private static void Execute()
{
// Load the input data
AirportCollection airports = AirportCollection.LoadFromFile(AirportsFilePath);
AdsbEventCollection events = AdsbEventCollection.LoadFromFile(AdsbEventsFilePath);
// Create collection of identifiable flights
FlightCollection flights = CalculateFlights(airports, events);
// Write the output data
flights.WriteToFile(OutputFilePath);
}
private static FlightCollection CalculateFlights(AirportCollection airports, AdsbEventCollection events)
{
// Organize all ADS-B events by aircraft ID
FlightCollection flights = new FlightCollection();
Dictionary <string, List <AdsbEvent> > eventsByID = new Dictionary <string, List <AdsbEvent> >();
foreach (AdsbEvent adsbEvent in events.Events)
{
if (!eventsByID.ContainsKey(adsbEvent.Identifier))
{
eventsByID.Add(adsbEvent.Identifier, new List <AdsbEvent>());
eventsByID[adsbEvent.Identifier].Add(adsbEvent);
}
else
{
// Remove events that are soon after the previous one to improve performance
int eventCount = eventsByID[adsbEvent.Identifier].Count;
AdsbEvent lastEvent = eventsByID[adsbEvent.Identifier][eventCount - 1];
TimeSpan timeDiff = adsbEvent.Timestamp - lastEvent.Timestamp;
if (timeDiff.TotalSeconds >= TimeThreshold)
{
eventsByID[adsbEvent.Identifier].Add(adsbEvent);
}
}
}
// For each aircraft identifier, step through the logged events in sequence to identify flights
foreach (string identifier in eventsByID.Keys)
{
List <AdsbEvent> eventLog = eventsByID[identifier];
FlightStatus flightStatus = FlightStatus.Unknown;
Airport lastAirport = new Airport();
DateTime lastGroundTime = DateTime.MinValue;
foreach (AdsbEvent adsbEvent in eventLog)
{
// Find closest airport to the logged coordinates, as long as the event has coordinate values
GeoCoordinate eventLoc = new GeoCoordinate(adsbEvent.Latitude ?? double.NaN, adsbEvent.Longitude ?? double.NaN);
if (eventLoc.HasLocation())
{
Airport closestAirport = airports.GetClosestAirport(eventLoc);
GeoCoordinate airportLoc = new GeoCoordinate(closestAirport.Latitude, closestAirport.Longitude);
double airportDistance = eventLoc.GetDistanceTo(airportLoc);
double altitudeDiff = adsbEvent.Altitude.HasValue ? Math.Abs(adsbEvent.Altitude.Value - closestAirport.Elevation) : 0f;
double speed = adsbEvent.Speed ?? 0f;
// If the event was logged close to an airport, assume the aircraft has landed at that airport
if (airportDistance <= DistanceThreshold && altitudeDiff <= AltitudeThreshold && speed <= SpeedThreshold)
{
// If this is not the first event (status unknown) and the new closest airport is different, create a new completed flight record
if (flightStatus != FlightStatus.Unknown && closestAirport.Identifier != lastAirport.Identifier)
{
flights.Flights.Add(new Flight
{
AircraftIdentifier = identifier,
DepartureTime = lastGroundTime,
DepartureAirport = lastAirport.Identifier,
ArrivalTime = adsbEvent.Timestamp,
ArrivalAirport = closestAirport.Identifier
});
}
// In any case, update the status for the new airport
flightStatus = FlightStatus.Ground;
lastAirport = closestAirport;
lastGroundTime = adsbEvent.Timestamp;
}
// If the aircraft is not close to an airport and was not previously flying, set the status to airborne
else if ((airportDistance > DistanceThreshold || altitudeDiff > AltitudeThreshold) && flightStatus != FlightStatus.Air)
{
flightStatus = FlightStatus.Air;
}
// Otherwise, assume no status change
}
}
// If all events have been read and the aircraft was last known to be flying, record a final flight with no arrival
if (flightStatus == FlightStatus.Air)
{
flights.Flights.Add(new Flight
{
AircraftIdentifier = identifier,
DepartureTime = lastGroundTime,
DepartureAirport = lastAirport.Identifier,
ArrivalTime = DateTime.MaxValue,
ArrivalAirport = null
});
}
}
return(flights);
}
