From e85807e298d38432b1550d4afa7e94249a71b3a4 Mon Sep 17 00:00:00 2001
From: Mark Nelson <markn@moodle.com>
Date: Fri, 13 Mar 2015 20:53:11 -0700
Subject: [PATCH] Fixed sequence values when deleting an element

---
 edit.php     |  7 +------
 locallib.php | 28 ++++++++++++++++++++++++++++
 2 files changed, 29 insertions(+), 6 deletions(-)

diff --git a/edit.php b/edit.php
index 44faf19..98de3b8 100644
--- a/edit.php
+++ b/edit.php
@@ -118,12 +118,7 @@ if ((!empty($moveup)) || (!empty($movedown))) {
     }
 } else if (!empty($deleteelement)) { // Check if we are deleting an element.
     if (!empty($confirm)) { // Check they have confirmed the deletion.
-        // Ensure element exists and delete it.
-        $element = $DB->get_record('customcert_elements', array('id' => $deleteelement), '*', MUST_EXIST);
-        // Get an instance of the element class.
-        if ($e = customcert_get_element_instance($element)) {
-            $e->delete_element();
-        }
+        customcert_delete_element($deleteelement);
     } else {
         // Set deletion flag to true.
         $deleting = true;
diff --git a/locallib.php b/locallib.php
index 324c186..d9f0675 100644
--- a/locallib.php
+++ b/locallib.php
@@ -274,6 +274,34 @@ function customcert_add_page($data) {
     $DB->insert_record('customcert_pages', $page);
 }
 
+/**
+ * Handles deleting an element from the customcert.
+ *
+ * @param int $elementid the customcert page
+ */
+function customcert_delete_element($elementid) {
+    global $DB;
+
+    // Ensure element exists and delete it.
+    $element = $DB->get_record('customcert_elements', array('id' => $elementid), '*', MUST_EXIST);
+
+    // Get an instance of the element class.
+    if ($e = customcert_get_element_instance($element)) {
+        $e->delete_element();
+    } else {
+        // The plugin files are missing, so just remove the entry from the DB.
+        $DB->delete_records('customcert_elements', array('id' => $elementid));
+    }
+
+    // Now we want to decrease the sequence numbers of the elements
+    // that are greater than the element we deleted.
+    $sql = "UPDATE {customcert_elements}
+               SET sequence = sequence - 1
+             WHERE pageid = :pageid
+               AND sequence > :sequence";
+    $DB->execute($sql, array('pageid' => $element->pageid, 'sequence' => $element->sequence));
+}
+
 /**
  * Handles deleting a page from the customcert.
  *