class LanguageNegotiationContentEntity

class LanguageNegotiationContentEntity extends LanguageNegotiationMethodBase implements OutboundPathProcessorInterface, LanguageSwitcherInterface, ContainerFactoryPluginInterface {
    
    /**
     * The language negotiation method ID.
     */
    const METHOD_ID = 'language-content-entity';
    
    /**
     * The query string parameter.
     */
    const QUERY_PARAMETER = 'language_content_entity';
    
    /**
     * A list of all the link paths of enabled content entities.
     *
     * @var array
     */
    protected $contentEntityPaths;
    
    /**
     * Static cache for the language negotiation order check.
     *
     * @see \Drupal\language\Plugin\LanguageNegotiation\LanguageNegotiationContentEntity::hasLowerLanguageNegotiationWeight()
     *
     * @var bool
     */
    protected $hasLowerLanguageNegotiationWeightResult;
    
    /**
     * Static cache of outbound route paths per request.
     *
     * @var \SplObjectStorage
     */
    protected $paths;
    
    /**
     * The entity type manager.
     *
     * @var \Drupal\Core\Entity\EntityTypeManagerInterface
     */
    protected $entityTypeManager;
    
    /**
     * Constructs a new LanguageNegotiationContentEntity instance.
     *
     * @param \Drupal\Core\Entity\EntityTypeManagerInterface $entity_type_manager
     *   The entity type manager.
     */
    public function __construct(EntityTypeManagerInterface $entity_type_manager) {
        $this->entityTypeManager = $entity_type_manager;
        $this->paths = new \SplObjectStorage();
    }
    
    /**
     * {@inheritdoc}
     */
    public static function create(ContainerInterface $container, array $configuration, $plugin_id, $plugin_definition) {
        return new static($container->get('entity_type.manager'));
    }
    
    /**
     * {@inheritdoc}
     */
    public function getLangcode(?Request $request = NULL) {
        if ($request === NULL || $this->languageManager === NULL) {
            return NULL;
        }
        $langcode = $request->query
            ->get(static::QUERY_PARAMETER);
        $language_enabled = array_key_exists($langcode, $this->languageManager
            ->getLanguages());
        return $language_enabled ? $langcode : NULL;
    }
    
    /**
     * {@inheritdoc}
     */
    public function processOutbound($path, &$options = [], ?Request $request = NULL, ?BubbleableMetadata $bubbleable_metadata = NULL) {
        // If appropriate, process outbound to add a query parameter to the URL and
        // remove the language option, so that URL negotiator does not rewrite the
        // URL.
        // First, check if processing conditions are met.
        if (!($request && !empty($options['route']) && $this->hasLowerLanguageNegotiationWeight() && $this->meetsContentEntityRoutesCondition($options['route'], $request))) {
            return $path;
        }
        if (isset($options['language']) || ($langcode = $this->getLangcode($request))) {
            // If the language option is set, unset it, so that the URL language
            // negotiator does not rewrite the URL.
            if (isset($options['language'])) {
                $langcode = $options['language']->getId();
                unset($options['language']);
            }
            if (!isset($options['query'][static::QUERY_PARAMETER])) {
                $options['query'][static::QUERY_PARAMETER] = $langcode;
            }
            if ($bubbleable_metadata) {
                // Cached URLs that have been processed by this outbound path
                // processor must be:
                $bubbleable_metadata->addCacheContexts([
                    'url.query_args:' . static::QUERY_PARAMETER,
                ]);
            }
        }
        return $path;
    }
    
    /**
     * {@inheritdoc}
     */
    public function getLanguageSwitchLinks(Request $request, $type, Url $url) {
        $links = [];
        $query = [];
        parse_str($request->getQueryString() ?? '', $query);
        foreach ($this->languageManager
            ->getNativeLanguages() as $language) {
            $langcode = $language->getId();
            $query[static::QUERY_PARAMETER] = $langcode;
            $links[$langcode] = [
                'url' => $url,
                'title' => $language->getName(),
                'attributes' => [
                    'class' => [
                        'language-link',
                    ],
                ],
                'query' => $query,
            ];
        }
        return $links;
    }
    
