package com.campus.trade.common;

import org.springframework.stereotype.Component;

import java.util.List;
import java.util.Map;

@Component
public class OrderStatusMachine {

    private static final Map<String, List<String>> ALLOWED_TRANSITIONS = Map.of(
            "PENDING", List.of("CONFIRMED", "CANCELLED"),
            "CONFIRMED", List.of("DELIVERED", "CANCELLED"),
            "DELIVERED", List.of("COMPLETED", "CANCELLED"),
            "COMPLETED", List.of(),
            "CANCELLED", List.of()
    );

    public void validateTransition(String currentStatus, String targetStatus) {
        if (currentStatus == null || targetStatus == null) {
            throw new BusinessException(StatusCode.BAD_REQUEST, "订单状态参数不能为空");
        }
        List<String> allowed = ALLOWED_TRANSITIONS.get(currentStatus);
        if (allowed == null || !allowed.contains(targetStatus)) {
            throw new BusinessException(StatusCode.BAD_REQUEST,
                    "订单状态不允许从 " + currentStatus + " 转移到 " + targetStatus);
        }
    }
}