Enterprise Java,
engineered
for scale.

@Service
@Slf4j
public class OrderService {

    private final OrderRepository orders;
    private final KafkaTemplate<String, OrderEvent> kafka;

    // Java 21 record — concise, immutable, no Lombok needed
    public record CreateOrderCommand(
        UUID customerId,
        List<LineItem> items,
        Currency currency
    ) {}

    @Transactional
    public OrderResult placeOrder(CreateOrderCommand cmd) {

        // Pattern matching switch — Java 21 style
        var status = switch (cmd.currency()) {
            case GBP  -> ValidationStatus.APPROVED;
            case USD  -> ValidationStatus.APPROVED;
            default   -> ValidationStatus.REVIEW_REQUIRED;
        };

        var order = orders.save(Order.from(cmd, status));

        // Publish domain event — decoupled, async
        kafka.send("orders.placed", order.id().toString(),
                   OrderEvent.placed(order));

        log.info("Order {} placed for customer {}",
                  order.id(), cmd.customerId());

        return new OrderResult(order.id(), status);
    }
}