/**
 * Build an airport route. Find 2 cities that are big enough and try to build airport in both cities.
 * Then we can build an aircraft and make some money.
 */
function WrightAI::BuildAirportRoute()
{
    /* Check if we can build more aircraft. */
    if (GetAircraftCount() >= AIGameSettings.GetValue("max_aircraft") || AIGameSettings.IsDisabledVehicleType(AIVehicle.VT_AIR)) return 0;
	
    /* Create a list of available airports */
    local airportTypes = AIList();
	airportTypes.AddItem(AIAirport.GetPrice(AIAirport.AT_INTERCON), AIAirport.AT_INTERCON);           // 7
	airportTypes.AddItem(AIAirport.GetPrice(AIAirport.AT_INTERNATIONAL), AIAirport.AT_INTERNATIONAL); // 4
	airportTypes.AddItem(AIAirport.GetPrice(AIAirport.AT_METROPOLITAN), AIAirport.AT_METROPOLITAN);   // 3
	airportTypes.AddItem(AIAirport.GetPrice(AIAirport.AT_LARGE), AIAirport.AT_LARGE);                 // 1
	airportTypes.AddItem(AIAirport.GetPrice(AIAirport.AT_COMMUTER), AIAirport.AT_COMMUTER);           // 5
	airportTypes.AddItem(AIAirport.GetPrice(AIAirport.AT_SMALL), AIAirport.AT_SMALL);                 // 0
	airportTypes.AddItem(AIAirport.GetPrice(AIAirport.AT_HELISTATION), AIAirport.AT_HELISTATION);     // 8
	airportTypes.AddItem(AIAirport.GetPrice(AIAirport.AT_HELIDEPOT), AIAirport.AT_HELIDEPOT);         // 6
	airportTypes.AddItem(AIAirport.GetPrice(AIAirport.AT_HELIPORT), AIAirport.AT_HELIPORT);           // 2
	
    /* Filter out airports larger than the maximum value of a station size */
	local list = airportTypes;
	local station_spread = AIGameSettings.GetValue("station_spread");
	for (local i = list.Begin(); list.HasNext(); i = list.Next()) {
	    local airport_type = airportTypes.GetValue(i);
//		AILog.Info("airport_type = " + airport_type);
		local airport_x = AIAirport.GetAirportWidth(airport_type);
//		AILog.Info("airport_x = " + airport_x);
	    local airport_y = AIAirport.GetAirportHeight(airport_type);
//		AILog.Info("airport_y = " + airport_y);
		if (airport_x > station_spread || airport_y > station_spread) {
		    airportTypes.RemoveValue(airport_type);
		}
		/* Also filter out unavailable airports */
		if (!AIAirport.IsValidAirportType(airport_type)) {
		    airportTypes.RemoveValue(airport_type);
		}
//		/* Filter out heliports while helistations and helidepots aren't available, because it is required that one of the airports in a route to have a hangar */
//		if (airport_type == AIAirport.AT_HELIPORT && !AIAirport.IsValidAirportType(AIAirport.AT_HELISTATION) && !AIAirport.IsValidAirportType(AIAirport.AT_HELIDEPOT)) {
//		    airportTypes.RemoveValue(airport_type);
//		}
	}
	/* No airports available. Abort */
	if (airportTypes.Count() == 0) return 0;
	
	local available_engines = false;
	local engine_costs = 0;
	if (big_engine_list.Count() == 0) {
//	    airportTypes.RemoveValue(AIAirport.AT_INTERCON);
//		airportTypes.RemoveValue(AIAirport.AT_INTERNATIONAL);
//		airportTypes.RemoveValue(AIAirport.AT_METROPOLITAN);
//		airportTypes.RemoveValue(AIAirport.AT_LARGE);
	} else {
	    available_engines = true;
	    engine_costs = engine_costs + AIEngine.GetPrice(big_engine_list.Begin());
	}

	if (small_engine_list.Count() == 0) {
//	    airportTypes.RemoveValue(AIAirport.AT_COMMUTER);
//		airportTypes.RemoveValue(AIAirport.AT_SMALL);
	} else {
	    available_engines = true;
	    engine_costs = engine_costs + AIEngine.GetPrice(small_engine_list.Begin());
	}
	
	if (helicopter_list.Count() == 0) {
	    airportTypes.RemoveValue(AIAirport.AT_HELISTATION);
		airportTypes.RemoveValue(AIAirport.AT_HELIDEPOT);
		airportTypes.RemoveValue(AIAirport.AT_HELIPORT);
	} else {
	    available_engines = true;
	    engine_costs = engine_costs + AIEngine.GetPrice(helicopter_list.Begin());
	}
	
