='undefined'? false: true);
	var debugmsg = '';
	
	var ScrollX = (document.body.parentNode.scrollLeft
				? document.body.parentNode.scrollLeft
				: document.body.scrollLeft);
	var ScrollY = (document.body.parentNode.scrollTop
				? document.body.parentNode.scrollTop
				: document.body.scrollTop);
	
	if(debug === true)
	{
		alert('offsetx = '+ ScrollX + "\n"+ 'offsety = '+ ScrollY + "\n\nmethod used = " + debugmsg);
	}
	return [ScrollX,ScrollY];
}

Core.getElementSize = function(target,debug){
	debug = (typeof(debug)=='undefined'? false: debug);
	var debugmsg = '';
	var width = Core.getComputedStyle(target,'width');
	if(isNaN(width)){
		if(width.search('px')!=-1){
			width = ((width.split('px')[0])*1); 
		} else if (target.offsetWidth){
			width = target.offsetWidth;
			debugmsg += 'offsetWidth';
		}
	}
	var height = Core.getComputedStyle(target,'height');
	if(isNaN(height)){
		if(height.search('px')!=-1){
			height = ((height.split('px')[0])*1); 
		}else if (target.offsetHeight){
			height = target.offsetHeight;
			debugmsg += 'offsetHeight';
		}
	}
	if(debug === true)
	{
		alert('height = '+ height + "\n"+ 'width = '+ width + "\n\nmethod used = " + debugmsg);
	}
	return [width,height];
}

Core.start = function(runnable){
	Core.addEventListener(window, "load" , runnable.init);
};