// Copyright 2014 The go-ethereum Authors
// This file is part of the go-ethereum library.
//
// Modified by Prysmatic Labs 2018
//
// The go-ethereum library is free software: you can redistribute it and/or modify
// it under the terms of the GNU Lesser General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// The go-ethereum library is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU Lesser General Public License for more details.
//
// You should have received a copy of the GNU Lesser General Public License
// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.

package keystore

import (
	"crypto/aes"
	"crypto/cipher"
	"encoding/hex"
	"fmt"
	"time"

	"github.com/prysmaticlabs/prysm/shared/bls"
	"github.com/prysmaticlabs/prysm/shared/timeutils"
)

func aesCTRXOR(key, inText, iv []byte) ([]byte, error) {
	// AES-128 is selected due to size of encryptKey.
	aesBlock, err := aes.NewCipher(key)
	if err != nil {
		return nil, err
	}
	stream := cipher.NewCTR(aesBlock, iv)
	outText := make([]byte, len(inText))
	stream.XORKeyStream(outText, inText)
	return outText, err
}

func ensureInt(x interface{}) int {
	res, ok := x.(int)
	if !ok {
		res = int(x.(float64))
	}
	return res
}

// keyFileName implements the naming convention for keyfiles:
// UTC--<created_at UTC ISO8601>-<first 8 character of address hex>
func keyFileName(pubkey bls.PublicKey) string {
	ts := timeutils.Now().UTC()
	return fmt.Sprintf("UTC--%s--%s", toISO8601(ts), hex.EncodeToString(pubkey.Marshal())[:8])
}

func toISO8601(t time.Time) string {
	var tz string
	name, offset := t.Zone()
	if name == "UTC" {
		tz = "Z"
	} else {
		tz = fmt.Sprintf("%03d00", offset/3600)
	}
	return fmt.Sprintf("%04d-%02d-%02dT%02d-%02d-%02d.%09d%s", t.Year(), t.Month(), t.Day(), t.Hour(), t.Minute(), t.Second(), t.Nanosecond(), tz)
}