Add README documentation to ExtensionPage (#3094)

Co-authored-by: Alexander Skvortsov <sasha.skvortsov109@gmail.com>

src/Api/Controller/ShowExtensionReadmeController.php

@@ -0,0 +1,47 @@
+<?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\Api\Controller;
+
+use Flarum\Api\Serializer\ExtensionReadmeSerializer;
+use Flarum\Extension\ExtensionManager;
+use Flarum\Http\RequestUtil;
+use Illuminate\Support\Arr;
+use Psr\Http\Message\ServerRequestInterface;
+use Tobscure\JsonApi\Document;
+
+class ShowExtensionReadmeController extends AbstractShowController
+{
+    /**
+     * @var ExtensionManager
+     */
+    protected $extensions;
+
+    /**
+     * {@inheritdoc}
+     */
+    public $serializer = ExtensionReadmeSerializer::class;
+
+    public function __construct(ExtensionManager $extensions)
+    {
+        $this->extensions = $extensions;
+    }
+
+    /**
+     * {@inheritdoc}
+     */
+    protected function data(ServerRequestInterface $request, Document $document)
+    {
+        $extensionName = Arr::get($request->getQueryParams(), 'name');
+
+        RequestUtil::getActor($request)->assertAdmin();
+
+        return $this->extensions->getExtension($extensionName);
+    }
+}

src/Api/Serializer/ExtensionReadmeSerializer.php

@@ -0,0 +1,35 @@
+<?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\Api\Serializer;
+
+class ExtensionReadmeSerializer extends AbstractSerializer
+{
+    /**
+     * {@inheritdoc}
+     */
+    protected function getDefaultAttributes($extension)
+    {
+        $attributes = [
+            'content' => $extension->getReadme()
+        ];
+
+        return $attributes;
+    }
+
+    public function getId($extension)
+    {
+        return $extension->getId();
+    }
+
+    public function getType($extension)
+    {
+        return 'extension-readmes';
+    }
+}

src/Api/routes.php

@@ -265,6 +265,13 @@ return function (RouteCollection $map, RouteHandlerFactory $route) {
         $route->toController(Controller\UninstallExtensionController::class)
     );
 
+    // Get readme for an extension
+    $map->get(
+        '/extension-readmes/{name}',
+        'extension-readmes.show',
+        $route->toController(Controller\ShowExtensionReadmeController::class)
+    );
+
     // Update settings
     $map->post(
         '/settings',

src/Extension/Extension.php

@@ -19,6 +19,7 @@ use Illuminate\Filesystem\Filesystem;
 use Illuminate\Support\Arr;
 use Illuminate\Support\Collection;
 use Illuminate\Support\Str;
+use s9e\TextFormatter\Bundles\Fatdown;
 use Throwable;
 
 /**
@@ -525,4 +526,28 @@ class Extension implements Arrayable
             'links'                  => $this->getLinks(),
         ], $this->composerJson);
     }
+
+    /**
+     * Gets the rendered contents of the extension README file as a HTML string.
+     *
+     * @return string|null
+     */
+    public function getReadme(): ?string
+    {
+        $content = null;
+
+        if (file_exists($file = "$this->path/README.md")) {
+            $content = file_get_contents($file);
+        } elseif (file_exists($file = "$this->path/README")) {
+            $content = file_get_contents($file);
+        }
+
+        if ($content) {
+            $xml = Fatdown::parse($content);
+
+            return Fatdown::render($xml);
+        }
+
+        return null;
+    }
 }