//OBJECTS

//objects inside the RSS2Item object

function RSS2Enclosure(encElement)
{
	if (encElement == null)
	{
		this.url = null;
		this.length = null;
		this.type = null;
	}
	else
	{
		this.url = encElement.getAttribute("url");
		this.length = encElement.getAttribute("length");
		this.type = encElement.getAttribute("type");
	}
}

function RSS2Guid(guidElement)
{
	if (guidElement == null)
	{
		this.isPermaLink = null;
		this.value = null;
	}
	else
	{
		this.isPermaLink = guidElement.getAttribute("isPermaLink");
		this.value = guidElement.childNodes[0].nodeValue;
	}
}

function RSS2Source(souElement)
{
	if (souElement == null)
	{
		this.url = null;
		this.value = null;
	}
	else
	{
		this.url = souElement.getAttribute("url");
		this.value = souElement.childNodes[0].nodeValue;
	}
}

//object containing the RSS 2.0 item

function RSS2Item(itemxml)
{
	//required
	this.title;
	this.link;
	this.description;

	//optional vars
	this.author;
	this.comments;
	this.pubDate;

	//optional objects
	this.category;
	this.enclosure;
	this.guid;
	this.source;

	var properties = new Array("title", "link", "description", "author", "comments", "pubDate");
	var tmpElement = null;
	for (var i=0; i<properties.length; i++)
	{
		tmpElement = itemxml.getElementsByTagName(properties[i])[0];
		if (tmpElement != null)
			eval("this."+properties[i]+"=tmpElement.childNodes[0].nodeValue");
	}

	this.category = new RSS2Category(itemxml.getElementsByTagName("category")[0]);
	this.enclosure = new RSS2Enclosure(itemxml.getElementsByTagName("enclosure")[0]);
	this.guid = new RSS2Guid(itemxml.getElementsByTagName("guid")[0]);
	this.source = new RSS2Source(itemxml.getElementsByTagName("source")[0]);
}

//objects inside the RSS2Channel object

function RSS2Category(catElement)
{
	if (catElement == null)
	{
		this.domain = null;
		this.value = null;
	}
	else
	{
		this.domain = catElement.getAttribute("domain");
		this.value = catElement.childNodes[0].nodeValue;
	}
}

//object containing RSS image tag info

function RSS2Image(imgElement)
{
	if (imgElement == null)
	{
	this.url = null;
	this.link = null;
	this.width = null;
	this.height = null;
	this.description = null;
	}
	else
	{
		imgAttribs = new Array("url","title","link","width","height","description");
		for (var i=0; i<imgAttribs.length; i++)
			if (imgElement.getAttribute(imgAttribs[i]) != null)
				eval("this."+imgAttribs[i]+"=imgElement.getAttribute("+imgAttribs[i]+")");
	}
}


//PROCESSES

//shows the RSS content in the browser

function showRSS(RSS,maxitems)
{
	//default values for html tags used
	var imageTag = "<img id='chan_image'";
	var startItemTag = "<div id='item'>";
	var startTitle = "<div id='item_title'>";
//var startLink = "<div id='item_link'>";
	var openLink = "<a id='item_link' href='";
	var closeLink = "'>";
	var endLink = "</a>";
	var startDescription = "<div id='item_description'>";
	var endTag = "</div>";

	//populate channel data
	/*
	var properties = new Array("title","link","description","pubDate","copyright");
	for (var i=0; i<properties.length; i++)
	{
		eval("document.getElementById('chan_"+properties[i]+"').innerHTML = ''");
		curProp = eval("RSS."+properties[i]);
		if (curProp != null)
			eval("document.getElementById('chan_"+properties[i]+"').innerHTML = curProp");
	}
	*/

	//show the image
	document.getElementById("chan_image_link").innerHTML = "";
	if (RSS.image)
	{
	if (RSS.image.src != null)
	{
		document.getElementById("chan_image_link").href = RSS.image.link;
		document.getElementById("chan_image_link").innerHTML = imageTag
			+" alt='"+RSS.image.description
			+"' width='"+RSS.image.width
			+"' height='"+RSS.image.height
			+"' src='"+RSS.image.url
			+"' "+"/>";
	}
	}

	//populate the items
	document.getElementById("chan_items").innerHTML = "";
	for (var i=0; i<RSS.items.length && i<maxitems; i++)
	{
		item_html = startItemTag;
//	item_html += (RSS.items[i].title == null) ? "" : startTitle + RSS.items[i].title + endTag;
//	item_html += (RSS.items[i].link == null) ? "" : startLink + RSS.items[i].link + endTag;
		item_html += (RSS.items[i].link == null) ? "" : openLink + RSS.items[i].link + closeLink + RSS.items[i].title + endLink;
		item_html += (RSS.items[i].description == null) ? "" : startDescription + RSS.items[i].description + endTag;
		item_html += endTag;
		document.getElementById("chan_items").innerHTML += item_html;
	}

