LanguageNegotiationBrowser.php

<?php

namespace Drupal\language\Plugin\LanguageNegotiation;

use Drupal\Component\Utility\UserAgent;
use Drupal\Core\Plugin\ContainerFactoryPluginInterface;
use Drupal\Core\StringTranslation\TranslatableMarkup;
use Drupal\language\Attribute\LanguageNegotiation;
use Drupal\language\LanguageNegotiationMethodBase;
use Symfony\Component\DependencyInjection\ContainerInterface;
use Symfony\Component\HttpFoundation\Request;

/**
 * Class for identifying language from the browser Accept-language HTTP header.
 */
class LanguageNegotiationBrowser extends LanguageNegotiationMethodBase implements ContainerFactoryPluginInterface {
  
  /**
   * The language negotiation method id.
   */
  const METHOD_ID = 'language-browser';
  
  /**
   * The page cache disabling policy.
   *
   * @var \Drupal\Core\PageCache\ResponsePolicy\KillSwitch
   */
  protected $pageCacheKillSwitch;
  
  /**
   * {@inheritdoc}
   */
  public static function create(ContainerInterface $container, array $configuration, $plugin_id, $plugin_definition) {
    $instance = new static();
    $instance->pageCacheKillSwitch = $container->get('page_cache_kill_switch');
    return $instance;
  }
  
  /**
   * {@inheritdoc}
   */
  public function getLangcode(?Request $request = NULL) {
    $langcode = NULL;
    if ($this->languageManager && $request && $request->server
      ->get('HTTP_ACCEPT_LANGUAGE')) {
      $http_accept_language = $request->server
        ->get('HTTP_ACCEPT_LANGUAGE');
      $langcodes = array_keys($this->languageManager
        ->getLanguages());
      $mappings = $this->config
        ->get('language.mappings')
        ->get('map');
      $langcode = UserAgent::getBestMatchingLangcode($http_accept_language, $langcodes, $mappings);
    }
    // Internal page cache with multiple languages and browser negotiation
    // could lead to wrong cached sites. Therefore disabling the internal page
    // cache.
    // @todo Solve more elegantly in https://www.drupal.org/node/2430335.
    $this->pageCacheKillSwitch
      ->trigger();
    return $langcode;
  }

}