<?php
/**
* Wrapper for {@link http://bitzi.com/bitcollider/ bitcollider}
* and related standalone helper functions to create
* {@link http://magnet-uri.sourceforge.net/ MAGNET} links and
* perform {@link http://www.faqs.org/rfcs/rfc3548.html Base32} encoding.
*/

/**
* Wrapper for the {@link http://bitzi.com/bitcollider/ bitcollider}
* file metadata extraction tool.
*
* Currently is not able to interact with Bitzi web services.
*
* <code>
* $b = new Bitcollider();
*
* # Normally bitcollider doesn't calculate md5
* $b->set_calculate_md5(true);
* $b->analyze_file('/path/to/my/test.txt');
* echo($b->get_sha1());
* echo($b->get_md5());
*
* # There are many format-specific getters.  Because
* # we're looking at a text file, the following will
* # print nothing:
* echo($b->getmp3bitrate());
*
* # These utility functions generate MAGNET links
* #
* #   http://magnet-uri.sourceforge.net/
* #
* echo($b->getmagnetlink());
*
* # A magnet link can optionally include a direct
* # download file URL in addition to file hashes
* echo($b->getmagnetlink('http://example.com/test.txt));
* </code>
*/
class Bitcollider {
  var $BITCOLLIDER = '/usr/local/bin/bitcollider';
  function set_program_location($bitcollider_full_path) {
    $this->BITCOLLIDER = $bitcollider_full_path;
  }
  var $file_metadata;
  var $calculate_md5 = false;
  function set_calculate_md5($boolean) { $this->calculate_md5 = $boolean; }
  var $calculate_crc32 = false;
  function set_calculate_crc32($boolean) { $this->calculate_crc32 = $boolean; }
  /**
   * Invokes the bitcollider program.
   * @return bool false if the program exists with a nonzero error code.
   */
  function analyze_file($filename) {
    $filename = escapeshellarg($filename);
    $cmd = "$this->BITCOLLIDER -p";
    if ($this->calculate_md5) { $cmd .= " --md5"; }
    if ($this->calculate_crc32) { $cmd .= " --crc32"; }
    $cmd .= " $filename";
    exec($cmd, $out, $return_code);
    if ($return_code != 0) {
      return false;
    }
    $this->file_metadata = array();
    foreach($out as $line) {
      if (preg_match('/^(\S+?)=(.*)$/',$line,$matches)) {
        $key = $matches[1];
        $value = $matches[2];
        $this->file_metadata[$key] = $value;
      }
    }
    return true;
  }
  function get_magnetlink($file_url='') {
    return magnetlink($this->get_sha1(), $this->get_filename(), $file_url, $this->get_treetiger(), $this->get_kzhash());
  }
  function get_sha1() {
    $a = $this->get_sha1_treetiger();
    return $a[0];
  }
  function get_treetiger() {
    $a = $this->get_sha1_treetiger();
    return $a[1];
  }
  function get_bitprint() { return $this->file_metadata['bitprint']; }
  function get_md5() { return $this->file_metadata['tag.md5.md5']; }
  function get_ed2k() { return $this->file_metadata['tag.ed2k.ed2khash']; }
  function get_kzhash() { return $this->file_metadata['tag.kzhash.kzhash']; }
  function get_crc32() { return $this->file_metadata['tag.crc32.crc32']; }
  function get_filename() { return $this->file_metadata['tag.filename.filename']; }
  function get_filelength() { return $this->file_metadata['tag.file.length']; }
  function get_first20bytes() { return $this->file_metadata['tag.file.first20']; }
  function get_audiotracktitle() { return $this->file_metadata['tag.audiotrack.title']; }
  function get_audiotrackartist() { return $this->file_metadata['tag.audiotrack.artist']; }
  function get_audiotrackalbum() { return $this->file_metadata['tag.audiotrack.album']; }
  function get_audiotracknumber() { return $this->file_metadata['tag.audiotrack.tracknumber']; }
  function get_audiotrackyear() { return $this->file_metadata['tag.audiotrack.year']; }
  function get_vorbisbitrate() { return $this->file_metadata['tag.vorbis.bitrate']; }
  function get_vorbisduration() { return $this->file_metadata['tag.vorbis.duration']; }
  function get_vorbissamplerate() { return $this->file_metadata['tag.vorbis.samplerate']; }
  function get_vorbischannels() { return $this->file_metadata['tag.vorbis.channels']; }
  function get_vorbisencoder() { return $this->file_metadata['tag.vorbis.encoder']; }
  function get_vorbisaudiosha1() { return $this->file_metadata['tag.vorbis.audio_sha1']; }
  function get_mp3bitrate() { return $this->file_metadata['tag.mp3.bitrate']; }
  function get_mp3vbr() { return $this->file_metadata['tag.mp3.vbr']; }
  function get_mp3duration() { return $this->file_metadata['tag.mp3.duration']; }
  function get_mp3stereo() { return $this->file_metadata['tag.mp3.stereo']; }
  function get_mp3encoder() { return $this->file_metadata['tag.mp3.encoder']; }
  function get_mp3audiosha1() { return $this->file_metadata['tag.mp3.audio_sha1']; }
  function get_imageformat() { return $this->file_metadata['tag.image.format']; }
  function get_imagewidth() { return $this->file_metadata['tag.image.width']; }
  function get_imageheight() { return $this->file_metadata['tag.image.height']; }
  function get_imagebpp() { return $this->file_metadata['tag.image.bpp']; }
  function get_id3genre() { return $this->file_metadata['tag.id3genre.genre']; }
  function get_wavsamplesize() { return $this->file_metadata['tag.wav.samplesize']; }
  function get_wavduration() { return $this->file_metadata['tag.wav.duration']; }
  function get_wavsamplerate() { return $this->file_metadata['tag.wav.samplerate']; }
  function get_wavchannels() { return $this->file_metadata['tag.wav.channels']; }
  function get_wavaudiosha1() { return $this->file_metadata['tag.wav.audio_sha1']; }
  function get_videoformat() { return $this->file_metadata['tag.video.format']; }
  function get_videowidth() { return $this->file_metadata['tag.video.width']; }
  function get_videoheight() { return $this->file_metadata['tag.video.height']; }
  function get_videofps() { return $this->file_metadata['tag.video.fps']; }
  function get_videoduration() { return $this->file_metadata['tag.video.duration']; }
  function get_videobitrate() { return $this->file_metadata['tag.video.bitrate']; }
  function get_videocodec() { return $this->file_metadata['tag.video.codec']; }
  function get_sha1_treetiger() {
    if (preg_match('/([A-Za-z2-7]{32})\.([A-Za-z2-7]{39})/',$this->get_bitprint(),$matches)) {
      return array($matches[1],$matches[2]);
    }
    return array('','');
  }
}

