[5.3] Add offline mode support in the API

libraries/src/Application/ApiApplication.php

@@ -146,8 +146,32 @@ public function addFormatMap($contentHeader, $format)
      */
     protected function render()
     {
+        // Trigger the onBeforeRender event.
+        PluginHelper::importPlugin('system');
+        $this->triggerEvent('onBeforeRender');
+
+        /**
+         * Check we aren't in offline mode. In which case for users who can't access the site the API is disabled
+         * and we won't show anything!
+         */
+        if ($this->get('offline') && !$this->getIdentity()->authorise('core.login.offline')) {
+            $offlineMessage = '';
+
+            if ($this->get('display_offline_message', true) == true) {
+                $offlineMessage = $this->get('offline_message');
+            }
+
+            throw new Exception\OfflineWebsiteException($offlineMessage);
+        }
+
         // Render the document
         $this->setBody($this->document->render($this->allowCache()));
+
+        // Trigger the onAfterRender event.
+        $this->triggerEvent('onAfterRender');
+
+        // Mark afterRender in the profiler.
+        JDEBUG ? $this->profiler->mark('afterRender') : null;
     }
 
     /**

libraries/src/Application/Exception/OfflineWebsiteException.php

@@ -0,0 +1,19 @@
+<?php
+
+/**
+ * Joomla! Content Management System
+ *
+ * @copyright  (C) 2021 Open Source Matters, Inc. <https://www.joomla.org>
+ * @license    GNU General Public License version 2 or later; see LICENSE.txt
+ */
+
+namespace Joomla\CMS\Application\Exception;
+
+/**
+ * Exception class for a website that is in offline mode!
+ *
+ * @since  __DEPLOY_VERSION__
+ */
+class OfflineWebsiteException extends \RuntimeException
+{
+}

libraries/src/Error/JsonApi/OfflineWebsiteExceptionHandler.php

@@ -0,0 +1,61 @@
+<?php
+
+/**
+ * Joomla! Content Management System
+ *
+ * @copyright  (C) 2021 Open Source Matters, Inc. <https://www.joomla.org>
+ * @license    GNU General Public License version 2 or later; see LICENSE.txt
+ */
+
+namespace Joomla\CMS\Error\JsonApi;
+
+use Exception;
+use Joomla\CMS\Application\Exception\OfflineWebsiteException;
+use Tobscure\JsonApi\Exception\Handler\ExceptionHandlerInterface;
+use Tobscure\JsonApi\Exception\Handler\ResponseBag;
+
+/**
+ * Handler for the site being in offline mode
+ *
+ * @since  __DEPLOY_VERSION__
+ */
+class OfflineWebsiteExceptionHandler implements ExceptionHandlerInterface
+{
+    /**
+     * If the exception handler is able to format a response for the provided exception,
+     * then the implementation should return true.
+     *
+     * @param   \Exception  $e  The exception to be handled
+     *
+     * @return boolean
+     *
+     * @since  __DEPLOY_VERSION__
+     */
+    public function manages(Exception $e)
+    {
+        return $e instanceof OfflineWebsiteException;
+    }
+
+    /**
+     * Handle the provided exception.
+     *
+     * @param   Exception  $e  The exception being handled
+     *
+     * @return  \Tobscure\JsonApi\Exception\Handler\ResponseBag
+     *
+     * @since  __DEPLOY_VERSION__
+     */
+    public function handle(Exception $e)
+    {
+        $status = 503;
+        $error = ['title' => $e->getMessage()];
+
+        $code = $e->getCode();
+
+        if ($code) {
+            $error['code'] = $code;
+        }
+
+        return new ResponseBag($status, [$error]);
+    }
+}

libraries/src/Error/Renderer/JsonapiRenderer.php

@@ -16,6 +16,7 @@
 use Joomla\CMS\Error\JsonApi\InvalidRouteExceptionHandler;
 use Joomla\CMS\Error\JsonApi\NotAcceptableExceptionHandler;
 use Joomla\CMS\Error\JsonApi\NotAllowedExceptionHandler;
+use Joomla\CMS\Error\JsonApi\OfflineWebsiteExceptionHandler;
 use Joomla\CMS\Error\JsonApi\ResourceNotFoundExceptionHandler;
 use Joomla\CMS\Error\JsonApi\SaveExceptionHandler;
 use Joomla\CMS\Error\JsonApi\SendEmailExceptionHandler;
@@ -57,6 +58,7 @@ public function render(\Throwable $error): string
         if ($error instanceof \Exception) {
             $errors = new ErrorHandler();
 
+            $errors->registerHandler(new OfflineWebsiteExceptionHandler());
             $errors->registerHandler(new InvalidRouteExceptionHandler());
             $errors->registerHandler(new AuthenticationFailedExceptionHandler());
             $errors->registerHandler(new NotAcceptableExceptionHandler());