class BlockHooks

class BlockHooks {
  use StringTranslationTrait;
  
  /**
   * Implements hook_help().
   */
  public function help($route_name, RouteMatchInterface $route_match) : ?string {
    switch ($route_name) {
      case 'help.page.block':
        $block_content = \Drupal::moduleHandler()->moduleExists('block_content') ? Url::fromRoute('help.page', [
          'name' => 'block_content',
        ])->toString() : '#';
        $output = '';
        $output .= '<h2>' . $this->t('About') . '</h2>';
        $output .= '<p>' . $this->t('The Block module allows you to place blocks in regions of your installed themes, and configure block settings. For more information, see the <a href=":blocks-documentation">online documentation for the Block module</a>.', [
          ':blocks-documentation' => 'https://www.drupal.org/documentation/modules/block/',
        ]) . '</p>';
        $output .= '<h2>' . $this->t('Uses') . '</h2>';
        $output .= '<dl>';
        $output .= '<dt>' . $this->t('Placing and moving blocks') . '</dt>';
        $output .= '<dd>' . $this->t('You can place a new block in a region by selecting <em>Place block</em> on the <a href=":blocks">Block layout page</a>. Once a block is placed, it can be moved to a different region by drag-and-drop or by using the <em>Region</em> drop-down list, and then clicking <em>Save blocks</em>.', [
          ':blocks' => Url::fromRoute('block.admin_display')->toString(),
        ]) . '</dd>';
        $output .= '<dt>' . $this->t('Toggling between different themes') . '</dt>';
        $output .= '<dd>' . $this->t('Blocks are placed and configured specifically for each theme. The Block layout page opens with the default theme, but you can toggle to other installed themes.') . '</dd>';
        $output .= '<dt>' . $this->t('Demonstrating block regions for a theme') . '</dt>';
        $output .= '<dd>' . $this->t('You can see where the regions are for the current theme by clicking the <em>Demonstrate block regions</em> link on the <a href=":blocks">Block layout page</a>. Regions are specific to each theme.', [
          ':blocks' => Url::fromRoute('block.admin_display')->toString(),
        ]) . '</dd>';
        $output .= '<dt>' . $this->t('Configuring block settings') . '</dt>';
        $output .= '<dd>' . $this->t('To change the settings of an individual block click on the <em>Configure</em> link on the <a href=":blocks">Block layout page</a>. The available options vary depending on the module that provides the block. For all blocks you can change the block title and toggle whether to display it.', [
          ':blocks' => Url::fromRoute('block.admin_display')->toString(),
        ]) . '</dd>';
        $output .= '<dt>' . $this->t('Controlling visibility') . '</dt>';
        $output .= '<dd>' . $this->t('You can control the visibility of a block by restricting it to specific pages, content types, and/or roles by setting the appropriate options under <em>Visibility settings</em> of the block configuration.') . '</dd>';
        $output .= '<dt>' . $this->t('Adding content blocks') . '</dt>';
        $output .= '<dd>' . $this->t('You can add content blocks, if the <em>Block Content</em> module is installed. For more information, see the <a href=":blockcontent-help">Block Content help page</a>.', [
          ':blockcontent-help' => $block_content,
        ]) . '</dd>';
        $output .= '</dl>';
        return $output;
    }
    if ($route_name == 'block.admin_display' || $route_name == 'block.admin_display_theme') {
      $demo_theme = $route_match->getParameter('theme') ?: \Drupal::config('system.theme')->get('default');
      $themes = \Drupal::service('theme_handler')->listInfo();
      $output = '<p>' . $this->t('Block placement is specific to each theme on your site. Changes will not be saved until you click <em>Save blocks</em> at the bottom of the page.') . '</p>';
      $output .= '<p>' . Link::fromTextAndUrl($this->t('Demonstrate block regions (@theme)', [
        '@theme' => $themes[$demo_theme]->info['name'],
      ]), Url::fromRoute('block.admin_demo', [
        'theme' => $demo_theme,
      ]))
        ->toString() . '</p>';
      return $output;
    }
    return NULL;
  }
  
  /**
   * Implements hook_theme().
   */
  public function theme() : array {
    return [
      'block' => [
        'render element' => 'elements',
        'initial preprocess' => static::class . ':preprocessBlock',
      ],
    ];
  }
  
  /**
   * Prepares variables for block templates.
   *
   * Default template: block.html.twig.
   *
   * Prepares the values passed to the theme_block function to be passed
   * into a pluggable template engine. Uses block properties to generate a
   * series of template file suggestions. If none are found, the default
   * block.html.twig is used.
   *
   * Most themes use their own copy of block.html.twig. The default is located
   * inside "core/modules/block/templates/block.html.twig". Look in there for
   * the full list of available variables.
   *
   * @param array $variables
   *   An associative array containing:
   *   - elements: An associative array containing the properties of the
   *     element. Properties used: #block, #configuration, #children,
   *     and #plugin_id.
   */
  public function preprocessBlock(&$variables) : void {
    $variables['configuration'] = $variables['elements']['#configuration'];
    $variables['plugin_id'] = $variables['elements']['#plugin_id'];
    $variables['base_plugin_id'] = $variables['elements']['#base_plugin_id'];
    $variables['derivative_plugin_id'] = $variables['elements']['#derivative_plugin_id'];
    $variables['in_preview'] = $variables['elements']['#in_preview'] ?? FALSE;
    $variables['label'] = !empty($variables['configuration']['label_display']) ? $variables['configuration']['label'] : '';
    $variables['content'] = $variables['elements']['content'];
    // A block's label is configuration: it is static. Allow dynamic labels to
    // be set in the render array.
    if (isset($variables['elements']['content']['#title']) && !empty($variables['configuration']['label_display'])) {
      $variables['label'] = $variables['elements']['content']['#title'];
    }
    // Create a valid HTML ID and make sure it is unique.
    if (!empty($variables['elements']['#id'])) {
      $variables['attributes']['id'] = Html::getUniqueId('block-' . $variables['elements']['#id']);
    }
    // Proactively add aria-describedby if possible to improve accessibility.
    if ($variables['label'] && isset($variables['attributes']['role'])) {
      $variables['title_attributes']['id'] = Html::getUniqueId($variables['label']);
      $variables['attributes']['aria-describedby'] = $variables['title_attributes']['id'];
    }
  }
  