	//we're done
	//document.getElementById("chan").style.visibility = "visible";
	return true;
}


//object containing the parsed RSS 2.0 channel

function RSS2Channel(rssxml)
{
	//required
	this.title;
	this.link;
	this.description;

	//array of RSS2Item objects
	this.items = new Array();

	//optional vars
	this.language;
	this.copyright;
	this.managingEditor;
	this.webMaster;
	this.pubDate;
	this.lastBuildDate;
	this.generator;
	this.docs;
	this.ttl;
	this.rating;

	//optional objects
	this.category;
	this.image;

//  alert('count of channels in feed: ' + rssxml.getElementsByTagName("channel").length	+ '\n' + 'count of items in feed: ' + rssxml.getElementsByTagName("item").length);
//  alert(print_r(rssxml));
  
//	var chanElement = rssxml.getElementsByTagName("channel")[0];
//	var itemElements = rssxml.getElementsByTagName("item");

//  alert('Info: <rss> element count: '+rssxml.getElementsByTagName("rss").length);
	if (rssxml.getElementsByTagName("channel").length == 0)
	{
		alert('Error: no <channel> found in RSS data');
	}
	else
	{
		var chanElement = rssxml.getElementsByTagName("channel")[0];
		var itemElements = rssxml.getElementsByTagName("item");
		
		for (var i=0; i<itemElements.length; i++)
		{
			Item = new RSS2Item(itemElements[i]);
			this.items.push(Item);
			//chanElement.removeChild(itemElements[i]);
		}

		var properties = new Array("title", "link", "description", "language", "copyright", "managingEditor", "webMaster", "pubDate", "lastBuildDate", "generator", "docs", "ttl", "rating");
		var tmpElement = null;
		for (var i=0; i<properties.length; i++)
		{
			tmpElement = chanElement.getElementsByTagName(properties[i])[0];
			if (tmpElement!= null)
				eval("this."+properties[i]+"=tmpElement.childNodes[0].nodeValue");
		}

		this.category = new RSS2Category(chanElement.getElementsByTagName("category")[0]);
		this.image = new RSS2Image(chanElement.getElementsByTagName("image")[0]);
	}
}



//processes the received rss xml

function processRSS(rssxml,maxitems)
{
	RSS = new RSS2Channel(rssxml);
	showRSS(RSS,maxitems);
}



//uses xmlhttpreq to get the raw rss xml

function getRSS(rssurl,maxitems)
{
	//call the right constructor for the browser being used
	if (window.ActiveXObject)
		xhr = new ActiveXObject("Microsoft.XMLHTTP");
	else if (window.XMLHttpRequest)
		xhr = new XMLHttpRequest();
	else
		alert("XMLHttpRequest not supported in your browser");

	//prepare the xmlhttprequest object
//xhr.open("GET",document.rssform.rssurl.value,true);
//alert("Opening RSS Feed from: " + rssurl);
	xhr.open("GET",rssurl,true);
	xhr.setRequestHeader("Cache-Control", "no-cache");
	xhr.setRequestHeader("Pragma", "no-cache");
	xhr.onreadystatechange = function() 
	{
		if (xhr.readyState == 4)
		{
			if (xhr.status == 200)
			{
//				if (xhr.responseText != null)
				if (xhr.responseXML != null)
				{
//					alert("Received RSS Feed from server: " + xhr.responseText);
//					alert("Received RSS Feed from server: " + xhr.responseXML.xml); // IE only
//					xhr.responseXML.loadXML(xhr.responseText);
					processRSS(xhr.responseXML,maxitems);
				}
				else
				{
					alert("Error: failed to receive RSS data from the server - file not found.");
					return false;
				}
			}
			else
				alert("Error code " + xhr.status + " received: " + xhr.statusText);
		}
	}
	//send the request
	xhr.send(null);
}


var xhr;



/*
* Function to print an associative array/object/hash.
* @param Object a The collection to be printed
* @param String dTab This is used for indentation. Its recommended NOT to pass this variable in the function call.
* @return String ret The string representation of the collection.
* @author Kapil Chhabra
* @blog http://my-experiments-with-it.blogspot.com/
*/

print_r = function(a, dTab) {
//initiate the return variable
var ret = "";

//the depth tabbing variable helps in indentation
if(!dTab) dTab = "\t";

//If the input variable is a collection object then iterate
if(typeof(a) == 'object'){

//foreach implementation in javascript
for(var sub in a) {
var val = a[sub];
ret += "'" + sub + "' =>";

//incase the value obtained is again a collection
if(typeof(val) == 'object') {

//drill it down by calling the print_r function recurrsively
ret += "\n" + dTab + "[" + print_r(val, dTab + "\t") + "]\n" + (dTab.substring(0, (dTab.length-1)));
} else {
ret += " \"" + val + "\"";
}
}
} else {
//Not a collection
ret = "'" + a + "' is of type '" + typeof(a) + "', not array/object.";
}
return ret;
}