pdf PLUGIN - Change file name

function _getPDFInvoice($orderIds = array()){

		$app = JFactory::getApplication();

		if(!class_exists('HTML2PDF')) include(dirname(__FILE__).DS.'attachinvoice'.DS.'html2pdf.class.php');

		$config =& hikashop_config();
		$class = hikashop_get('class.order');
		$currencyHelper = hikashop_get('class.currency');
		$fields = array();
		$null = null;
		$fieldsClass = hikashop_get('class.field');
		$fields['item'] = $fieldsClass->getFields('backend_listing',$null,'item');

		if(!empty($order->order_payment_id)){
			$pluginsPayment = hikashop_get('type.plugins');
			$pluginsPayment->type='payment';
		}
		if(!empty($order->order_shipping_id)){
			$pluginsShipping = hikashop_get('type.plugins');
			$pluginsShipping->type='shipping';
		}

		//This array stores all pdf pages...
		$pdfContent = array();

		foreach($orderIds as $orderId){
			$order = $class->loadFullOrder($orderId,true,false);
			$fields['order'] = $fieldsClass->getFields('backend',$order,'order');
			ob_start();
			if(file_exists(HIKASHOP_MEDIA.'plugins'.DS.'invoice.php')){
				$file = HIKASHOP_MEDIA.'plugins'.DS.'invoice.php';
			}else{
				$file = dirname(__FILE__).DS.'attachinvoice'.DS.'invoice.php';
			}
			require($file);
			$pdfContent[] = ob_get_clean();
		}

		$content = implode('<div style="page-break-before:always"></div>',$pdfContent);
		$content = hikashop_absoluteURL($content);

		//$html2pdf = new HTML2PDF('P', 'A4', 'en');
		$html2pdf = new HTML2PDF('P', 'A4', 'en',true, 'UTF-8');
		$font =	$this->params->get('font');
		if(!empty($font)){
			$html2pdf->setDefaultFont($font);
		}
		$html2pdf->pdf->SetDisplayMode('fullpage');
		$html2pdf->writeHTML($content);
		if(count($orderIds) == 1){
			if(empty( $order->order_invoice_number)) $order->order_invoice_number = $order->order_number;
			$fileName = 
			JText::_('INVOICE').(string)$order->order_invoice_number;
			}
		$html2pdf->Output($fileName.'.pdf','D');
		if(count($orderIds) == 1) $fileName.= '_'.reset($orderIds);
		$html2pdf->Output($fileName.'.pdf','D');

		exit;
	}