package main

import (
	"crypto/rand"
	"crypto/sha1"
	"encoding/base64"
	"encoding/hex"
	"fmt"
	"io"
)

func newUUID() string {
	var b [16]byte
	if _, err := io.ReadFull(rand.Reader, b[:]); err != nil {
		panic(err)
	}
	b[6] = (b[6] & 0x0f) | 0x40 // version 4
	b[8] = (b[8] & 0x3f) | 0x80 // variant RFC 4122
	return fmt.Sprintf("%08x-%04x-%04x-%04x-%012x",
		b[0:4], b[4:6], b[6:8], b[8:10], b[10:16])
}

func hashSHA1(s string) string {
	h := sha1.Sum([]byte(s))
	return hex.EncodeToString(h[:])
}

func encodeB64(s string) string {
	return base64.StdEncoding.EncodeToString([]byte(s))
}

func decodeB64(s string) string {
	b, err := base64.StdEncoding.DecodeString(s)
	if err != nil {
		return "[decode error]"
	}
	return string(b)
}