class Bytes

class Bytes {
  
  /**
   * The number of bytes in a kilobyte.
   *
   * @see http://wikipedia.org/wiki/Kilobyte
   */
  const KILOBYTE = 1024;
  
  /**
   * The allowed suffixes of a bytes string in lowercase.
   *
   * @see http://wikipedia.org/wiki/Kilobyte
   */
  const ALLOWED_SUFFIXES = [
    '',
    'b',
    'byte',
    'bytes',
    'k',
    'kb',
    'kilobyte',
    'kilobytes',
    'm',
    'mb',
    'megabyte',
    'megabytes',
    'g',
    'gb',
    'gigabyte',
    'gigabytes',
    't',
    'tb',
    'terabyte',
    'terabytes',
    'p',
    'pb',
    'petabyte',
    'petabytes',
    'e',
    'eb',
    'exabyte',
    'exabytes',
    'z',
    'zb',
    'zettabyte',
    'zettabytes',
    'y',
    'yb',
    'yottabyte',
    'yottabytes',
  ];
  
  /**
   * Parses a given byte size.
   *
   * @param int|float|string $size
   *   An integer, float, or string size expressed as a number of bytes with
   *   optional SI or IEC binary unit prefix (e.g. 2, 2.4, 3K, 5MB, 10G, 6GiB,
   *   8 bytes, 9mbytes).
   *
   * @return float
   *   The floating point value of the size in bytes.
   */
  public static function toNumber($size) : float {
    // Remove the non-unit characters from the size.
    $unit = preg_replace('/[^bkmgtpezy]/i', '', $size);
    // Remove the non-numeric characters from the size.
    $size = preg_replace('/[^0-9\\.]/', '', $size);
    if ($unit) {
      // Find the position of the unit in the ordered string which is the power
      // of magnitude to multiply a kilobyte by.
      return round($size * pow(self::KILOBYTE, stripos('bkmgtpezy', $unit[0])));
    }
    else {
      // Ensure size is a proper number type.
      return round((double) $size);
    }
  }
  
  /**
   * Validate that a string is a representation of a number of bytes.
   *
   * @param string $string
   *   The string to validate.
   *
   * @return bool
   *   TRUE if the string is valid, FALSE otherwise.
   */
  public static function validate($string) : bool {
    // Ensure that the string starts with a numeric character.
    if (!preg_match('/^[0-9]/', $string)) {
      return FALSE;
    }
    // Remove the numeric characters from the beginning of the value.
    $string = preg_replace('/^[0-9\\.]+/', '', $string);
    // Remove remaining spaces from the value.
    $string = trim($string);
    return in_array(strtolower($string), self::ALLOWED_SUFFIXES);
  }
  
  /**
   * Validates a string is a representation of a number of bytes.
   *
   * To be used with the `Callback` constraint.
   *
   * @param string|int|float|null $value
   *   The string, integer or float to validate.
   * @param \Symfony\Component\Validator\Context\ExecutionContextInterface $context
   *   The validation execution context.
   *
   * @see \Symfony\Component\Validator\Constraints\CallbackValidator
   * @see core/config/schema/core.data_types.schema.yml
   */
  public static function validateConstraint(string|int|float|null $value, ExecutionContextInterface $context) : void {
    // Ignore NULL values (i.e. support `nullable: true`).
    if ($value === NULL) {
      return;
    }
    if (!self::validate((string) $value)) {
      $context->addViolation('This value must be a number of bytes, optionally with a unit such as "MB" or "megabytes". %value does not represent a number of bytes.', [
        '%value' => $value,
      ]);
    }
  }

}