class BlockContent

class BlockContent extends EditorialContentEntityBase implements BlockContentInterface {
    use RefinableDependentAccessTrait;
    
    /**
     * The theme the block is being created in.
     *
     * When creating a new content block from the block library, the user is
     * redirected to the configure form for that block in the given theme. The
     * theme is stored against the block when the content block add form is shown.
     *
     * @var string
     */
    protected $theme;
    
    /**
     * {@inheritdoc}
     */
    public function createDuplicate() {
        $duplicate = parent::createDuplicate();
        $duplicate->revision_id->value = NULL;
        $duplicate->id->value = NULL;
        return $duplicate;
    }
    
    /**
     * {@inheritdoc}
     */
    public function setTheme($theme) {
        $this->theme = $theme;
        return $this;
    }
    
    /**
     * {@inheritdoc}
     */
    public function getTheme() {
        return $this->theme;
    }
    
    /**
     * {@inheritdoc}
     */
    public function postSave(EntityStorageInterface $storage, $update = TRUE) {
        parent::postSave($storage, $update);
        if ($this->isReusable() || isset($this->original) && $this->original
            ->isReusable()) {
            static::invalidateBlockPluginCache();
        }
    }
    
    /**
     * {@inheritdoc}
     */
    public static function preDelete(EntityStorageInterface $storage, array $entities) {
        parent::preDelete($storage, $entities);
        
        /** @var \Drupal\block_content\BlockContentInterface $block */
        foreach ($entities as $block) {
            foreach ($block->getInstances() as $instance) {
                $instance->delete();
            }
        }
    }
    
    /**
     * {@inheritdoc}
     */
    public static function postDelete(EntityStorageInterface $storage, array $entities) {
        parent::postDelete($storage, $entities);
        
        /** @var \Drupal\block_content\BlockContentInterface $block */
        foreach ($entities as $block) {
            if ($block->isReusable()) {
                // If any deleted blocks are reusable clear the block cache.
                static::invalidateBlockPluginCache();
                return;
            }
        }
    }
    
    /**
     * {@inheritdoc}
     */
    public function getInstances() {
        return \Drupal::entityTypeManager()->getStorage('block')
            ->loadByProperties([
            'plugin' => 'block_content:' . $this->uuid(),
        ]);
    }
    
    /**
     * {@inheritdoc}
     */
    public function preSaveRevision(EntityStorageInterface $storage, \stdClass $record) {
        parent::preSaveRevision($storage, $record);
        if (!$this->isNewRevision() && isset($this->original) && empty($record->revision_log_message)) {
            // If we are updating an existing block_content without adding a new
            // revision and the user did not supply a revision log, keep the existing
            // one.
            $record->revision_log = $this->original
                ->getRevisionLogMessage();
        }
    }
    
    /**
     * {@inheritdoc}
     */
    public static function baseFieldDefinitions(EntityTypeInterface $entity_type) {
        
        /** @var \Drupal\Core\Field\BaseFieldDefinition[] $fields */
        $fields = parent::baseFieldDefinitions($entity_type);
        $fields['id']->setLabel(t('Content block ID'))
            ->setDescription(t('The content block ID.'));
        $fields['uuid']->setDescription(t('The content block UUID.'));
        $fields['revision_id']->setDescription(t('The revision ID.'));
        $fields['langcode']->setDescription(t('The content block language code.'));
        $fields['type']->setLabel(t('Block type'))
            ->setDescription(t('The block type.'));
        $fields['revision_log']->setDescription(t('The log entry explaining the changes in this revision.'));
        $fields['info'] = BaseFieldDefinition::create('string')->setLabel(t('Block description'))
            ->setDescription(t('A brief description of your block.'))
            ->setRevisionable(TRUE)
            ->setTranslatable(TRUE)
            ->setRequired(TRUE)
            ->setDisplayOptions('form', [
            'type' => 'string_textfield',
            'weight' => -5,
        ])
            ->setDisplayConfigurable('form', TRUE);
        $fields['changed'] = BaseFieldDefinition::create('changed')->setLabel(t('Changed'))
            ->setDescription(t('The time that the content block was last edited.'))
            ->setTranslatable(TRUE)
            ->setRevisionable(TRUE);
        $fields['reusable'] = BaseFieldDefinition::create('boolean')->setLabel(t('Reusable'))
            ->setDescription(t('A boolean indicating whether this block is reusable.'))
            ->setTranslatable(FALSE)
            ->setRevisionable(FALSE)
            ->setDefaultValue(TRUE);
        return $fields;
    }
    
    /**
     * {@inheritdoc}
     */
    public function setInfo($info) {
        $this->set('info', $info);
        return $this;
    }
    
    /**
     * {@inheritdoc}
     */
    public function isReusable() {
        return (bool) $this->get('reusable')->value;
    }
    
    /**
     * {@inheritdoc}
     */
    public function setReusable() {
        return $this->set('reusable', TRUE);
    }
    
    /**
     * {@inheritdoc}
     */
    public function setNonReusable() {
        return $this->set('reusable', FALSE);
    }
    
    /**
     * Invalidates the block plugin cache after changes and deletions.
     */
    protected static function invalidateBlockPluginCache() {
        // Invalidate the block cache to update content block-based derivatives.
        \Drupal::service('plugin.manager.block')->clearCachedDefinitions();
    }

}