Bug 1698699: Rewrite path to PDF in HTML export

This patch rewrites the path to the html export version of the PDF file

behatnotneeded

Change-Id: I8d534af41258d219046e5f3586bf904777242cb9
Signed-off-by: Robert Lyon <robertl@catalyst.net.nz>
(cherry picked from commit d094f841)
(cherry picked from commit 9b29d17e)
(cherry picked from commit bd2c77df)

htdocs/export/html/lib.php

@@ -731,6 +731,13 @@ class HtmlExportOutputFilter {
             $html
         );
 
+        // Links to pdf block files
+        $html = preg_replace_callback(
+            '#(?<=[\'"])(' . $wwwroot . ')?/?artefact/file/blocktype/pdf/viewer\.php\?.*?file=(\d+)(?:&amp;|&|%26).*?(?=[\'"])#',
+            array($this, 'replace_pdf_link'),
+            $html
+        );
+
         // Thumbnails
         require_once('file.php');
         $html = preg_replace_callback(
@@ -827,6 +834,28 @@ class HtmlExportOutputFilter {
         return $this->get_export_path_for_file($artefact, $options);
     }
 
+    /**
+     * Callback to replace links to artefact/file/blocktype/pdf/viewer.php to point to the
+     * correct file in the HTML export
+     */
+    private function replace_pdf_link($matches) {
+        $artefactid = $matches[2];
+        try {
+            $artefact = artefact_instance_from_id($artefactid);
+        }
+        catch (ArtefactNotFoundException $e) {
+            return '';
+        }
+
+        // If artefact type not something that would be served by download.php,
+        // replace link with nothing
+        if ($artefact->get_plugin_name() != 'file') {
+            return '';
+        }
+
+        return $this->get_export_path_for_file($artefact, array());
+    }
+
     /**
      * Callback to replace links to thumb.php to point to the correct file in
      * the HTML export