interface IRemindersEmptyCalculator{
    bool IsRemindersEmpty(List<Remider> reminders);
}

class RemindersEmptyCalculatorFactory{
    readonly Context context;
    readonly DefaultIsRemindersEmptyCalculator defaultIsRemindersEmptyCalculator
    RemindersEmptyCalculatorFactory(Context context){
        this.context = context;
    }

    public IRemindersEmptyCalculator GetCalculator(){
        switch context.State{
            case Web:
            break;
            case Local:
            break;
            default:
            return new DefaultIsRemindersEmptyCalculator();
    }
}

public class DefaultIsRemindersEmptyCalculator:IRemindersEmptyCalculator
{
    private static readonly Lazy<DefaultIsRemindersEmptyCalculator> _instance =
        new Lazy<DefaultIsRemindersEmptyCalculator>(() => new DefaultIsRemindersEmptyCalculator());

    public static DefaultIsRemindersEmptyCalculator Instance => _instance.Value;

    private DefaultIsRemindersEmptyCalculator() {}

    public bool IsRemindersEmpty(List<Remider> remiders){
        return reminders.Count > 0 ? true : false;
    }
}

static void Main(List<Remider> reminders){
    Context = GetCurrentContext();
    RemindersEmptyCalculatorFactory factory = new RemindersEmptyCalculatorFactory(context);
    IRemindersEmptyCalculator isRemindersEmptyCalculator = factory.GetCalcylator();
    bool isRemindersEmpty = isRemindersEmptyCalculator.IsRemindersEmpty(reminders);
}