class BlockForm

class BlockForm extends EntityForm {

  /**
   * The block entity.
   *
   * @var \Drupal\block\BlockInterface
   */
  protected $entity;

  /**
   * The block storage.
   *
   * @var \Drupal\Core\Config\Entity\ConfigEntityStorageInterface
   */
  protected $storage;

  /**
   * The condition plugin manager.
   *
   * @var \Drupal\Core\Condition\ConditionManager
   */
  protected $manager;

  /**
   * The language manager service.
   *
   * @var \Drupal\Core\Language\LanguageManagerInterface
   */
  protected $language;

  /**
   * The theme handler.
   *
   * @var \Drupal\Core\Extension\ThemeHandler
   */
  protected $themeHandler;

  /**
   * The context repository service.
   *
   * @var \Drupal\Core\Plugin\Context\ContextRepositoryInterface
   */
  protected $contextRepository;

  /**
   * The plugin form manager.
   *
   * @var \Drupal\Core\Plugin\PluginFormFactoryInterface
   */
  protected $pluginFormFactory;

  /**
   * The block repository service.
   *
   * @var \Drupal\block\BlockRepositoryInterface
   */
  protected $blockRepository;

  /**
   * Constructs a BlockForm object.
   *
   * @param \Drupal\Core\Entity\EntityTypeManagerInterface $entity_type_manager
   *   The entity type manager.
   * @param \Drupal\Core\Executable\ExecutableManagerInterface $manager
   *   The ConditionManager for building the visibility UI.
   * @param \Drupal\Core\Plugin\Context\ContextRepositoryInterface $context_repository
   *   The lazy context repository service.
   * @param \Drupal\Core\Language\LanguageManagerInterface $language
   *   The language manager.
   * @param \Drupal\Core\Extension\ThemeHandlerInterface $theme_handler
   *   The theme handler.
   * @param \Drupal\Core\Plugin\PluginFormFactoryInterface $plugin_form_manager
   *   The plugin form manager.
   * @param \Drupal\block\BlockRepositoryInterface|null $block_repository
   *   The block repository service.
   */
  public function __construct(EntityTypeManagerInterface $entity_type_manager, ExecutableManagerInterface $manager, ContextRepositoryInterface $context_repository, LanguageManagerInterface $language, ThemeHandlerInterface $theme_handler, PluginFormFactoryInterface $plugin_form_manager, ?BlockRepositoryInterface $block_repository = NULL) {
    if ($block_repository === NULL) {
      @trigger_error('Calling ' . __METHOD__ . ' without the $block_repository argument is deprecated in drupal:10.2.0 and will be required in drupal:11.0.0. See https://www.drupal.org/node/3333575', E_USER_DEPRECATED);
      $block_repository = \Drupal::service('block.repository');
    }
    $this->storage = $entity_type_manager
      ->getStorage('block');
    $this->manager = $manager;
    $this->contextRepository = $context_repository;
    $this->language = $language;
    $this->themeHandler = $theme_handler;
    $this->pluginFormFactory = $plugin_form_manager;
    $this->blockRepository = $block_repository;
  }

  /**
   * {@inheritdoc}
   */
  public static function create(ContainerInterface $container) {
    return new static($container
      ->get('entity_type.manager'), $container
      ->get('plugin.manager.condition'), $container
      ->get('context.repository'), $container
      ->get('language_manager'), $container
      ->get('theme_handler'), $container
      ->get('plugin_form.factory'), $container
      ->get('block.repository'));
  }

  /**
   * {@inheritdoc}
   */
  public function form(array $form, FormStateInterface $form_state) {
    $entity = $this->entity;

    // Store the gathered contexts in the form state for other objects to use
    // during form building.
    $form_state
      ->setTemporaryValue('gathered_contexts', $this->contextRepository
      ->getAvailableContexts());
    $form['#tree'] = TRUE;
    $form['settings'] = [];
    $subform_state = SubformState::createForSubform($form['settings'], $form, $form_state);
    $form['settings'] = $this
      ->getPluginForm($entity
      ->getPlugin())
      ->buildConfigurationForm($form['settings'], $subform_state);
    $form['visibility'] = $this
      ->buildVisibilityInterface([], $form_state);

    // If creating a new block, calculate a safe default machine name.
    $form['id'] = [
      '#type' => 'machine_name',
      '#maxlength' => 64,
      '#description' => $this
        ->t('A unique name for this block instance. Must be alpha-numeric and underscore separated.'),
      '#default_value' => !$entity
        ->isNew() ? $entity
        ->id() : $this
        ->getUniqueMachineName($entity),
      '#machine_name' => [
        'exists' => '\\Drupal\\block\\Entity\\Block::load',
        'replace_pattern' => '[^a-z0-9_.]+',
        'source' => [
          'settings',
          'label',
        ],
      ],
      '#required' => TRUE,
      '#disabled' => !$entity
        ->isNew(),
    ];

