var loadingImage = 'loading.gif';		
var closeButton = 'xito.gif';		

function pause(numberMillis) {
	var now = new Date();
	var exitTime = now.getTime() + numberMillis;
	while (true) {
		now = new Date();
		if (now.getTime() > exitTime)
			return;
	}
}

// showLightbox()

function showLightbox(objLink)
{
	// prep objects
	var objOverlay = $('overlay');
	var objLightbox = $('lightbox');
	var objCaption = $('lightboxCaption');
	var objImage = $('lightboxImage');
	var objLoadingImage = $('loadingImage');

	var windowSize = getWindowSize();
	var pageSize = getPageSize();

	// center loadingImage if it exists
	if (objLoadingImage) {
		objLoadingImage.style.top = ((windowSize.height - 35 - objLoadingImage.height) / 2) + 'px';
		objLoadingImage.style.left = ((pageSize.width - 20 - objLoadingImage.width) / 2) + 'px';
		objLoadingImage.style.display = 'block';
	}

	// set height of Overlay to take up whole page and show
	objOverlay.style.height = (pageSize.height + 'px');
	objOverlay.style.display = 'block';

	// preload image
	imgPreload = new Image();

	imgPreload.onload=function(){
		objImage.src = objLink.href;

		// center lightbox and make sure that the top and left values are not negative
		// and the image placed outside the viewport
		var lightboxTop = ((windowSize.height - 35 - imgPreload.height) / 2);
		var lightboxLeft = ((pageSize.width - 20 - imgPreload.width) / 2);
		
		objLightbox.style.top = (lightboxTop < 0) ? "0px" : lightboxTop + "px";
		objLightbox.style.left = (lightboxLeft < 0) ? "0px" : lightboxLeft + "px";

		objCaption.style.width = imgPreload.width + 'px';
		
		var titleImg = objLink.getElementsByTagName("img");
		for (var i=0; i<titleImg.length; i++){
		  objCaption.style.display = 'block';
			objCaption.innerHTML = titleImg[0].alt;
		}

		// A small pause between the image loading and displaying is required with IE,
		// this prevents the previous image displaying for a short burst causing flicker.
		if (navigator.appVersion.indexOf("MSIE")!=-1){
			pause(250);
		} 

		if (objLoadingImage) {	objLoadingImage.style.display = 'none'; }

	
		objLightbox.style.display = 'block';
		objLightbox.onclick = function(){hideLightbox(); return false;}
		objLink.onclick = function () {hideLightbox(); return false;}


		return false;
	}

	imgPreload.src = objLink.href;
	
}

// hideLightbox()
function hideLightbox(){
	$('overlay').style.display = 'none';
	$('lightbox').style.display = 'none';
  initLightbox('portfolio');
}



function initLightbox(context){
	
	var anchors = $(context).getElementsByTagName("a");

	// loop through all anchor tags
	for (var i=0; i<anchors.length; i++){
		if (anchors[i].className == "photoviewer"){
			anchors[i].onclick = function () {
        showLightbox(this); 
        return false;}
		}
	}

	
	var objBody = document.getElementsByTagName("body").item(0);
	
	// create overlay div and hardcode some functional styles (aesthetic styles are in CSS file)
	var objOverlay = document.createElement("div");
	objOverlay.setAttribute('id','overlay');
	objOverlay.onclick = function(){hideLightbox(); return false;}
	objOverlay.style.display = 'none';
	objOverlay.style.position = 'absolute';
	objOverlay.style.top = '0';
	objOverlay.style.left = '0';
	objOverlay.style.zIndex = '90';
 	objOverlay.style.width = '100%';
	objBody.insertBefore(objOverlay, objBody.firstChild);

	// preload and create loader image
	var imgPreloader = new Image();
	
	// if loader image found, create link to hide lightbox and create loadingimage
	imgPreloader.onload=function(){

		var objLoadingImageLink = document.createElement("a");
		objLoadingImageLink.setAttribute('href','#');
		objLoadingImageLink.onclick = function(){hideLightbox(); return false;}
		objOverlay.appendChild(objLoadingImageLink);
		
		var objLoadingImage = document.createElement("img");
		objLoadingImage.src = loadingImage;
		objLoadingImage.setAttribute('id','loadingImage');
		objLoadingImage.style.position = 'absolute';
		objLoadingImage.style.zIndex = '150';
		objLoadingImageLink.appendChild(objLoadingImage);

		imgPreloader.onload=function(){};	
		return false;
	}

	imgPreloader.src = loadingImage;

	// create lightbox div, same note about styles as above
	var objLightbox = document.createElement("div");
	objLightbox.setAttribute('id','lightbox');
	objLightbox.style.display = 'none';
	objLightbox.style.position = 'absolute';
	objLightbox.style.zIndex = '100';	
	objBody.insertBefore(objLightbox, objOverlay.nextSibling);
	
	// create link
	var objLink = document.createElement("a");
	objLink.setAttribute('href','#');
	objLink.setAttribute('title','Click to close');
	objLink.onclick = function () {hideLightbox(); return false;}
	objLightbox.appendChild(objLink);

	// preload and create close button image
	var imgPreloadCloseButton = new Image();

	// if close button image found, 
	imgPreloadCloseButton.onload=function(){

		var objCloseButton = document.createElement("img");
		objCloseButton.src = closeButton;
		objCloseButton.setAttribute('id','closeButton');
		objCloseButton.style.position = 'absolute';
		objCloseButton.style.zIndex = '200';
		objLink.appendChild(objCloseButton);

		return false;
		}
	

	imgPreloadCloseButton.src = closeButton;

	// create image
	var objImage = document.createElement("img");
	objImage.setAttribute('id','lightboxImage');
	objLink.appendChild(objImage);
	
	// create caption
	var objCaption = document.createElement("div");
	objCaption.setAttribute('id','lightboxCaption');
	objCaption.style.display = 'none';
	objLightbox.appendChild(objCaption);

}