package jwtx

import (
	"errors"
	"time"

	"github.com/dgrijalva/jwt-go"
)

var (
	TokenExpired        error = errors.New("token is expired")
	TokenNotValidYet    error = errors.New("token not active yet")
	TokenMalformed      error = errors.New("that's not even a token")
	TokenInvalid        error = errors.New("couldn't handle this token")
	TokenGenerateFailed error = errors.New("generate token failed!")

	// defaultSignKey string = "hcVI@Nm4cjhjPVvCpL5^1%jY"
	defaultSignKey = "XiaoXinPlus"

	RedisUserKey string = "user:%d"
)

type jwtx struct {
	SigningKey []byte
}

type Claims struct {
	TenantId int64 `json:"tenant_id"`
	ClientId int64 `json:"client_id"`
	UserId   int64 `json:"user_id"`

	Tag string `json:"tag"` // 额外标记 

	jwt.StandardClaims
}

func NewJWT() *jwtx {
	return &jwtx{
		[]byte(defaultSignKey),
	}
}

// 仅解析Token
func (j *jwtx) Decode(tokenString string) (*Claims, error) {
	token, err := jwt.ParseWithClaims(tokenString, &Claims{}, func(token *jwt.Token) (interface{}, error) {
		return j.SigningKey, nil
	})
	if err != nil {
		if ve, ok := err.(*jwt.ValidationError); ok {
			if ve.Errors&jwt.ValidationErrorMalformed == jwt.ValidationErrorMalformed {
				return nil, TokenMalformed
			} else if ve.Errors&jwt.ValidationErrorExpired == jwt.ValidationErrorExpired {
				// Token is expired
				return nil, TokenExpired
			} else if ve.Errors&jwt.ValidationErrorNotValidYet == jwt.ValidationErrorNotValidYet {
				return nil, TokenNotValidYet
			} else {
				return nil, TokenInvalid
			}
		}
	}
	claims, ok := token.Claims.(*Claims)
	if !ok || !token.Valid {
		return nil, TokenInvalid
	}
	return claims, nil
}

// 根据参数生成和设置 token
func (j *jwtx) Encode(claims *Claims, expiresTime time.Time) (string, error) {

	expSecond := expiresTime.Unix()
	nowSecond := time.Now().Unix()

	if expSecond-nowSecond < 0 {
		return "", errors.New("时间无效")
	}

	// 设置有效时间
	claims.StandardClaims.ExpiresAt = expiresTime.Unix()
	token := jwt.NewWithClaims(jwt.SigningMethodHS256, claims)
	tokenString, err := token.SignedString(j.SigningKey)
	if err != nil {
		return "", TokenGenerateFailed
	}
	return tokenString, nil
}