<?php

// static class which provides extended Session functionality
// in particular, it creates an entire directory for each session, and allows arbitrary file storage in it
// this directory will automatically be deleted on session close

// test for whether a file exists in their session dir
function exists( $filename )
{
	return file_exists( Session::getDir() . $filename );
}

class Session
{
	static $SUBDIR = _SESSION_SUBDIR_; // subdir off of main session path
	static $DATAFILE = 'sessiondata'; // filename for session data
	
	
	static function setSubDir( $dir )
	{
		self::$SUBDIR = $dir;
	}
	
	static function setDataFile( $filename )
	{
		self::$DATAFILE = $filename;
	}
	
	static function getBaseDir()
	{
		global $sess_save_path;
		return "$sess_save_path/" . self::$SUBDIR;
	}
	
	static function getDir( $id=false )
	{
		global $sess_save_path;
		if( !$id ) $id = session_id();
		return "$sess_save_path/" . self::$SUBDIR . "sess_$id/";
	}
	
	// delete all "thumb-*.jpg" from session dir
	static function clearThumbnails()
	{
		$files = glob( Session::getDir() . 'thumb-*.' . _THUMB_FORMAT_ );
		foreach( $files as $file )
			unlink( $file );
			
		unlink( Session::getDir() . 'diagram.jpg' );
	}
	
	static function getDataFile( $id=false )
	{
		if( !$id ) $id = session_id();
		return Session::getDir( $id ) . self::$DATAFILE;
	}

	// initialize a session (save some variables)
	static function open($save_path, $session_name)
	{
		global $sess_save_path, $sess_session_name;
		$sess_save_path = $save_path;
		$sess_session_name = $session_name;
		return(true);
	}
	
	// executed on shutdown of a session (at end of every page request served)
	static function close()
	{
		return(true);
	}
	
	// returns stored session data
	static function read($id)
	{
		$sess_file = Session::getDataFile($id);
		if( file_exists( $sess_file) && filesize( $sess_file ) > 0 && $fp = @fopen($sess_file, "r") )
		{
			$sess_data = fread($fp, filesize($sess_file));
			return($sess_data);
		}
		else
			return(""); // Must return "" here.
	}
	
	// writes session data
	static function write($id, $sess_data)
	{
		$dir = Session::getDir( $id );
        
		if( !file_exists( $dir ) )
		{
			if( mkdir( $dir, 0775, true ) )
			{
				trigger_error( 'Created new session folder for ' . $id . ', from: ' . $_SERVER['PHP_SELF'] );
				if( !chmod( $dir, 0775 ) )
					trigger_error( 'Unable to set permissions on new session folder ' . $dir );
			}
			else
				trigger_error( 'Unable to create new session folder for ' . $id . ', from: ' . $_SERVER['PHP_SELF'] );
		}
	
		$sess_file = Session::getDataFile( $id );
		if ($fp = fopen($sess_file, 'w'))
		{
			return(fwrite($fp, $sess_data));
		}
		else
		{
			if( file_exists( $sess_file ) )
			{
				if( chmod( $sess_file, 0775 ) )
					trigger_error( 'Error writing session file, fixed permissions ' . $sess_file );
				else
					trigger_error( 'Error writing session file, unable to fix permissions ' . $dir );
			}
			else
				trigger_error( 'Unable to create session file ' . $sess_file );
				
			return false;
		}
	
	}
	
	// called for session_destroy()
	static function destroy($id)
	{
		$dir = self::getDir($id);
		$files = scandir( $dir );
		foreach( $files as $file )
			unlink( $file );
			
		return rmdir( $dir );
		
		
/*		
		$sess_file = Session::getDataFile($id);
		echo "destroy[$sess_file]\n";
		return(@unlink($sess_file));
*/
	}
	
	// garbage collection routine (called periodically, based on a set probability)
	static function gc($maxlifetime)
	{
		$dirs = glob( self::getBaseDir() . '*' );
		$del = 0;
		for( $i = count( $dirs ) - 1; $i >= 0; $i-- )
		{
			if( ( time() - filemtime( $dirs[$i] . '/' . self::$DATAFILE ) ) / 60 > 60 )
			{
				// older than 1 hour, delete
				$files = glob( $dirs[$i] . '/*' );
				for( $j = count( $files ) - 1; $j >= 0; $j-- )
					unlink( $files[$j] );
				rmdir( $dirs[$i] );
				$del++;
			}
		}
		trigger_error( 'Session GC called.  Total sessions: ' . count( $dirs ) . ', Deleted: ' . $del );
		return true;
	}
}


// initialize class and session


// need to use this weird array style to use static methods (see bottom comment on PHP docs for session_set_save_handler)

ini_set( 'session.gc_probability', 10 );

session_set_save_handler(
  array("Session", "open"),
  array("Session", "close"),
  array("Session", "read"),
  array("Session", "write"),
  array("Session", "destroy"),
  array("Session", "gc")
); 


session_start();
?>