class BlockContentHooks

class BlockContentHooks {
    
    /**
     * Implements hook_help().
     */
    public function help($route_name, RouteMatchInterface $route_match) {
        switch ($route_name) {
            case 'help.page.block_content':
                $field_ui = \Drupal::moduleHandler()->moduleExists('field_ui') ? Url::fromRoute('help.page', [
                    'name' => 'field_ui',
                ])->toString() : '#';
                $output = '';
                $output .= '<h2>' . t('About') . '</h2>';
                $output .= '<p>' . t('The Block Content module allows you to create and manage custom <em>block types</em> and <em>content-containing blocks</em>. For more information, see the <a href=":online-help">online documentation for the Block Content module</a>.', [
                    ':online-help' => 'https://www.drupal.org/documentation/modules/block_content',
                ]) . '</p>';
                $output .= '<h2>' . t('Uses') . '</h2>';
                $output .= '<dl>';
                $output .= '<dt>' . t('Creating and managing block types') . '</dt>';
                $output .= '<dd>' . t('Users with the <em>Administer blocks</em> permission can create and edit block types with fields and display settings, from the <a href=":types">Block types</a> page under the Structure menu. For more information about managing fields and display settings, see the <a href=":field-ui">Field UI module help</a> and <a href=":field">Field module help</a>.', [
                    ':types' => Url::fromRoute('entity.block_content_type.collection')->toString(),
                    ':field-ui' => $field_ui,
                    ':field' => Url::fromRoute('help.page', [
                        'name' => 'field',
                    ])->toString(),
                ]) . '</dd>';
                $output .= '<dt>' . t('Creating content blocks') . '</dt>';
                $output .= '<dd>' . t('Users with the <em>Administer blocks</em> permission can create, edit, and delete content blocks of each defined block type, from the <a href=":block-library">Content blocks page</a>. After creating a block, place it in a region from the <a href=":blocks">Block layout page</a>, just like blocks provided by other modules.', [
                    ':blocks' => Url::fromRoute('block.admin_display')->toString(),
                    ':block-library' => Url::fromRoute('entity.block_content.collection')->toString(),
                ]) . '</dd>';
                $output .= '</dl>';
                return $output;
        }
    }
    
    /**
     * Implements hook_theme().
     */
    public function theme($existing, $type, $theme, $path) : array {
        return [
            'block_content_add_list' => [
                'variables' => [
                    'content' => NULL,
                ],
                'file' => 'block_content.pages.inc',
            ],
        ];
    }
    
    /**
     * Implements hook_entity_type_alter().
     */
    public function entityTypeAlter(array &$entity_types) : void {
        
        /** @var \Drupal\Core\Entity\EntityTypeInterface[] $entity_types */
        // Add a translation handler for fields if the language module is enabled.
        if (\Drupal::moduleHandler()->moduleExists('language')) {
            $translation = $entity_types['block_content']->get('translation');
            $translation['block_content'] = TRUE;
            $entity_types['block_content']->set('translation', $translation);
        }
        // Swap out the default EntityChanged constraint with a custom one with
        // different logic for inline blocks.
        $constraints = $entity_types['block_content']->getConstraints();
        unset($constraints['EntityChanged']);
        $constraints['BlockContentEntityChanged'] = NULL;
        $entity_types['block_content']->setConstraints($constraints);
    }
    
    /**
     * Implements hook_query_TAG_alter().
     *
     * Alters any 'entity_reference' query where the entity type is
     * 'block_content' and the query has the tag 'block_content_access'.
     *
     * These queries should only return reusable blocks unless a condition on
     * 'reusable' is explicitly set.
     *
     * Block_content entities that are not reusable should by default not be
     * selectable as entity reference values. A module can still create an instance
     * of \Drupal\Core\Entity\EntityReferenceSelection\SelectionInterface
     * that will allow selection of non-reusable blocks by explicitly setting
     * a condition on the 'reusable' field.
     *
     * @see \Drupal\block_content\BlockContentAccessControlHandler
     */
    public function queryEntityReferenceAlter(AlterableInterface $query) : void {
        if ($query instanceof SelectInterface && $query->getMetaData('entity_type') === 'block_content' && $query->hasTag('block_content_access')) {
            $data_table = \Drupal::entityTypeManager()->getDefinition('block_content')
                ->getDataTable();
            if (array_key_exists($data_table, $query->getTables()) && !_block_content_has_reusable_condition($query->conditions(), $query->getTables())) {
                $query->condition("{$data_table}.reusable", TRUE);
            }
        }
    }
    
    /**
     * Implements hook_theme_suggestions_HOOK_alter() for block templates.
     */
    public function themeSuggestionsBlockAlter(array &$suggestions, array $variables) : void {
        $suggestions_new = [];
        $content = $variables['elements']['content'];
        $block_content = $variables['elements']['content']['#block_content'] ?? NULL;
        if ($block_content instanceof BlockContentInterface) {
            $bundle = $content['#block_content']->bundle();
            $view_mode = strtr($variables['elements']['#configuration']['view_mode'], '.', '_');
            $suggestions_new[] = 'block__block_content__view__' . $view_mode;
            $suggestions_new[] = 'block__block_content__type__' . $bundle;
            $suggestions_new[] = 'block__block_content__view_type__' . $bundle . '__' . $view_mode;
            if (!empty($variables['elements']['#id'])) {
                $suggestions_new[] = 'block__block_content__id__' . $variables['elements']['#id'];
                $suggestions_new[] = 'block__block_content__id_view__' . $variables['elements']['#id'] . '__' . $view_mode;
            }
            // Remove duplicate block__block_content.
            $suggestions = array_unique($suggestions);
            array_splice($suggestions, 1, 0, $suggestions_new);
        }
    }
    
    /**
     * Implements hook_entity_operation().
     */
    public function entityOperation(EntityInterface $entity) : array {
        $operations = [];
        if ($entity instanceof BlockInterface) {
            $plugin = $entity->getPlugin();
            if ($plugin->getBaseId() === 'block_content') {
                $custom_block = \Drupal::entityTypeManager()->getStorage('block_content')
                    ->loadByProperties([
                    'uuid' => $plugin->getDerivativeId(),
                ]);
                $custom_block = reset($custom_block);
                if ($custom_block && $custom_block->access('update')) {
                    $operations['block-edit'] = [
                        'title' => t('Edit block'),
                        'url' => $custom_block->toUrl('edit-form')
                            ->setOptions([]),
                        'weight' => 50,
                    ];
                }
            }
        }
        return $operations;
    }

}