// Copyright (C) 2019 Marius Schellenberger

package main

import (
	"flag"
	"fmt"
	"github.com/pquerna/otp/totp"
	"golang.org/x/crypto/ssh/terminal"
	"os"
	"strconv"
	"time"
)

var loop bool

func init() {
	flag.BoolVar(&loop, "loop", false, "print new code every 30 seconds")
	flag.Parse()
}

func printCode(secret []byte) {
	now := time.Now()
	code, err := totp.GenerateCode(string(secret), now)
	if err != nil {
		fmt.Println(err)
		os.Exit(1)
	}
	s := 30 - (now.Second() % 30)
	sec := strconv.Itoa(s)
	if s < 10 {
		sec = " " + sec
	}
	fmt.Printf("Code: %s Seconds left: %s", code, sec)
}

func main() {
	fmt.Print("Enter secret key: ")
	secret, err := terminal.ReadPassword(int(os.Stdin.Fd()))
	fmt.Println("")
	if err != nil {
		fmt.Println(err)
		os.Exit(1)
	}
	if loop {
		for {
			printCode(secret)
			fmt.Print("\r")
			time.Sleep(time.Second)
		}
	} else {
		printCode(secret)
		fmt.Println("")
	}
}