class InlineBlock

class InlineBlock extends BlockBase implements ContainerFactoryPluginInterface, RefinableDependentAccessInterface {
  use RefinableDependentAccessTrait;

  /**
   * The entity type manager.
   *
   * @var \Drupal\Core\Entity\EntityTypeManagerInterface
   */
  protected $entityTypeManager;

  /**
   * The block content entity.
   *
   * @var \Drupal\block_content\BlockContentInterface
   */
  protected $blockContent;

  /**
   * The entity display repository.
   *
   * @var \Drupal\Core\Entity\EntityDisplayRepositoryInterface
   */
  protected $entityDisplayRepository;

  /**
   * Whether a new block is being created.
   *
   * @var bool
   */
  protected $isNew = TRUE;

  /**
   * The current user.
   *
   * @var \Drupal\Core\Session\AccountInterface
   */
  protected $currentUser;

  /**
   * Constructs a new InlineBlock.
   *
   * @param array $configuration
   *   A configuration array containing information about the plugin instance.
   * @param string $plugin_id
   *   The plugin ID for the plugin instance.
   * @param mixed $plugin_definition
   *   The plugin implementation definition.
   * @param \Drupal\Core\Entity\EntityTypeManagerInterface $entity_type_manager
   *   The entity type manager service.
   * @param \Drupal\Core\Entity\EntityDisplayRepositoryInterface $entity_display_repository
   *   The entity display repository.
   * @param \Drupal\Core\Session\AccountInterface $current_user
   *   The current user.
   */
  public function __construct(array $configuration, $plugin_id, $plugin_definition, EntityTypeManagerInterface $entity_type_manager, EntityDisplayRepositoryInterface $entity_display_repository, AccountInterface $current_user) {
    parent::__construct($configuration, $plugin_id, $plugin_definition);
    $this->entityTypeManager = $entity_type_manager;
    $this->entityDisplayRepository = $entity_display_repository;
    $this->currentUser = $current_user;
    if (!empty($this->configuration['block_revision_id']) || !empty($this->configuration['block_serialized'])) {
      $this->isNew = FALSE;
    }
  }

  /**
   * {@inheritdoc}
   */
  public static function create(ContainerInterface $container, array $configuration, $plugin_id, $plugin_definition) {
    return new static($configuration, $plugin_id, $plugin_definition, $container
      ->get('entity_type.manager'), $container
      ->get('entity_display.repository'), $container
      ->get('current_user'));
  }

  /**
   * {@inheritdoc}
   */
  public function defaultConfiguration() {
    return [
      'view_mode' => 'full',
      'block_id' => NULL,
      'block_revision_id' => NULL,
      'block_serialized' => NULL,
    ];
  }

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

    // Add the entity form display in a process callback so that #parents can
    // be successfully propagated to field widgets.
    $form['block_form'] = [
      '#type' => 'container',
      '#process' => [
        [
          static::class,
          'processBlockForm',
        ],
      ],
      '#block' => $block,
      '#access' => $this->currentUser
        ->hasPermission('create and edit custom blocks'),
    ];
    $options = $this->entityDisplayRepository
      ->getViewModeOptionsByBundle('block_content', $block
      ->bundle());
    $form['view_mode'] = [
      '#type' => 'select',
      '#options' => $options,
      '#title' => $this
        ->t('View mode'),
      '#description' => $this
        ->t('The view mode in which to render the block.'),
      '#default_value' => $this->configuration['view_mode'],
      '#access' => count($options) > 1,
    ];
    return $form;
  }

  /**
   * Process callback to insert a Content Block form.
   *
   * @param array $element
   *   The containing element.
   * @param \Drupal\Core\Form\FormStateInterface $form_state
   *   The form state.
   *
   * @return array
   *   The containing element, with the Content Block form inserted.
   */
  public static function processBlockForm(array $element, FormStateInterface $form_state) {

    /** @var \Drupal\block_content\BlockContentInterface $block */
    $block = $element['#block'];
    EntityFormDisplay::collectRenderDisplay($block, 'edit')
      ->buildForm($block, $element, $form_state);
    $element['revision_log']['#access'] = FALSE;
    $element['info']['#access'] = FALSE;
    return $element;
  }

  /**
   * {@inheritdoc}
   */
  public function blockValidate($form, FormStateInterface $form_state) {
    $block_form = $form['block_form'];

    /** @var \Drupal\block_content\BlockContentInterface $block */
    $block = $block_form['#block'];
    $form_display = EntityFormDisplay::collectRenderDisplay($block, 'edit');
    $complete_form_state = $form_state instanceof SubformStateInterface ? $form_state
      ->getCompleteFormState() : $form_state;
    $form_display
      ->extractFormValues($block, $block_form, $complete_form_state);
    $form_display
      ->validateFormValues($block, $block_form, $complete_form_state);

