Use our own markdown_to_html convertor

Which stashes LaTeX during conversion and pops it afterwards.

Otherwise things like `\\` get replaced with `\` which failed with:
DOMjudge#3099 (comment)

Author: vmcj

webapp/src/Twig/TwigExtension.php

@@ -27,6 +27,7 @@
 use App\Utils\Utils;
 use Doctrine\Common\Collections\Collection;
 use Doctrine\ORM\EntityManagerInterface;
+use Ramsey\Uuid\Uuid;
 use Symfony\Component\DependencyInjection\Attribute\Autowire;
 use Symfony\Component\Intl\Countries;
 use Symfony\Component\Intl\Exception\MissingResourceException;
@@ -38,12 +39,15 @@
 use Twig\Environment;
 use Twig\Extension\AbstractExtension;
 use Twig\Extension\GlobalsInterface;
+use Twig\Extra\Markdown\MarkdownRuntime;
 use Twig\Runtime\EscaperRuntime;
 use Twig\TwigFilter;
 use Twig\TwigFunction;
 
 class TwigExtension extends AbstractExtension implements GlobalsInterface
 {
+    private array $latexFound;
+
     /**
      * @param array<int, bool> $renderedSources
      */
@@ -126,6 +130,7 @@ public function getFilters(): array
             new TwigFilter('medalType', $this->awards->medalType(...)),
             new TwigFilter('numTableActions', $this->numTableActions(...)),
             new TwigFilter('extensionToMime', $this->extensionToMime(...)),
+            new TwigFilter('domjudgeMarkdownToHtml', $this->domjudgeMarkdownToHTML(...), ['is_safe' => ['html']]),
         ];
     }
 
@@ -1381,4 +1386,35 @@ public function extensionToMime(string $extension): string
     {
         return DOMJudgeService::EXTENSION_TO_MIMETYPE[$extension];
     }
+
+    /**
+     * Extract all LaTeX code from the given string, sanitize the markdown and
+     * inject the original LaTeX code back so MathJax can render it.
+     */
+    public function domjudgeMarkdownToHTML(string $markdown): string
+    {
+        $latexPlaceholder = Uuid::uuid4()->toString();
+        while(str_contains($markdown, $latexPlaceholder)) {
+            $latexPlaceholder = Uuid::uuid4()->toString();
+        }
+
+        $markdown = preg_replace_callback(
+            '/(\$[\s\S]*?\$)/',
+            function (array $matches) use ($latexPlaceholder) {
+                // Store and replace matches
+                $this->latexFound[] = $matches[1];
+                return $latexPlaceholder;
+            },
+            $markdown
+        );
+
+        /** @var MarkdownRuntime $runtime */
+        $runtime = $this->twig->getRuntime(MarkdownRuntime::class);
+        $markdown = (string)$runtime->convert($markdown);
+
+        return preg_replace_callback(
+            '/'.$latexPlaceholder.'/',
+            fn() => array_shift($this->latexFound), $markdown
+        );
+    }
 }

webapp/templates/jury/clarification.html.twig

@@ -110,7 +110,7 @@
 
                     <hr/>
 
-                    <div class="card-text">{{ clar.body | markdown_to_html | sanitize_html('app.clarification_sanitizer') }}</div>
+                    <div class="card-text">{{ clar.body | domjudgeMarkdownToHtml | sanitize_html('app.clarification_sanitizer') }}</div>
 
                 </div>
             </div>

webapp/templates/jury/config.html.twig

@@ -218,7 +218,7 @@
                                                 {{ errors[option.name] }}
                                             </div>
                                         {% endif %}
-                                        <div class="small text-muted">{{ option.description | markdown_to_html }}</div>
+                                        <div class="small text-muted">{{ option.description | domjudgeMarkdownToHtml }}</div>
                                     </div>
                                 </li>
                             {% endfor %}

webapp/templates/jury/config_check.html.twig

@@ -99,7 +99,7 @@
         {% if testresult.escape is not defined or testresult.escape %}
           {% set description = description | escape %}
         {% endif %}
-        {{ description | markdown_to_html }}
+        {{ description | domjudgeMarkdownToHtml }}
       </div>
     </div>
   </div>

webapp/templates/jury/export/clarifications.html.twig

@@ -98,7 +98,7 @@
                 <tr>
                     <td><b>Content</b></td>
                     <td colspan="5">
-                        <div class="card-text">{{ clarification.body | markdown_to_html | sanitize_html('app.clarification_sanitizer') }}</div>
+                        <div class="card-text">{{ clarification.body | domjudgeMarkdownToHtml | sanitize_html('app.clarification_sanitizer') }}</div>
                     </td>
                 </tr>
                 {% if clarification.replies is not empty %}
@@ -114,7 +114,7 @@
                                 </b>
                             </td>
                             <td colspan="5">
-                                <div class="card-text">{{ reply.body | markdown_to_html | sanitize_html('app.clarification_sanitizer') }}</div>
+                                <div class="card-text">{{ reply.body | domjudgeMarkdownToHtml | sanitize_html('app.clarification_sanitizer') }}</div>
                             </td>
                         </tr>
                     {% endfor %}

webapp/templates/team/partials/clarification.html.twig

@@ -40,7 +40,7 @@
         <hr/>
 
         <div class="card-text">
-            {{ clarification.body | markdown_to_html | sanitize_html('app.clarification_sanitizer') }}
+            {{ clarification.body | domjudgeMarkdownToHtml | sanitize_html('app.clarification_sanitizer') }}
         </div>
     </div>
 </div>

webapp/templates/team/partials/clarification_list.html.twig

@@ -51,7 +51,7 @@
                 <td class="clarification-text">
                     <a data-ajax-modal data-ajax-modal-after="markSeen" href="{{ link }}">
                         <i>{{ clarification.summary
-                            | markdown_to_html
+                            | domjudgeMarkdownToHtml
                             | replace({'<p>': '', '</p>': ''})
                             | sanitize_html('app.clarification_sanitizer')
                             | raw