package utils

import (
	"errors"
	"github.com/golang-jwt/jwt/v4"
	"github.com/spf13/viper"
)

type JWT struct {
	SigningKey []byte
}

var (
	TokenExpired     = errors.New("token已过期")
	TokenNotValidYet = errors.New("token未生效")
	TokenMalformed   = errors.New("token非法")
	TokenInvalid     = errors.New("无法处理此token")
)

func NewJWT() *JWT {
	return &JWT{
		[]byte(viper.GetString("signingKey")),
	}
}

// CreateToken 创建一个token
func (j *JWT) CreateToken(claims CustomClaims) (string, error) {
	token := jwt.NewWithClaims(jwt.SigningMethodHS256, claims)
	return token.SignedString(j.SigningKey)
}

// ParseToken 解析 token
func (j *JWT) ParseToken(tokenString string) (*CustomClaims, error) {
	token, err := jwt.ParseWithClaims(tokenString, &CustomClaims{}, func(token *jwt.Token) (i interface{}, e error) {
		return j.SigningKey, nil
	})
	if err != nil {
		if ve, ok := err.(*jwt.ValidationError); ok {
			if ve.Errors&jwt.ValidationErrorMalformed != 0 {
				return nil, TokenMalformed
			} else if ve.Errors&jwt.ValidationErrorExpired != 0 {
				// Token is expired
				return nil, TokenExpired
			} else if ve.Errors&jwt.ValidationErrorNotValidYet != 0 {
				return nil, TokenNotValidYet
			} else {
				return nil, TokenInvalid
			}
		}
	}
	if token != nil {
		if claims, ok := token.Claims.(*CustomClaims); ok && token.Valid {
			return claims, nil
		}
		return nil, TokenInvalid
	} else {
		return nil, TokenInvalid
	}
}

type CustomClaims struct {
	ID         uint
	Name       string
	Uuid       string
	BufferTime int64
	jwt.StandardClaims
}