Error handling: Rename renderers to formatters

Refs #1641.

src/Foundation/ErrorHandling/ViewFormatter.php

@@ -0,0 +1,81 @@
+<?php
+
+/*
+ * This file is part of Flarum.
+ *
+ * (c) Toby Zerner <toby.zerner@gmail.com>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace Flarum\Foundation\ErrorHandling;
+
+use Flarum\Settings\SettingsRepositoryInterface;
+use Illuminate\Contracts\View\Factory as ViewFactory;
+use Psr\Http\Message\ResponseInterface as Response;
+use Psr\Http\Message\ServerRequestInterface as Request;
+use Symfony\Component\Translation\TranslatorInterface;
+use Zend\Diactoros\Response\HtmlResponse;
+
+class ViewFormatter implements HttpFormatter
+{
+    /**
+     * @var ViewFactory
+     */
+    protected $view;
+
+    /**
+     * @var TranslatorInterface
+     */
+    protected $translator;
+
+    /**
+     * @var SettingsRepositoryInterface
+     */
+    protected $settings;
+
+    public function __construct(ViewFactory $view, TranslatorInterface $translator, SettingsRepositoryInterface $settings)
+    {
+        $this->view = $view;
+        $this->translator = $translator;
+        $this->settings = $settings;
+    }
+
+    public function format(HandledError $error, Request $request): Response
+    {
+        $view = $this->view->make($this->determineView($error))
+            ->with('error', $error->getError())
+            ->with('message', $this->getMessage($error));
+
+        return new HtmlResponse($view->render(), $error->getStatusCode());
+    }
+
+    const ERRORS_WITH_VIEWS = ['csrf_token_mismatch', 'not_found'];
+
+    private function determineView(HandledError $error): string
+    {
+        $type = $error->getType();
+
+        if (in_array($type, self::ERRORS_WITH_VIEWS)) {
+            return "flarum.forum::error.$type";
+        } else {
+            return 'flarum.forum::error.default';
+        }
+    }
+
+    private function getMessage(HandledError $error)
+    {
+        return $this->getTranslationIfExists($error->getType())
+            ?? $this->getTranslationIfExists('unknown')
+            ?? 'An error occurred while trying to load this page.';
+    }
+
+    private function getTranslationIfExists(string $errorType)
+    {
+        $key = "core.views.error.$errorType";
+        $translation = $this->translator->trans($key, ['{forum}' => $this->settings->get('forum_title')]);
+
+        return $translation === $key ? null : $translation;
+    }
+}