  /**
   * Implements hook_page_top().
   */
  public function pageTop(array &$page_top) : void {
    if (\Drupal::routeMatch()->getRouteName() === 'block.admin_demo') {
      $theme = \Drupal::theme()->getActiveTheme()
        ->getName();
      $page_top['backlink'] = [
        '#type' => 'link',
        '#title' => $this->t('Exit block region demonstration'),
        '#options' => [
          'attributes' => [
            'class' => [
              'block-demo-backlink',
            ],
          ],
        ],
        '#weight' => -10,
      ];
      if (\Drupal::config('system.theme')->get('default') == $theme) {
        $page_top['backlink']['#url'] = Url::fromRoute('block.admin_display');
      }
      else {
        $page_top['backlink']['#url'] = Url::fromRoute('block.admin_display_theme', [
          'theme' => $theme,
        ]);
      }
    }
  }
  
  /**
   * Implements hook_modules_installed().
   *
   * @see block_themes_installed()
   */
  public function modulesInstalled($modules, bool $is_syncing) : void {
    // Do not create blocks during config sync.
    if ($is_syncing) {
      return;
    }
    // block_themes_installed() does not call block_theme_initialize() during
    // site installation because block configuration can be optional or provided
    // by the profile. Now, when the profile is installed, this configuration
    // exists, call block_theme_initialize() for all installed themes.
    $profile = \Drupal::installProfile();
    if (in_array($profile, $modules, TRUE)) {
      foreach (\Drupal::service('theme_handler')->listInfo() as $theme => $data) {
        block_theme_initialize($theme);
      }
    }
  }
  
  /**
   * Implements hook_rebuild().
   */
  public function rebuild() : void {
    foreach (\Drupal::service('theme_handler')->listInfo() as $theme => $data) {
      if ($data->status) {
        $regions = system_region_list($theme);
        /** @var \Drupal\block\BlockInterface[] $blocks */
        $blocks = \Drupal::entityTypeManager()->getStorage('block')
          ->loadByProperties([
          'theme' => $theme,
        ]);
        foreach ($blocks as $block_id => $block) {
          // Disable blocks in invalid regions.
          if (!isset($regions[$block->getRegion()])) {
            if ($block->status()) {
              \Drupal::messenger()->addWarning($this->t('The block %info was assigned to the invalid region %region and has been disabled.', [
                '%info' => $block_id,
                '%region' => $block->getRegion(),
              ]));
            }
            $block->setRegion(system_default_region($theme))
              ->disable()
              ->save();
          }
        }
      }
    }
  }
  
  /**
   * Implements hook_ENTITY_TYPE_delete() for user_role entities.
   *
   * Removes deleted role from blocks that use it.
   */
  public function userRoleDelete($role) : void {
    foreach (Block::loadMultiple() as $block) {
      /** @var \Drupal\block\BlockInterface $block */
      $visibility = $block->getVisibility();
      if (isset($visibility['user_role']['roles'][$role->id()])) {
        unset($visibility['user_role']['roles'][$role->id()]);
        $block->setVisibilityConfig('user_role', $visibility['user_role']);
        $block->save();
      }
    }
  }
  
  /**
   * Implements hook_ENTITY_TYPE_delete() for menu entities.
   */
  public function menuDelete(Menu $menu) : void {
    if (!$menu->isSyncing()) {
      foreach (Block::loadMultiple() as $block) {
        if ($block->getPluginId() == 'system_menu_block:' . $menu->id()) {
          $block->delete();
        }
      }
    }
  }
  
  /**
   * Implements hook_ENTITY_TYPE_delete() for 'configurable_language'.
   *
   * Delete the potential block visibility settings of the deleted language.
   */
  public function configurableLanguageDelete(ConfigurableLanguageInterface $language) : void {
    // Remove the block visibility settings for the deleted language.
    foreach (Block::loadMultiple() as $block) {
      /** @var \Drupal\block\BlockInterface $block */
      $visibility = $block->getVisibility();
      if (isset($visibility['language']['langcodes'][$language->id()])) {
        unset($visibility['language']['langcodes'][$language->id()]);
        $block->setVisibilityConfig('language', $visibility['language']);
        $block->save();
      }
    }
  }
  
  /**
   * Implements hook_block_build_BASE_BLOCK_ID_alter().
   */
  public function blockBuildLocalActionsBlockAlter(array &$build, BlockPluginInterface $block) : void {
    $build['#lazy_builder_preview'] = [
      '#type' => 'container',
      '#attributes' => [
        'class' => [
          'invisible',
        ],
      ],
      'actions' => [
        '#theme' => 'menu_local_action',
        '#link' => [
          'title' => $this->t('Add'),
          'url' => Url::fromUserInput('#'),
        ],
      ],
    ];
  }

}