/**
 * This class is used for event handling related functionality.
 * This utility class is an adapter class that masks the different implementation
 * of event handling in the different browsers.
 * It initializes the event listening, and element fetching methods.
 *
 * @author Kem Apak.
 * @author Tony Breckner.
 */
function Event(){
    // IE does not support addEventListener but uses attachEvent.
	if (!document.addEventListener){                	
		Event.addEventListener = function(element, eventName, functionName, isCapture) {
			element.attachEvent("on" + eventName, functionName);
		}
		
		Event.removeEventListener = function(element, eventName, functionName, isCapture) {
			element.detachEvent("on" + eventName, functionName);
		}
	} else {
		Event.addEventListener = function(element, eventName, functionName, isCapture) {
			element.addEventListener(eventName, functionName, isCapture);
		}
		Event.removeEventListener = function(element, eventName, functionName, isCapture) {
			element.removeEventListener(eventName, functionName, isCapture);
		}
	}
	
	// To do: reconfigure this code so the logic is outside the function call
	Event.getTarget = function(eventObject){
  		// Grab the appropriate event object.
		eventObject = (eventObject) ? eventObject : ((window.event) ? window.event : "");
		// we will eventually return this object after assigning the target
		var returnTarget;
  	
		if (!eventObject.target){
   			returnTarget = eventObject.srcElement;
  		} else {
			// we want to grab the currentTarget if it is available
			if (eventObject.currentTarget && (eventObject.currentTarget != eventObject.target)) {
				returnTarget = eventObject.currentTarget;
			} else {
				returnTarget = eventObject.target;
			}
		} 
  		return returnTarget;
 	}	
 }

/**
 * This class member represents change event.
 * 
 * @author Kem Apak
 */
Event.CHANGE = 'change';

/**
 * This class member represents focus event.
 * 
 * @author Kem Apak
 */
 Event.FOCUS = 'focus';
 
 /**
  * This class member represents blur event.
  * 
  * @author Kem Apak
  */
 Event.BLUR = 'blur';
 
 /**
  * This class member represents keydown event.
  * 
  * @author Kem Apak
  */
 Event.KEYDOWN = 'keydown';
 
 /**
  * This class member represents keyup event.
  * 
  * @author Kem Apak
  */
 Event.KEYUP = 'keyup';
 
 /**
  * This class member represents keypress event.
  * 
  * @deprecated Please use Event.KEYDOWN
  * @author Kem Apak
  */
 Event.KEYPRESS = 'keypress';

/**
 * This class member represents mouse event mousedown.
 * 
 * @author Kem Apak
 */
Event.MOUSEDOWN = 'mousedown';

/**
 * This class member represents mouse event mouseup.
 * 
 * @author Kem Apak
 */
Event.MOUSEUP = 'mouseup';

/**
 * This class member represents mouse event mouseover.
 * 
 * @author Kem Apak
 */
Event.MOUSEOVER = 'mouseover';

/**
 * This class member represents mouse event mouseout.
 * 
 * @author Kem Apak.
 */
Event.MOUSEOUT = 'mouseout';

/**
 * This class member represents mouse event mousemove.
 * 
 * @author Kem Apak
 */ 
Event.MOUSEMOVE = 'mousemove';

/**
 * This class member represents mouse event click.
 * 
 * @author Kem Apak
 */ 
Event.CLICK = 'click';

/**
 * This class member represents mouse event doubleclick.
 * 
 * @author Kem Apak
 */ 
Event.DOUBLECLICK = 'dblclick';

/** 
 * This class member represents load event.
 * Works only with window, document, object, applet, image.
 * 
 * @author Kem Apak
 */
Event.LOAD = 'load';

/** 
 * This class member represents unload event.
 * Works only with window, document, object, applet, image.
 * 
 * @author Kem Apak
 */
Event.UNLOAD = 'unload';
 
/** 
 * This class member represents submit event.
 * Works only with forms.
 * 
 * @author Kem Apak
 */
Event.SUBMIT = 'submit';

/** 
 * This class member represents reset event.
 * Works only with forms.
 * 
 * @author Kem Apak
 */
Event.RESET = 'reset';

/**
 * This class member represents DOM property change.
 * This is a class property that represent the event property change. Microsoft does not use the
 * standard naming convention for this event. It is set to property 'onpropertychange' for IE, and 
 * 'DOMAttrModified' for DOM complaint browsers.
 * 
 * @author Kem Apak
 * For now all the DOM events are included.

