package common

import (
	"github.com/golang-jwt/jwt/v4"
	"github.com/pkg/errors"
	"time"
)

var SecretKey []byte

type UserClaims struct {
	Username string `json:"username"`
	jwt.RegisteredClaims
}

func GenerateToken(username string) (tokenString string, err error) {
	claim := UserClaims{
		Username: username,
		RegisteredClaims: jwt.RegisteredClaims{
			ExpiresAt: jwt.NewNumericDate(time.Now().Add(12 * time.Hour)),
			IssuedAt:  jwt.NewNumericDate(time.Now()),
			NotBefore: jwt.NewNumericDate(time.Now()),
		}}
	token := jwt.NewWithClaims(jwt.SigningMethodHS256, claim)
	tokenString, err = token.SignedString(SecretKey)
	return tokenString, err
}

func ParseToken(tokenString string) (*UserClaims, error) {
	token, err := jwt.ParseWithClaims(tokenString, &UserClaims{}, func(token *jwt.Token) (interface{}, error) {
		return SecretKey, nil
	})
	if err != nil {
		if ve, ok := err.(*jwt.ValidationError); ok {
			if ve.Errors&jwt.ValidationErrorMalformed != 0 {
				return nil, errors.New("that's not even a token")
			} else if ve.Errors&jwt.ValidationErrorExpired != 0 {
				return nil, errors.New("token is expired")
			} else if ve.Errors&jwt.ValidationErrorNotValidYet != 0 {
				return nil, errors.New("token not active yet")
			} else {
				return nil, errors.New("couldn't handle this token")
			}
		}
	}
	if claims, ok := token.Claims.(*UserClaims); ok && token.Valid {
		return claims, nil
	}
	return nil, errors.New("couldn't handle this token")
}