public AttendantsReadModel When(AttendantsReadModel state, object @event)
{
switch (@event)
{
case Events.MeetupCreated created:
state.MeetupId = created.MeetupId;
break;
case Events.NumberOfSeatsUpdated seats:
state.MeetupCapacity = seats.NumberOfSeats;
break;
case Events.RSVPAccepted accepted:
if (state.MeetupCapacity > state.Going.Count)
{
state.Going.Add(accepted.MemberId);
}
else
{
state.Waiting.Add(accepted.MemberId);
}
break;
case Events.RSVPDeclined declined:
state.Going.Remove(declined.MemberId);
state.NotGoing.Add(declined.MemberId);
UpdateWaitingList();
break;
}
void UpdateWaitingList()
{
if (state.MeetupCapacity > state.Going.Count)
{
var first = state.Waiting.First();
state.Going.Add(first);
state.Waiting.Remove(first);
}
}
return(state);
}
public AttendantsReadModel Project(AttendantsReadModel readModel, params object[] events) => events.Aggregate(readModel, When);
