using System;

using System.Collections.Generic;

​

public class Door

{

    public string Color;

    public IDoorState State;

    public void Open()

    {

        var newState = State.Open(this);

        if (newState != State) Console.WriteLine($"Door wih color {Color} was opened");

        else Console.WriteLine($"Door wih color {Color} remains in state {State.GetType().Name}");

        State = newState;

    }

    public void Close()

    {

        var newState = State.Close(this);

        if (newState != State) Console.WriteLine($"Door wih color {Color} was closed");

        else Console.WriteLine($"Door wih color {Color} remains in state {State.GetType().Name}");

        State = newState;

    }

}

​

​

public delegate bool Condition(Door door);

public struct ConditionKey

{

    public readonly Type FromState;

    public readonly Type ToState;

    public ConditionKey(Type fromState, Type toState)

    {

        FromState = fromState;

        ToState = toState;

    }

}

​

public class DoorStates

{

    private readonly DoorOpen _open;

    private readonly DoorClosed _closed;

    public DoorStates(IDictionary<ConditionKey, Condition> conditions)

    {

        _open = new DoorOpen(conditions[new ConditionKey(typeof(DoorOpen), typeof(DoorClosed))]);

        _closed = new DoorClosed(conditions[new ConditionKey(typeof(DoorClosed), typeof(DoorOpen))]);

        _open.ClosedState = _closed;

        _closed.OpenState = _open;

    }

    public IDoorState GenerateStateMachine()

    {

        return _open;

    }

}

​

public interface IDoorState

{

    IDoorState Open(Door door);

    IDoorState Close(Door door);

}

​

public class DoorOpen : IDoorState

{

    public DoorClosed ClosedState;

    private readonly Condition _canClose;

​

    public DoorOpen(Condition canClose)

    {

        _canClose = canClose;

    }

​

    public IDoorState Open(Door _)

    {

        return this;

    }

    public IDoorState Close(Door door)

    {

        if (_canClose(door)) return ClosedState;

        return this;

    }

}

​

public class DoorClosed : IDoorState

{

    public DoorOpen OpenState;

    private readonly Condition _canOpen;

​

    public DoorClosed(Condition canOpen)

    {

        _canOpen = canOpen;

    }

​

    public IDoorState Open(Door door)

    {

        if (_canOpen(door)) return OpenState;

        return this;

    }

    public IDoorState Close(Door _)

    {

        return this;

    }

}

​

public class Program

{

    public static void Main()

    {

        var conditions = new Dictionary<ConditionKey, Condition>

        {

            [new ConditionKey(typeof(DoorOpen), typeof(DoorClosed))] = ((Door door) => door.Color == "red"),

            [new ConditionKey(typeof(DoorClosed), typeof(DoorOpen))] = ((_) => true),

        };

        var states = new DoorStates(conditions);

        var door = new Door

        {

            Color = "red",

            State = states.GenerateStateMachine(),

        };

        door.Close();

        door.Open();

        door.Color = "green";

        door.Close();

        door.Open();

    }

}