facets_block.module

<?php

/**
 * @file
 * This is the primary module file.
 */

use Drupal\Core\Block\BlockPluginInterface;
use Drupal\Core\Routing\RouteMatchInterface;

/**
 * Implements hook_help().
 */
function facets_block_help($route_name, RouteMatchInterface $route_match) {
  switch ($route_name) {
    case 'help.page.facets_block':
      $output = '';
      $output .= '<h3>' . t('About') . '</h3>';
      $output .= '<p>' . t('Render Facets in a single block.') . '</p>';
      return $output;
  }
}

/**
 * Implements hook_theme().
 */
function facets_block_theme($existing, $type, $theme, $path) {
  return [
    'facets_block' => [
      'variables' => [
        'show_title' => TRUE,
        'facets' => '',
      ],
    ],
  ];
}

/**
 * Implements hook_block_view_BASE_BLOCK_ID_alter().
 */
function facets_block_block_view_facets_block_alter(array &$build, BlockPluginInterface $block) {
  if (!empty($build['#configuration']['add_js_classes'])) {
    $build['#pre_render'][] = '\Drupal\facets_block\AddJsClasses::preRender';
  }

  if (!empty($build['#configuration']['hide_empty_block'])) {
    $build['#pre_render'][] = '\Drupal\facets_block\AddCssClasses::preRender';
  }
}