@Override
    public SendNotificationVM sendNotification(ManagedSendNotificationVM notificationVM) {
        Set<User> users = getUsers(notificationVM);
        Notification notification = Notification.builder()
                .message(notificationVM.getMessage())
                .status(NotificationStatus.SENT)
                .messageType(notificationVM.getMessageType())
                .title(notificationVM.getTitle())
                .build();
        repository.save(notification);
        log.debug("Saved notification");

        users.forEach(user -> {
            NotificationHistory notificationHistory = NotificationHistory.builder()
                    .user(user)
                    .notification(notification)
                    .readStatus(HistoryNotificationStatus.UNREAD)
                    .build();
            notificationHistoryRepository.save(notificationHistory);
            log.debug("Updated notification history");
        });
        log.info("Notification[id={}] has been created for users{}. Producer: [{}]", notification.getId(), users.stream().map(User::getId).collect(Collectors.toList()), getCurrentUserLogin());
        return mapper.toDto(notification);
    }

    private Set<User> getUsers(ManagedSendNotificationVM notificationVM) {
        List<User> users = userService.findAllOrThrow(getList(notificationVM.getUsers()));
        List<Group> groups = groupService.findAllOrThrow(getList(notificationVM.getGroups()));
        List<User> usersFromGroup = groups.stream()
                .map(Group::getUsers)
                .flatMap(Collection::stream)
                .collect(Collectors.toList());
        users.addAll(usersFromGroup);
        if (users.isEmpty()) {
            log.warn("Cannot find valid users from [{}] idS and groups[]", notificationVM.getUsers(), notificationVM.getGroups());
            throw new com.longulf.net.errors.EntityNotFoundException("Cannot find any users to send notification");
        }
        return Sets.newHashSet(users);
    }

@Override
    public HistoryNotificationStatus markNotificationForCurrentUser(HistoryNotificationStatus status, Long id) {
        User user = userService.getUserWithAuthority()
                .orElseThrow(() -> new EntityNotFoundException("User could not be found"));

        NotificationHistory notificationHistory = user.getNotifications()
                .stream()
                .filter(n -> n.getNotification().getId().equals(id))
                .findFirst()
                .orElseThrow(() -> new com.longulf.net.errors.EntityNotFoundException("Cannot find user's notification with notificationId=" + id));
        notificationHistory.setReadStatus(HistoryNotificationStatus.READ);
        log.info("Notification[id={}] status has been marked as READ by user[{}]",id, getCurrentUserLoginOrThrow());
        return status;
    }