Show the diff of element edited log entries on detail pages

src/Services/LogSystem/LogDataFormatter.php

@@ -50,7 +50,14 @@ class LogDataFormatter
     public function formatData($data, AbstractLogEntry $logEntry, string $fieldName): string
     {
         if (is_string($data)) {
-            return '"' . mb_strimwidth(htmlspecialchars($data), 0, self::STRING_MAX_LENGTH, ) . '"';
+            $tmp = '<span class="text-muted user-select-none">"</span>' . mb_strimwidth(htmlspecialchars($data), 0, self::STRING_MAX_LENGTH, ) . '<span class="text-muted user-select-none">"</span>';
+
+            //Show special characters and line breaks
+            $tmp = preg_replace('/\n/', '<span class="text-muted user-select-none">\\n</span><br>', $tmp);
+            $tmp = preg_replace('/\r/', '<span class="text-muted user-select-none">\\r</span>', $tmp);
+            $tmp = preg_replace('/\t/', '<span class="text-muted user-select-none">\\t</span>', $tmp);
+
+            return $tmp;
         }
 
         if (is_bool($data)) {

src/Services/LogSystem/LogDiffFormatter.php

@@ -0,0 +1,76 @@
+<?php
+/*
+ * This file is part of Part-DB (https://github.com/Part-DB/Part-DB-symfony).
+ *
+ *  Copyright (C) 2019 - 2023 Jan Böhmer (https://github.com/jbtronics)
+ *
+ *  This program is free software: you can redistribute it and/or modify
+ *  it under the terms of the GNU Affero General Public License as published
+ *  by the Free Software Foundation, either version 3 of the License, or
+ *  (at your option) any later version.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU Affero General Public License for more details.
+ *
+ *  You should have received a copy of the GNU Affero General Public License
+ *  along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+namespace App\Services\LogSystem;
+
+use Jfcherng\Diff\DiffHelper;
+
+class LogDiffFormatter
+{
+    /**
+     * Format the diff between the given data, depending on the type of the data.
+     * If the diff is not possible, an empty string is returned.
+     * @param $old_data
+     * @param $new_data
+     * @return string
+     */
+    public function formatDiff($old_data, $new_data): string
+    {
+        if (is_string($old_data) && is_string($new_data)) {
+            return $this->diffString($old_data, $new_data);
+        }
+
+        if (is_numeric($old_data) && is_numeric($new_data)) {
+            return $this->diffNumeric($old_data, $new_data);
+        }
+
+        return '';
+    }
+
+    private function diffString(string $old_data, string $new_data): string
+    {
+        return DiffHelper::calculate($old_data, $new_data, 'Combined',
+            [ //Diff options
+                'context' => 2,
+            ],
+            [ //Render options
+                'detailLevel' => 'char',
+                'showHeader' => false,
+            ]);
+    }
+
+    private function diffNumeric($old_data, $new_data): string
+    {
+        if ((!is_numeric($old_data)) || (!is_numeric($new_data))) {
+            throw new \InvalidArgumentException('The given data is not numeric.');
+        }
+
+        $difference = $new_data - $old_data;
+
+        //Positive difference
+        if ($difference > 0) {
+            return sprintf('<span class="text-success">+%s</span>', $difference);
+        } else if ($difference < 0) {
+            return sprintf('<span class="text-danger">%s</span>', $difference);
+        } else {
+            return sprintf('<span class="text-muted">%s</span>', $difference);
+        }
+    }
+}

src/Twig/LogExtension.php

@@ -21,20 +21,27 @@
 namespace App\Twig;
 
 use App\Services\LogSystem\LogDataFormatter;
+use App\Services\LogSystem\LogDiffFormatter;
 use Twig\Extension\AbstractExtension;
 use Twig\TwigFunction;
 
-class LogExtension extends AbstractExtension
+final class LogExtension extends AbstractExtension
 {
-    public function __construct(LogDataFormatter $logDataFormatter)
+
+    private LogDataFormatter $logDataFormatter;
+    private LogDiffFormatter $logDiffFormatter;
+
+    public function __construct(LogDataFormatter $logDataFormatter, LogDiffFormatter $logDiffFormatter)
     {
         $this->logDataFormatter = $logDataFormatter;
+        $this->logDiffFormatter = $logDiffFormatter;
     }
 
     public function getFunctions()
     {
         return [
-            new TwigFunction('format_log_data', [$this->logDataFormatter, 'formatData'], ['is_safe' => ['html']])
+            new TwigFunction('format_log_data', [$this->logDataFormatter, 'formatData'], ['is_safe' => ['html']]),
+            new TwigFunction('format_log_diff', [$this->logDiffFormatter, 'formatDiff'], ['is_safe' => ['html']]),
         ];
     }
 }