<?php

namespace Drupal\Core\Field\Plugin\Field\FieldWidget;

use Drupal\Core\Field\Attribute\FieldWidget;
use Drupal\Core\Field\FieldItemListInterface;
use Drupal\Core\Form\FormStateInterface;
use Drupal\Core\StringTranslation\TranslatableMarkup;

/**
 * Plugin implementation of the 'options_buttons' widget.
 */
#[FieldWidget(
  id: 'options_buttons',
  label: new TranslatableMarkup('Check boxes/radio buttons'),
  field_types: [
    'boolean',
    'entity_reference',
    'list_integer',
    'list_float',
    'list_string',
  ],
  multiple_values: TRUE,
)]
class OptionsButtonsWidget extends OptionsWidgetBase {

  /**
   * {@inheritdoc}
   */
  public function formElement(FieldItemListInterface $items, $delta, array $element, array &$form, FormStateInterface $form_state) {
    $element = parent::formElement($items, $delta, $element, $form, $form_state);

    $options = $this->getOptions($items->getEntity());
    $selected = $this->getSelectedOptions($items);

    // If required and there is one single option, preselect it.
    if ($this->required && count($options) == 1) {
      $selected = [array_key_first($options)];
    }

    if ($this->multiple) {
      $element += [
        '#type' => 'checkboxes',
        '#default_value' => $selected,
        '#options' => $options,
      ];
    }
    else {
      $element += [
        '#type' => 'radios',
        // Radio buttons need a scalar value. Take the first default value, or
        // default to NULL so that the form element is properly recognized as
        // not having a default value.
        '#default_value' => $selected ? reset($selected) : NULL,
        '#options' => $options,
      ];
    }

    return $element;
  }

  /**
   * {@inheritdoc}
   */
  protected function getEmptyLabel() {
    if (!$this->required && !$this->multiple) {
      return $this->t('N/A');
    }
  }

}
