package toolm

import (
	"crypto/hmac"
	"crypto/sha256"
	"fmt"
	"math/rand"
	"time"
)

const (
	CharsAll = 1 << iota
	Digit
	LowerCase
	UpperCase
)

const (
	digit     = "0123456789"
	lowercase = "abcdefghijklmnopqrstuvwxyz"
	uppercase = "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
	//octal = "01234567"
	//hex = "0123456789abcdefg"
)

func RandString(l, chars int) string {
	charset := ""
	if chars&CharsAll > 0 {
		charset = digit + lowercase + uppercase
	}

	charsetLen := len(charset)

	seededRand := rand.New(rand.NewSource(time.Now().UnixNano()))

	b := make([]byte, l)
	for i := range b {
		b[i] = charset[seededRand.Intn(charsetLen)]
	}

	return string(b)
}

func Sha256HMacString(message, key string) string {
	mac := hmac.New(sha256.New, []byte(key))
	mac.Write([]byte(message))
	expectedMAC := mac.Sum(nil)
	return fmt.Sprintf("%X", expectedMAC)
}