class UserAccessTestHooks

class UserAccessTestHooks {
    
    /**
     * Implements hook_ENTITY_TYPE_access() for entity type "user".
     */
    public function userAccess(User $entity, $operation, $account) {
        if ($entity->getAccountName() == "no_edit" && $operation == "update") {
            // Deny edit access.
            return AccessResult::forbidden();
        }
        if ($entity->getAccountName() == "no_delete" && $operation == "delete") {
            // Deny delete access.
            return AccessResult::forbidden();
        }
        // Account with role sub-admin can manage users with no roles.
        if (count($entity->getRoles()) == 1) {
            return AccessResult::allowedIfHasPermission($account, 'sub-admin');
        }
        return AccessResult::neutral();
    }
    
    /**
     * Implements hook_entity_create_access().
     */
    public function entityCreateAccess(AccountInterface $account, array $context, $entity_bundle) {
        if ($context['entity_type_id'] != 'user') {
            return AccessResult::neutral();
        }
        // Account with role sub-admin can create users.
        return AccessResult::allowedIfHasPermission($account, 'sub-admin');
    }
    
    /**
     * Implements hook_entity_field_access().
     */
    public function entityFieldAccess($operation, FieldDefinitionInterface $field_definition, AccountInterface $account, ?FieldItemListInterface $items = NULL) {
        // Account with role sub-admin can view the status, init and mail fields for
        // user with no roles.
        if ($field_definition->getTargetEntityTypeId() == 'user' && $operation === 'view' && in_array($field_definition->getName(), [
            'status',
            'init',
            'mail',
        ])) {
            if ($items == NULL || count($items->getEntity()
                ->getRoles()) == 1) {
                return AccessResult::allowedIfHasPermission($account, 'sub-admin');
            }
        }
        if (\Drupal::state()->get('user_access_test_forbid_mail_edit', FALSE)) {
            if ($operation === 'edit' && $items && $items->getEntity()
                ->getEntityTypeId() === 'user' && $field_definition->getName() === 'mail') {
                return AccessResult::forbidden();
            }
        }
        return AccessResult::neutral();
    }

}