package auth

import (
	"errors"
	"time"

	"perms-system-server/internal/consts"
	"perms-system-server/internal/middleware"

	"github.com/golang-jwt/jwt/v4"
)

var ErrTokenTypeMismatch = errors.New("token type mismatch")

// ParseWithHMAC 转发到 middleware 包的统一 JWT 解析入口。保留本别名以兼容旧调用方（测试与
// 历史 logic 代码）；真实实现已经上移到 middleware 层，避免 middleware↔auth 循环依赖，
// 同时把"算法混淆防御"的审计覆盖收敛到唯一一个函数（见审计 L-N1）。
func ParseWithHMAC(tokenStr, secret string, claims jwt.Claims) (*jwt.Token, error) {
	return middleware.ParseWithHMAC(tokenStr, secret, claims)
}

type RefreshClaims struct {
	TokenType    string `json:"tokenType"`
	UserId       int64  `json:"userId"`
	ProductCode  string `json:"productCode"`
	TokenVersion int64  `json:"tokenVersion"`
	jwt.RegisteredClaims
}

func GenerateAccessToken(secret string, expireSeconds int64, userId int64, username, productCode, memberType string, tokenVersion int64) (string, error) {
	now := time.Now()
	claims := middleware.Claims{
		TokenType:    consts.TokenTypeAccess,
		UserId:       userId,
		Username:     username,
		ProductCode:  productCode,
		MemberType:   memberType,
		TokenVersion: tokenVersion,
		RegisteredClaims: jwt.RegisteredClaims{
			ExpiresAt: jwt.NewNumericDate(now.Add(time.Duration(expireSeconds) * time.Second)),
			IssuedAt:  jwt.NewNumericDate(now),
		},
	}
	token := jwt.NewWithClaims(jwt.SigningMethodHS256, claims)
	return token.SignedString([]byte(secret))
}

func GenerateRefreshToken(secret string, expireSeconds int64, userId int64, productCode string, tokenVersion int64) (string, error) {
	now := time.Now()
	claims := RefreshClaims{
		TokenType:    consts.TokenTypeRefresh,
		UserId:       userId,
		ProductCode:  productCode,
		TokenVersion: tokenVersion,
		RegisteredClaims: jwt.RegisteredClaims{
			ExpiresAt: jwt.NewNumericDate(now.Add(time.Duration(expireSeconds) * time.Second)),
			IssuedAt:  jwt.NewNumericDate(now),
		},
	}
	token := jwt.NewWithClaims(jwt.SigningMethodHS256, claims)
	return token.SignedString([]byte(secret))
}

// GenerateRefreshTokenWithExpiry 签发 refreshToken，使用绝对过期时间（用于 token 轮转场景）。
func GenerateRefreshTokenWithExpiry(secret string, expiresAt time.Time, userId int64, productCode string, tokenVersion int64) (string, error) {
	now := time.Now()
	if !expiresAt.After(now) {
		return "", errors.New("refresh token has expired")
	}
	claims := RefreshClaims{
		TokenType:    consts.TokenTypeRefresh,
		UserId:       userId,
		ProductCode:  productCode,
		TokenVersion: tokenVersion,
		RegisteredClaims: jwt.RegisteredClaims{
			ExpiresAt: jwt.NewNumericDate(expiresAt),
			IssuedAt:  jwt.NewNumericDate(now),
		},
	}
	token := jwt.NewWithClaims(jwt.SigningMethodHS256, claims)
	return token.SignedString([]byte(secret))
}

func ParseRefreshToken(tokenStr, secret string) (*RefreshClaims, error) {
	token, err := ParseWithHMAC(tokenStr, secret, &RefreshClaims{})
	if err != nil {
		return nil, err
	}
	claims, ok := token.Claims.(*RefreshClaims)
	if !ok || !token.Valid {
		return nil, jwt.ErrSignatureInvalid
	}
	if claims.TokenType != consts.TokenTypeRefresh {
		return nil, ErrTokenTypeMismatch
	}
	return claims, nil
}