Folder download in zip format in php

<?php
class zip
{
   private $zip;
   public function __construct( $file_name, $zip_directory)
   {
        $this->zip = new ZipArchive();
        $this->path = dirname( __FILE__ ) . $zip_directory . $file_name . '.zip';
        $this->zip->open( $this->path, ZipArchive::CREATE );
    }
     
   /**
     * Get the absolute path to the zip file
     * @return string
     */
    public function get_zip_path()
    {
        return $this->path;
    }  
      
    /**
     * Add a directory to the zip
     * @param $directory
     */
    public function add_directory( $directory )
    {
        if( is_dir( $directory ) && $handle = opendir( $directory ) )
        {
            $this->zip->addEmptyDir( $directory );
            while( ( $file = readdir( $handle ) ) !== false )
            {
                if (!is_file($directory . '/' . $file))
                {
                    if (!in_array($file, array('.', '..')))
                    {
                        $this->add_directory($directory . '/' . $file );
                    }
                }
                else
                {
                    $this->add_file($directory . '/' . $file);                }
            }
        }
    }
  
    /**
     * Add a single file to the zip
     * @param string $path
     */
    public function add_file( $path )
    {
        $this->zip->addFile( $path, $path);
    }
  
    /**
     * Close the zip file
     */
    public function save()
    {
        $this->zip->close();
    }
}

$zip_name = 'zip_' . time();
$zip_directory = '/';
$zip = new zip( $zip_name, $zip_directory );
$zip->add_directory( 'uploadpdf' );
$zip->save();
$zip_path = $zip->get_zip_path();
header( "Pragma: public" );
header( "Expires: 0" );
header( "Cache-Control: must-revalidate, post-check=0, pre-check=0" );
header( "Cache-Control: public" );
header( "Content-Description: File Transfer" );
header( "Content-type: application/zip" );
header( "Content-Disposition: attachment; filename=\"" . $zip_name . "\"" );
header( "Content-Transfer-Encoding: binary" );
header( "Content-Length: " . filesize( $zip_path ) );
readfile( $zip_path );
?>