Allow hide the certificate export link to students - refs BT#9237

Conflicts:
	main/gradebook/lib/be/category.class.php

certificates/index.php

@@ -18,6 +18,13 @@ $certificate = new Certificate($_GET['id']);
 
 switch ($action) {
     case 'export':
+        if (
+            api_is_student() &&
+            api_get_configuration_value('hide_certificate_export_link_students')
+        ) {
+            api_not_allowed(true);
+        }
+
         $certificate->generate(array('hide_print_button' => true));
 
         if ($certificate->html_file_is_generated()) {

main/gradebook/lib/be/category.class.php

@@ -1859,6 +1859,13 @@ class Category implements GradebookItem
                     "$url&action=export"
                 );
 
+                if (
+                    api_is_student() &&
+                    api_get_configuration_value('hide_certificate_export_link_students')
+                ) {
+                    $exportToPDF = null;
+                }
+
                 $html = array(
                     'certificate_link' => $certificates,
                     'pdf_link' => $exportToPDF

main/install/configuration.dist.php

@@ -326,4 +326,5 @@ $_configuration['system_stable']     = NEW_VERSION_STABLE;
 //$_configuration['limit_session_admin_role'] = false;
 // Show session description
 //$_configuration['show_session_description'] = false;
-
+// Hide only for students the link to export certificates to PDF 
+//$_configuration['hide_certificate_export_link_students'] = false;