Frontend refactor (#1471)

Refactor Frontend + Asset code

- Use Laravel's Filesystem component for asset IO, meaning theoretically
  assets should be storable on S3 etc.

- More reliable checking for asset recompilation when debug mode is on,
  so you don't have to constantly delete the compiled assets to force
  a recompile. Should also fix issues with locale JS files being
  recompiled with the same name and cached.

- Remove JavaScript minification, because it will be done by Webpack
  (exception is for the TextFormatter JS).

- Add support for JS sourcemaps.

- Separate frontend view and assets completely. This is an important
  distinction because frontend assets are compiled independent of a
  request, whereas putting together a view depends on a request.

- Bind frontend view/asset factory instances to the container (in
  service providers) rather than subclassing. Asset and content
  populators can be added to these factories – these are simply objects
  that populate the asset compilers or the view with information.

- Add RouteHandlerFactory functions that make it easy to hook up a
  frontend controller with a frontend instance ± some content.

- Remove the need for "nojs"

- Fix cache:clear command

- Recompile assets when settings/enabled extensions change

src/Forum/ForumServiceProvider.php

@@ -13,8 +13,6 @@ namespace Flarum\Forum;
 
 use Flarum\Event\ConfigureForumRoutes;
 use Flarum\Event\ConfigureMiddleware;
-use Flarum\Extension\Event\Disabled;
-use Flarum\Extension\Event\Enabled;
 use Flarum\Foundation\AbstractServiceProvider;
 use Flarum\Http\Middleware\AuthenticateWithSession;
 use Flarum\Http\Middleware\CollectGarbage;
@@ -28,7 +26,6 @@ use Flarum\Http\Middleware\StartSession;
 use Flarum\Http\RouteCollection;
 use Flarum\Http\RouteHandlerFactory;
 use Flarum\Http\UrlGenerator;
-use Flarum\Settings\Event\Saved;
 use Flarum\Settings\SettingsRepositoryInterface;
 use Symfony\Component\Translation\TranslatorInterface;
 use Zend\Stratigility\MiddlewarePipe;
@@ -69,6 +66,27 @@ class ForumServiceProvider extends AbstractServiceProvider
 
             return $pipe;
         });
+
+        $this->app->bind('flarum.forum.assets', function () {
+            $assets = $this->app->make('flarum.frontend.assets.defaults')('forum');
+
+            $assets->add(function () {
+                return [
+                    $this->app->make(Asset\FormatterJs::class),
+                    $this->app->make(Asset\CustomCss::class)
+                ];
+            });
+
+            return $assets;
+        });
+
+        $this->app->bind('flarum.forum.frontend', function () {
+            $view = $this->app->make('flarum.frontend.view.defaults')('forum');
+
+            $view->setAssets($this->app->make('flarum.forum.assets'));
+
+            return $view;
+        });
     }
 
     /**
@@ -85,9 +103,13 @@ class ForumServiceProvider extends AbstractServiceProvider
             'settings' => $this->app->make(SettingsRepositoryInterface::class)
         ]);
 
-        $this->flushWebAppAssetsWhenThemeChanged();
-
-        $this->flushWebAppAssetsWhenExtensionsChanged();
+        $this->app->make('events')->subscribe(
+            new RecompileFrontendAssets(
+                $this->app->make('flarum.forum.assets'),
+                $this->app->make('flarum.locales'),
+                $this->app
+            )
+        );
     }
 
     /**
@@ -111,7 +133,7 @@ class ForumServiceProvider extends AbstractServiceProvider
         if (isset($routes->getRouteData()[0]['GET'][$defaultRoute])) {
             $toDefaultController = $routes->getRouteData()[0]['GET'][$defaultRoute];
         } else {
-            $toDefaultController = $factory->toController(Controller\IndexController::class);
+            $toDefaultController = $factory->toForum(Content\Index::class);
         }
 
         $routes->get(
@@ -120,34 +142,4 @@ class ForumServiceProvider extends AbstractServiceProvider
             $toDefaultController
         );
     }
-
-    protected function flushWebAppAssetsWhenThemeChanged()
-    {
-        $this->app->make('events')->listen(Saved::class, function (Saved $event) {
-            if (preg_match('/^theme_|^custom_less$/i', $event->key)) {
-                $this->getWebAppAssets()->flushCss();
-            }
-        });
-    }
-
-    protected function flushWebAppAssetsWhenExtensionsChanged()
-    {
-        $events = $this->app->make('events');
-
-        $events->listen(Enabled::class, [$this, 'flushWebAppAssets']);
-        $events->listen(Disabled::class, [$this, 'flushWebAppAssets']);
-    }
-
-    public function flushWebAppAssets()
-    {
-        $this->getWebAppAssets()->flush();
-    }
-
-    /**
-     * @return \Flarum\Frontend\FrontendAssets
-     */
-    protected function getWebAppAssets()
-    {
-        return $this->app->make(Frontend::class)->getAssets();
-    }
 }