Topics and EventManager

class PlaceOrderTopic extends AbstractTopic<PlaceOrderTopic> {(1)

    (2)
    protected PlaceOrderTopic(String topicName, float topicKey, SagaEventType sagaEventType, String targetService) {
        super(topicName, topicKey, sagaEventType, targetService);
    }


    (3)
    protected PlaceOrderTopic(String topicName, float topicKey, SagaEventType sagaEventType, String targetService, PlaceOrderTopic parent) {
        super(topicName, topicKey, sagaEventType, targetService, parent);
    }

    (4)
    //primary execution topics.
    public static final PlaceOrderTopic DO_FETCH_USER_DETAILS = new PlaceOrderTopic("user.fetch", 1, SagaEventType.QUERY_DO_ACTION, "user-service");
    public static final PlaceOrderTopic DO_INITIALIZE_ORDER = new PlaceOrderTopic("order.init", 2, SagaEventType.COMMAND_DO_ACTION, "order-service");
    public static final PlaceOrderTopic DO_MAKE_PAYMENT = new PlaceOrderTopic("payment.make", 3, SagaEventType.COMMAND_DO_ACTION, "payment-service");
    public static final PlaceOrderTopic DO_INVENTORY_UPDATE = new PlaceOrderTopic("inventory.update", 4, SagaEventType.COMMAND_DO_ACTION, "inventory-service");

    (5)
    //revert/compensation topics.
    public static final PlaceOrderTopic UNDO_INITIALIZE_ORDER = new PlaceOrderTopic("order.init", -2, SagaEventType.COMMAND_UNDO_ACTION, "order-service", DO_INITIALIZE_ORDER);
    public static final PlaceOrderTopic UNDO_MAKE_PAYMENT = new PlaceOrderTopic("payment.make", -3, SagaEventType.COMMAND_UNDO_ACTION, "payment-service", DO_MAKE_PAYMENT);
    public static final PlaceOrderTopic UNDO_INVENTORY_UPDATE = new PlaceOrderTopic("inventory.update", -4, SagaEventType.COMMAND_UNDO_ACTION, "inventory-service", DO_INVENTORY_UPDATE);
}

(2)
@SagaEventManager(
        value = "placeOrderEventManager", (3)
        listenerScope = ListenerScope.SHARED, (4)
        domainRootTopicSuffix = "place-order" (5)
)
public class PlaceOrderEventManager extends AbstractEventManager<OrderDomainEntity, PlaceOrderTopic> { (1)

    (6)
    @Override
    public Supplier<List<PlaceOrderTopic>> registerTopics() {
        return () -> List.of(
                PlaceOrderTopic.DO_FETCH_USER_DETAILS,
                PlaceOrderTopic.DO_INITIALIZE_ORDER,
                PlaceOrderTopic.DO_MAKE_PAYMENT,
                PlaceOrderTopic.DO_INVENTORY_UPDATE,
                PlaceOrderTopic.UNDO_INITIALIZE_ORDER,
                PlaceOrderTopic.UNDO_MAKE_PAYMENT,
                PlaceOrderTopic.UNDO_INVENTORY_UPDATE
        );
    }

    (7)
    @Override
    public @NonNull SagaPrimaryEventAction<PlaceOrderTopic> onNext(PlaceOrderTopic recentTopic, OrderDomainEntity currentDomainEntityState) {
        if (recentTopic.equals(PlaceOrderTopic.DO_FETCH_USER_DETAILS)) {
            currentDomainEntityState.getMetadata().put("navigated-do-initialize-order-at", LocalDateTime.now().toString());
            return SagaPrimaryEventAction.next(PlaceOrderTopic.DO_INITIALIZE_ORDER);
        }
        if (recentTopic.equals(PlaceOrderTopic.DO_INITIALIZE_ORDER)) {
            currentDomainEntityState.getMetadata().put("navigated-do-make-payment-at", LocalDateTime.now().toString());
            return SagaPrimaryEventAction.next(PlaceOrderTopic.DO_MAKE_PAYMENT);
        }
        if (recentTopic.equals(PlaceOrderTopic.DO_MAKE_PAYMENT)) {
            currentDomainEntityState.getMetadata().put("navigated-do-inventory-update-at", LocalDateTime.now().toString());
            return SagaPrimaryEventAction.next(PlaceOrderTopic.DO_INVENTORY_UPDATE);
        }
        if (recentTopic.equals(PlaceOrderTopic.DO_INVENTORY_UPDATE)) {
            return SagaPrimaryEventAction.complete();
        }
        return SagaPrimaryEventAction.error(new IllegalStateException("Unexpected topic: " + recentTopic));
    }

    (8)
    @Override
    public void onNextRevert(
            PlaceOrderTopic recentExecutedTopic,
            PlaceOrderTopic nextTopic,
            OrderDomainEntity lastDomainEntityState,
            NonRetryableExecutorException nonRetryableExecutorException,
            RevertHintStore revertHintStore,
            Supplier<NavigableMap<Integer, PlaceOrderTopic>> remainingReverts
    ) {

        (9)
        {//sample usage of revert hint store and next topic in the onNextRevert method.
            if (nextTopic.equals(PlaceOrderTopic.UNDO_MAKE_PAYMENT)) {
                revertHintStore.put("BEFORE_NOTE:UNDO_MAKE_PAYMENT", "Sample value before reverting UNDO_MAKE_PAYMENT");
            }
            if (nextTopic.equals(PlaceOrderTopic.UNDO_INITIALIZE_ORDER)) {
                revertHintStore.put("BEFORE_NOTE:UNDO_INITIALIZE_ORDER", "Sample value before reverting UNDO_INITIALIZE_ORDER");
            }
        }

        (10)
        {//sample usage of remaining reverts and recentExecutedTopic
            if (recentExecutedTopic.equals(PlaceOrderTopic.UNDO_MAKE_PAYMENT)) {
                log.info("Remaining reverts after reverting UNDO_MAKE_PAYMENT: {}", remainingReverts);
            }

            if (recentExecutedTopic.equals(PlaceOrderTopic.UNDO_INITIALIZE_ORDER)) {
                log.info("Remaining reverts after reverting UNDO_INITIALIZE_ORDER: {}", remainingReverts);
            }
        }
    }
}