	/* There are no engines available */
	if (!available_engines) return 0;
	
	/* Not enough money */
	local estimated_costs = airportTypes.Begin() + engine_costs;
	if (!this.HasMoney(estimated_costs + 25000)) return 0;

//	AILog.Info("airportTypes contains " + airportTypes.Count() + " type " + airportTypes.GetValue(0));
	airportTypes.Sort(AIList.SORT_BY_ITEM, AIList.SORT_DESCENDING);
	
    /* Ensure there are at least 2 unused towns */
    local town_list = AITownList();
	if (AIController.GetSetting("cities_only")) {
        town_list.Valuate(AITown.IsCity);
        town_list.KeepValue(1);
    }
	if (town_list.Count() - this.towns_used.Count() < 2) return 0;

	AILog.Info("Trying to build an airport route...");
	
	local tile_1 = this.FindSuitableAirportSpot(airportTypes, 0, false, false, false);
	
	local airport1_location = tile_1[0];
	local airport1_type = tile_1[1];
	local airport1_stationId = tile_1[5];
	
    if (airport1_location < 0) {
	    AILog.Info("Couldn't find a suitable town to build the first airport in");
	    return -1;
	}
	
    if (airport1_type == AIAirport.AT_HELIPORT) {
	    airportTypes.RemoveValue(AIAirport.AT_HELIPORT);
		airportTypes.Sort(AIList.SORT_BY_ITEM, AIList.SORT_ASCENDING);
	}
	
    local large_aircraft = tile_1[2];
    local small_aircraft = tile_1[3];
    local helicopter = tile_1[4];
	
	local tile_2 = this.FindSuitableAirportSpot(airportTypes, airport1_location, large_aircraft, small_aircraft, helicopter);
	
	local airport2_location = tile_2[0];
	local airport2_type = tile_2[1];
	local airport2_stationId = tile_2[5];
	
	if (airport2_location < 0) {
	    AILog.Info("Couldn't find a suitable town to build the second airport in");
		return -1;
	}

	/* Build the airports for real */
//	local last_cost.AIAccounting();
	local tap = TestBuildAirport();
	if (!tap.TryBuild(airport1_location, airport1_type, airport1_stationId)) {
//	
//	local last_cost = AIAccounting();
//	if (AITestMode() && AIAirport.BuildAirport(airport1_location, airport1_type, airport1_stationId)) {
//	    if (HasMoney(last_cost.GetCosts())) GetMoney(last_cost.GetCosts());
//	}
//	if (!AIAirport.BuildAirport(airport1_location, airport1_type, airport1_stationId)) {
//	    RepayLoan();
		AILog.Warning("Although the testing told us we could build 2 airports, it still failed on the first airport at tile " + airport1_location + ".");
//		assert(AIError.GetLastError() != AIError.ERR_STATION_TOO_SPREAD_OUT);
		return -1;
	}
//	RepayLoan();
//
//	last_cost.ResetCosts();
    tap = TestBuildAirport();
	if (!tap.TryBuild(airport2_location, airport2_type, airport2_stationId)) {
//	
//  if (AITestMode() && AIAirport.BuildAirport(airport2_location, airport2_type, airport2_stationId)) {
//	    if (HasMoney(last_cost.GetCosts())) GetMoney(last_cost.GetCosts());
//	}
//	if (!AIAirport.BuildAirport(airport2_location, airport2_type, airport2_stationId)) {
//	    RepayLoan();
		AILog.Warning("Although the testing told us we could build 2 airports, it still failed on the second airport at tile " + airport2_location + ".");
//		assert(AIError.GetLastError() != AIError.ERR_STATION_TOO_SPREAD_OUT);
		return -1;
	}
//	RepayLoan();

	local ret = this.BuildAircraft(airport1_location, airport2_location, false, GetAircraftCount() == 0 ? true : false);
	if (ret < 0) {
		return ret;
	}
	
	local airport1_town = AITile.GetClosestTown(airport1_location);
	local airport2_town = AITile.GetClosestTown(airport2_location);
	this.towns_used.AddItem(airport1_town, airport1_location);
	this.towns_used.AddItem(airport2_town, airport2_location);

//  AILog.Warning("Done building aicraft route.");
	return ret;
}