Add onBeforeExecute event, move languagefilter plugin detection to th…

…is event

installation/application/web.php

@@ -229,6 +229,35 @@ protected function doExecute()
 		$this->dispatch();
 	}
 
+	/**
+	 * Execute the application.
+	 *
+	 * @return  void
+	 *
+	 * @since   4.0
+	 */
+	public function execute()
+	{
+		// Perform application routines.
+		$this->doExecute();
+
+		// If we have an application document object, render it.
+		if ($this->document instanceof JDocument)
+		{
+			// Render the application output.
+			$this->render();
+		}
+
+		// If gzip compression is enabled in configuration and the server is compliant, compress the output.
+		if ($this->get('gzip') && !ini_get('zlib.output_compression') && (ini_get('output_handler') != 'ob_gzhandler'))
+		{
+			$this->compress();
+		}
+
+		// Send the application response.
+		$this->respond();
+	}
+
 	/**
 	 * Method to load a PHP configuration class file based on convention and return the instantiated data object.  You
 	 * will extend this method in child classes to provide configuration data from whatever data source is relevant

libraries/cms/application/cms.php

@@ -9,6 +9,8 @@
 
 defined('JPATH_PLATFORM') or die;
 
+use Joomla\Cms\Event\AbstractEvent;
+use Joomla\Cms\Event\BeforeExecuteEvent;
 use Joomla\DI\Container;
 use Joomla\DI\ContainerAwareInterface;
 use Joomla\DI\ContainerAwareTrait;
@@ -300,6 +302,20 @@ public function enqueueMessage($msg, $type = 'message')
 	 */
 	public function execute()
 	{
+		JPluginHelper::importPlugin('system');
+
+		// Trigger the onBeforeExecute event.
+		$this->triggerEvent(
+			'onBeforeExecute',
+			AbstractEvent::create(
+				'onBeforeExecute',
+				[
+					'subject'    => $this,
+					'eventClass' => BeforeExecuteEvent::class,
+				]
+			)
+		);
+
 		// Perform application routines.
 		$this->doExecute();
 

libraries/cms/application/site.php

@@ -575,22 +575,6 @@ protected function initialiseApp($options = array())
 			$user->groups = array($guestUsergroup);
 		}
 
-		/*
-		 * If a language was specified it has priority, otherwise use user or default language settings
-		 * Check this only if the languagefilter plugin is enabled
-		 *
-		 * @TODO - Remove the hardcoded dependency to the languagefilter plugin
-		 */
-		if (JPluginHelper::isEnabled('system', 'languagefilter'))
-		{
-			$plugin = JPluginHelper::getPlugin('system', 'languagefilter');
-
-			$pluginParams = new Registry($plugin->params);
-
-			$this->setLanguageFilter(true);
-			$this->setDetectBrowser($pluginParams->get('detect_browser', '1') == '1');
-		}
-
 		if (empty($options['language']))
 		{
 			// Detect the specified language

libraries/src/Cms/Event/BeforeExecuteEvent.php

@@ -0,0 +1,33 @@
+<?php
+/**
+ * Joomla! Content Management System
+ *
+ * @copyright  Copyright (C) 2005 - 2016 Open Source Matters, Inc. All rights reserved.
+ * @license    GNU General Public License version 2 or later; see LICENSE
+ */
+
+namespace Joomla\Cms\Event;
+
+use Joomla\Application\AbstractApplication;
+
+defined('JPATH_PLATFORM') or die;
+
+/**
+ * Event class for representing the application's `onBeforeExecute` event
+ *
+ * @since  __DEPLOY_VERSION__
+ */
+class BeforeExecuteEvent extends AbstractImmutableEvent
+{
+	/**
+	 * Get the event's application object
+	 *
+	 * @return  AbstractApplication
+	 *
+	 * @since  __DEPLOY_VERSION__
+	 */
+	public function getApplication()
+	{
+		return $this->getArgument('subject');
+	}
+}

plugins/system/languagefilter/languagefilter.php

@@ -9,6 +9,7 @@
 
 defined('_JEXEC') or die;
 
+use Joomla\Cms\Event\BeforeExecuteEvent;
 use Joomla\Registry\Registry;
 
 JLoader::register('MenusHelper', JPATH_ADMINISTRATOR . '/components/com_menus/helpers/menus.php');
@@ -163,6 +164,30 @@ public function onAfterRoute()
 		}
 	}
 
+	/**
+	 * Listener for the onBeforeExecute event
+	 *
+	 * @param   BeforeExecuteEvent  $event
+	 *
+	 * @return  void
+	 *
+	 * @since   4.0
+	 */
+	public function onBeforeExecute(BeforeExecuteEvent $event)
+	{
+		/** @var JApplicationCms $app */
+		$app = $event->getApplication();
+
+		if (!$app->isSite())
+		{
+			return;
+		}
+
+		// If a language was specified it has priority, otherwise use user or default language settings
+		$app->setLanguageFilter(true);
+		$app->setDetectBrowser($this->params->get('detect_browser', '1') == '1');
+	}
+
 	/**
 	 * Add build preprocess rule to router.
 	 *