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

function insertAfter(targetElement,newElement) {
  var parent = targetElement.parentNode;
  if (parent.lastChild == targetElement) {
    parent.appendChild(newElement);
  } else {
    parent.insertBefore(newElement,targetElement.nextSibling);
  }
}

function hideOriginalText () {
	var origText = document.getElementById("originalText");
	origText.style.display = "none";
}

function showOriginalText () {
	var origText = document.getElementById("originalText");
	var placeholder = document.getElementById("placeholder");
	var description = document.getElementById("description");
	var restoreLink = document.getElementById("restoreLink");

	//origText.style.display = "block";
	new Effect.Appear(origText,3);
	placeholder.style.display = "none";
	description.style.display = "none";
	restoreLink.style.display = "none";
	//new Effect.SlideUp(placeholder,2);
	//new Effect.SlideUp(description,2);
	//new Effect.SlideUp(restoreLink,2);
}

function preparePlaceholder() {
//alert("preparePlaceholder invoked");
  if (!document.createElement) return false;
  if (!document.createTextNode) return false;
  if (!document.getElementById) return false;
  if (!document.getElementById("imageGallery")) return false;
  
  // Create placeholder for image
  var placeholder = document.createElement("img");
  placeholder.setAttribute("id","placeholder");
  placeholder.setAttribute("alt","Image Gallery");
  
  // Create description for image
  var description = document.createElement("h1");
  description.setAttribute("id","description");
  var desctext = document.createTextNode("Choose an image");
  description.appendChild(desctext);
  
  // Create link to restore the original text  
  var restoreLink = document.createElement("a");
  restoreLink.setAttribute("href","index.html");
  restoreLink.setAttribute("onclick","showOriginalText(); return false;");
  restoreLink.setAttribute("id","restoreLink");
  var restorePara = document.createElement("p");
  var restoreText = document.createTextNode("Restore original text");
  restorePara.appendChild(restoreText);
  restoreLink.appendChild(restorePara);
  
  // Insert into the document
  var origText = document.getElementById("originalText");
  insertAfter(origText,description);
  insertAfter(description,placeholder);
  insertAfter(placeholder,restoreLink);

  // Set default display
  placeholder.style.display = "none";
  description.style.display = "none";
  restoreLink.style.display = "none";
}

function prepareGallery() {
//alert("prepareGallery invoked");
  if (!document.getElementsByTagName) return false;
  if (!document.getElementById) return false;
  if (!document.getElementById("imageGallery")) return false;
  var gallery = document.getElementById("imageGallery");
  var links = gallery.getElementsByTagName("a");
  for ( var i=0; i < links.length; i++) {
	  if (links[i].className=="category") {
		links[i].onclick = function() {
    	  return showCategory(this);
		}
	  } else {
	    links[i].onclick = function() {
    	  return showPic(this);
		}
	  }
  }
}

function hideCategories() {
//alert("hideCategories invoked");
	var gallery = document.getElementById("imageGallery");
	var links = gallery.getElementsByTagName("a");
	for (var i=0; i<links.length; i++) {
		if (links[i].className=="category") {
			var divName=document.getElementById(links[i].id+"Thumbs");
			//divName.style.display = "none";
			if (divName.style.display != "none") {
				new Effect.SlideUp(divName);
			}
		}
	}
}

function showCategory(whichCategory) {
  var category = whichCategory.getAttribute("id");
  var categoryDiv = document.getElementById(category+"Thumbs");
  hideCategories();
  if (categoryDiv.style.display=="none") {
    //categoryDiv.style.display = "block";
	new Effect.SlideDown(categoryDiv);
  } else {
	//categoryDiv.style.display = "none";
	new Effect.SlideUp(categoryDiv);
  }
  return false;
}

function showPic(whichpic) {
//alert("showPic invoked");
  hideOriginalText();
  if (!document.getElementById("placeholder")) return true;
  var source = whichpic.getAttribute("href");
  var placeholder = document.getElementById("placeholder");
  placeholder.setAttribute("src",source);
  if (!document.getElementById("description")) return false;
  if (whichpic.getAttribute("title")) {
    var text = whichpic.getAttribute("title");
  } else {
    var text = "";
  }
  var description = document.getElementById("description");
  if (description.firstChild.nodeType == 3) {
    description.firstChild.nodeValue = text;
  }
  var restoreLink = document.getElementById("restoreLink");
  
  // Display toggle
  //placeholder.style.display = "block";
  Effect.Appear("placeholder");
  description.style.display = "block";
  restoreLink.style.display = "block";
  return false;
}

addLoadEvent(prepareGallery);
addLoadEvent(hideCategories);
addLoadEvent(preparePlaceholder);