package com.campus.trade.service;

import com.campus.trade.common.BusinessException;
import com.campus.trade.common.FileUploadUtil;
import com.campus.trade.common.StatusCode;
import com.campus.trade.dto.ChangePasswordRequest;
import com.campus.trade.dto.LoginRequest;
import com.campus.trade.dto.RegisterRequest;
import com.campus.trade.entity.User;
import com.campus.trade.mapper.UserMapper;
import com.campus.trade.vo.UserProfileVO;
import jakarta.servlet.http.HttpSession;
import org.springframework.beans.BeanUtils;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;
import org.springframework.util.DigestUtils;

import java.nio.charset.StandardCharsets;

@Service
public class AuthService {

    @Autowired
    private UserMapper userMapper;

    @Autowired
    private FileUploadUtil fileUploadUtil;

    // 用户注册
    public Long register(RegisterRequest req) {
        // 检查学号是否已注册
        User existing = userMapper.selectByStudentId(req.getStudentId());
        if (existing != null) {
            throw new BusinessException(StatusCode.CONFLICT, "学号已注册");
        }
        // 上传校园卡照片
        String campusCardUrl = null;
        if (req.getCampusCardImage() != null && !req.getCampusCardImage().isEmpty()) {
            campusCardUrl = fileUploadUtil.upload(req.getCampusCardImage());
        }
        // MD5 加密密码
        String passwordHash = DigestUtils.md5DigestAsHex(
                req.getPassword().getBytes(StandardCharsets.UTF_8)
        );
        // 构建用户实体
        User user = new User();
        user.setStudentId(req.getStudentId());
        user.setName(req.getName());
        user.setPasswordHash(passwordHash);
        user.setCampusCardUrl(campusCardUrl);
        user.setAuthStatus("PENDING");     // 待审核
        user.setStatus("NORMAL");
        user.setRole("USER");
        // 默认昵称为姓名
        user.setNickname(req.getName());
        userMapper.insert(user);
        return user.getId();
    }

    // 用户登录
    public UserProfileVO login(LoginRequest req, HttpSession session) {
        User user = userMapper.selectByStudentId(req.getStudentId());
        if (user == null) {
            throw new BusinessException(StatusCode.BAD_REQUEST, "学号或密码错误");
        }
        // 检查是否被封禁
        if ("BANNED".equals(user.getStatus())) {
            throw new BusinessException(StatusCode.FORBIDDEN, "账号已被封禁");
        }
        // MD5 密码比对
        String inputHash = DigestUtils.md5DigestAsHex(
                req.getPassword().getBytes(StandardCharsets.UTF_8)
        );
        if (!inputHash.equals(user.getPasswordHash())) {
            throw new BusinessException(StatusCode.BAD_REQUEST, "学号或密码错误");
        }
        // 创建 Session
        session.setAttribute("userId", user.getId());
        session.setAttribute("role", user.getRole());

        UserProfileVO vo = new UserProfileVO();
        BeanUtils.copyProperties(user, vo);
        return vo;
    }

    // 修改密码
    public void changePassword(ChangePasswordRequest req, HttpSession session) {
        Long userId = (Long) session.getAttribute("userId");
        User user = userMapper.selectById(userId);
        // 验证旧密码
        String oldHash = DigestUtils.md5DigestAsHex(
                req.getOldPassword().getBytes(StandardCharsets.UTF_8)
        );
        if (!oldHash.equals(user.getPasswordHash())) {
            throw new BusinessException(StatusCode.BAD_REQUEST, "旧密码错误");
        }
        // 更新为新密码
        String newHash = DigestUtils.md5DigestAsHex(
                req.getNewPassword().getBytes(StandardCharsets.UTF_8)
        );
        user.setPasswordHash(newHash);
        userMapper.updatePassword(user);
    }
}