import {
  SerializableEvent,
  VersionedAggregateRoot,
} from '@task-stream/api/shared/domain';

/**
 * Round-trips uncommitted events like the event store does (JSON + class
 * prototype) and rebuilds a fresh aggregate from them.
 */
export function replay<T extends VersionedAggregateRoot>(
  aggregate: T,
  AggregateCls: new (id: string) => T,
  previous: SerializableEvent[] = [],
): { rebuilt: T; history: SerializableEvent[] } {
  const history = [
    ...previous,
    ...aggregate.getUncommittedEvents().map((event, index) => ({
      streamId: aggregate.id,
      type: event.constructor.name,
      position: previous.length + index + 1,
      data: Object.assign(
        Object.create(Object.getPrototypeOf(event)),
        JSON.parse(JSON.stringify(event)),
      ),
    })),
  ];
  const rebuilt = new AggregateCls(aggregate.id);
  rebuilt.loadFromHistory(history);
  return { rebuilt, history };
}