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_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 Custom 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 Custom 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 custom 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_revision_id'] = $block->getRevisionId();
            $this->configuration['block_serialized'] = NULL;
        }
    }

}