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   1  <?php
   2  
   3  declare(strict_types=1);
   4  
   5  /*
   6   * The MIT License (MIT)
   7   *
   8   * Copyright (c) 2018-2020 Spomky-Labs
   9   *
  10   * This software may be modified and distributed under the terms
  11   * of the MIT license.  See the LICENSE file for details.
  12   */
  13  
  14  namespace CBOR;
  15  
  16  use Brick\Math\BigInteger;
  17  use function chr;
  18  use function count;
  19  use InvalidArgumentException;
  20  
  21  final class LengthCalculator
  22  {
  23      public static function getLengthOfString(string $data): array
  24      {
  25          $length = mb_strlen($data, '8bit');
  26  
  27          return self::computeLength($length);
  28      }
  29  
  30      public static function getLengthOfArray(array $data): array
  31      {
  32          $length = count($data);
  33  
  34          return self::computeLength($length);
  35      }
  36  
  37      private static function computeLength(int $length): array
  38      {
  39          switch (true) {
  40              case $length < 24:
  41                  return [$length, null];
  42              case $length < 0xFF:
  43                  return [24, chr($length)];
  44              case $length < 0xFFFF:
  45                  return [25, self::hex2bin(static::fixHexLength(Utils::intToHex($length)))];
  46              case $length < 0xFFFFFFFF:
  47                  return [26, self::hex2bin(static::fixHexLength(Utils::intToHex($length)))];
  48              case BigInteger::of($length)->isLessThan(BigInteger::fromBase('FFFFFFFFFFFFFFFF', 16)):
  49                  return [27, self::hex2bin(static::fixHexLength(Utils::intToHex($length)))];
  50              default:
  51                  return [31, null];
  52          }
  53      }
  54  
  55      private static function hex2bin(string $data): string
  56      {
  57          $result = hex2bin($data);
  58          if (false === $result) {
  59              throw new InvalidArgumentException('Unable to convert the data');
  60          }
  61  
  62          return $result;
  63      }
  64  
  65      private static function fixHexLength(string $data): string
  66      {
  67          return str_pad($data, (int) (2 ** ceil(log(mb_strlen($data, '8bit'), 2))), '0', STR_PAD_LEFT);
  68      }
  69  }