// JavaScript Document - from Sitepoint text Simply Javascript by Kevin Yank and Cameron Adams - thank you.
var Core = {};

// W3C DOM 2 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)
	{
		//prevents adding the same listerner twice, since DOM 2
		// Events ingnores duplicates like this
		if(Core._findListener(target, type, listener) != -1) return;
		
		// listener2 calls listerner as a method of target in one of
		//two ways, depending on what this version of IE supports, 
		// and passes it the global event object as an argument
		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;
		 	}
		};
		//add listener2 using IE's attachEvent method
		target.attachEvent("on" + type, listener2);
		
		//create an object describing this listener so we can clean it up later
		var listenerRecord =
		{
			target: target,
			type: type,
			listener: listener,
			listener2: listener2
		};
		//get a reference to the window object containing target
		var targetDocument = target.document || target;
		var targetWindow = targetDocument.parentWindow;
	
		//create a unique ID for this listener
		var listenerId = "1" + Core._listenerCounter++;
		
		//store a record of this listener in the window object
		if (!targetWindow._allListeners) targetWindow._allListeners = {};
		targetWindow._allListeners[listenerId] = listenerRecord;
	
		//store this listener's ID in target
		if (!target._listeners) target._listeners = [];
			target._listeners[target._listeners.length] = listenerId;
	
		//set up Core._removeAllListeners to clean up all listeners on unload
		if (!targetWindow._unloadListenerAdded)
		{
			targetWindow._unloadListenerAdded = true;
			targetWindow.attachEvent ("onunload", Core._removeAllListeners);
		}
	};
	
	Core.removeEventListener = function(target, type, listener)
	{
		// find out if the listener was actually added to the target
		var listenerIndex = Core._findListener(target, type, listener);
		if (listenerIndex == -1) return;
	
		//get a reference to the window object containing target
		var targetDocument = target.document || target;
		var targetWindow = targetDocument.parentWindow;
	
		//obtain the record of the listener from the window object
		var listenerId = target._listeners[listenerIndex];
		var listenerRecord = targetWindow._allListeners[listenerId];
	
		//remove the listener, and remove its ID from target
		target.detachEvent("on" + type, listenerRecord.listener2);
		target._listeners.splice(listenerIndex, 1);
	
		//remove the record of the listener frm the wndow object
		delete targetWindow._allListeners[listenerId];
	};

	Core.preventDefault = function(event)
	{
		event.returnValue = false;
	};

	Core.stopPropagation = function(event)
	{
		event.cancelBubble = true;
	};
	Core._findListener = function (target, type, listener)
	{
	// get the array of Listener IDs added to target
		var listeners = target._listeners;
		if (!listeners) return -1;
	
	//get a reference to the window object containing the target
		var targetDocument = target.document || target;
		var targetWindow = targetDocument.parentWindow;
	
	// searching backward (to speed up onunload processing), find the listener
		for (var i = listeners.length -1; i >= 0; i--)
		{
		//get the listener's ID from target
			var listenerId = listeners[i];
		
		// get the record of the listener from the window object
			var listenerRecord = targetWindow._allListeners[listenerId];
		
		// compare type and listener with the retrieved record
			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)
{
	var elementArray = [];
	if (document.all)
	{
		elementArray = document.all;
	}
	else
	{
		elementArray = document.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.start = function(runnable)
{
	Core.addEventListener(window, "load", runnable.init);
};