    // @todo Remove when https://www.drupal.org/project/drupal/issues/2948549 is closed.
    $form_state
      ->setTemporaryValue('block_form_parents', $block_form['#parents']);
  }

  /**
   * {@inheritdoc}
   */
  public function blockSubmit($form, FormStateInterface $form_state) {
    $this->configuration['view_mode'] = $form_state
      ->getValue('view_mode');

    // @todo Remove when https://www.drupal.org/project/drupal/issues/2948549 is closed.
    $block_form = NestedArray::getValue($form, $form_state
      ->getTemporaryValue('block_form_parents'));

    /** @var \Drupal\block_content\BlockContentInterface $block */
    $block = $block_form['#block'];
    $form_display = EntityFormDisplay::collectRenderDisplay($block, 'edit');
    $complete_form_state = $form_state instanceof SubformStateInterface ? $form_state
      ->getCompleteFormState() : $form_state;
    $form_display
      ->extractFormValues($block, $block_form, $complete_form_state);
    $block
      ->setInfo($this->configuration['label']);
    $this->configuration['block_serialized'] = serialize($block);
  }

  /**
   * {@inheritdoc}
   */
  protected function blockAccess(AccountInterface $account) {
    if ($entity = $this
      ->getEntity()) {
      return $entity
        ->access('view', $account, TRUE);
    }
    return AccessResult::forbidden();
  }

  /**
   * {@inheritdoc}
   */
  public function build() {
    $block = $this
      ->getEntity();
    return $this->entityTypeManager
      ->getViewBuilder($block
      ->getEntityTypeId())
      ->view($block, $this->configuration['view_mode']);
  }

  /**
   * Loads or creates the block content entity of the block.
   *
   * @return \Drupal\block_content\BlockContentInterface
   *   The block content entity.
   */
  protected function getEntity() {
    if (!isset($this->blockContent)) {
      if (!empty($this->configuration['block_serialized'])) {
        $this->blockContent = unserialize($this->configuration['block_serialized']);
      }
      elseif (!empty($this->configuration['block_revision_id'])) {
        $entity = $this->entityTypeManager
          ->getStorage('block_content')
          ->loadRevision($this->configuration['block_revision_id']);
        $this->blockContent = $entity;
      }
      else {
        $this->blockContent = $this->entityTypeManager
          ->getStorage('block_content')
          ->create([
          'type' => $this
            ->getDerivativeId(),
          'reusable' => FALSE,
        ]);
      }
      if ($this->blockContent instanceof RefinableDependentAccessInterface && ($dependee = $this
        ->getAccessDependency())) {
        $this->blockContent
          ->setAccessDependency($dependee);
      }
    }
    return $this->blockContent;
  }

  /**
   * {@inheritdoc}
   */
  public function buildConfigurationForm(array $form, FormStateInterface $form_state) {
    $form = parent::buildConfigurationForm($form, $form_state);
    if ($this->isNew) {

      // If the Content Block is new then don't provide a default label.
      unset($form['label']['#default_value']);
    }
    $form['label']['#description'] = $this
      ->t('The title of the block as shown to the user.');
    return $form;
  }

  /**
   * Saves the block_content entity for this plugin.
   *
   * @param bool $new_revision
   *   Whether to create new revision, if the block was modified.
   * @param bool $duplicate_block
   *   Whether to duplicate the "block_content" entity.
   */
  public function saveBlockContent($new_revision = FALSE, $duplicate_block = FALSE) {

    /** @var \Drupal\block_content\BlockContentInterface $block */
    $block = NULL;
    if (!empty($this->configuration['block_serialized'])) {
      $block = unserialize($this->configuration['block_serialized']);
    }
    if ($duplicate_block) {
      if (empty($block) && !empty($this->configuration['block_revision_id'])) {
        $block = $this->entityTypeManager
          ->getStorage('block_content')
          ->loadRevision($this->configuration['block_revision_id']);
      }
      if ($block) {
        $block = $block
          ->createDuplicate();
      }
    }
    if ($block) {

      // Since the content block is only set if it was unserialized, the flag
      // will only effect blocks which were modified or serialized originally.
      if ($new_revision) {
        $block
          ->setNewRevision();
      }
      $block
        ->save();
      $this->configuration['block_id'] = $block
        ->id();
      $this->configuration['block_revision_id'] = $block
        ->getRevisionId();
      $this->configuration['block_serialized'] = NULL;
    }
  }

}