1package com.acme.order;
 2
 3import com.acme.payment.PaymentClient;
 4import org.springframework.stereotype.Service;
 5import org.springframework.transaction.annotation.Transactional;
 6import java.math.BigDecimal;
 7import java.util.List;
 8
 9@Service
10public class OrderService {
11
12    private final OrderRepository orderRepository;
13    private final PaymentClient paymentClient;
14
15    public OrderService(OrderRepository orderRepository, PaymentClient paymentClient) {
16        this.orderRepository = orderRepository;
17        this.paymentClient = paymentClient;
18    }
19
20    @Transactional
21    public Order placeOrder(CreateOrderRequest request) {
22        BigDecimal total = request.items().stream()
23                .map(item -> item.price().multiply(BigDecimal.valueOf(item.quantity())))
24                .reduce(BigDecimal.ZERO, BigDecimal::add);
25
26        if (total.compareTo(BigDecimal.ZERO) <= 0) {
27            throw new IllegalArgumentException("Order total must be positive");
28        }
29
30        Order order = Order.create(request.customerId(), request.items(), total);
31        orderRepository.save(order);
32
33        PaymentResult result = paymentClient.charge(order.id(), total);
34        if (!result.success()) {
35            order.markFailed(result.reason());
36            return order;
37        }
38
39        order.markPaid(result.transactionId());
40        return order;
41    }
42
43    public List<Order> findRecent(String customerId, int limit) {
44        // TODO: move paging to repository layer
45        return orderRepository.findByCustomerIdOrderByCreatedAtDesc(customerId)
46                .stream()
47                .limit(limit)
48                .toList();
49    }
50}