From 8ee47dfc41c3f22afd9f30d6b6fda465b0f27b11 Mon Sep 17 00:00:00 2001
From: Kevin Pham <keevan.pham@gmail.com>
Date: Thu, 19 Oct 2023 16:38:38 +1100
Subject: [PATCH] fix: restore issue for an instance with empty configdata

- Add some additional checks to optimise route
- The syncing of slides from old to new will only happen if there are slides and data to facilitate it.

Resolves #50
---
 backup/moodle2/restore_carousel_stepslib.php | 51 +++++++++++++++-----
 1 file changed, 38 insertions(+), 13 deletions(-)

diff --git a/backup/moodle2/restore_carousel_stepslib.php b/backup/moodle2/restore_carousel_stepslib.php
index e247e6c..d8a03c5 100644
--- a/backup/moodle2/restore_carousel_stepslib.php
+++ b/backup/moodle2/restore_carousel_stepslib.php
@@ -78,21 +78,13 @@ public function process_block($data) {
         // Save the mapping to reuse in the after_execute step.
         $this->slidemapping = $slidesarr;
 
-        // Adjust the serialized configdata->order to the created/mapped feeds.
-        $configdata = $DB->get_field('block_instances', 'configdata', ['id' => $this->task->get_blockid()]);
-        $config = unserialize(base64_decode($configdata));
-
-        $oldorder = explode(',', $config->order);
-        $neworder = [];
-        foreach ($oldorder as $oldid) {
-            $neworder[] = $slidesarr[$oldid];
+        // If no slides are present (e.g. user has not configured the carousel), return early.
+        if (empty($slidesarr)) {
+            return;
         }
 
-        // Set csv of new slide order.
-        $config->order = implode(',', $neworder);
-        $configdata = base64_encode(serialize($config));
-
-        $DB->set_field('block_instances', 'configdata', $configdata, ['id' => $this->task->get_blockid()]);
+        // Syncs the order for the carousel block.
+        $this->update_slide_references($slidesarr);
     }
 
     /**
@@ -132,4 +124,37 @@ protected function after_execute() {
 
         $files->close();
     }
+
+    /**
+     * Adjust the serialized configdata->order to the created/mapped feeds.
+     *
+     * @param array $slidesarr
+     */
+    private function update_slide_references(array $slidesarr) {
+        global $DB;
+
+        $configdata = $DB->get_field('block_instances', 'configdata', ['id' => $this->task->get_blockid()]);
+        $config = unserialize(base64_decode($configdata));
+        if ($config === false) {
+            return;
+        }
+
+        // If there are no slides or the order is not defined, there is nothing to update, return early.
+        if (empty($slidesarr) || !isset($config->order)) {
+            return;
+        }
+
+        // Update the slide references to the new slides (preserving original order).
+        $oldorder = explode(',', $config->order);
+        $neworder = [];
+        foreach ($oldorder as $oldid) {
+            $neworder[] = $slidesarr[$oldid];
+        }
+
+        // Set csv of new slide order.
+        $config->order = implode(',', $neworder);
+        $configdata = base64_encode(serialize($config));
+
+        $DB->set_field('block_instances', 'configdata', $configdata, ['id' => $this->task->get_blockid()]);
+    }
 }