feature: adds advanced link handling in core

framework/core/src/Extend/Link.php

@@ -0,0 +1,62 @@
+<?php
+
+/*
+ * This file is part of Flarum.
+ *
+ * For detailed copyright and license information, please view the
+ * LICENSE file that was distributed with this source code.
+ */
+
+namespace Flarum\Extend;
+
+use Flarum\Extension\Extension;
+use Flarum\Foundation\Config;
+use Illuminate\Contracts\Container\Container;
+use Laminas\Diactoros\Uri;
+use s9e\TextFormatter\Renderer;
+use s9e\TextFormatter\Utils;
+
+class Link implements ExtenderInterface
+{
+    protected $setRel = null;
+    protected $setTarget = null;
+
+    public function setRel(callable $callable): static
+    {
+        $this->setRel = $callable;
+
+        return $this;
+    }
+
+    public function setTarget(callable $callable): static
+    {
+        $this->setTarget = $callable;
+
+        return $this;
+    }
+
+    public function extend(Container $container, Extension $extension = null)
+    {
+        $siteUrl = $container->make(Config::class)->url();
+
+        (new Formatter)->render(function (Renderer $renderer, $context, string $xml) use ($siteUrl) {
+            return Utils::replaceAttributes($xml, 'URL', function ($attributes) use ($siteUrl) {
+                $uri = isset($attributes['url'])
+                    ? new Uri($attributes['url'])
+                    : null;
+
+                $setRel = $this->setRel;
+                if ($setRel && $rel = $setRel($uri, $siteUrl, $attributes)) {
+                    $attributes['rel'] = $rel;
+                }
+
+                $setTarget = $this->setTarget;
+                if ($setTarget && $target = $setTarget($uri, $siteUrl, $attributes)) {
+                    $attributes['target'] = $target;
+                }
+
+                return $attributes;
+            });
+        })->extend($container);
+    }
+}

framework/core/src/Formatter/Formatter.php

@@ -9,10 +9,14 @@
 
 namespace Flarum\Formatter;
 
+use DOMDocument;
+use DOMElement;
 use Illuminate\Contracts\Cache\Repository;
 use Psr\Http\Message\ServerRequestInterface;
 use s9e\TextFormatter\Configurator;
+use s9e\TextFormatter\Renderer;
 use s9e\TextFormatter\Unparser;
+use s9e\TextFormatter\Utils;
 
 class Formatter
 {
@@ -98,7 +102,7 @@ public function parse($text, $context = null)
      * Render parsed XML.
      *
      * @param string $xml
-     * @param mixed $context
+     * @param mixed|null $context
      * @param ServerRequestInterface|null $request
      * @return string
      */
@@ -110,6 +114,8 @@ public function render($xml, $context = null, ServerRequestInterface $request =
             $xml = $callback($renderer, $context, $xml, $request);
         }
 
+        $xml = $this->configureDefaultsOnLinks($renderer, $xml, $context, $request);
+
         return $renderer->render($xml);
     }
 
@@ -174,11 +180,13 @@ protected function getConfigurator()
      */
     protected function configureExternalLinks(Configurator $configurator)
     {
+        /** @var DOMDocument $dom */
         $dom = $configurator->tags['URL']->template->asDOM();
 
+        /** @var DOMElement $a */
         foreach ($dom->getElementsByTagName('a') as $a) {
-            $rel = $a->getAttribute('rel');
-            $a->setAttribute('rel', "$rel nofollow ugc");
+            $a->prependXslCopyOf('@target');
+            $a->prependXslCopyOf('@rel');
         }
 
         $dom->saveChanges();
@@ -217,7 +225,7 @@ protected function getParser($context = null)
     /**
      * Get the renderer.
      *
-     * @return \s9e\TextFormatter\Renderer
+     * @return Renderer
      */
     protected function getRenderer()
     {
@@ -239,4 +247,17 @@ public function getJs()
     {
         return $this->getComponent('js');
     }
+
+    protected function configureDefaultsOnLinks(
+        Renderer $renderer,
+        string $xml,
+        $context = null,
+        ServerRequestInterface $request = null
+    ): string {
+        return Utils::replaceAttributes($xml, 'URL', function ($attributes) {
+            $attributes['rel'] = $attributes['rel'] ?? 'ugc nofollow';
+
+            return $attributes;
+        });
+    }
 }