var loadingImage = './images/loading.gif';

function getPageScroll(){

        var yScroll;

        if (self.pageYOffset) {
                yScroll = self.pageYOffset;
        } else if (document.documentElement && document.documentElement.scrollTop){
                yScroll = document.documentElement.scrollTop;
        } else if (document.body) {
                yScroll = document.body.scrollTop;
        }

        arrayPageScroll = new Array('',yScroll)
        return arrayPageScroll;
}


function getPageSize(){

        var xScroll, yScroll;

        if (document.body.scrollHeight > document.body.offsetHeight){
                xScroll = document.body.scrollWidth;
                yScroll = document.body.scrollHeight;
        } else {
                xScroll = document.body.offsetWidth;
                yScroll = document.body.offsetHeight;
        }

        var windowWidth, windowHeight;
        if (self.innerHeight) {
                windowWidth = self.innerWidth;
                windowHeight = self.innerHeight;
        } else if (document.documentElement && document.documentElement.clientHeight) {
                windowWidth = document.documentElement.clientWidth;
                windowHeight = document.documentElement.clientHeight;
        } else if (document.body) {
                windowWidth = document.body.clientWidth;
                windowHeight = document.body.clientHeight;
        }


        if(yScroll < windowHeight){
                pageHeight = windowHeight;
        } else {
                pageHeight = yScroll;
        }


        if(xScroll < windowWidth){
                pageWidth = windowWidth;
        } else {
                pageWidth = xScroll;
        }


        arrayPageSize = new Array(pageWidth,pageHeight,windowWidth,windowHeight)
        return arrayPageSize;
}


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



function showLightbox(objLink)
{

        var objOverlay = document.getElementById('overlay');
        var objLightbox = document.getElementById('lightbox');
        var objImage = document.getElementById('lightboxImage');
        var objLoadingImage = document.getElementById('loadingImage');

        var arrayPageSize = getPageSize();
        var arrayPageScroll = getPageScroll();


        if (objLoadingImage) {
                objLoadingImage.style.top = (arrayPageScroll[1] + ((arrayPageSize[3] - 35 - objLoadingImage.height) / 2) + 'px');
                objLoadingImage.style.left = (((arrayPageSize[0] - 40 - objLoadingImage.width) / 2) + 'px');
        }


        objOverlay.style.height = (arrayPageSize[1] + 'px');
        objOverlay.style.display = 'block';


        imgPreload = new Image();

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


                objLightbox.style.top = (arrayPageScroll[1] + ((arrayPageSize[3] - 35 - imgPreload.height) / 2) + 'px');
                objLightbox.style.left = (((arrayPageSize[0] - 40 - imgPreload.width) / 2) + 'px');


                if (navigator.appVersion.indexOf("MSIE")!=-1){
                        pause(250);
                }

                objLightbox.style.display = 'block';

                return false;
        }

        imgPreload.src = objLink.href;

}


function hideLightbox()
{

        objOverlay = document.getElementById('overlay');
        objLightbox = document.getElementById('lightbox');


        objOverlay.style.display = 'none';
        objLightbox.style.display = 'none';
}


function initLightbox()
{

        if (!document.getElementsByTagName){ return; }
        var anchors = document.getElementsByTagName("a");


        for (var i=0; i<anchors.length; i++){
                var anchor = anchors[i];

                if (anchor.getAttribute("href") && (anchor.getAttribute("rel") == "lightbox")){
                        anchor.onclick = function () {showLightbox(this); return false;}
                }
        }



        var objBody = document.getElementsByTagName("body").item(0);


        var objOverlay = document.createElement("div");
        objOverlay.setAttribute('id','overlay');
        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);

        var arrayPageSize = getPageSize();
        var arrayPageScroll = getPageScroll();


        var imgPreloader = new Image();


        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;


        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);


        var objLink = document.createElement("a");
        objLink.setAttribute('href','#');
        objLink.setAttribute('title','click to close image'); 
        objLink.onclick = function () {hideLightbox(); return false;}
        objLightbox.appendChild(objLink);


        var objImage = document.createElement("img");
        objImage.setAttribute('id','lightboxImage');
        objLink.appendChild(objImage);
}



function addLoadEvent(func)
{
        var oldonload = window.onload;
        if (typeof window.onload != 'function'){
            window.onload = func;
        } else {
                window.onload = function(){
                oldonload();
                func();
                }
        }

}




addLoadEvent(initLightbox);