package pub

import (
	"context"
	"errors"
	"fmt"
	"strings"
	"time"

	"perms-system-server/internal/consts"
	authHelper "perms-system-server/internal/logic/auth"
	userModel "perms-system-server/internal/model/user"
	"perms-system-server/internal/response"
	"perms-system-server/internal/svc"
	"perms-system-server/internal/types"

	"github.com/zeromicro/go-zero/core/limit"
	"github.com/zeromicro/go-zero/core/logx"
)

type RefreshTokenLogic struct {
	logx.Logger
	ctx    context.Context
	svcCtx *svc.ServiceContext
}

func NewRefreshTokenLogic(ctx context.Context, svcCtx *svc.ServiceContext) *RefreshTokenLogic {
	return &RefreshTokenLogic{
		Logger: logx.WithContext(ctx),
		ctx:    ctx,
		svcCtx: svcCtx,
	}
}

// RefreshToken 刷新令牌。使用有效的 refreshToken 换取新的 accessToken/refreshToken 令牌对，旧令牌即时失效（单会话轮转）。
// 路由层已挂载 RefreshTokenRateLimit 做 IP 维度限流；本处再叠加 per-user 限流，形成"IP + 用户"双层防护。
func (l *RefreshTokenLogic) RefreshToken(req *types.RefreshTokenReq) (resp *types.LoginResp, err error) {
	tokenStr := strings.TrimPrefix(req.Authorization, "Bearer ")
	if tokenStr == "" || tokenStr == req.Authorization {
		return nil, response.ErrUnauthorized("refreshToken格式错误")
	}

	claims, err := authHelper.ParseRefreshToken(tokenStr, l.svcCtx.Config.Auth.RefreshSecret)
	if err != nil {
		return nil, response.ErrUnauthorized("refreshToken无效或已过期")
	}

	productCode := claims.ProductCode
	if req.ProductCode != "" && req.ProductCode != productCode {
		return nil, response.ErrBadRequest("刷新令牌不允许切换产品")
	}

	ud, err := l.svcCtx.UserDetailsLoader.Load(l.ctx, claims.UserId, productCode)
	if err != nil {
		return nil, response.NewCodeError(503, "服务暂时不可用，请稍后重试")
	}
	if ud.Username == "" {
		return nil, response.ErrUnauthorized("用户不存在或已被删除")
	}

	if ud.Status != consts.StatusEnabled {
		return nil, response.ErrForbidden("账号已被冻结")
	}

	if productCode != "" && ud.ProductStatus != consts.StatusEnabled {
		return nil, response.ErrForbidden("该产品已被禁用")
	}

	if productCode != "" && !ud.IsSuperAdmin && ud.MemberType == "" {
		return nil, response.ErrForbidden("您已不是该产品的成员")
	}

	if claims.TokenVersion != ud.TokenVersion {
		return nil, response.ErrUnauthorized("登录状态已失效，请重新登录")
	}

	if l.svcCtx.TokenOpLimiter != nil {
		code, _ := l.svcCtx.TokenOpLimiter.Take(fmt.Sprintf("refresh:%d", claims.UserId))
		if code == limit.OverQuota {
			return nil, response.ErrTooManyRequests("刷新操作过于频繁，请稍后再试")
		}
	}

	// 审计 M-3：把签名放在 CAS 之前，让"签名失败"不再污染 tokenVersion。原顺序是
	//   CAS → Clean → 签 access → 签 refresh
	// 一旦签名失败 tokenVersion 已+1，但客户端没收到新 refreshToken，下一次带旧 version 来
	// 会被 "登录状态已失效" 踢掉，变成"签名 bug → 用户被强制登出"的放大效应。新顺序：
	//   试签 access → 试签 refresh → CAS → Clean
	// 签名走不通直接 500，DB/缓存都不动；CAS 赢家才推进 tokenVersion 并 Clean 缓存。
	predictedVersion := claims.TokenVersion + 1

	accessToken, err := authHelper.GenerateAccessToken(
		l.svcCtx.Config.Auth.AccessSecret,
		l.svcCtx.Config.Auth.AccessExpire,
		ud.UserId, ud.Username, ud.ProductCode, ud.MemberType, predictedVersion,
	)
	if err != nil {
		return nil, err
	}

	newRefreshToken, err := authHelper.GenerateRefreshTokenWithExpiry(
		l.svcCtx.Config.Auth.RefreshSecret,
		claims.ExpiresAt.Time,
		ud.UserId, ud.ProductCode, predictedVersion,
	)
	if err != nil {
		return nil, err
	}

	newVersion, err := l.svcCtx.SysUserModel.IncrementTokenVersionIfMatch(l.ctx, claims.UserId, ud.Username, claims.TokenVersion)
	if err != nil {
		if errors.Is(err, userModel.ErrTokenVersionMismatch) {
			return nil, response.ErrUnauthorized("登录状态已失效，请重新登录")
		}
		return nil, err
	}
	if newVersion != predictedVersion {
		logx.WithContext(l.ctx).Errorw("refresh token version prediction mismatch",
			logx.Field("audit", "refresh_token_version_mismatch"),
			logx.Field("userId", claims.UserId),
			logx.Field("claimed", claims.TokenVersion),
			logx.Field("predicted", predictedVersion),
			logx.Field("actual", newVersion),
		)
		return nil, response.ErrUnauthorized("登录状态已失效，请重新登录")
	}
	l.svcCtx.UserDetailsLoader.Clean(l.ctx, claims.UserId)

	return &types.LoginResp{
		AccessToken:  accessToken,
		RefreshToken: newRefreshToken,
		Expires:      time.Now().Unix() + l.svcCtx.Config.Auth.AccessExpire,
		UserInfo: types.UserInfo{
			UserId:             ud.UserId,
			Username:           ud.Username,
			Nickname:           ud.Nickname,
			Avatar:             ud.Avatar,
			Email:              ud.Email,
			Phone:              ud.Phone,
			IsSuperAdmin:       ud.IsSuperAdminRaw,
			MustChangePassword: ud.MustChangePwdRaw,
			MemberType:         ud.MemberType,
			Perms:              ud.Perms,
		},
	}, nil
}