// Created: 2006.01.12
// Author: Demian Martinez <demian@activeidealab.com>
// Based on: http://dean.edwards.name/weblog/2005/10/add-event/

function addEvent(element, type, handler, args)
{
	// Assign each event handler a unique ID
	if (!handler.$$guid) handler.$$guid = addEvent.guid++;
	
	// Ensure the element has a the a events hashtable
	if (!element.events) element.events = {};

	// Ensure events[type] entry has a handlers hashtable
	var handlers = element.events[type];
	if (!handlers)
	{
		handlers = element.events[type] = {};
		
		// If a handler was already wired to the event type, add it as the first handler
		if (element["on" + type])
		{
			handlers[0] = element["on" + type];
		}
	}
	
	// Add the handler to the handlers hashtable
	if (args)
	{
		// If args were specified, add a handler/args JSON object
		handlers[handler.$$guid] = { 'handler' : handler , 'args' : args }
	}
	else
	{
		// If no args were specified, add the handler only (this is the original way)
		handlers[handler.$$guid] = handler;
	}
	
	// Assign a global event handler to do all the work
	element["on" + type] = handleEvent;
};

// a counter used to create unique IDs
addEvent.guid = 1;

function removeEvent(element, type, handler)
{
	// delete the event handler from the hash table
	if (element.events && element.events[type])
	{
		delete element.events[type][handler.$$guid];
	}
};

function handleEvent(event)
{
	var returnValue = true;
	
	// Grab the event object (IE uses a global event object)
	event = event || fixEvent(window.event);
	// event = event || fixEvent(window.event||(this.ownerDocument||this).parentWindow.event)

	// Get a reference to the hash table of event handlers
	var handlers = this.events[event.type];
	
	// Execute each event handler in turn
	for (var i in handlers)
	{
		var handler = handlers[i];
		
		if (handler.handler)
		{
			// If a handler/args JSON object was found, call handler with arguments
			this.$$handleEvent = handler.handler;
			if (this.$$handleEvent(this, handler.args) === false)
			{
				returnValue = false;
			}
		}
		else
		{
			// Else, call handler with no args (the original way)
			this.$$handleEvent = handlers[i];
			if (this.$$handleEvent(event) === false)
			{
				returnValue = false;
			}
		}
	}
	return returnValue;
};

function fixEvent(event)
{
	// add W3C standard event methods
	event.preventDefault = fixEvent.preventDefault;
	event.stopPropagation = fixEvent.stopPropagation;
	return event;
};

fixEvent.preventDefault = function()
{
	this.returnValue = false;
};

fixEvent.stopPropagation = function()
{
	this.cancelBubble = true;
};


// <OriginalCode>
/*
function addEvent(element, type, handler) {
	// assign each event handler a unique ID
	if (!handler.$$guid) handler.$$guid = addEvent.guid++;
	// create a hash table of event types for the element
	if (!element.events) element.events = {};
	// create a hash table of event handlers for each element/event pair
	var handlers = element.events[type];
	if (!handlers) {
		handlers = element.events[type] = {};
		// store the existing event handler (if there is one)
		if (element["on" + type]) {
			handlers[0] = element["on" + type];
		}
	}
	// store the event handler in the hash table
	handlers[handler.$$guid] = handler;
	// assign a global event handler to do all the work
	element["on" + type] = handleEvent;
};
// a counter used to create unique IDs
addEvent.guid = 1;

function removeEvent(element, type, handler) {
	// delete the event handler from the hash table
	if (element.events && element.events[type]) {
		delete element.events[type][handler.$$guid];
	}
};

function handleEvent(event) {
	var returnValue = true;
	// grab the event object (IE uses a global event object)
	event = event || fixEvent(window.event);
 // event = event || fixEvent(window.event||(this.ownerDocument||this).parentWindow.event)
	// get a reference to the hash table of event handlers
	var handlers = this.events[event.type];
	// execute each event handler
	for (var i in handlers) {
		this.$$handleEvent = handlers[i];
		if (this.$$handleEvent(event) === false) {
			returnValue = false;
		}
	}
	return returnValue;
};

function fixEvent(event) {
	// add W3C standard event methods
	event.preventDefault = fixEvent.preventDefault;
	event.stopPropagation = fixEvent.stopPropagation;
	return event;
};
fixEvent.preventDefault = function() {
	this.returnValue = false;
};
fixEvent.stopPropagation = function() {
	this.cancelBubble = true;
};
*/
// </OriginalCode>