Add syntax highlighting to the source code form option

phpstan-baseline.neon

@@ -1872,12 +1872,6 @@ parameters:
 			count: 2
 			path: wcfsetup/install/files/lib/system/html/output/node/HtmlOutputNodeImg.class.php
 
-		-
-			message: '#^Construct empty\(\) is not allowed\. Use more strict comparison\.$#'
-			identifier: empty.notAllowed
-			count: 1
-			path: wcfsetup/install/files/lib/system/html/output/node/HtmlOutputNodePre.class.php
-
 		-
 			message: '#^Construct empty\(\) is not allowed\. Use more strict comparison\.$#'
 			identifier: empty.notAllowed

wcfsetup/install/files/lib/system/code/SourceCodeRenderer.class.php

@@ -0,0 +1,251 @@
+<?php
+
+namespace wcf\system\code;
+
+use wcf\system\bbcode\BBCodeHandler;
+use wcf\system\Regex;
+use wcf\system\WCF;
+
+/**
+ * Renders source code listings including syntax highlighting.
+ *
+ * @author      Marcel Werk
+ * @copyright   2001-2026 WoltLab GmbH
+ * @license     GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
+ * @since       6.3
+ */
+class SourceCodeRenderer
+{
+    /**
+     * aliases for highlighters that are not known by the client-side highlighter
+     * @var array<string, string>
+     */
+    private const HIGHLIGHTER_ALIASES = [
+        'js' => 'javascript',
+        'c++' => 'cpp',
+        'tex' => 'latex',
+        'shell' => 'bash',
+    ];
+
+    /**
+     * already used ids for line numbers to prevent duplicate ids in the output
+     * @var array<string, bool>
+     */
+    private static array $codeIDs = [];
+
+    /**
+     * Renders the given source code. If no highlighter is provided, the used
+     * language is guessed based on the content.
+     */
+    public function render(
+        string $content,
+        string $highlighter = '',
+        string $filename = '',
+        int $startLineNumber = 1,
+        string $codeIDPrefix = ''
+    ): string {
+        $content = $this->trimContent($content);
+
+        if ($startLineNumber < 1) {
+            $startLineNumber = 1;
+        }
+
+        $highlighter = $this->getHighlighter($content, $highlighter);
+
+        $meta = BBCodeHandler::getInstance()->getHighlighterMeta();
+        $title = WCF::getLanguage()->get('wcf.bbcode.code');
+        if (isset($meta[$highlighter])) {
+            $title = $meta[$highlighter]['title'];
+        } else {
+            $highlighter = '';
+        }
+
+        $lines = $this->splitLines($content);
+
+        return WCF::getTPL()->render('wcf', 'shared_codeMetaCode', [
+            'codeID' => $this->getCodeID($codeIDPrefix, $content),
+            'startLineNumber' => $startLineNumber,
+            'content' => $lines,
+            'language' => $highlighter,
+            'filename' => $filename,
+            'title' => $title,
+            'lines' => \count($lines),
+        ]);
+    }
+
+    /**
+     * Removes a leading and a trailing empty line from the given content.
+     */
+    public function trimContent(string $content): string
+    {
+        $content = \preg_replace('/^\s*\n/', '', $content);
+
+        return \preg_replace('/\n\s*$/', '', $content);
+    }
+
+    /**
+     * Returns the highlighter that should be used for the given content. The
+     * highlighter is guessed if no highlighter is provided.
+     */
+    public function getHighlighter(string $content, string $highlighter = ''): string
+    {
+        $highlighter = $this->normalizeHighlighter($highlighter);
+        if ($highlighter === '') {
+            $highlighter = $this->guessHighlighter($content);
+        }
+
+        return $highlighter;
+    }
+
+    /**
+     * Resolves known aliases of highlighter names.
+     */
+    public function normalizeHighlighter(string $highlighter): string
+    {
+        return self::HIGHLIGHTER_ALIASES[$highlighter] ?? $highlighter;
+    }
+
+    /**
+     * Splits the content into single lines while preserving the line breaks.
