Automatically get latest download link from Sparkle in PHP

<?php
 
// We're looking for the latest link link this:
// 			<pubDate>Thu, 14 Oct 2010 10:34:03 +0100</pubDate>
//			<enclosure url="http://downloads.whatever.com/MyDownload.dmg" sparkle:version="1.0.0.5"
 
class AppCastXMLParser
{
   var $tag_name;
   var $tag_data;
   var $tag_prev_name;
   var $tag_parent_name;
   var $latest_date;
   var $use_next_url;
   var $download_url;
   function AppCastXMLParser ()
   {
	   $tag_name = NULL;
	   $tag_data = array ();
	   $tag_prev_name = NULL;
	   $tag_parent_name = NULL;
 
	   $latest_date = NULL;
	   $use_next_url = true;
	   $download_url = NULL;
   }
   function startElement ($parser, $name, $attrs)
   {
	  if ($this->tag_name != NULL)
	  {
		 $this->tag_parent_name = $this->tag_name;
	  }
	  $this->tag_name = $name;
 
	  if ($name == "enclosure" && $this->use_next_url)
	  {
	  	$this->download_url = $attrs['url'];
	  	$this->use_next_url = false;
	  }
 
   }
   function endElement ($parser, $name)
   {
	  if ($this->tag_name == NULL)
	  {
		 $this->tag_parent_name = NULL;
	  }
	  $this->tag_name = NULL;
	  $this->tag_prev_name = NULL;
   }
   function characterData ($parser, $data)
   {
	  if ($this->tag_name == $this->tag_prev_name)
	  {
		 $data = $this->tag_data[$this->tag_name] . $data;
	  }
	  $this->tag_data[$this->tag_name] = $data;
	  if ($this->tag_parent_name != NULL)
	  {
		 $this->tag_data[$this->tag_parent_name . "." . $this->tag_name] = $data;
	  }
	  $this->tag_prev_name = $this->tag_name;
 
	  if ($this->tag_name == "pubDate")
	  {
		if ($thisdate = strtotime($this->tag_data[$this->tag_name]))
		{
			if ($this->latest_date == NULL || $this->latest_date < $thisdate)
			{
				$this->use_next_url = true;
				$this->latest_date = $thisdate;
			}
		}
	  }
 
   }
   function parse ($data)
   {
	  $xml_parser = xml_parser_create ();
	  xml_set_object ($xml_parser, $this);
	  xml_parser_set_option ($xml_parser, XML_OPTION_CASE_FOLDING, false);
	  xml_set_element_handler ($xml_parser, "startElement", "endElement");
	  xml_set_character_data_handler ($xml_parser, "characterData");
	  $success = xml_parse ($xml_parser, $data, true);
	  if (!$success)
	  {
		  $this->tag_data['error'] =  sprintf ("XML error: %s at line %d", xml_error_string(xml_get_error_code ($xml_parser)), xml_get_current_line_number ($xml_parser));
	  }
	  xml_parser_free ($xml_parser);
	  return ($success);
   }
   function getElement ($tag)
   {
	  return ($this->tag_data[$tag]);
   }
}
 
function getLatestDownloadURL()
{
 
	$appcastparser = new AppCastXMLParser ();
 
	$appcast = $contents=file_get_contents("http://www.myapp.com/path/to/SparkleAppcast.xml");
 
	if ($appcastparser->parse ($appcast))
	{
		return $appcastparser->download_url;
	}
	else
	{
		return NULL;
	}
}
 
$url = getLatestDownloadURL();
 
if ($url)
{
	echo "<p>Thank you for downloading MyRandomApp, your download should start automatically.</p>";
	echo "<p>If your download doesn't start within 5 seconds, you can use this <a href=\"$url\">direct link</a>.</p>\n";
 
	echo <<<EXCERPT
	<script type="text/javascript">
	<!--
	function godownload()
	{
		window.location = "$url"
	}
	setTimeout("godownload()", 2000)
	//-->
	</script>
EXCERPT;
 
}
 
?>