دیزاین پترن State در عمل

public static bool IsPrimary { get; private set; }
public static bool IsBefotrPrimary { get; private set; }
public static bool IsFirstTime { get; private set; }

private static int GetLastDispatchedMessageIdTypeCode()
{
    int result;

    switch (FailOverService.IsBeforePrimary)
    {
        case true when FailOverService.IsPrimary:
            result = PrimaryTypeCode;
            break;
        
        case true when !FailOverService.IsPrimary:
            result = SecondaryTypeCode;
            break;
        
        case false when !FailOverService.IsPrimary:
            result = SecondaryTypeCode;
            break;
        
        case false when FailOverService.IsPrimary && FailOverService.IsFirstTime:
            result = PrimaryTypeCode;
            break;
        
        case false when FailOverService.IsPrimary && !FailOverService.IsFirstTime:
            result = SecondaryTypeCode;
            break;
        
        default:
            throw new Exception("not valid input");
    }

    return result;
}

public class Context
{
    private State _state;

    public Context()
    {
        _state = new InitialState();
    }

    public void TransitionTo(State state)
    {
        Logger.WriteInformationLog($"Context: Transition to {state.GetType().Name}");

        _state = state;
        _state.SetContext(this);
    }

    public FailoverReadingTypeEnum GetState()
    {
        return _state.Handle();
    }
}

public abstract class State
{
    protected Context Context;

    public void SetContext(Context context)
    {
        Context = context;
    }

    public abstract FailoverReadingTypeEnum Handle();
}

public class InitialState : State
{
    public override FailoverReadingTypeEnum Handle()
    {
        Logger.WriteInformationLog($"FailoverReadingTypeEnum change to : {FailoverReadingTypeEnum.None.ToString()}");
        
        return FailoverReadingTypeEnum.None;
    }
}

public enum FailoverReadingTypeEnum
{
    None = 0,
    Primary = 1,
    Secondary = 2
}

public class PrimaryState : State
{
    public override FailoverReadingTypeEnum Handle()
    {
        Logger.WriteInformationLog($"FailoverReadingTypeEnum change to : {FailoverReadingTypeEnum.Primary.ToString()}");
        
        return FailoverReadingTypeEnum.Primary;
    }
}

public FailOverService(ProcessorType processorType)
{
    _context = new Context();
}

_context.TransitionTo(new PrimaryState());

public static FailoverReadingTypeEnum GetReadingType()
{
    return _context.GetState();
}

private static int GetLastDispatchedMessageIdTypeCode()
{
    return (int) FailOverService.GetReadingType();
}