<?php
/**
* PAjFF session handling
* 
* <p>This part handles sessions. It creates new ones or recreates old ones.
* A "garbage collector" is included to clear unused main sessions as they are
* the only ones that can't be closed. :)</p>
* 
* {@link http://sourceforge.net/projects/pajff Project home}
* 
* @package PAjFF
* @license http://www.gnu.org/copyleft/gpl.html GNU/GPL
* @author Atanas Markov hide@address.com
* @version 0.0.2
* @copyright 2006 by Atanas Markov
*
* @subpackage pajff_session
**/

include_once('pajff_common.php');

/**
 * Does an event with this id exist. 
 * Useful when the user has pressed a close button many times. :)
 *
 * @param sting $id event id
 * 
 */
function pajffSessionExists($id){
    if ($id) {
            global $pajffdefaultdatabase;
			$pajffdefaultdatabase->setQuery( "SELECT * "
			. "\nFROM pajff_ses"
			. "\nWHERE id='$id'" );
			$tmplist = $pajffdefaultdatabase->loadObjectList();
			if ($tmplist){
				return true; //event found
			} else {
				return false;
			}   
    } else {
        return false;
    }
}

/**
 * Session class
 *
 * @package PAjFF
 * @subpackage pajff_session
 */
class pajff_session{
    /**
     * Database to store sessions in
     * Still Joomla-aware
     *
     * @var database
     */
	protected $database;
	/**
	 * Parrent session ID
	 *
	 * @var string
	 */
	protected $parentsession;
	/**
	 * Session ID
	 *
	 * @var string
	 */
	protected $sessionid;
	/**
	 * A string to represent last session activity time. Used in the garbage
	 * collector.
	 *
	 * @var string
	 */
	protected $lastactivity;

	/**
	 * Gabage collector. It erases unused sessions older than 3 hrs
	 *
	 */
	protected function garbageCollect(){
		//delete old sessions. maybe older than 3-4 hours that haven't been deleted by the program
		$oldtime = time() - (3 * 60 * 60); //3 hrs ago

		$this->database->setQuery( "SELECT * "
		. "\nFROM pajff_ses"
		. "\nWHERE lastactivity < $oldtime" );
		$tmplist = $this->database->loadObjectList();
		if ($tmplist){
			foreach ($tmplist as $tmpses) {
				$this->database->setQuery( "delete from pajff_ses WHERE id='$tmpses->id'" );
				if (!$this->database->query()) {
				}
				$this->database->setQuery( "delete from pajff_sesvars WHERE sesid='$tmpses->id'" );
				if (!$this->database->query()) {
				}
			}
		}
	}

	/**
	 * Loads a session from database
	 *
	 * @param string $id
	 */
	public function loadSession($id){
		if ($id) {
			//An old session is to be loaded
			$this->database->setQuery( "SELECT * "
			. "\nFROM pajff_ses"
			. "\nWHERE id='$id'" );
			$tmplist = $this->database->loadObjectList();
			if ($tmplist){
				$tmpses = $tmplist[0];
			} else {
				$tmpses = new stdClass();
			}

			$this->sessionid = $tmpses->id;
			$this->parentsession= $tmpses->parentid;

			if ($tmpses->id) {
				//load variables from database into session
				$this->database->setQuery( "SELECT varname, varvalue "
				. "\nFROM pajff_sesvars"
				. "\nWHERE sesid='$id'" );
				$tmplist = $this->database->loadObjectList();
				foreach ($tmplist as $tmpvar) {
					$key= $tmpvar->varname;
					$value= $tmpvar->varvalue;
					$this->$key = unserialize(base64_decode($value));
				}
			}
		}
	}

	/**
	 * Clear a session from database
	 *
	 * @param string $id
	 */
	public function clearSession($id=null){
		if ($id) {
			$this->database->setQuery( "delete from pajff_ses WHERE id='$id'" );
			if (!$this->database->query()) {
			}

			$this->database->setQuery( "delete from pajff_sesvars WHERE sesid='$id'" );
			if (!$this->database->query()) {
			}
		} else {
			$this->database->setQuery( "delete from pajff_ses WHERE id='$this->sessionid'" );
			if (!$this->database->query()) {
			}

			$this->database->setQuery( "delete from pajff_sesvars WHERE sesid='$this->sessionid'" );
			if (!$this->database->query()) {
			}
		}
	}

	/**
	 * Save a session into database
	 *
	 */
	public function saveSession(){
		$this->clearSession();

		$this->database->setQuery( "insert into pajff_ses ".
		"\n(id, parentid, lastactivity)".
		"\nvalues ('$this->sessionid','$this->parentsession','$this->lastactivity')" );
		if (!$this->database->query()) {
			//error handler to be placed here
		}

		$valarr = get_object_vars($this);
		foreach ($valarr as $key => $value) {
			if ($key!='database'&&$key!='sessionform') {
				//do not save the database object itself :)
				$this->database->setQuery( "insert into pajff_sesvars ".
				"\n(sesid, varname, varvalue)".
				"\nvalues ('$this->sessionid','$key','".base64_encode(serialize($value))."')" );
				if (!$this->database->query()) {
					//error handler to be placed here
					print "err";
					print_r($this->database);
				}
			}
		}
	}

	/**
	 * Create a new session object. It may be a new session or an old one
	 *
	 * @param pajff_session $parentsession
	 * @param database $database
	 * @param string $id
	 *
	 * Recreate an old session using default database
	 * <code>
	 * $session= new pajff_session(null,null,'123');
	 * </code>
	 * Create a child session using default database
	 * <code>
	 * $session= new pajff_session($session,null);
	 * </code>
	 */
	public function __construct($parentsession=null, $database=null, $id=null) {
		if ($database){
			$this->database = $database;
		} else {
			global $pajffdefaultdatabase;
			$this->database = $pajffdefaultdatabase;
		}
		
		global $pajffcharset;
        if ($pajffcharset) {
            $this->database->setQuery( "set names '$pajffcharset'" );
            $this->database->query();
        }

		$this->sessionid = null;
		if (is_a($parentsession, 'pajff_session')) {
			$this->parentsession = $parentsession->sessionID();
		} else {
			$this->parentsession = $parentsession;
		}
		if ($id) {
			//load an old session
			$this->loadSession($id);
		}

		if (!$this->sessionid) {
			//new session id
			//Session id is a random number + microtime
			$this->sessionid = pajff_microtime_fmt().mt_rand();
		}

		$this->lastactivity = time();

		$this->garbageCollect();
	}

	/**
	 * If anything to be done on destruction. '
	 * Not used
	 *
	 */
	public function __destruct() {
		//Not implemented yet. Must decide whether to save the session and so on :(
	}

	/**
	 * A method to return session ID
	 *
	 * @return string
	 */
	public function sessionID(){
		//get the session id
		return $this->sessionid;
	}

	/**
	 * A method to return parrent session ID
	 *
	 * @return string
	 */
	public function parentID(){
		return $this->parentsession;
	}
}

//print "pajff_session";

?>