Add themed error pages

- Module init, post and rawContent-triggered HTTPException generate the classic bare HTTP status page
- Module content-triggered HTTPException generate themed error pages
- Trim System::httpExit to the bare minimum

src/Module/Special/HTTPException.php

@@ -0,0 +1,91 @@
+<?php
+
+
+namespace Friendica\Module\Special;
+
+use Friendica\Core\L10n;
+use Friendica\Core\Logger;
+use Friendica\Core\Renderer;
+use Friendica\Core\System;
+
+/**
+ * This special module displays HTTPException when they are thrown in modules.
+ *
+ * @package Friendica\Module\Special
+ */
+class HTTPException
+{
+	/**
+	 * Generates the necessary template variables from the caught HTTPException.
+	 *
+	 * Fills in the blanks if title or descriptions aren't provided by the exception.
+	 *
+	 * @param \Friendica\Network\HTTPException $e
+	 * @return array ['$title' => ..., '$description' => ...]
+	 */
+	private static function getVars(\Friendica\Network\HTTPException $e)
+	{
+		$message = $e->getMessage();
+
+		$titles = [
+			200 => 'OK',
+			400 => L10n::t('Bad Request'),
+			401 => L10n::t('Unauthorized'),
+			403 => L10n::t('Forbidden'),
+			404 => L10n::t('Not Found'),
+			500 => L10n::t('Internal Server Error'),
+			503 => L10n::t('Service Unavailable'),
+		];
+		$title = defaults($titles, $e->getCode(), 'Error ' . $e->getCode());
+
+		if (empty($message)) {
+			// Explanations are taken from https://en.wikipedia.org/wiki/List_of_HTTP_status_codes
+			$explanation = [
+				400 => L10n::t('The server cannot or will not process the request due to an apparent client error.'),
+				401 => L10n::t('Authentication is required and has failed or has not yet been provided.'),
+				403 => L10n::t('The request was valid, but the server is refusing action. The user might not have the necessary permissions for a resource, or may need an account.'),
+				404 => L10n::t('The requested resource could not be found but may be available in the future.'),
+				500 => L10n::t('An unexpected condition was encountered and no more specific message is suitable.'),
+				503 => L10n::t('The server is currently unavailable (because it is overloaded or down for maintenance). Please try again later.'),
+			];
+
+			$message = defaults($explanation, $e->getCode(), '');
+		}
+
+		return ['$title' => $title, '$description' => $message];
+	}
+
+	/**
+	 * Displays a bare message page with no theming at all.
+	 *
+	 * @param \Friendica\Network\HTTPException $e
+	 * @throws \Friendica\Network\HTTPException\InternalServerErrorException
+	 */
+	public static function rawContent(\Friendica\Network\HTTPException $e)
+	{
+		$content = '';
+
+		if ($e->getCode() >= 400) {
+			$tpl = Renderer::getMarkupTemplate('http_status.tpl');
+			$content = Renderer::replaceMacros($tpl, self::getVars($e));
+		}
+
+		System::httpExit($e->getCode(), $e->httpdesc, $content);
+	}
+
+	/**
+	 * Returns a content string that can be integrated in the current theme.
+	 *
+	 * @param \Friendica\Network\HTTPException $e
+	 * @return string
+	 * @throws \Friendica\Network\HTTPException\InternalServerErrorException
+	 */
+	public static function content(\Friendica\Network\HTTPException $e)
+	{
+		header($_SERVER["SERVER_PROTOCOL"] . ' ' . $e->getCode() . ' ' . $e->httpdesc);
+
+		$tpl = Renderer::getMarkupTemplate('exception.tpl');
+
+		return Renderer::replaceMacros($tpl, self::getVars($e));
+	}
+}