ar.cs

public class ShipmentAggregateRoot
{
    private readonly SortedList<int, Stop> _stops = new();
    private readonly List<IEvent> _events = new();

    private ShipmentAggregateRoot(IReadOnlyList<Stop> stops)
    {
        for(var x = 0; x < stops.Count; x++)
        {
            _stops.Add(x, stops[x]);
        }
    }

    public static ShipmentAggregateRoot Factory(PickupStop pickup, DeliveryStop delivery)
    {
        return new ShipmentAggregateRoot(new Stop[] { pickup, delivery });
    }

    public static ShipmentAggregateRoot Factory(Stop[] stops)
    {
        if (stops.Length < 2)
        {
            throw new InvalidOperationException("Shipment requires at least 2 stops.");
        }

        if (stops.First() is not PickupStop)
        {
            throw new InvalidOperationException("First stop must be a Pickup");
        }

        if (stops.Last() is not DeliveryStop)
        {
            throw new InvalidOperationException("first stop must be a Pickup");
        }

        return new ShipmentAggregateRoot(stops);
    }

    public List<IEvent> GetUncommittedEvents()
    {
        var evnts = new List<IEvent>(_events);
        _events.Clear();
        return evnts;
    }

    public void Arrive(int stopId, DateTime arrived)
    {
        var currentStop = _stops.SingleOrDefault(x => x.Value.StopId == stopId);
        if (currentStop.Value == null)
        {
            throw new InvalidOperationException("Stop does not exist.");
        }

        var previousStopsAreNotDeparted = _stops.Any(x => x.Key < currentStop.Key && x.Value.Status != StopStatus.Departed);
        if (previousStopsAreNotDeparted)
        {
            throw new InvalidOperationException("Previous stops have not departed.");
        }

        currentStop.Value.Arrive(arrived);

        _events.Add(new Arrived(stopId, arrived));

        var arrivedToScheduled = arrived - currentStop.Value.Scheduled;
        if (arrivedToScheduled.TotalHours > 0)
        {
            _events.Add(new ArrivedLate(stopId, arrivedToScheduled));
        }
    }

    public void Pickup(int stopId, DateTime departed)
    {
        var currentStop = _stops.SingleOrDefault(x => x.Value.StopId == stopId);
        if (currentStop.Value == null)
        {
            throw new InvalidOperationException("Stop does not exist.");
        }

        if (currentStop.Value is not PickupStop)
        {
            throw new InvalidOperationException("Stop is not a pickup.");
        }

        if (currentStop.Value.Status != StopStatus.Arrived)
        {
            Arrive(stopId, departed);
        }

        currentStop.Value.Depart(departed);
        _events.Add(new PickedUp(stopId, departed));
    }

    public void Deliver(int stopId, DateTime departed)
    {
        var currentStop = _stops.SingleOrDefault(x => x.Value.StopId == stopId);
        if (currentStop.Value == null)
        {
            throw new InvalidOperationException("Stop does not exist.");
        }

        if (currentStop.Value is not DeliveryStop)
        {
            throw new InvalidOperationException("Stop is not a delivery.");
        }

        if (currentStop.Value.Status != StopStatus.Arrived)
        {
            Arrive(stopId, departed);
        }

        currentStop.Value.Depart(departed);
        _events.Add(new Delivered(stopId, departed));
    }

    public bool IsComplete()
    {
        return _stops.All(x => x.Value.Status == StopStatus.Departed);
    }
}