package security

import (
	"crypto/rand"
	"crypto/sha256"
	"encoding/base64"
	"encoding/hex"
	"errors"
	"time"

	"github.com/golang-jwt/jwt/v5"
)

type AdminClaims struct {
	AdminID   string `json:"admin_id"`
	Username  string `json:"username"`
	TokenType string `json:"token_type"`
	jwt.RegisteredClaims
}

type TokenService struct {
	Secret     []byte
	AccessTTL  time.Duration
	RefreshTTL time.Duration
}

func (s TokenService) NewAccessToken(adminID, username string) (string, time.Time, error) {
	now := time.Now()
	expires := now.Add(s.AccessTTL)
	claims := AdminClaims{AdminID: adminID, Username: username, TokenType: "access", RegisteredClaims: jwt.RegisteredClaims{Subject: adminID, IssuedAt: jwt.NewNumericDate(now), ExpiresAt: jwt.NewNumericDate(expires)}}
	token, err := jwt.NewWithClaims(jwt.SigningMethodHS256, claims).SignedString(s.Secret)
	return token, expires, err
}

func (s TokenService) ParseAccessToken(raw string) (*AdminClaims, error) {
	claims := new(AdminClaims)
	token, err := jwt.ParseWithClaims(raw, claims, func(token *jwt.Token) (any, error) {
		if token.Method != jwt.SigningMethodHS256 {
			return nil, errors.New("不支持的签名算法")
		}
		return s.Secret, nil
	})
	if err != nil || !token.Valid || claims.TokenType != "access" {
		return nil, errors.New("登录凭证无效或已过期")
	}
	return claims, nil
}

func (s TokenService) NewRefreshToken() (plain, hash string, expires time.Time, err error) {
	data := make([]byte, 32)
	if _, err = rand.Read(data); err != nil {
		return
	}
	plain = base64.RawURLEncoding.EncodeToString(data)
	hash = HashToken(plain)
	expires = time.Now().Add(s.RefreshTTL)
	return
}

func HashToken(token string) string {
	sum := sha256.Sum256([]byte(token))
	return hex.EncodeToString(sum[:])
}