package jwt

import (
	"errors"
	"time"

	"github.com/golang-jwt/jwt/v5"
	"github.com/google/uuid"
	"golang.org/x/sync/singleflight"
)

var (
	Concurrency_Control = &singleflight.Group{}
)

func (j *jwtUtil) CreateClaims(baseClaims *BaseClaims) *CustomClaims {
	bf := j.config.GetBufferTime()
	ep := j.config.GetExpiresTime()
	ts := time.Now()
	return &CustomClaims{
		BaseClaims: *baseClaims,
		BufferTime: int64(bf / time.Second), // 缓冲时间, 缓冲时间内会获得新的token刷新令牌 此时一个用户会存在两个有效令牌 但是前端只留一个 另一个会丢失
		RegisteredClaims: jwt.RegisteredClaims{
			Audience:  jwt.ClaimStrings{j.config.GetAudience()}, // 受众
			NotBefore: jwt.NewNumericDate(ts.Add(-1000)),        // 签名生效时间
			ExpiresAt: jwt.NewNumericDate(ts.Add(ep)),           // 过期时间, from配置文件
			Issuer:    j.config.Issuer,                          // 签名的发行者
			IssuedAt:  jwt.NewNumericDate(ts),
		},
	}
}

func (j *jwtUtil) CreateTokenRaw(claims *CustomClaims) (string, error) {
	token := jwt.NewWithClaims(jwt.SigningMethodHS256, claims)
	signKey := j.config.SigningKey
	if signKey == "" {
		return "", errors.New("jwt signing key is empty")
	}

	return token.SignedString([]byte(signKey))
}

// 创建一个token
func (j *jwtUtil) CreateToken(claims *CustomClaims) (string, error) {
	claims.Issuer = j.config.Issuer

	ep := j.config.GetExpiresTime()
	if claims.ExpiresAt == nil {
		expiresAt := jwt.NewNumericDate(time.Now().Add(ep))
		claims.ExpiresAt = expiresAt
	}

	if claims.ID == "" {
		claims.ID = uuid.New().String()
	}

	return j.CreateTokenRaw(claims)
}

// CreateTokenByOldToken 旧token 换新token 使用归并回源避免并发问题
func (j *jwtUtil) CreateTokenByOldToken(oldToken string, claims *CustomClaims) (string, error) {
	v, err, _ := Concurrency_Control.Do("JWT:"+oldToken, func() (any, error) {
		return j.CreateToken(claims)
	})
	return v.(string), err
}

// 解析 token
func (j *jwtUtil) ParseToken(jwtToken string) (claims *CustomClaims, err error) {
	claims, err = ParseJwtTokenWithClaims(&jwtToken, j.config.SigningKey)
	return
}