/**
* Create {@link http://magnet-uri.sourceforge.net MAGNET link}.
*
* Standalone function, useful if you already know file hashes.
* If using a Bitcollider object call $b->magnet_link() instead.
*
* Any parameter may be an empty string, in which case it will
* be ignored.  Typically $sha1 and $filename are always used.
*
* @param string $sha1 Base32-encoded full file SHA1 hash
* @param string $filename
* @param string $fileurl Direct link for file, typically http
* @param string $treetiger Base32-encoded tiger tree hash
* @param string $kzhash Hex-encoded kazaa hash
*
* @return string A {@link http://magnet-uri.sourceforge.net MAGNET link}
*/
function magnetlink($sha1, $filename, $fileurl, $treetiger, $kzhash) {
  $m = "";
  if ($sha1 && $treetiger) {
    $m .= "xt=urn:bitprint:$sha1.$treetiger";
  } else {
    if ($sha1) {
      $m .= "xt=urn:sha1:$sha1";
    } else if ($treetiger) {
      $m .= "xt=urn:tree:tiger:$treetiger";
    }
  }
  if ($kzhash) {
    if ($m) { $m .= "&"; }
    $m .= "xt=urn:kzhash:$kzhash";
  }
  if ($filename) {
    if ($m) { $m .= "&"; }
    $filename = urlencode($filename);
    $m .= "dn=$filename";
  }
  if ($fileurl) {
    if ($m) { $m .= "&"; }
    $fileurl = urlencode($fileurl);
    $m .= "xs=$fileurl";
  }
  return "magnet:?$m";
}


/**
* Convert hex (base16) encoding to
* {@link http://www.faqs.org/rfcs/rfc3548.html Base32} encoding.
*
* Probably horribly inefficient. Quick hack to work around initial
* failure to get solution using pack() to work and length limitations
* of base_convert().
*
* Example use: obtain base32 encoded full-file SHA1 hash.
* <code>
* $sha1_32 = hex_to_base32(sha1_file($filename));
* </code>
*
* If you're using the Bitcollider object you do not need to use this
* function.
*
* @param string $hex Hex (Base16) encoded string
*
* @return string Base32 encoded string
*/
function hex_to_base32($hex) {
  $b32_alpha_to_rfc3548_chars = array(
    '0' => 'A',
    '1' => 'B',
    '2' => 'C',
    '3' => 'D',
    '4' => 'E',
    '5' => 'F',
    '6' => 'G',
    '7' => 'H',
    '8' => 'I',
    '9' => 'J',
    'a' => 'K',
    'b' => 'L',
    'c' => 'M',
    'd' => 'N',
    'e' => 'O',
    'f' => 'P',
    'g' => 'Q',
    'h' => 'R',
    'i' => 'S',
    'j' => 'T',
    'k' => 'U',
    'l' => 'V',
    'm' => 'W',
    'n' => 'X',
    'o' => 'Y',
    'p' => 'Z',
    'q' => '2',
    'r' => '3',
    's' => '4',
    't' => '5',
    'u' => '6',
    'v' => '7'
  );
  for ($pos = 0; $pos < strlen($hex); $pos += 10) {
    $hs = substr($hex,$pos,10);
    $b32_alpha_part = base_convert($hs,16,32);
    $expected_b32_len = strlen($hs) * 0.8;
    $actual_b32_len = strlen($b32_alpha_part);
    $b32_padding_needed = $expected_b32_len - $actual_b32_len;
    for ($i = $b32_padding_needed; $i > 0; $i--) {
      $b32_alpha_part = '0' . $b32_alpha_part;
    }
    $b32_alpha .= $b32_alpha_part;
  }
  for ($i = 0; $i < strlen($b32_alpha); $i++) {
    $b32_rfc3548 .= $b32_alpha_to_rfc3548_chars[$b32_alpha[$i]];
  }
  return $b32_rfc3548;
}

?>