package com.xuekairui.user.service;

import com.xuekairui.common.BusinessException;
import com.xuekairui.common.ErrorCode;
import com.xuekairui.common.RandomUtil;
import com.xuekairui.user.dto.LoginResponse;
import com.xuekairui.user.entity.Admin;
import com.xuekairui.user.mapper.AdminMapper;
import com.xuekairui.user.security.TokenVersionCache;
import com.xuekairui.user.util.JwtUtil;
import com.xuekairui.user.util.PasswordUtil;
import lombok.RequiredArgsConstructor;
import lombok.extern.slf4j.Slf4j;
import org.springframework.stereotype.Service;
import org.springframework.transaction.annotation.Transactional;

import java.time.LocalDateTime;

/**
 * 管理员认证服务（操作 t_admin 表，与普通用户 AuthService 隔离）
 */
@Slf4j
@Service
@RequiredArgsConstructor
public class AdminAuthService {

    private final AdminMapper adminMapper;
    private final JwtUtil jwtUtil;
    private final PasswordUtil passwordUtil;
    private final TokenVersionCache tokenVersionCache;

    private static final int RESET_LEN = 10;

    /**
     * 管理员密码登录（按用户名或手机号）
     */
    @Transactional
    public LoginResponse passwordLogin(String account, String password, String ip) {
        Admin admin = adminMapper.selectByUsername(account);
        if (admin == null) {
            admin = adminMapper.selectByPhone(account);
        }
        if (admin == null) {
            throw new BusinessException(ErrorCode.USER_NOT_FOUND);
        }
        if (admin.getPassword() == null || admin.getPassword().isEmpty()) {
            throw new BusinessException(ErrorCode.PASSWORD_NOT_SET);
        }
        if (!passwordUtil.matches(password, admin.getPassword())) {
            throw new BusinessException(ErrorCode.PASSWORD_INCORRECT);
        }
        if (admin.getStatus() != null && admin.getStatus() == 0) {
            throw new BusinessException(ErrorCode.USER_DISABLED);
        }

        return buildLoginResponse(admin, ip);
    }

    /**
     * 构建管理员登录响应（递增 tokenVersion，签发 Token）
     */
    private LoginResponse buildLoginResponse(Admin admin, String ip) {
        String roleCode = admin.getRole() != null ? admin.getRole() : "ADMIN";

        // 管理员允许多设备：最多5台
        long oldVersion = admin.getTokenVersion() != null ? admin.getTokenVersion() : 0L;
        long newVersion = oldVersion + 1;
        admin.setTokenVersion(newVersion);

        String accessToken = jwtUtil.generateAccessToken(admin.getId(), roleCode, "PC", newVersion);
        String refreshToken = jwtUtil.generateRefreshToken(admin.getId(), "PC");

        admin.setRefreshTokenHash(JwtUtil.hashToken(refreshToken));
        admin.setRefreshTokenStatus("ACTIVE");
        admin.setLastLoginTime(LocalDateTime.now());
        admin.setLastLoginIp(ip);
        adminMapper.updateById(admin);

        tokenVersionCache.putVersion(admin.getId(), true, newVersion);

        boolean hadPreviousSession = oldVersion >= 5;

        return LoginResponse.builder()
                .userId(admin.getId())
                .accessToken(accessToken)
                .refreshToken(refreshToken)
                .expiresIn(jwtUtil.getExpirationInSeconds(roleCode))
                .needBindPhone(false)
                .newUser(false)
                .role(roleCode)
                .kickedPreviousSession(hadPreviousSession)
                .build();
    }

    /**
     * 管理员自行修改密码（需验旧密码）
     */
    @Transactional
    public void setPassword(Long adminId, String oldPassword, String newPassword) {
        Admin admin = adminMapper.selectById(adminId);
        if (admin == null) {
            throw new BusinessException(ErrorCode.USER_NOT_FOUND);
        }
        if (admin.getPassword() != null && !admin.getPassword().isEmpty()
                && oldPassword != null && !passwordUtil.matches(oldPassword, admin.getPassword())) {
            throw new BusinessException(ErrorCode.OLD_PASSWORD_INCORRECT);
        }
        admin.setPassword(passwordUtil.encode(newPassword));
        adminMapper.updateById(admin);
    }

    /**
     * 重置管理员密码为随机密码，返回明文
     */
    @Transactional
    public String resetPassword(Long adminId) {
        Admin admin = adminMapper.selectById(adminId);
        if (admin == null) {
            throw new BusinessException(ErrorCode.USER_NOT_FOUND);
        }
        String rawPwd = RandomUtil.generateCode(RESET_LEN);
        admin.setPassword(passwordUtil.encode(rawPwd));
        adminMapper.updateById(admin);
        tokenVersionCache.putVersion(adminId, true,
                (admin.getTokenVersion() != null ? admin.getTokenVersion() : 0L) + 1);
        return rawPwd;
    }
}