<?php
declare(strict_types=1);
/*
* The MIT License (MIT)
*
* Copyright (c) 2018-2020 Spomky-Labs
*
* This software may be modified and distributed under the terms
* of the MIT license. See the LICENSE file for details.
*/
namespace CBOR;
use Brick\Math\BigInteger;
use function chr;
use function count;
use InvalidArgumentException;
final class LengthCalculator
{
public static function getLengthOfString(string $data): array
{
$length = mb_strlen($data, '8bit');
return self::computeLength($length);
}
public static function getLengthOfArray(array $data): array
{
$length = count($data);
return self::computeLength($length);
}
private static function computeLength(int $length): array
{
switch (true) {
case $length < 24:
return [$length, null];
case $length < 0xFF:
return [24, chr($length)];
case $length < 0xFFFF:
return [25, self::hex2bin(static::fixHexLength(Utils::intToHex($length)))];
case $length < 0xFFFFFFFF:
return [26, self::hex2bin(static::fixHexLength(Utils::intToHex($length)))];
case BigInteger::of($length)->isLessThan(BigInteger::fromBase('FFFFFFFFFFFFFFFF', 16)):
return [27, self::hex2bin(static::fixHexLength(Utils::intToHex($length)))];
default:
return [31, null];
}
}
private static function hex2bin(string $data): string
{
$result = hex2bin($data);
if (false === $result) {
throw new InvalidArgumentException('Unable to convert the data');
}
return $result;
}
private static function fixHexLength(string $data): string
{
return str_pad($data, (int) (2 ** ceil(log(mb_strlen($data, '8bit'), 2))), '0', STR_PAD_LEFT);
}
}