Extract file name from URI

$req = $_SERVER['REQUEST_URI'];

function parse_request_uri($req){
 $filename = strrchr($req, '/');

 if('/' == $filename[0]){
  $filename = substr($filename, 1);
 }
 
 if(($pos = strpos($filename, '?'))!== false){
  $filename = substr($filename, 0, $pos);
 }
 
 $parts = pathinfo($filename);
 return urldecode(strtolower($parts['filename']));
}