Event.DOMAttrModified = 'DOMAttrModified';
Event.DOMSubtreeModified = 'DOMSubtreeModified'; 
Event.Dom.DOMNodeInserted = 'DOMNodeInserted';  
Event.DOMNodeRemoved = 'DOMNodeRemoved';  
Event.DOMNodeRemovedFromDocument = 'DOMNodeRemovedFromDocument';  
Event.DOMNodeInsertedIntoDocument = 'DOMNodeInsertedIntoDocument';
Event.DOMCharacterDataModified = 'DOMCharacterDataModified'; 
 */ 

/**
 * This class method returns the element that fires the given event.
 *
 * @author Kem Apak
 * @param evt The event.
 * @returns The element that fired the event.
 */
Event.getTarget = function(eventObject) {
	// See the class constructor how this function is initialized.
}

/**
 * This class method adds an event to an element.
 *
 * @author Kem Apak.
 * @param element The element object that the event is to be added.
 * @param eventName The name of the event.
 * @param functionName The name of the function that will handle the event when it is fired.
 * @param isCapture If true event is fired in the capturing phase else in the bubbling phase. (Dom complaint browsers only).
 */
Event.addEventListener = function(element, eventName, functionName, isCapture) {
    // See the class constructor how this function is initialized.
}

/**
 * This class method removes an event to an element.
 *
 * @author Tony Breckner.
 * @param element The element object that the event is to be added.
 * @param eventName The name of the event.
 * @param functionName The name of the function that will handle the event when it is fired.
 * @param isCapture If true event is fired in the capturing phase else in the bubbling phase. (Dom complaint browsers only).
 */
Event.removeEventListener = function(element, eventName, functionName, isCapture) {
    // See the class constructor how this function is initialized.
}

/**
 * This class method register an event to the elements in the collection.
 * 
 * @author Kem Apak
 * @param elements The collection of element objects.
 * @param eventName The name of the event.
 * @param functionName The of the function that will handle the event when it is fired.
 * @param isCapture If true event is fired in the capturing phase else in the bubbling phase. (Dom complaint browsers only).
 */
Event.addEventListenerToElements = function(elements, eventName, functionName, isCapture) {

	// Get the size of the collection.
	var numberOfElements = elements.length;
	
	// Iterate thru the collection add register event to elements.
	for (var index = 0; index < numberOfElements; index++) {
		Event.addEventListener(elements[index], eventName, functionName, isCapture);
	}	
}

/**
 * This class method removes the event listeners from the objects in the collection.
 * 
 * @author Tony Breckner
 * @param elements The collection of element objects.
 * @param eventName The name of the event.
 * @param functionName The of the function that will handle the event when it is fired.
 * @param isCapture If true event is fired in the capturing phase else in the bubbling phase. (Dom complaint browsers only).
 */
Event.removeEventListenersFromElements = function(elements, eventName, functionName, isCapture) {

	// Get the size of the collection.
	var numberOfElements = elements.length;
	
	// Iterate thru the collection add register event to elements.
	for (var index = 0; index < numberOfElements; index++) {
		Event.removeEventListener(elements[index], eventName, functionName, isCapture);
	}	
}

/**
 * This class method register an event to the elements with the names passed in the collection.
 * IMPORTANT A name represents a collection XHTML, therefore you only need to pass the name once.
 * Otherwise the same event will be registered (and overidden) multiple time.
 * 
 * @author Kem Apak
 * @param elementNames The collection of element objects.
 * @param eventName The name of the event.
 * @param functionName The of the function that will handle the event when it is fired.
 * @param isCapture If true event is fired in the capturing phase else in the bubbling phase. (Dom complaint browsers only).
 */
Event.addEventListenerToElementsByName = function(elementName, eventName, functionName, isCapture) {
	// Get the collection by name.
	elements = document.getElementsByName(elementName);
		
	// Register the event to elements.
	Event.addEventListenerToElements(elements, eventName, functionName, isCapture);
}