+     *
+     * @return string[]
+     */
+    public function splitLines(string $content): array
+    {
+        $lines = \explode("\n", $content);
+        $last = \array_pop($lines);
+        $lines = \array_map(static fn (string $line) => $line . "\n", $lines);
+        $lines[] = $last;
+
+        return $lines;
+    }
+
+    /**
+     * Returns a likely highlighter for the given content.
+     */
+    public function guessHighlighter(string $content): string
+    {
+        // PHP at the beginning is almost surely PHP.
+        if (\str_starts_with($content, '<?php')) {
+            return 'php';
+        }
+
+        if (
+            \str_starts_with($content, 'SELECT')
+            || \str_starts_with($content, 'UPDATE')
+            || \str_starts_with($content, 'INSERT')
+            || \str_starts_with($content, 'DELETE')
+        ) {
+            return 'sql';
+        }
+
+        if (\str_contains($content, 'import java.')) {
+            return 'java';
+        }
+
+        if (\str_contains($content, 'using System;')) {
+            return 'csharp';
+        }
+
+        if (
+            \str_contains($content, "---")
+            && \str_contains($content, "\n+++")
+        ) {
+            return 'diff';
+        }
+
+        if (\str_contains($content, "\n#include ")) {
+            return 'c';
+        }
+
+        if (\str_starts_with($content, '#!/usr/bin/perl')) {
+            return 'perl';
+        }
+
+        if (
+            \str_starts_with($content, '#!/usr/bin/python')
+            || \str_contains($content, 'def __init__(self')
+            || Regex::compile("from (\\S+) import (\\S+)")->match($content) !== 0
+        ) {
+            return 'python';
+        }
+
+        if (Regex::compile('^#!(/usr)?/bin/(ba|z)?sh')->match($content) !== 0) {
+            return 'bash';
+        }
+
+        if (
+            \str_starts_with($content, 'FROM')
+            && \str_contains($content, "RUN")
+        ) {
+            return 'docker';
+        }
+
+        if (
+            \stripos($content, "RewriteRule") !== false
+            || \stripos($content, "RewriteEngine On") !== false
+            || \stripos($content, "AuthUserFile") !== false
+        ) {
+            return 'apacheconf';
+        }
+
+        if (\str_contains($content, '\\documentclass')) {
+            return 'latex';
+        }
+
+        // PHP somewhere later might not necessarily be PHP, it could also be
+        // a .patch or a Dockerfile.
+        if (\str_contains($content, '<?php')) {
+            return 'php';
+        }
+
+        if (
+            \str_contains($content, '{/if}')
+            && (
+                \str_contains($content, '<div')
+                || \str_contains($content, '<span')
+            )
+        ) {
+            return 'smarty';
+        }
+
+        if (\str_contains($content, '<html')) {
+            return 'html';
+        }
+
+        if (\str_starts_with($content, '<?xml')) {
+            return 'xml';
+        }
+
+        if (\str_contains($content, '@mixin')) {
+            return 'scss';
+        }
+
+        if (\str_contains($content, '!important;')) {
+            return 'css';
+        }
+
+        if (\preg_match('/(^|\n)HTTP\\/[0-9]\\.[0-9] [0-9]{3}/', $content)) {
+            return 'http';
+        }
+
+        return '';
+    }
+
+    /**
+     * Returns a unique ID for the given code block.
+     */
+    public function getCodeID(string $prefix, string $code): string
+    {
+        $i = -1;
+        // find an unused codeID
+        do {
+            $codeID = $prefix . \mb_substr(\sha1($code), 0, 6) . (++$i !== 0 ? '_' . $i : '');
+        } while (isset(self::$codeIDs[$codeID]));
+
+        // mark codeID as used
+        self::$codeIDs[$codeID] = true;
+
+        return $codeID;
+    }
+}

wcfsetup/install/files/lib/system/form/option/SharedConfigurationFormFields.class.php