    /**
     * Determines if content entity language negotiator has higher priority.
     *
     * The content entity language negotiator having higher priority than the URL
     * language negotiator, is a criteria in
     * \Drupal\language\Plugin\LanguageNegotiation\LanguageNegotiationContentEntity::processOutbound().
     *
     * @return bool
     *   TRUE if the content entity language negotiator has higher priority than
     *   the URL language negotiator, FALSE otherwise.
     */
    protected function hasLowerLanguageNegotiationWeight() {
        if (!isset($this->hasLowerLanguageNegotiationWeightResult)) {
            // Only run if the LanguageNegotiationContentEntity outbound function is
            // being executed before the outbound function of LanguageNegotiationUrl.
            $content_method_weights = $this->config
                ->get('language.types')
                ->get('negotiation.language_content.enabled') ?: [];
            // Check if the content language is configured to be dependent on the
            // URL negotiator directly or indirectly over the interface negotiator.
            if (isset($content_method_weights[LanguageNegotiationUrl::METHOD_ID]) && $content_method_weights[static::METHOD_ID] > $content_method_weights[LanguageNegotiationUrl::METHOD_ID]) {
                $this->hasLowerLanguageNegotiationWeightResult = FALSE;
            }
            else {
                $check_interface_method = FALSE;
                if (isset($content_method_weights[LanguageNegotiationUI::METHOD_ID])) {
                    $interface_method_weights = $this->config
                        ->get('language.types')
                        ->get('negotiation.language_interface.enabled') ?: [];
                    $check_interface_method = isset($interface_method_weights[LanguageNegotiationUrl::METHOD_ID]);
                }
                if ($check_interface_method) {
                    $max_weight = $content_method_weights[LanguageNegotiationUI::METHOD_ID];
                    $max_weight = isset($content_method_weights[LanguageNegotiationUrl::METHOD_ID]) ? max($max_weight, $content_method_weights[LanguageNegotiationUrl::METHOD_ID]) : $max_weight;
                }
                else {
                    $max_weight = $content_method_weights[LanguageNegotiationUrl::METHOD_ID] ?? PHP_INT_MAX;
                }
                $this->hasLowerLanguageNegotiationWeightResult = $content_method_weights[static::METHOD_ID] < $max_weight;
            }
        }
        return $this->hasLowerLanguageNegotiationWeightResult;
    }
    
    /**
     * Determines if content entity route condition is met.
     *
     * Requirements: currently being on a content entity route and processing
     * outbound URL pointing to the same content entity.
     *
     * @param \Symfony\Component\Routing\Route $outbound_route
     *   The route object for the current outbound URL being processed.
     * @param \Symfony\Component\HttpFoundation\Request $request
     *   The HttpRequest object representing the current request.
     *
     * @return bool
     *   TRUE if the content entity route condition is met, FALSE otherwise.
     */
    protected function meetsContentEntityRoutesCondition(Route $outbound_route, Request $request) {
        $outbound_path_pattern = $outbound_route->getPath();
        $storage = $this->paths[$request] ?? [];
        if (!isset($storage[$outbound_path_pattern])) {
            $storage[$outbound_path_pattern] = FALSE;
            // Check if the outbound route points to the current entity.
            if ($content_entity_type_id_for_current_route = $this->getContentEntityTypeIdForCurrentRequest($request)) {
                if (!empty($this->getContentEntityPaths()[$outbound_path_pattern]) && $content_entity_type_id_for_current_route == $this->getContentEntityPaths()[$outbound_path_pattern]) {
                    $storage[$outbound_path_pattern] = TRUE;
                }
            }
            $this->paths[$request] = $storage;
        }
        return $storage[$outbound_path_pattern];
    }
    
    /**
     * Returns the content entity type ID from the current request for the route.
     *
     * @param \Symfony\Component\HttpFoundation\Request $request
     *   The HttpRequest object representing the current request.
     *
     * @return string
     *   The entity type ID for the route from the request.
     */
    protected function getContentEntityTypeIdForCurrentRequest(Request $request) {
        $content_entity_type_id_for_current_route = '';
        if ($current_route = $request->attributes
            ->get(RouteObjectInterface::ROUTE_OBJECT)) {
            $current_route_path = $current_route->getPath();
            $content_entity_type_id_for_current_route = $this->getContentEntityPaths()[$current_route_path] ?? '';
        }
        return $content_entity_type_id_for_current_route;
    }
    
    /**
     * Returns the paths for the link templates of all content entities.
     *
     * @return array
     *   An array of all content entity type IDs, keyed by the corresponding link
     *   template paths.
     */
    protected function getContentEntityPaths() {
        if (!isset($this->contentEntityPaths)) {
            $this->contentEntityPaths = [];
            $entity_types = $this->entityTypeManager
                ->getDefinitions();
            foreach ($entity_types as $entity_type_id => $entity_type) {
                if ($entity_type->entityClassImplements(ContentEntityInterface::class)) {
                    $entity_paths = array_fill_keys($entity_type->getLinkTemplates(), $entity_type_id);
                    $this->contentEntityPaths = array_merge($this->contentEntityPaths, $entity_paths);
                }
            }
        }
        return $this->contentEntityPaths;
    }

}