using System;

using System.Collections.Generic;

using System.Linq;

public class Program

{

    public static void Main()

    {

        Console.WriteLine("Flight Builder");

​

    }

    // Create an implementation of IFlightFilter that will take the flights from FlightBuider.GetFlights() and removes any flight where the arrival date is before the departure dat

    public interface IFlightFilter

    {

        IList<Flight> Filter(IList<Flight> flights);

    }

​

    public sealed class FlightBuilder

    {

        public IList<Flight> GetFlights()

        {

            var threeDaysFromNow = DateTime.Now.AddDays(3);

​

            return new List<Flight>

            {

                // A normal flight with two hour duration

                CreateFlight(threeDaysFromNow, threeDaysFromNow.AddHours(2)),

​

                // A normal multi-segment flight

                CreateFlight(threeDaysFromNow, threeDaysFromNow.AddHours(2), threeDaysFromNow.AddHours(3), threeDaysFromNow.AddHours(5)),

                // A flight departing in the past

                CreateFlight(threeDaysFromNow.AddDays(-6), threeDaysFromNow),

​

                // A flight that departs before it arrives

                CreateFlight(threeDaysFromNow, threeDaysFromNow.AddHours(-6)),

​

                // A flight with more than two hours ground time

                CreateFlight(threeDaysFromNow, threeDaysFromNow.AddHours(2), threeDaysFromNow.AddHours(5), threeDaysFromNow.AddHours(6)),

​

                // Another flight with more than two hours ground time

                CreateFlight(threeDaysFromNow, threeDaysFromNow.AddHours(2), threeDaysFromNow.AddHours(3), threeDaysFromNow.AddHours(4), threeDaysFromNow.AddHours(6), threeDaysFromNow.AddHours(7))

            };

        }

​

        private static Flight CreateFlight(params DateTime[] dates)

        {

            if (dates.Length % 2 != 0) 

                throw new ArgumentException("You must pass an even number of dates,", "dates");

​

            var departureDates = dates.Where((date, index) => index % 2 == 0);

            var arrivalDates = dates.Where((date, index) => index % 2 == 1);

​

            var segments = departureDates

                .Zip(arrivalDates, (departureDate, arrivalDate) => new Segment { DepartureDate = departureDate, ArrivalDate = arrivalDate })

                .ToList();

​

            return new Flight { Segments = segments };

        }

    }

    public class Flight

    {

        public IList<Segment> Segments { get; set; }

    }

​

    public class Segment

    {

        public DateTime DepartureDate { get; set; }

        public DateTime ArrivalDate { get; set; }

    }

}