<?php

/*
 * This file is part of PHAR Utils.
 *
 * (c) Jordi Boggiano <j.boggiano@seld.be>
 *
 * For the full copyright and license information, please view the LICENSE
 * file that was distributed with this source code.
 */

namespace Seld\PharUtils;

class Timestamps
{
    private $contents;

    /**
     * @param string $file path to the phar file to use
     */
    public function __construct($file)
    {
        $this->contents = file_get_contents($file);
    }

    /**
     * Updates each file's unix timestamps in the PHAR
     *
     * The PHAR signature can then be produced in a reproducible manner.
     *
     * @param int|DateTime|string $timestamp Date string or DateTime or unix timestamp to use
     */
    public function updateTimestamps($timestamp = null)
    {
        if ($timestamp instanceof \DateTime) {
            $timestamp = $timestamp->getTimestamp();
        } elseif (is_string($timestamp)) {
            $timestamp = strtotime($timestamp);
        } elseif (!is_int($timestamp)) {
            $timestamp = strtotime('1984-12-24T00:00:00Z');
        }

        // detect manifest offset / end of stub
        if (!preg_match('{__HALT_COMPILER\(\);(?: +\?>)?\r?\n}', $this->contents, $match, PREG_OFFSET_CAPTURE)) {
            throw new \RuntimeException('Could not detect the stub\'s end in the phar');
        }

        // set starting position and skip past manifest length
        $pos = $match[0][1] + strlen($match[0][0]);
        $stubEnd = $pos + $this->readUint($pos, 4);
        $pos += 4;

        $numFiles = $this->readUint($pos, 4);
        $pos += 4;

        // skip API version (YOLO)
        $pos += 2;

        // skip PHAR flags
        $pos += 4;

        $aliasLength = $this->readUint($pos, 4);
        $pos += 4 + $aliasLength;

        $metadataLength = $this->readUint($pos, 4);
        $pos += 4 + $metadataLength;

        while ($pos < $stubEnd) {
            $filenameLength = $this->readUint($pos, 4);
            $pos += 4 + $filenameLength;

            // skip filesize
            $pos += 4;

            // update timestamp to a fixed value
            $this->contents = substr_replace($this->contents, pack('L', $timestamp), $pos, 4);

            // skip timestamp, compressed file size, crc32 checksum and file flags
            $pos += 4*4;

            $metadataLength = $this->readUint($pos, 4);
            $pos += 4 + $metadataLength;

            $numFiles--;
        }

        if ($numFiles !== 0) {
            throw new \LogicException('All files were not processed, something must have gone wrong');
        }
    }

    /**
     * Saves the updated phar file, optionally with an updated signature.
     *
     * @param  string $path
     * @param  int $signatureAlgo One of Phar::MD5, Phar::SHA1, Phar::SHA256 or Phar::SHA512
     * @return bool
     */
    public function save($path, $signatureAlgo)
    {
        $pos = $this->determineSignatureBegin();

        $algos = array(
            \Phar::MD5 => 'md5',
            \Phar::SHA1 => 'sha1',
            \Phar::SHA256 => 'sha256',
            \Phar::SHA512 => 'sha512',
        );

        if (!isset($algos[$signatureAlgo])) {
            throw new \UnexpectedValueException('Invalid hash algorithm given: '.$signatureAlgo.' expected one of Phar::MD5, Phar::SHA1, Phar::SHA256 or Phar::SHA512');
        }
        $algo = $algos[$signatureAlgo];

        // re-sign phar
        //           signature
        $signature = hash($algo, substr($this->contents, 0, $pos), true)
            // sig type
            . pack('L', $signatureAlgo)
            // ohai Greg & Marcus
            . 'GBMB';

        $this->contents = substr($this->contents, 0, $pos) . $signature;

        return file_put_contents($path, $this->contents);
    }

    private function readUint($pos, $bytes)
    {
        $res = unpack("L", substr($this->contents, $pos, $bytes));

        return $res[1];
    }

    /**
     * Determine the beginning of the signature.
     *
     * @return int
     */
    private function determineSignatureBegin()
    {
        // detect signature position
        if (!preg_match('{__HALT_COMPILER\(\);(?: +\?>)?\r?\n}', $this->contents, $match, PREG_OFFSET_CAPTURE)) {
            throw new \RuntimeException('Could not detect the stub\'s end in the phar');
        }

        // set starting position and skip past manifest length
        $pos = $match[0][1] + strlen($match[0][0]);
        $stubEnd = $pos + $this->readUint($pos, 4);

        $pos += 4;
        $numFiles = $this->readUint($pos, 4);

        $pos += 4;

        // skip API version (YOLO)
        $pos += 2;

        // skip PHAR flags
        $pos += 4;

        $aliasLength = $this->readUint($pos, 4);
        $pos += 4 + $aliasLength;

        $metadataLength = $this->readUint($pos, 4);
        $pos += 4 + $metadataLength;

        $compressedSizes = 0;
        while ($pos < $stubEnd) {
            $filenameLength = $this->readUint($pos, 4);
            $pos += 4 + $filenameLength;

            // skip filesize and timestamp
            $pos += 2*4;

            $compressedSizes += $this->readUint($pos, 4);
            // skip compressed file size, crc32 checksum and file flags
            $pos += 3*4;

            $metadataLength = $this->readUint($pos, 4);
            $pos += 4 + $metadataLength;

            $numFiles--;
        }

        if ($numFiles !== 0) {
            throw new \LogicException('All files were not processed, something must have gone wrong');
        }

        return $pos + $compressedSizes;
    }
}