private TAggregateRootState CreateState(IEventStream stream)
{
Contract.Requires(stream != null);
Contract.Ensures(Contract.Result <TAggregateRootState>() != null);
var snapshotRevision = stream.FirstOrDefault(x => x is SnapshotRevision) as SnapshotRevision;
// order domain events and flatten list
IReadOnlyCollection <IDomainEvent> domainEvents = stream.Where(x => x is DomainEventRevision)
.OrderBy(x => x.Version)
.Cast <DomainEventRevision>()
.SelectMany(x => x.DomainEvents)
.ToList();
var domainEventsExist = domainEvents.Any();
TAggregateRootState state;
// check for valid stream
if (snapshotRevision == null)
{
if (domainEventsExist)
{
// domain events only
state = _aggregateRootStateBuilder.Build(domainEvents);
}
else
{
throw new InvalidOperationException("Event stream does not contain a snapshot or domain event revision.");
}
}
else
{
if (domainEventsExist)
{
// snapshot and domain events
state = _aggregateRootStateBuilder.Build(snapshotRevision.Snapshot.Data, domainEvents);
}
else
{
// snapshot only
state = _aggregateRootStateBuilder.Build(snapshotRevision.Snapshot.Data);
}
}
Contract.Assume(state != null);
return(state);
}
