TheAirline.Models.Airlines.Airline.GetCodesharingAirlines C# (CSharp) Method

        public List<Airline> GetCodesharingAirlines()
        {
            return Codeshares.Select(c => c.Airline1 == this ? c.Airline2 : c.Airline1).ToList();
        }

        //returns if an airline wants to have code sharing with another airline
        public static bool AcceptCodesharing(Airline airline, Airline asker, CodeshareAgreement.CodeshareType type)
        {
            double coeff = type == CodeshareAgreement.CodeshareType.OneWay ? 0.25 : 0.40;

            IEnumerable<Country> sameCountries = asker.Airports.Select(a => a.Profile.Country).Distinct().Intersect(airline.Airports.Select(a => a.Profile.Country).Distinct());
            IEnumerable<Airport> sameDestinations = asker.Airports.Distinct().Intersect(airline.Airports);
            IEnumerable<Country> sameCodesharingCountries =
                airline.GetCodesharingAirlines().SelectMany(a => a.Airports).Select(a => a.Profile.Country).Distinct().Intersect(airline.Airports.Select(a => a.Profile.Country).Distinct());

            double airlineDestinations = airline.Airports.Count;
            double airlineRoutes = airline.Routes.Count;
            double airlineCountries = airline.Airports.Select(a => a.Profile.Country).Distinct().Count();
            double airlineCodesharings = airline.Codeshares.Count;
            double airlineAlliances = airline.Alliances.Count;

            //declines if asker is much smaller than the invited airline
            if (airlineRoutes > 3*asker.Routes.Count)
                return false;

            //declines if there is a match for x% of the airlines
            if (sameDestinations.Count() >= airlineDestinations*coeff)
                return false;

            //declines if there is a match for 75% of the airlines
            if (sameCountries.Count() >= airlineCountries*0.75)
                return false;

            //declines if the airline already has a code sharing or alliance in that area
            if (sameCodesharingCountries.Count() >= airlineCountries*coeff)
                return false;

            return true;
        }