From 40544c9b5844ceb2de11fce196f379b412e348fa Mon Sep 17 00:00:00 2001
From: Frederic Massart <fred@moodle.com>
Date: Mon, 15 Sep 2014 18:54:49 +0800
Subject: [PATCH] MDL-46824 core_grades: Prevent user from using drop
 lowest/keep highest

Part of: MDL-46576
---
 grade/edit/tree/category_form.php | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/grade/edit/tree/category_form.php b/grade/edit/tree/category_form.php
index f352b788c70..78cdfe3f48d 100644
--- a/grade/edit/tree/category_form.php
+++ b/grade/edit/tree/category_form.php
@@ -331,6 +331,18 @@ class edit_category_form extends moodleform {
 
             }
 
+            // Prevent the user from using drop lowest/keep highest when the aggregation method cannot handle it.
+            if (!$grade_category->can_apply_limit_rules()) {
+                if ($mform->elementExists('keephigh')) {
+                    $mform->setConstant('keephigh', 0);
+                    $mform->hardFreeze('keephigh');
+                }
+                if ($mform->elementExists('droplow')) {
+                    $mform->setConstant('droplow', 0);
+                    $mform->hardFreeze('droplow');
+                }
+            }
+
             if ($grade_item->is_calculated()) {
                 // following elements are ignored when calculation formula used
                 if ($mform->elementExists('aggregation')) {