class EditorSelector

class EditorSelector implements EditorSelectorInterface {
    
    /**
     * The manager for editor plugins.
     *
     * @var \Drupal\Component\Plugin\PluginManagerInterface
     */
    protected $editorManager;
    
    /**
     * The manager for formatter plugins.
     *
     * @var \Drupal\Core\Field\FormatterPluginManager
     */
    protected $formatterManager;
    
    /**
     * A list of alternative editor plugin IDs, keyed by editor plugin ID.
     *
     * @var array
     */
    protected $alternatives;
    
    /**
     * Constructs a new EditorSelector.
     *
     * @param \Drupal\Component\Plugin\PluginManagerInterface $editor_manager
     *   The manager for editor plugins.
     * @param \Drupal\Core\Field\FormatterPluginManager $formatter_manager
     *   The manager for formatter plugins.
     */
    public function __construct(PluginManagerInterface $editor_manager, FormatterPluginManager $formatter_manager) {
        $this->editorManager = $editor_manager;
        $this->formatterManager = $formatter_manager;
    }
    
    /**
     * {@inheritdoc}
     */
    public function getEditor($formatter_type, FieldItemListInterface $items) {
        // Check if the formatter defines an appropriate in-place editor. For
        // example, text formatters displaying plain text can choose to use the
        // 'plain_text' editor. If the formatter doesn't specify, fall back to the
        // 'form' editor, since that can work for any field. Formatter definitions
        // can use 'disabled' to explicitly opt out of in-place editing.
        $formatter_info = $this->formatterManager
            ->getDefinition($formatter_type);
        $editor_id = $formatter_info['quickedit']['editor'];
        if ($editor_id === 'disabled') {
            return;
        }
        elseif ($editor_id === 'form') {
            return 'form';
        }
        // No early return, so create a list of all choices.
        $editor_choices = [
            $editor_id,
        ];
        if (isset($this->alternatives[$editor_id])) {
            $editor_choices = array_merge($editor_choices, $this->alternatives[$editor_id]);
        }
        // Make a choice.
        foreach ($editor_choices as $editor_id) {
            $editor = $this->editorManager
                ->createInstance($editor_id);
            if ($editor->isCompatible($items)) {
                return $editor_id;
            }
        }
        // We still don't have a choice, so fall back to the default 'form' editor.
        return 'form';
    }
    
    /**
     * {@inheritdoc}
     */
    public function getEditorAttachments(array $editor_ids) {
        $attachments = [];
        $editor_ids = array_unique($editor_ids);
        // Editor plugins' attachments.
        foreach ($editor_ids as $editor_id) {
            $editor = $this->editorManager
                ->createInstance($editor_id);
            $attachments[] = $editor->getAttachments();
        }
        return NestedArray::mergeDeepArray($attachments);
    }

}