@@ -3,16 +3,19 @@
 namespace wcf\system\form\option;
 
 use wcf\event\form\option\SharedConfigurationFormFieldCollecting;
+use wcf\system\bbcode\BBCodeHandler;
 use wcf\system\event\EventHandler;
 use wcf\system\form\builder\field\AbstractNumericFormField;
 use wcf\system\form\builder\field\BooleanFormField;
 use wcf\system\form\builder\field\FloatFormField;
 use wcf\system\form\builder\field\IFormField;
 use wcf\system\form\builder\field\IntegerFormField;
 use wcf\system\form\builder\field\SelectOptionsFormField;
+use wcf\system\form\builder\field\SingleSelectionFormField;
 use wcf\system\form\builder\field\TextFormField;
 use wcf\system\form\builder\field\validation\FormFieldValidationError;
 use wcf\system\form\builder\field\validation\FormFieldValidator;
+use wcf\system\WCF;
 
 /**
  * Provides the available shared configuration form fields.
@@ -72,6 +75,12 @@ private function getDefaultFormFields(): array
             'required' => BooleanFormField::create('required')
                 ->label('wcf.form.option.shared.required')
                 ->value(false),
+            'sourceCodeLanguage' => SingleSelectionFormField::create('sourceCodeLanguage')
+                ->label('wcf.form.option.shared.sourceCodeLanguage')
+                ->description('wcf.form.option.shared.sourceCodeLanguage.description')
+                ->options($this->getSourceCodeLanguageOptions(), labelLanguageItems: false)
+                ->filterable()
+                ->nullable(),
             'unit' => TextFormField::create('unit')
                 ->label('wcf.form.option.shared.unit')
                 ->addFieldClass('short'),
@@ -82,6 +91,23 @@ private function getDefaultFormFields(): array
         ];
     }
 
+    /**
+     * Returns the list of available syntax highlighters.
+     *
+     * @return array<string, string>
+     */
+    private function getSourceCodeLanguageOptions(): array
+    {
+        $options = [];
+        foreach (BBCodeHandler::getInstance()->getHighlighterMeta() as $identifier => $data) {
+            $options[$identifier] = $data['title'] . (\strtolower($data['title']) !== $identifier ? ' (' . $identifier . ')' : '');
+        }
+
+        \asort($options);
+
+        return ['' => WCF::getLanguage()->get('wcf.global.noSelection')] + $options;
+    }
+
     /**
      * Returns a validator that ensures that the maximum value of a form field is not
      * smaller than the minimum value provided by the form field with the given id.

wcfsetup/install/files/lib/system/form/option/SourceCodeFormOption.class.php

@@ -26,10 +26,23 @@ public function getId(): string
         return 'sourceCode';
     }
 
+    #[\Override]
+    public function getConfigurationFormFields(): array
+    {
+        return \array_merge(parent::getConfigurationFormFields(), ['sourceCodeLanguage']);
+    }
+
     #[\Override]
     public function getFormField(string $id, array $configuration = []): AbstractFormField
     {
-        return SourceCodeFormField::create($id);
+        $formField = SourceCodeFormField::create($id);
+
+        $language = (string)($configuration['sourceCodeLanguage'] ?? '');
+        if (\in_array($language, SourceCodeFormField::LANGUAGES, true)) {
+            $formField->language($language);
+        }
+
+        return $formField;
     }
 
     #[\Override]

wcfsetup/install/files/lib/system/form/option/formatter/SourceCodeFormatter.class.php

@@ -2,7 +2,7 @@
 
 namespace wcf\system\form\option\formatter;
 
-use wcf\util\StringUtil;
+use wcf\system\code\SourceCodeRenderer;
 
 /**
  * Formatter for source code values.
@@ -17,6 +17,10 @@ final class SourceCodeFormatter implements IFormOptionFormatter
     #[\Override]
     public function format(string $value, int $languageID, array $configuration): string
     {
-        return '<pre style="overflow: auto">' . StringUtil::encodeHTML($value) . '</pre>';
+        return (new SourceCodeRenderer())->render(
+            $value,
+            (string)($configuration['sourceCodeLanguage'] ?? ''),
+            codeIDPrefix: 'formOption_'
+        );
     }
 }