View source  
  <?php
namespace Drupal\social_group_request\Plugin\Block;
use Drupal\Core\Access\AccessResult;
use Drupal\Core\Block\BlockBase;
use Drupal\Core\Cache\Cache;
use Drupal\Core\Entity\EntityTypeManagerInterface;
use Drupal\Core\Link;
use Drupal\Core\Plugin\ContainerFactoryPluginInterface;
use Drupal\Core\Session\AccountInterface;
use Drupal\Core\StringTranslation\TranslationManager;
use Drupal\Core\Url;
use Drupal\grequest\Plugin\GroupContentEnabler\GroupMembershipRequest;
use Drupal\social_group\Entity\Group;
use Symfony\Component\DependencyInjection\ContainerInterface;
class SocialGroupRequestMembershipNotification extends BlockBase implements ContainerFactoryPluginInterface {
  
  protected $account;
  
  protected $group;
  
  protected $entityTypeManager;
  
  protected $translation;
  
  public function __construct(array $configuration, $plugin_id, $plugin_definition, AccountInterface $account, EntityTypeManagerInterface $entity_type_manager, TranslationManager $translation) {
    parent::__construct($configuration, $plugin_id, $plugin_definition);
    $this->account = $account;
    $this->group = _social_group_get_current_group();
    $this->entityTypeManager = $entity_type_manager;
    $this->translation = $translation;
  }
  
  public static function create(ContainerInterface $container, array $configuration, $plugin_id, $plugin_definition) {
    return new static($configuration, $plugin_id, $plugin_definition, $container
      ->get('current_user'), $container
      ->get('entity_type.manager'), $container
      ->get('string_translation'));
  }
  
  public function build() {
    if (!$this->group
      ->getGroupType()
      ->hasContentPlugin('group_membership_request')) {
      return [];
    }
    if ($this->group
      ->getGroupType()
      ->id() === 'flexible_group') {
      $join_methods = $this->group
        ->get('field_group_allowed_join_method')
        ->getValue();
      $request_option = in_array('request', array_column($join_methods, 'value'), FALSE);
      if (!$request_option) {
        return [];
      }
    }
    else {
      $allow_request = $this->group
        ->get('allow_request');
      if ($allow_request
        ->isEmpty() || $allow_request->value == 0) {
        return [];
      }
    }
    $contentTypeConfigId = $this->group
      ->getGroupType()
      ->getContentPlugin('group_membership_request')
      ->getContentTypeConfigId();
    $requests = $this->entityTypeManager
      ->getStorage('group_content')
      ->getQuery()
      ->condition('type', $contentTypeConfigId)
      ->condition('gid', $this->group
      ->id())
      ->condition('grequest_status', GroupMembershipRequest::REQUEST_PENDING)
      ->count()
      ->execute();
    if (!$requests) {
      return [];
    }
    return [
      '#type' => 'html_tag',
      '#tag' => 'div',
      '#value' => $this
        ->t('There @link to join this group.', [
        '@link' => Link::fromTextAndUrl($this->translation
          ->formatPlural($requests, 'is (1) new request', 'are (@count) new requests'), Url::fromRoute('view.group_pending_members.membership_requests', [
          'arg_0' => $this->group
            ->id(),
        ]))
          ->toString(),
      ]),
      '#attributes' => [
        'class' => [
          'alert',
          'alert-warning',
        ],
      ],
    ];
  }
  
  public function access(AccountInterface $account, $return_as_object = FALSE) {
    $is_group_page = isset($this->group);
    if ($this->group instanceof Group) {
      $is_group_manager = $this->group
        ->hasPermission('administer members', $account);
      return AccessResult::allowedIf($is_group_page && $is_group_manager);
    }
    return AccessResult::forbidden();
  }
  
  public function getCacheContexts() {
    $contexts = parent::getCacheContexts();
    
    $contexts = Cache::mergeContexts($contexts, [
      'url',
      'user.permissions',
      'group',
    ]);
    return $contexts;
  }
  
  public function getCacheTags() {
    return Cache::mergeTags(parent::getCacheTags(), [
      'request-membership:' . $this->group
        ->id(),
      'group:' . $this->group
        ->id(),
    ]);
  }
}