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

function getPageScroll(){

   var yScroll;

   if (self.pageYOffset) {
      yScroll = self.pageYOffset;
   } else if (document.documentElement && document.documentElement.scrollTop){    // Explorer 6 Strict
      yScroll = document.documentElement.scrollTop;
   } else if (document.body) {// all other Explorers
      yScroll = document.body.scrollTop;
   }

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


function getPageSize(){
   
   var xScroll, yScroll;
   
   if (window.innerHeight && window.scrollMaxY) {  
      xScroll = document.body.scrollWidth;
      yScroll = window.innerHeight + window.scrollMaxY;
   } else if (document.body.scrollHeight > document.body.offsetHeight){ // all but Explorer Mac
      xScroll = document.body.scrollWidth;
      yScroll = document.body.scrollHeight;
   } else { // Explorer Mac...would also work in Explorer 6 Strict, Mozilla and Safari
      xScroll = document.body.offsetWidth;
      yScroll = document.body.offsetHeight;
   }
   
   var windowWidth, windowHeight;
   if (self.innerHeight) { // all except Explorer
      windowWidth = self.innerWidth;
      windowHeight = self.innerHeight;
   } else if (document.documentElement && document.documentElement.clientHeight) { // Explorer 6 Strict Mode
      windowWidth = document.documentElement.clientWidth;
      windowHeight = document.documentElement.clientHeight;
   } else if (document.body) { // other Explorers
      windowWidth = document.body.clientWidth;
      windowHeight = document.body.clientHeight;
   }  
   
   // for small pages with total height less then height of the viewport
   if(yScroll < windowHeight){
      pageHeight = windowHeight;
   } else { 
      pageHeight = yScroll;
   }

   // for small pages with total width less then width of the viewport
   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 getKey(e){
   if (e == null) { // ie
      keycode = event.keyCode;
   } else { // mozilla
      keycode = e.which;
   }
   key = String.fromCharCode(keycode).toLowerCase();
   
   if(key == 'x'){ hideLightbox(); }
}


function listenKey () { document.onkeypress = getKey; }
   

function showLightbox(objLink)
{
   // prep objects
   var objOverlay = document.getElementById('overlay');
   var objLightbox = document.getElementById('lightbox');
   var objCaption = document.getElementById('lightboxCaption');
   var objImage = document.getElementById('lightboxImage');
   var objLoadingImage = document.getElementById('loadingImage');
   var objLightboxDetails = document.getElementById('lightboxDetails');

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

   // center loadingImage if it exists
   if (objLoadingImage) {
      objLoadingImage.style.top = (arrayPageScroll[1] + ((arrayPageSize[3] - 35 - objLoadingImage.height) / 2) + 'px');
      objLoadingImage.style.left = (((arrayPageSize[0] - 20 - objLoadingImage.width) / 2) + 'px');
      objLoadingImage.style.display = 'block';
   }

   // set height of Overlay to take up whole page and show
   objOverlay.style.height = (arrayPageSize[1] + '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 = arrayPageScroll[1] + ((arrayPageSize[3] - 35 - imgPreload.height) / 2);
      var lightboxLeft = ((arrayPageSize[0] - 20 - imgPreload.width) / 2);
      
      objLightbox.style.top = (lightboxTop < 0) ? "0px" : lightboxTop + "px";
      objLightbox.style.left = (lightboxLeft < 0) ? "0px" : lightboxLeft + "px";


      objLightboxDetails.style.width = imgPreload.width + 'px';
      
      if(objLink.getAttribute('title')){
         objCaption.style.display = 'block';
         //objCaption.style.width = imgPreload.width + 'px';
         objCaption.innerHTML = objLink.getAttribute('title');
      } else {
         objCaption.style.display = 'none';
      }
      
      // 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'; }

      // Hide select boxes as they will 'peek' through the image in IE
      selects = document.getElementsByTagName("select");
        for (i = 0; i != selects.length; i++) {
                selects[i].style.visibility = "hidden";
        }

   
      objLightbox.style.display = 'block';

      // After image is loaded, update the overlay height as the new image might have
      // increased the overall page height.
      arrayPageSize = getPageSize();
      objOverlay.style.height = (arrayPageSize[1] + 'px');
      
      // Check for 'x' keypress
      listenKey();

      return false;
   }

   imgPreload.src = objLink.href;
   
}


function hideLightbox()
{
   // get objects
   objOverlay = document.getElementById('overlay');
   objLightbox = document.getElementById('lightbox');

   // hide lightbox and overlay
   objOverlay.style.display = 'none';
   objLightbox.style.display = 'none';

   // make select boxes visible
   selects = document.getElementsByTagName("select");
    for (i = 0; i != selects.length; i++) {
      selects[i].style.visibility = "visible";
   }

   // disable keypress listener
   document.onkeypress = '';
}




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

   // loop through all anchor tags
   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);
   
   // 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);
   
   var arrayPageSize = getPageSize();
   var arrayPageScroll = getPageScroll();

   // 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(){};   // clear onLoad, as IE will flip out w/animated gifs

      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 details div, a container for the caption and keyboard message
   var objLightboxDetails = document.createElement("div");
   objLightboxDetails.setAttribute('id','lightboxDetails');
   objLightbox.appendChild(objLightboxDetails);

   // create caption
   var objCaption = document.createElement("div");
   objCaption.setAttribute('id','lightboxCaption');
   objCaption.style.display = 'none';
   objLightboxDetails.appendChild(objCaption);

   // create keyboard message
   var objKeyboardMsg = document.createElement("div");
   objKeyboardMsg.setAttribute('id','keyboardMsg');
   objKeyboardMsg.innerHTML = 'zamknij: <a href="#" onclick="hideLightbox(); return false;"><b>x</b></a>';
   objLightboxDetails.appendChild(objKeyboardMsg);


}




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

}



//addLoadEvent(initLightbox); // run initLightbox onLoad