public async Task <IActionResult> GetDroneUtilization([FromQuery] string ownerId, [FromQuery] int year, [FromQuery] int month)
        {
            // TODO: improve binding model --> improve err msg.
            if (string.IsNullOrEmpty(ownerId) ||
                year < 1 ||
                month < 1)
            {
                return(BadRequest());
            }

            var(traveledMiles, assignedHours) = await _invoicingRepository.
                                                GetAggreatedInvoincingDataAsync(ownerId, year, month);

            if (traveledMiles == 0d &&
                assignedHours == 0d)
            {
                return(NotFound());
            }

            return(Ok(new DroneUtilization
            {
                TraveledMiles = traveledMiles,
                AssignedHours = assignedHours
            }));
        }