class EntityTypeInfo

class EntityTypeInfo implements ContainerInjectionInterface {
    use StringTranslationTrait;
    
    /**
     * The current user.
     *
     * @var \Drupal\Core\Session\AccountInterface
     */
    protected $currentUser;
    
    /**
     * EntityTypeInfo constructor.
     *
     * @param \Drupal\Core\Session\AccountInterface $current_user
     *   Current user.
     */
    public function __construct(AccountInterface $current_user) {
        $this->currentUser = $current_user;
    }
    
    /**
     * {@inheritdoc}
     */
    public static function create(ContainerInterface $container) {
        return new static($container->get('current_user'));
    }
    
    /**
     * Adds devel links to appropriate entity types.
     *
     * This is an alter hook bridge.
     *
     * @param \Drupal\Core\Entity\EntityTypeInterface[] $entity_types
     *   The master entity type list to alter.
     *
     * @see hook_entity_type_alter()
     */
    public function entityTypeAlter(array &$entity_types) {
        foreach ($entity_types as $entity_type_id => $entity_type) {
            if (($entity_type->getFormClass('default') || $entity_type->getFormClass('edit')) && $entity_type->hasLinkTemplate('edit-form')) {
                // We use edit-form template to extract and set additional parameters
                // dynamically.
                $entity_link = $entity_type->getLinkTemplate('edit-form');
                $this->setEntityTypeLinkTemplate($entity_type, $entity_link, 'devel-load', "/devel/{$entity_type_id}", $entity_link);
            }
            if ($entity_type->hasViewBuilderClass() && $entity_type->hasLinkTemplate('canonical')) {
                // We use canonical template to extract and set additional parameters
                // dynamically.
                $entity_link = $entity_type->getLinkTemplate('canonical');
                $this->setEntityTypeLinkTemplate($entity_type, $entity_link, 'devel-render', "/devel/render/{$entity_type_id}", 'canonical');
            }
            if ($entity_type->hasLinkTemplate('devel-render') || $entity_type->hasLinkTemplate('devel-load')) {
                // We use canonical or edit-form template to extract and set additional
                // parameters dynamically.
                $entity_link = $entity_type->getLinkTemplate('edit-form');
                if (empty($entity_link)) {
                    $entity_link = $entity_type->getLinkTemplate('canonical');
                }
                $this->setEntityTypeLinkTemplate($entity_type, $entity_link, 'devel-definition', "/devel/definition/{$entity_type_id}");
            }
        }
    }
    
    /**
     * Sets entity type link template.
     *
     * @param \Drupal\Core\Entity\EntityTypeInterface $entity_type
     *   Entity type.
     * @param string $entity_link
     *   Entity link.
     * @param string $devel_link_key
     *   Devel link key.
     * @param string $base_path
     *   Base path for devel link key.
     */
    protected function setEntityTypeLinkTemplate(EntityTypeInterface $entity_type, $entity_link, $devel_link_key, $base_path) {
        // Extract all route parameters from the given template and set them to
        // the current template.
        // Some entity templates can contain not only entity id,
        // for example /user/{user}/documents/{document}
        // /group/{group}/content/{group_content}
        // We use canonical or edit-form templates to get these parameters and set
        // them for devel entity link templates.
        $path_parts = $this->getPathParts($entity_link);
        $entity_type->setLinkTemplate($devel_link_key, $base_path . $path_parts);
    }
    
    /**
     * Get path parts.
     *
     * @param string $entity_path
     *   Entity path.
     *
     * @return string
     *   Path parts.
     */
    protected function getPathParts($entity_path) {
        $path = '';
        if (preg_match_all('/{\\w*}/', $entity_path, $matches)) {
            foreach ($matches[0] as $match) {
                $path .= "/{$match}";
            }
        }
        return $path;
    }
    
    /**
     * Adds devel operations on entity that supports it.
     *
     * @param \Drupal\Core\Entity\EntityInterface $entity
     *   The entity on which to define an operation.
     *
     * @return array
     *   An array of operation definitions.
     *
     * @see hook_entity_operation()
     */
    public function entityOperation(EntityInterface $entity) {
        $operations = [];
        if ($this->currentUser
            ->hasPermission('access devel information')) {
            if ($entity->hasLinkTemplate('devel-load')) {
                $operations['devel'] = [
                    'title' => $this->t('Devel'),
                    'weight' => 100,
                    'url' => $entity->toUrl('devel-load'),
                ];
            }
            elseif ($entity->hasLinkTemplate('devel-render')) {
                $operations['devel'] = [
                    'title' => $this->t('Devel'),
                    'weight' => 100,
                    'url' => $entity->toUrl('devel-render'),
                ];
            }
        }
        return $operations;
    }

}