package se.bilhalsning.service;

import lombok.RequiredArgsConstructor;
import org.springframework.stereotype.Service;
import se.bilhalsning.entity.Order;
import se.bilhalsning.entity.OrderStatus;
import se.bilhalsning.exception.InvalidOrderStateException;
import se.bilhalsning.exception.OrderNotFoundException;
import se.bilhalsning.repository.OrderRepository;

import java.util.List;
import java.util.UUID;

@Service
@RequiredArgsConstructor
public class OrderService {

    private final OrderRepository orderRepository;
    private final OrderNotificationService orderNotificationService;

    public Order createOrder(UUID userId, String plate, String letterText) {
        Order order = new Order();
        order.setUserId(userId);
        order.setPlate(plate.toUpperCase().trim());
        order.setLetterText(letterText);
        order.setStatus(OrderStatus.PENDING_PAYMENT);
        return orderRepository.save(order);
    }

    /**
     * Guest checkout — creates an order with no registered user. The
     * {@code guestToken} is generated in {@link Order#onCreate()} so the
     * caller does not need to handle token creation logic. Returned
     * order's {@link Order#getGuestToken()} is the only credential the
     * client receives.
     */
    public Order createGuestOrder(String plate, String letterText, String email) {
        Order order = new Order();
        // userId stays null — guest order. guestToken auto-generated in PrePersist.
        order.setGuestEmail(email == null ? null : email.trim().toLowerCase());
        order.setPlate(plate.toUpperCase().trim());
        order.setLetterText(letterText);
        order.setStatus(OrderStatus.PENDING_PAYMENT);
        return orderRepository.save(order);
    }

    /**
     * Guest-path order lookup by opaque token. Never exposes user-owned
     * orders via this path: if a guest token resolves to an order with a
     * non-null {@code userId} (corrupted data, manual SQL insert, etc.),
     * treat as not-found rather than leak the order.
     */
    public Order getOrderByGuestToken(UUID guestToken) {
        Order order = orderRepository.findByGuestToken(guestToken)
                .orElseThrow(() -> new OrderNotFoundException(guestToken));
        if (order.getUserId() != null) {
            // Token points at a user-owned order — refuse to serve it.
            throw new OrderNotFoundException(guestToken);
        }
        return order;
    }

    /**
     * Honor-system payment confirmation for guest orders. Mirrors
     * {@link #confirmPayment(UUID, UUID)} but authenticates via the
     * guest token instead of {@code userId}.
     */
    public Order confirmGuestPayment(UUID guestToken) {
        Order order = getOrderByGuestToken(guestToken);
        if (order.getStatus() != OrderStatus.PENDING_PAYMENT) {
            throw new InvalidOrderStateException(
                    "Beställningen kan inte ändras i detta tillstånd");
        }
        order.setStatus(OrderStatus.PROCESSING);
        Order saved = orderRepository.save(order);
        orderNotificationService.notifyOrderProcessing(saved);
        return saved;
    }

    public List<Order> getOrdersByUserId(UUID userId) {
        return orderRepository.findByUserIdOrderByCreatedAtDesc(userId);
    }

    public Order getOrderById(UUID id) {
        return orderRepository.findById(id)
                .orElseThrow(() -> new OrderNotFoundException(id));
    }

    public List<Order> getAllOrders() {
        return orderRepository.findAllByOrderByCreatedAtDesc();
    }

    public Order confirmPayment(UUID orderId, UUID userId) {
        Order order = requirePendingOwnedBy(orderId, userId);
        order.setStatus(OrderStatus.PROCESSING);
        Order saved = orderRepository.save(order);
        orderNotificationService.notifyOrderProcessing(saved);
        return saved;
    }

    public Order cancelOrder(UUID orderId, UUID userId) {
        Order order = requirePendingOwnedBy(orderId, userId);
        order.setStatus(OrderStatus.CANCELLED);
        return orderRepository.save(order);
    }

    public Order updatePendingOrder(UUID orderId, UUID userId, String letterText) {
        Order order = requirePendingOwnedBy(orderId, userId);
        order.setLetterText(letterText);
        return orderRepository.save(order);
    }

    private Order requirePendingOwnedBy(UUID orderId, UUID userId) {
        Order order = orderRepository.findById(orderId)
                .orElseThrow(() -> new OrderNotFoundException(orderId));

        if (!order.getUserId().equals(userId)) {
            throw new OrderNotFoundException(orderId);
        }

        if (order.getStatus() != OrderStatus.PENDING_PAYMENT) {
            throw new InvalidOrderStateException(
                    "Beställningen kan inte ändras i detta tillstånd");
        }

        return order;
    }
}