Problems with JEvents

<?php
/**
 * 
 * TODO add catids and limit etc properly - refer to cache arguments!!!
 *
 */
class sef_jevents {

	var $pos = 0;
	var $offset = 0;
	var $string="";
	var $sefstring="";
	
	function set($name,$forcecode=false){
		$leader=$forcecode?"$forcecode":"";
		if (eregi("&$name=",$this->string)) {
			$temp = split("&$name=", $this->string);
			$temp = split("&", $temp[1]);
			$this->sefstring .= $leader.$temp[0]."/";
			return $temp[0];
		}
		$this->sefstring .= $forcecode?($leader."/"):"";
		return "n/a";		
	}
	
	function get($name,$stripcode=false){
		if (isset($this->url_array[$this->pos+$this->offset]) && $this->url_array[$this->pos+$this->offset]!="") {
			// .../example/$var1/
			$var1 = $this->url_array[$this->pos+$this->offset];
			if ($stripcode){
				$var1=preg_replace("/$stripcode/","",$var1,1);
			}
			if (isset($var1) && strlen($var1)>0){
				$_GET[$name] = $var1;
				$_REQUEST[$name] = $var1;
				$this->QUERY_STRING .= "&$name=$var1";
			}
			else {
				$var1 = "n/a";
			}
		}
		else {
			$var1 = "n/a";
		}
		$this->offset++;
		return  $var1;		
	}
	
	/**
	* Creates the SEF advance URL out of the request
	* Input: $string, string, The request URL (index.php?option=com_example&Itemid=$Itemid)
	* Output: $sefstring, string, SEF advance URL ($var1/$var2/)
	**/
	function create ($string) {
		// $string == "index.php?option=com_example&Itemid=$Itemid&var1=$var1&var2=$var2"
		$this->sefstring = "";
		$this->string = $string;
		$task = $this->set("task","t");
		// add catids at the start with a forced leader
		$this->set("catids","c");
		
		switch ($task) {
			case "modify":
				$this->set("agid");
				break;
			case "n/a":
				return $this->sefstring;
				break;		
			case "view_cat":
				$this->set("year");
				$this->set("month");
				$this->set("day");
				$this->set("catid");
				$this->set("limit");
				$this->set("limitstart");
				break;
			case "view_year":
				$this->set("year");
				$this->set("month");
				$this->set("day");
				$this->set("limit");
				$this->set("limitstart");
				break;
/*				
			case 'publish' :
*/
/*
// from a form so not important
			case 'cancel':
			case 'search':
				$this->set("year");
				$this->set("month");
				$this->set("day");
				$this->set("keyword");				
				$this->set("limit");
				$this->set("limitstart");
				break;
*/
			case 'delete':
				$this->set("agid");
				$this->set("year");
				$this->set("month");
				$this->set("day");
				break;

			case 'view_detail':
				$this->set("agid");
				$this->set("year");
				$this->set("month");
				$this->set("day");
				$this->set("pop");
				break;

			case 'add':
			case 'admin':
			case 'view_search':
			case 'view_month':
			case 'view_week':
			case 'view_day':
			case 'view_last':
			default:
				$this->set("year");
				$this->set("month");
				$this->set("day");
				$this->set("pop"); // only for view_month
				break;
		}
		
		// $sefstring == "$var1/$var2/"
		return $this->sefstring;
	}

	/**
	* Reverts to the query string out of the SEF advance URL
	* Input:
	*    $url_array, array, The SEF advance URL split in arrays
	*    $pos, int, The position offset for virtual directories (first virtual directory, which is the component name, begins at $pos+1)
	* Output: $QUERY_STRING, string, query string (var1=$var1&var2=$var2)
	*    Note that this will be added to already defined first part (option=com_example&Itemid=$Itemid)
	**/
	function revert ($url_array, $pos) {
 		// Examine the SEF advance URL and extract the variables building the query string
		$this->QUERY_STRING = "";		
		$this->pos = $pos;
		$this->offset=2;
		$this->url_array = $url_array;
		
		$task = $this->get("task","t");		

		// catids always get a forced strip
		$this->get("catids","c");

		switch ($task) {
			case "n/a":				
				break;		
			case "modify":
				$this->get("agid");
				break;
			case "view_cat":
				$this->get("year");
				$this->get("month");
				$this->get("day");
				$this->get("catid");
				$this->get("limit");
				$this->get("limitstart");
				break;
			case "view_year":
				$this->get("year");
				$this->get("month");
				$this->get("day");
				$this->get("limit");
				$this->get("limitstart");
				break;
/*				
			case 'publish' :
*/
/*
// from a form so not important
			case 'cancel':
			case 'search':
				$this->get("year");
				$this->get("month");
				$this->get("day");
				$this->get("keyword");				
				$this->get("limit");
				$this->get("limitstart");
				break;
*/
			case 'delete':
				$this->get("agid");
				$this->get("year");
				$this->get("month");
				$this->get("day");
				break;
			case 'view_detail':
				$this->get("agid");
				$this->get("year");
				$this->get("month");
				$this->get("day");
				$this->get("pop");
				break;

			case 'add':
			case 'admin':
			case 'view_search':
			case 'view_week':
			case 'view_day':
			case 'view_last':
		    case 'view_month':
			default:
				$this->get("year");
				$this->get("month");
				$this->get("day");
				$this->get("pop"); // only for view_month
				break;
		}		
				
		return $this->QUERY_STRING;
	}

}
?>