/**
 * This class method removes an event to the elements with the names passed in the collection.
 * IMPORTANT A name represents a collection XHTML, therefore you only need to pass the name once.
 * Otherwise the same event will be registered (and overidden) multiple time.
 * 
 * @author Tony Breckner
 * @param elementNames The collection of element objects.
 * @param eventName The name of the event.
 * @param functionName The of the function that will handle the event when it is fired.
 * @param isCapture If true event is fired in the capturing phase else in the bubbling phase. (Dom complaint browsers only).
 */
Event.removeEventListenerFromElementsByName = function(elementName, eventName, functionName, isCapture) {
	// Get the collection by name.
	elements = document.getElementsByName(elementName);
		
	// Register the event to elements.
	Event.removeEventListenersFromElements(elements, eventName, functionName, isCapture);
}

/**
 * This class method register an event to the elements with the ids passed in the collection.
 * 
 * @author Kem Apak
 * @param elementIds The collection of element objects.
 * @param eventName The name of the event.
 * @param functionName The of the function that will handle the event when it is fired.
 * @param isCapture If true event is fired in the capturing phase else in the bubbling phase. (Dom complaint browsers only).
 */
Event.addEventListenersByIds = function(elementIds, eventName, functionName, isCapture) {

	// Get the size of the collection.
	var numberOfElements = elementIds.length;
	
	// Create the variable that represents a single element.
	var element;
	
	// Create the collection that represents the elements.
	var elements = new Array();
	
	// Iterate thru the element ids and add element to the elements collection.
	for (var index = 0; index < numberOfElements; index++) {

		elements[index] = document.getElementById(elementIds[index]);
	}	
	
	// Register the event to elements.
	Event.addEventListenerToElements(elements, eventName, functionName, isCapture);
}

/**
 * This class method removes an event to the elements with the ids passed in the collection.
 * 
 * @author Tony Breckner
 * @param elementIds The collection of element objects.
 * @param eventName The name of the event.
 * @param functionName The of the function that will handle the event when it is fired.
 * @param isCapture If true event is fired in the capturing phase else in the bubbling phase. (Dom complaint browsers only).
 */
Event.removeEventListenersByIds = function(elementIds, eventName, functionName, isCapture) {

	// Get the size of the collection.
	var numberOfElements = elementIds.length;
	
	// Create the variable that represents a single element.
	var element;
	
	// Create the collection that represents the elements.
	var elements = new Array();
	
	// Iterate thru the element ids and add element to the elements collection.
	for (var index = 0; index < numberOfElements; index++) {

		elements[index] = document.getElementById(elementIds[index]);
	}	
	
	// Register the event to elements.
	Event.removeEventListenersFromElements(elements, eventName, functionName, isCapture);
}

/**
 * This class method registers an event to the elements with the CSS class names passed as a collection.
 * 
 * @author Kem Apak
 * @param className The name of the CSS class.
 * @param eventName The name of the event.
 * @param functionName The of the function that will handle the event when it is fired.
 * @param isCapture If true event is fired in the capturing phase else in the bubbling phase. (Dom complaint browsers only).
 */
Event.addEventListenerByCssClassName = function(className, eventName, functionName, isCapture) {
	
	// TODO Kem implement.
}

/**
 * This class helper method registers an event to the window onload event. Currently different and buggy implementations
 * cause window onload event to be overriden accidentally or not work working. Thanks Micth Cohen from Foresee for the code 
 * help.
 * 
 * The location of where this method is called is very important. Try to call this as last in the page.
 * 
 * @author Kem Apak
 * @param functionName The of the function that will handle the event when it is fired.
 * @param isCapture If true event is fired in the capturing phase else in the bubbling phase. (Dom complaint browsers only).
 */
Event.addLoadEventListenerToWindow = function(functionName, isCapture) {
	
	// Check if window is already assinged with window.onload = some funciton.
	if (typeof window.onload != 'function') 
		
		Event.addEventListener(window, Event.LOAD, functionName, isCapture);
	else {
		
		// Get the reference for the current window onload.
		var currentOnloadFunction = window.onload;
		
		// Using a anonymous function set the window onload with both the current and our function.
		window.onload = function() {
			currentOnloadFunction();
			functionName();
		}
	}
}

// Intantiate the singleton class to set the event variables.
new Event();