package main

import (
	"fmt"
	"github.com/dgrijalva/jwt-go"
	"strconv"
)

type TokenClaims struct {
	ID float64 `json:"id"`
	jwt.StandardClaims
}

func main() {
	c, err := parseToken("eyJhbGciOiJIUzI1NiIsImlhdCI6MTUzNzg0Njc4MywiZXhwIjoxNTM5MDU2MzgzfQ.eyJpZCI6MzI0NTEzNH0.RqRoad8H5oAGY6L3qMLcxCUYE5Fl7-MXtpSyfSU4aqU")
	if nil != err {
		println(err)
	}
	fmt.Printf("%v\n", c)
	fmt.Printf("%v", strconv.FormatFloat(c.ID, 'f', 0, 64))
}

func parseToken(tokenString string) (*TokenClaims, error) {
	token, err := jwt.ParseWithClaims(tokenString, &TokenClaims{}, func(token *jwt.Token) (interface{}, error) {
		if _, ok := token.Method.(*jwt.SigningMethodHMAC); !ok {
			return nil, fmt.Errorf("Unexpected signing method: %v", token.Header["alg"])
		}

		return []byte("hard to guess string"), nil
	})
	if err != nil {
		return nil, err
	}

	if claims, ok := token.Claims.(*TokenClaims); ok && token.Valid {
		return claims, nil
	}
	return nil, nil
}