    // Theme settings.
    if ($theme = $entity
      ->getTheme()) {
      $form['theme'] = [
        '#type' => 'value',
        '#value' => $theme,
      ];
    }
    else {
      $theme = $this
        ->config('system.theme')
        ->get('default');
      $theme_options = [];
      foreach ($this->themeHandler
        ->listInfo() as $theme_name => $theme_info) {
        if (!empty($theme_info->status)) {
          $theme_options[$theme_name] = $theme_info->info['name'];
        }
      }
      $form['theme'] = [
        '#type' => 'select',
        '#options' => $theme_options,
        '#title' => $this
          ->t('Theme'),
        '#default_value' => $theme,
        '#ajax' => [
          'callback' => '::themeSwitch',
          'wrapper' => 'edit-block-region-wrapper',
        ],
      ];
    }

    // Hidden weight setting.
    $weight = $entity
      ->isNew() ? $this
      ->getRequest()->query
      ->get('weight', 0) : $entity
      ->getWeight();
    $form['weight'] = [
      '#type' => 'hidden',
      '#default_value' => $weight,
    ];

    // Region settings.
    $entity_region = $entity
      ->getRegion();
    $region = $entity
      ->isNew() ? $this
      ->getRequest()->query
      ->get('region', $entity_region) : $entity_region;
    $form['region'] = [
      '#type' => 'select',
      '#title' => $this
        ->t('Region'),
      '#description' => $this
        ->t('Select the region where this block should be displayed.'),
      '#default_value' => $region,
      '#required' => TRUE,
      '#options' => system_region_list($form_state
        ->getValue('theme', $theme), REGIONS_VISIBLE),
      '#prefix' => '<div id="edit-block-region-wrapper">',
      '#suffix' => '</div>',
    ];
    $form['#attached']['library'][] = 'block/drupal.block.admin';
    return $form;
  }

  /**
   * Handles switching the available regions based on the selected theme.
   */
  public function themeSwitch($form, FormStateInterface $form_state) {
    return $form['region'];
  }

  /**
   * Helper function for building the visibility UI form.
   *
   * @param array $form
   *   An associative array containing the structure of the form.
   * @param \Drupal\Core\Form\FormStateInterface $form_state
   *   The current state of the form.
   *
   * @return array
   *   The form array with the visibility UI added in.
   */
  protected function buildVisibilityInterface(array $form, FormStateInterface $form_state) {
    $form['visibility_tabs'] = [
      '#type' => 'vertical_tabs',
      '#title' => $this
        ->t('Visibility'),
      '#parents' => [
        'visibility_tabs',
      ],
      '#attached' => [
        'library' => [
          'block/drupal.block',
        ],
      ],
    ];

    // @todo Allow list of conditions to be configured in
    //   https://www.drupal.org/node/2284687.
    $visibility = $this->entity
      ->getVisibility();
    $definitions = $this->manager
      ->getFilteredDefinitions('block_ui', $form_state
      ->getTemporaryValue('gathered_contexts'), [
      'block' => $this->entity,
    ]);
    foreach ($definitions as $condition_id => $definition) {

      // Don't display the current theme condition.
      if ($condition_id == 'current_theme') {
        continue;
      }

      // Don't display the language condition until we have multiple languages.
      if ($condition_id == 'language' && !$this->language
        ->isMultilingual()) {
        continue;
      }

      /** @var \Drupal\Core\Condition\ConditionInterface $condition */
      $condition = $this->manager
        ->createInstance($condition_id, $visibility[$condition_id] ?? []);
      $form_state
        ->set([
        'conditions',
        $condition_id,
      ], $condition);
      $condition_form = $condition
        ->buildConfigurationForm([], $form_state);
      $condition_form['#type'] = 'details';
      $condition_form['#title'] = $condition
        ->getPluginDefinition()['label'];
      $condition_form['#group'] = 'visibility_tabs';
      $form[$condition_id] = $condition_form;
    }

    // Disable negation for specific conditions.
    $disable_negation = [
      'entity_bundle:node',
      'language',
      'response_status',
      'user_role',
    ];
    foreach ($disable_negation as $condition) {
      if (isset($form[$condition])) {
        $form[$condition]['negate']['#type'] = 'value';
        $form[$condition]['negate']['#value'] = $form[$condition]['negate']['#default_value'];
      }
    }
    if (isset($form['user_role'])) {
      $form['user_role']['#title'] = $this
        ->t('Roles');
      unset($form['user_role']['roles']['#description']);
    }
    if (isset($form['request_path'])) {
      $form['request_path']['#title'] = $this
        ->t('Pages');
      $form['request_path']['negate']['#type'] = 'radios';
      $form['request_path']['negate']['#default_value'] = (int) $form['request_path']['negate']['#default_value'];
      $form['request_path']['negate']['#title_display'] = 'invisible';
      $form['request_path']['negate']['#options'] = [
        $this
          ->t('Show for the listed pages'),
        $this
          ->t('Hide for the listed pages'),
      ];
    }
    return $form;
  }

