using System;
using System.Collections.Generic;
using System.Linq;

namespace BoundaryLab.Domain;

public record OrderAccepted(string Id, int Units);
public record OrderTransition(OrderState State, OrderAccepted Event);
public record OrderState(string Id, int Units, bool Accepted)
{
    public OrderTransition? Accept() => Accepted || Units < 1 ? null : new(this with { Accepted = true }, new OrderAccepted(Id, Units));
}