class GalleryIdHelper

class GalleryIdHelper {
    
    /**
     * The Gallery Token.
     *
     * @var null
     */
    protected $galleryToken = NULL;
    
    /**
     * The Configuration Factory.
     *
     * @var \Drupal\Core\Config\ConfigFactoryInterface
     */
    protected $configFactory;
    
    /**
     * The Token.
     *
     * @var \Drupal\Core\Utility\Token
     */
    protected $token;
    
    /**
     * GalleryIdHelper constructor.
     *
     * @param \Drupal\Core\Config\ConfigFactoryInterface $configFactory
     *   The Configuration Factory.
     * @param \Drupal\Core\Utility\Token $token
     *   The Token.
     */
    public function __construct(ConfigFactoryInterface $configFactory, Token $token) {
        $this->configFactory = $configFactory;
        $this->token = $token;
    }
    
    /**
     * Generate ID.
     *
     * @param \Drupal\Core\Entity\ContentEntityInterface $entity
     *   The Entity.
     * @param \Drupal\Core\Field\FieldItemInterface $item
     *   The Item.
     * @param array $settings
     *   The Settings.
     *
     * @return string
     *   Return string.
     */
    public function generateId(ContentEntityInterface $entity, FieldItemInterface $item, array $settings) {
        $entity_bundle = $entity->bundle();
        $entity_type = $entity->getEntityTypeId();
        $config = $this->configFactory
            ->get('colorbox.settings');
        // Build the gallery id.
        $id = $entity->id();
        $entity_id = !empty($id) ? $entity_bundle . '-' . $id : 'entity-id';
        $field_name = $item->getParent()
            ->getName();
        switch ($settings['colorbox_gallery']) {
            case 'post':
                $gallery_id = 'gallery-' . $entity_id;
                break;
            case 'page':
                $gallery_id = 'gallery-all';
                break;
            case 'field_post':
                $gallery_id = 'gallery-' . $entity_id . '-' . $field_name;
                break;
            case 'field_page':
                $gallery_id = 'gallery-' . $field_name;
                break;
            case 'custom':
                $gallery_id = $this->token
                    ->replace($settings['colorbox_gallery_custom'], [
                    $entity_type => $entity,
                    'file' => $item,
                ], [
                    'clear' => TRUE,
                ]);
                break;
            default:
                $gallery_id = '';
        }
        // If gallery id is not empty add unique per-request token to avoid.
        // images being added manually to galleries.
        if (!empty($gallery_id) && $config->get('advanced.unique_token')) {
            // Check if gallery token has already been set, we need to reuse.
            // the token for the whole request.
            if (is_null($this->galleryToken)) {
                // We use a short token since randomness is not critical.
                $this->galleryToken = Crypt::randomBytesBase64(8);
            }
            $gallery_id = $gallery_id . '-' . $this->galleryToken;
        }
        return $gallery_id;
    }

}