  /**
   * {@inheritdoc}
   */
  protected function actions(array $form, FormStateInterface $form_state) {
    $actions = parent::actions($form, $form_state);
    $actions['submit']['#value'] = $this
      ->t('Save block');
    $actions['delete']['#title'] = $this
      ->t('Remove block');
    return $actions;
  }

  /**
   * {@inheritdoc}
   */
  public function validateForm(array &$form, FormStateInterface $form_state) {
    parent::validateForm($form, $form_state);
    $form_state
      ->setValue('weight', (int) $form_state
      ->getValue('weight'));

    // The Block Entity form puts all block plugin form elements in the
    // settings form element, so just pass that to the block for validation.
    $this
      ->getPluginForm($this->entity
      ->getPlugin())
      ->validateConfigurationForm($form['settings'], SubformState::createForSubform($form['settings'], $form, $form_state));
    $this
      ->validateVisibility($form, $form_state);
  }

  /**
   * Helper function to independently validate the visibility UI.
   *
   * @param array $form
   *   A nested array form elements comprising the form.
   * @param \Drupal\Core\Form\FormStateInterface $form_state
   *   The current state of the form.
   */
  protected function validateVisibility(array $form, FormStateInterface $form_state) {

    // Validate visibility condition settings.
    foreach ($form_state
      ->getValue('visibility') as $condition_id => $values) {

      // Allow the condition to validate the form.
      $condition = $form_state
        ->get([
        'conditions',
        $condition_id,
      ]);
      $condition
        ->validateConfigurationForm($form['visibility'][$condition_id], SubformState::createForSubform($form['visibility'][$condition_id], $form, $form_state));
    }
  }

  /**
   * {@inheritdoc}
   */
  public function submitForm(array &$form, FormStateInterface $form_state) {
    parent::submitForm($form, $form_state);
    $entity = $this->entity;

    // The Block Entity form puts all block plugin form elements in the
    // settings form element, so just pass that to the block for submission.
    $sub_form_state = SubformState::createForSubform($form['settings'], $form, $form_state);

    // Call the plugin submit handler.
    $block = $entity
      ->getPlugin();
    $this
      ->getPluginForm($block)
      ->submitConfigurationForm($form, $sub_form_state);

    // If this block is context-aware, set the context mapping.
    if ($block instanceof ContextAwarePluginInterface && $block
      ->getContextDefinitions()) {
      $context_mapping = $sub_form_state
        ->getValue('context_mapping', []);
      $block
        ->setContextMapping($context_mapping);
    }
    $this
      ->submitVisibility($form, $form_state);
  }

  /**
   * {@inheritdoc}
   */
  public function save(array $form, FormStateInterface $form_state) {
    $value = parent::save($form, $form_state);
    $this
      ->messenger()
      ->addStatus($this
      ->t('The block configuration has been saved.'));
    $form_state
      ->setRedirect('block.admin_display_theme', [
      'theme' => $form_state
        ->getValue('theme'),
    ], [
      'query' => [
        'block-placement' => Html::getClass($this->entity
          ->id()),
      ],
    ]);
    return $value;
  }

  /**
   * Helper function to independently submit the visibility UI.
   *
   * @param array $form
   *   A nested array form elements comprising the form.
   * @param \Drupal\Core\Form\FormStateInterface $form_state
   *   The current state of the form.
   */
  protected function submitVisibility(array $form, FormStateInterface $form_state) {
    foreach ($form_state
      ->getValue('visibility') as $condition_id => $values) {

      // Allow the condition to submit the form.
      $condition = $form_state
        ->get([
        'conditions',
        $condition_id,
      ]);
      $condition
        ->submitConfigurationForm($form['visibility'][$condition_id], SubformState::createForSubform($form['visibility'][$condition_id], $form, $form_state));
      $condition_configuration = $condition
        ->getConfiguration();

      // Update the visibility conditions on the block.
      $this->entity
        ->getVisibilityConditions()
        ->addInstanceId($condition_id, $condition_configuration);
    }
  }

  /**
   * Generates a unique machine name for a block based on a suggested string.
   *
   * @param \Drupal\block\BlockInterface $block
   *   The block entity.
   *
   * @return string
   *   Returns the unique name.
   */
  public function getUniqueMachineName(BlockInterface $block) {
    $suggestion = $block
      ->getPlugin()
      ->getMachineNameSuggestion();
    return $this->blockRepository
      ->getUniqueMachineName($suggestion, $block
      ->getTheme());
  }

  /**
   * Retrieves the plugin form for a given block and operation.
   *
   * @param \Drupal\Core\Block\BlockPluginInterface $block
   *   The block plugin.
   *
   * @return \Drupal\Core\Plugin\PluginFormInterface
   *   The plugin form for the block.
   */
  protected function getPluginForm(BlockPluginInterface $block) {
    if ($block instanceof PluginWithFormsInterface) {
      return $this->pluginFormFactory
        ->createInstance($block, 'configure');
    }
    return $block;
  }

}