/*
* ARKive Slideshow "class"
* Ben Capewell
*	May 2009
*
*	Object to contain properties and methods related to the large
*	image slideshow that is powered by the separate Shadowbox class.
*
*	On inclusion in the page this script will set up links that
*	have class "slideshow" to activate Shadowbox
*
*/
var Slideshow = {
	
	//
	//	Filename for slideshow XML data file
	//
	filename: "imageRSS.xml",
	
	//
	//	The XmlHttpRequest object
	// 
	xmlDoc: null,
	
	//
	// Array of objects representing items to be displayed
	//
	items: new Array(),
	
	//
	//	Record of which place in the whole set the current item is at
	//
	index: null,
	
	//
  //	Setup links to activate slideshow
  //
  init: function(){
  	var links = $$('.slideshow');
  	for(var i=0;i<links.length;i++){
  		links[i].observe('click', function(e){
  			this.processClick();
  			e.stop();
  		}.bindAsEventListener(this));
  	}
  },
	
	//
	//	Respond to a click on a slideshow-activating link
	//
	processClick: function(){
		if(this.items.length>0)
			this.loadShadowbox();
		else
			this.loadXML();
	},
	
  //
  //	Load the XML
  //
  loadXML: function(galleryName){
    if (window.XMLHttpRequest){
      this.xmlDoc=new XMLHttpRequest();
    }
    else if (window.ActiveXObject){
    	this.xmlDoc=new ActiveXObject("Microsoft.XMLHTTP");
    }  
    if (this.xmlDoc!=null){
    	this.xmlDoc.onreadystatechange=this.XhrParseXML.bind(this);
    	this.xmlDoc.open("GET",this.filename,true);
    	this.xmlDoc.send(null);
    }else{
    	alert("Your browser does not support XMLHTTP.");
    }  
  },
  
  //
  //	Process XmlHttpRequest response and parse data from XML into the 'items' object
  //
  XhrParseXML: function(){
    if (this.xmlDoc.readyState==4)
    {
      if (this.xmlDoc.status==200 || this.xmlDoc.status==304)
      {
      	var cururl = window.location.pathname;  			
      	var retrieve = this.xmlDoc.responseXML.getElementsByTagName('item');        
        for(var i=0;i<retrieve.length;i++){
    			if(retrieve[i].nodeType == 1){
    				var url = retrieve[i].getElementsByTagName('link')[0].childNodes[0].nodeValue;
          	if(retrieve[i].getElementsByTagNameNS){ //IE doesn't support getElementsByTagNameNS, but it is required by Safari/Chrome/Opera
          		var content = retrieve[i].getElementsByTagNameNS('http://search.yahoo.com/mrss/', 'content')[0].attributes.getNamedItem('url').value;
      				var credit = retrieve[i].getElementsByTagNameNS('http://search.yahoo.com/mrss/', 'copyright')[0].childNodes[0].nodeValue;
      			}else{
      				var content = retrieve[i].getElementsByTagName('media:content')[0].attributes.getNamedItem('url').value;
      				var credit = retrieve[i].getElementsByTagName('media:copyright')[0].childNodes[0].nodeValue;
      			}
      			this.items.push({
    					content: content,
    					title: retrieve[i].getElementsByTagName('description')[0].childNodes[0].nodeValue,	    					 					    					
    					credit: credit,
    					link: url,    
    					player: 'img'
     				});    			
     				if(url.substring(url.length-cururl.length, url.length) == cururl)
     					this.index=i;     				   				
    			}
    		}    		
    		if(this.items.length>0)
    			this.loadShadowbox();
      }
      else
      {
        alert("Problem retrieving XML data: " + this.xmlDoc.statusText);
      }
    }
  },
  
  //
  //	Call Shadowbox
  //
  loadShadowbox: function(){
  	Shadowbox.open(this.items, this.index);
  }
          
}

Event.observe(window, 'load', Slideshow.init.bind(Slideshow));