public async Task <ActionResult <IEnumerable <TaskDto> > > PutTask(long taskId, TaskDto task)
        {
            if (taskId != task.Id)
            {
                return(BadRequest());
            }

            var taskEntity = TaskMapper.mapFromDto(task);

            if (taskEntity.State == State.Closed)
            {
                taskEntity.ClosedAt = DateTime.Now;
            }

            var oldTask = _context.Tasks
                          .AsNoTracking()
                          .FirstOrDefault(t => t.Id == taskId);

            if (oldTask.State == State.Closed && taskEntity.State != State.Closed)
            {
                taskEntity.ClosedAt = null;
            }

            _context.Entry(taskEntity).State = EntityState.Modified;

            try
            {
                await _context.SaveChangesAsync();
            }
            catch (DbUpdateConcurrencyException)
            {
                if (!TaskExists(taskId))
                {
                    return(NotFound());
                }
                else
                {
                    throw;
                }
            }

            List <TaskDto> states = new List <TaskDto>();

            states.Add(TaskMapper.mapToDto(oldTask));
            states.Add(task);
            return(states);
        }