/// <summary>
/// Get the coordination information of airport asynchronously
/// Firstly, the method checks if airport informations exist in database.
/// If exist, directly returns coordinates from database.
/// If not exist, it calls external api and parse informations to get coordinations
/// On the last step, it saves informations to database for get it on the next request and avoid api calls
/// </summary>
/// <param name="airportIataCode">Iata code of airport</param>
/// <returns>coordination informations in Tuple: (Item1:latitude, Item2:longitude)</returns>
private async Task <Tuple <double, double> > GetAirportCoordinations(string airportIataCode)
{
using (var con = new AppDbContext(new DbContextOptions <AppDbContext>()))
{
var repository = new AirportRepository(con);
double latitude = 0.0;
double longitude = 0.0;
var savedAirport = await repository.GetAirport(airportIataCode);
// If airport exist in db, no need to call external api
if (savedAirport != null)
{
SetCoordinates(savedAirport, out latitude, out longitude);
}
else
{
IRestResponse response = AirportHelper.CallApi(airportIataCode);
if (response.IsSuccessful == false)
{
throw new Exception(AirportHelper.ParseApiError(response));
}
var airport = AirportHelper.GetAirportFromResponse(response);
if (airport != null)
{
SetCoordinates(airport, out latitude, out longitude);
// Save airport to in-memory database using by repository
await repository.AddAirport(airport);
}
}
return(Tuple.Create(latitude, longitude));
}
}