class UserRequirements

class UserRequirements {
  use StringTranslationTrait;
  public function __construct(protected readonly EntityTypeManagerInterface $entityTypeManager, protected readonly Connection $connection) {
  }
  
  /**
   * Implements hook_runtime_requirements().
   */
  public function runtime() : array {
    $requirements = [];
    $result = (bool) $this->entityTypeManager
      ->getStorage('user')
      ->getQuery()
      ->accessCheck(FALSE)
      ->condition('uid', 0)
      ->range(0, 1)
      ->execute();
    if ($result === FALSE) {
      $requirements['anonymous user'] = [
        'title' => $this->t('Anonymous user'),
        'description' => $this->t('The anonymous user does not exist. See the <a href=":url">restore the anonymous (user ID 0) user record</a> for more information', [
          ':url' => 'https://www.drupal.org/node/1029506',
        ]),
        'severity' => RequirementSeverity::Warning,
      ];
    }
    $query = $this->connection
      ->select('users_field_data');
    $query->addExpression('LOWER(mail)', 'lower_mail');
    $query->isNotNull('mail');
    $query->groupBy('lower_mail');
    $query->having('COUNT(uid) > :matches', [
      ':matches' => 1,
    ]);
    $conflicts = $query->countQuery()
      ->execute()
      ->fetchField();
    if ($conflicts > 0) {
      $requirements['conflicting emails'] = [
        'title' => $this->t('Conflicting user emails'),
        'description' => $this->t('Some user accounts have email addresses that differ only by case. For example, one account might have alice@example.com and another might have Alice@Example.com. See <a href=":url">Conflicting User Emails</a> for more information.', [
          ':url' => 'https://www.drupal.org/node/3486109',
        ]),
        'severity' => RequirementSeverity::Warning,
      ];
    }
    return $requirements;
  }

}