public function export()
    {
        $export = $_GET['export'];

        $self  = new ReportController;
        $self->export = $export;
        if($export === 'xls')
        {
            $self->generate_report(false);
            $self->generate_xls();
            exit;
        }
        else if($export === 'pdf')
        {
            include( plugin_dir_path ( __FILE__ ) . implode(DIRECTORY_SEPARATOR, array('..', 'lib', 'MPDF57', 'mpdf.php')) );
            ob_start();
            $self->generate_report();
            $html = ob_get_contents();
            ob_end_clean();

            $mpdf=new \mPDF();
            $mpdf->useOnlyCoreFonts = true;
            $mpdf->WriteHTML($html);
            $mpdf->Output();
            exit;
        }
        else if($export === 'print')
        {
            $self->generate_report();
            exit;
        }
        
    }