add read the docs layout

Author: nikophil

src/Command/BuildDocsCommand.php

@@ -18,6 +18,7 @@
 use SymfonyDocsBuilder\Generator\HtmlForPdfGenerator;
 use SymfonyDocsBuilder\Generator\JsonGenerator;
 use SymfonyDocsBuilder\KernelFactory;
+use SymfonyDocsBuilder\Listener\AssetsCopyListener;
 use SymfonyDocsBuilder\Listener\BuildProgressListener;
 use SymfonyDocsBuilder\Listener\CopyImagesDirectoryListener;
 
@@ -171,6 +172,13 @@ private function initializeListeners(EventManager $eventManager)
             new CopyImagesDirectoryListener($this->buildContext)
         );
 
+        if (!$this->buildContext->getParseSubPath()) {
+            $eventManager->addEventListener(
+                [PostBuildRenderEvent::POST_BUILD_RENDER],
+                new AssetsCopyListener($this->buildContext->getOutputDir())
+            );
+        }
+
         $progressListener = new BuildProgressListener($this->io);
         $progressListener->attachListeners($eventManager);
     }

src/KernelFactory.php

@@ -3,10 +3,13 @@
 namespace SymfonyDocsBuilder;
 
 use Doctrine\RST\Configuration as RSTParserConfiguration;
+use Doctrine\RST\Event\PostBuildRenderEvent;
 use Doctrine\RST\Kernel;
 use SymfonyDocsBuilder\CI\UrlChecker;
 use SymfonyDocsBuilder\Directive as SymfonyDirectives;
 use SymfonyDocsBuilder\Reference as SymfonyReferences;
+use SymfonyDocsBuilder\Listener\AssetsCopyListener;
+use SymfonyDocsBuilder\Twig\AssetsExtension;
 
 /**
  * Class KernelFactory
@@ -41,6 +44,9 @@ static function (string $path) use ($parseSubPath) : bool {
             );
         }
 
+        $twig = $configuration->getTemplateRenderer()->getTwigEnvironment();
+        $twig->addExtension(new AssetsExtension($buildContext->getHtmlOutputDir()));
+
         return new Kernel(
             $configuration,
             self::getDirectives(),

src/Listener/AssetsCopyListener.php

@@ -0,0 +1,25 @@
+<?php declare(strict_types=1);
+
+namespace SymfonyDocsBuilder\Listener;
+
+use Symfony\Component\Filesystem\Filesystem;
+
+final class AssetsCopyListener
+{
+    /** @var string */
+    private $targetDir;
+
+    public function __construct(string $targetDir)
+    {
+        $this->targetDir = $targetDir;
+    }
+
+    public function postBuildRender()
+    {
+        $fs = new Filesystem();
+        $fs->mirror(
+            sprintf('%s/../Templates/default/assets', __DIR__),
+            sprintf('%s/assets', $this->targetDir)
+        );
+    }
+}