public void AcceptGroupInvite([FromBody] string messageId)
        {
            var userId  = HttpContext.User.Id();
            var message = _messageSource.GetMessageById(userId, messageId);

            if (message == null || message.Type != "Group")
            {
                return;
            }
            var groupInvite = message as GroupInviteMessage;
            var groupId     = groupInvite.GroupId;

            _groupSource.AddUser(groupId, userId);
            var user = _userSource.Get(userId);

            user.Groups.Add(groupId);
            _userSource.Update(user);

            _messageSource.DeleteMessage(userId, groupInvite.MessageId);
        }