plugin.php

<?php

class Sample {
	public function register_invoice_endpoint() {
		register_rest_route( 'prefix/v1/endoint', '/invoice/(?P<id>\d+)', array(
			'methods'             => 'GET',
			'callback'            => array( $this, 'get_invoice' ),
			'permission_callback' => array( $this, 'get_items_permissions_check' )
		) );
	}
	
	public function get_items_permissions_check() {
		
		if ( ! current_user_can( 'manage_options' ) ) {
			return new WP_Error( 'rest_forbidden_context', __( 'Sorry, you are not allowed to download invoices' ), array( 'status' => rest_authorization_required_code() ) );
		}
		
		return true;
	}
	
	public function get_invoice( $request ) {
		
		$params        = $request->get_params();
		$document_type = 'packing-slip'; // can be invoice, proforma, credit-note, packing-slip..
		
		$id = ( isset( $params['id'] ) && ! empty( $params['id'] ) ? (int) $params['id'] : false );
		
		if ( ! $id ) {
			return array( 'status' => 400, 'message' => __( 'The ID provided is invalid.', 'stroopwafels-templates' ) );
		}
		
		$order = wc_get_order( $id );
		
		if ( is_wp_error( $order ) ) {
			return array( 'status' => 400, 'message' => __( 'The order ID does not exist.', 'stroopwafels-templates' ) );
		}
		
		// if we got here, we're safe to go!
		try {
			$document = wcpdf_get_document( $document_type, $order, true );
			
			if ( $document ) {
				$output_format = WPO_WCPDF()->settings->get_output_format( $document_type );
				// allow URL override
				if ( isset( $_GET['output'] ) && in_array( $_GET['output'], array( 'html', 'pdf' ) ) ) {
					$output_format = $_GET['output'];
				}
				switch ( $output_format ) {
					case 'html':
						add_filter( 'wpo_wcpdf_use_path', '__return_false' );
						$document->output_html();
						break;
					case 'pdf':
					default:
						if ( has_action( 'wpo_wcpdf_created_manually' ) ) {
							do_action( 'wpo_wcpdf_created_manually', $document->get_pdf(), $document->get_filename() );
						}
						$output_mode = WPO_WCPDF()->settings->get_output_mode( $document_type );
						$document->output_pdf( $output_mode );
						break;
				}
			} else {
				wp_die( sprintf( __( "Document of type '%s' for the selected order(s) could not be generated", 'woocommerce-pdf-invoices-packing-slips' ), $document_type ) );
			}
		} catch ( \Dompdf\Exception $e ) {
			$message = 'DOMPDF Exception: ' . $e->getMessage();
			wcpdf_log_error( $message, 'critical', $e );
			wcpdf_output_error( $message, 'critical', $e );
		} catch ( \Exception $e ) {
			$message = 'Exception: ' . $e->getMessage();
			wcpdf_log_error( $message, 'critical', $e );
			wcpdf_output_error( $message, 'critical', $e );
		} catch ( \Error $e ) {
			$message = 'Fatal error: ' . $e->getMessage();
			wcpdf_log_error( $message, 'critical', $e );
			wcpdf_output_error( $message, 'critical', $e );
		}
		exit;
	}
}