using System;

public class Program

{

    public static void Main()

    {

        var shipment = new Shipment(Guid.NewGuid(), "RU", "Istanbul");

        shipment.ToInTransit();

        shipment.ToInCustoms();

        shipment.ToCustomsCleared();

        shipment.ToOutForDelivery();

        shipment.ToNotDelivered();

        shipment.ToDelivered();

        Console.WriteLine("-----------------------------------------------------------------");

        var shipment1 = new Shipment(Guid.NewGuid(), "TR", "Istanbul");

        shipment1.ToInTransit();

        shipment1.ToInCustoms();

        shipment1.ToCustomsCleared();

        shipment1.ToOutForDelivery();

        shipment1.ToNotDelivered();

        shipment1.ToDelivered();

    }

}

​

public abstract class ShipmentState

{

    public virtual void InTransit(Shipment shipment)

    {

        Console.WriteLine(GetInvalidMessage(nameof(InTransit), shipment.State));

    }

​

    public virtual void InCustoms(Shipment shipment)

    {

        Console.WriteLine(GetInvalidMessage(nameof(InCustoms), shipment.State));

    }

​

    public virtual void CustomsCleared(Shipment shipment)

    {

        Console.WriteLine(GetInvalidMessage(nameof(CustomsCleared), shipment.State));

    }

​

    public virtual void OutForDelivery(Shipment shipment)

    {

        Console.WriteLine(GetInvalidMessage(nameof(OutForDelivery), shipment.State));

    }

​

    public virtual void Delivered(Shipment shipment)

    {

        Console.WriteLine(GetInvalidMessage(nameof(Delivered), shipment.State));

    }

​

    public virtual void NotDelivered(Shipment shipment)

    {

        Console.WriteLine(GetInvalidMessage(nameof(NotDelivered), shipment.State));

    }

​

    protected string GetInvalidMessage(string newState, ShipmentState currentState) =>

        $"{newState} cannot be performed in {currentState.GetType().Name}.";

}

​

public class OrderPlacedState : ShipmentState

{

    public override void InTransit(Shipment shipment)

    {

        if (shipment.FromCountry == "TR")

        {

            Console.WriteLine(GetInvalidMessage(nameof(InTransit), shipment.State));

            return;

        }

​

        Console.WriteLine("The cargo has been loaded onto the ship.");

​

        shipment.MoveTo(new InTransitState());

    }

​

    public override void OutForDelivery(Shipment shipment)

    {

        if (shipment.FromCountry != "TR")

        {

            Console.WriteLine(GetInvalidMessage(nameof(OutForDelivery), shipment.State));

            return;

        }

​

        Console.WriteLine("The cargo is out for delivery.");

​

        shipment.MoveTo(new OutForDeliveryState());

    }

}

​

public class InTransitState : ShipmentState

{

    public override void InCustoms(Shipment shipment)

    {

        Console.WriteLine("The cargo has arrived at customs.");

​

        shipment.MoveTo(new InCustomsState());

    }

}

​

public class InCustomsState : ShipmentState

{

    public override void CustomsCleared(Shipment shipment)

    {

        Console.WriteLine("Customs clearance procedures have been completed.");

        shipment.MoveTo(new CustomsClearedState());

    }

}

​

public class CustomsClearedState : ShipmentState

{

    public override void OutForDelivery(Shipment shipment)

    {

        Console.WriteLine("The cargo is out for delivery.");

​

        shipment.MoveTo(new OutForDeliveryState());

    }

}

​

public class OutForDeliveryState : ShipmentState

{

    public override void Delivered(Shipment shipment)

    {

        Console.WriteLine("The cargo has been delivered.");

​

        shipment.MoveTo(new DeliveredState());

    }

​

    public override void NotDelivered(Shipment shipment)

    {

        if (shipment.DeliveryAttempts < 1)

        {

            shipment.DeliveryAttempts++;

            Console.WriteLine("The cargo could not be delivered. We will attempt delivery again.");

            return;

        }

​

        Console.WriteLine("The cargo could not be delivered. The return process has been initiated.");

​

        shipment.MoveTo(new NotDeliveredState());

    }

}

​

public class NotDeliveredState : ShipmentState

{

}

​

public class DeliveredState : ShipmentState

{

}

​

public class Shipment

{

    public Guid OrderId { get; private set; }

    public string FromCountry { get; private set; }

    public string To { get; private set; }

    public ShipmentState State { get; private set; }

    public int DeliveryAttempts { get; internal set; }

​

    public Shipment(Guid orderId, string fromCountry, string to)

    {

        OrderId = orderId;

        FromCountry = fromCountry;

        To = to;

        State = new OrderPlacedState();

    }

​

    public void MoveTo(ShipmentState state)

    {

        State = state;

    }

​

    public void ToInTransit()

    {

        State.InTransit(this);

    }

​

    public void ToInCustoms()

    {

        State.InCustoms(this);

    }

​

    public void ToCustomsCleared()

    {

        State.CustomsCleared(this);

    }

​

    public void ToOutForDelivery()

    {

        State.OutForDelivery(this);

    }

​

    public void ToDelivered()

    {

        State.Delivered(this);

    }

​

    public void ToNotDelivered()

    {

        State.NotDelivered(this);

    }

}