<?php
/**
 * Simple class to support some very basic operations on 64 bit intergers
 * on 32 bit machines.
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program 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 General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 *
 * @author Nicolai Ehemann <en@enlightened.de>
 * @copyright Copyright (C) 2013-2014 Nicolai Ehemann and contributors
 * @license GNU GPL
 */
namespace ZipStreamer;

use ZipStreamer\Lib\Count64_32;
use ZipStreamer\Lib\Count64_64;
use ZipStreamer\Lib\Count64Base;

// Use bit shift operations instead of hex literals to avoid float representation in PHP 8.5+
/** @var int */
const INT64_HIGH_MAP = (0xffffffff << 32);
/** @var int */
const INT64_LOW_MAP = 0xffffffff;
/** @var int */
const INT_MAX_32 = 0xffffffff;

/**
 * Unsigned right shift
 *
 * @param int $bits integer to be shifted
 * @param int $shift number of bits to be shifted
 * @return int shifted integer
 */
function urShift($bits, $shift) {
  if ($shift == 0) {
    return $bits;
  }
  return ($bits >> $shift) & ~(1 << (8 * PHP_INT_SIZE - 1) >> ($shift - 1));
}

/**
 * Pack 1 byte data into binary string
 *
 * @param mixed $data data
 * @return string 1 byte binary string
 */
function pack8($data) {
  return pack('C', $data);
}

/**
 * Pack 2 byte data into binary string, little endian format
 *
 * @param mixed $data data
 * @return string 2 byte binary string
 */
function pack16le($data) {
  return pack('v', $data);
}

/**
 * Unpack 2 byte binary string, little endian format to 2 byte data
 *
 * @param string $data binary string
 * @return integer 2 byte data
 */
function unpack16le($data) {
  $result = unpack('v', $data);
  return $result[1];
}

/**
 * Pack 4 byte data into binary string, little endian format
 *
 * @param mixed $data data
 * @return 4 byte binary string
 */
function pack32le($data) {
  return pack('V', $data);
}

/**
 * Unpack 4 byte binary string, little endian format to 4 byte data
 *
 * @param string $data binary string
 * @return integer 4 byte data
 */
function unpack32le($data) {
  $result = unpack('V', $data);
  return $result[1];
}

/**
 * Pack 8 byte data into binary string, little endian format
 *
 * @param mixed $data data
 * @return string 8 byte binary string
 */
function pack64le($data) {
  if (is_object($data)) {
    if (Count64_32::class == get_class($data)) {
      $value = $data->_getValue();
      $hiBytess = $value[0];
      $loBytess = $value[1];
    } else {
      $hiBytess = ($data->_getValue() & INT64_HIGH_MAP) >> 32;
      $loBytess = $data->_getValue() & INT64_LOW_MAP;
    }
  } else if (4 == PHP_INT_SIZE) {
    $hiBytess = 0;
    $loBytess = $data;
  } else {
    $hiBytess = ($data & INT64_HIGH_MAP) >> 32;
    $loBytess = $data & INT64_LOW_MAP;
  }
  return pack('VV', $loBytess, $hiBytess);
}

/**
 * Unpack 8 byte binary string, little endian format to 8 byte data
 *
 * @param string $data binary string
 * @return Count64Base data
 */
function unpack64le($data) {
  $bytes = unpack('V2', $data);
  return Count64::construct(array(
      $bytes[1],
      $bytes[2]
  ));
}

abstract class Count64 {
  public static function construct($value = 0, $limit32Bit = False) {
    if (4 == PHP_INT_SIZE) {
      return new Count64_32($value, $limit32Bit);
    }

      return new Count64_64($value, $limit32Bit);
  }
}
