<?php
/**
 * @package Include
 * @subpackage External Scripts
 */

/*
   Copyright (c) 2003 Danilo Segan <danilo@kvota.net>.
   Copyright (c) 2005 Nico Kaiser <nico@siriux.net>
   
   This file is part of PHP-gettext.

   PHP-gettext 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 2 of the License, or
   (at your option) any later version.

   PHP-gettext 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 PHP-gettext; if not, write to the Free Software
   Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA

*/
 
/**
 * Provides a simple gettext replacement that works independently from
 * the system's gettext abilities.
 * It can read MO files and use them for translating strings.
 * The files are passed to gettext_reader as a Stream (see streams.php)
 * 
 * This version has the ability to cache all strings and translations to
 * speed up the string lookup.
 * While the cache is enabled by default, it can be switched off with the
 * second parameter in the constructor (e.g. whenusing very large MO files
 * that you don't want to keep in memory)
 * 
 * @package Include
 */
class gettext_reader {
  //public:
   var $error = 0; // public variable that holds error code (0 if no error)
   
   //private:
  var $BYTEORDER = 0;        // 0: low endian, 1: big endian
  var $STREAM = NULL;
  var $short_circuit = false;
  var $enable_cache = false;
  var $originals = NULL;      // offset of original table
  var $translations = NULL;    // offset of translation table
  var $pluralheader = NULL;    // cache header field for plural forms
  var $total = 0;          // total string count
  var $table_originals = NULL;  // table for original strings (offsets)
  var $table_translations = NULL;  // table for translated strings (offsets)
  var $cache_translations = NULL;  // original -> translation mapping


  /* Methods */
  
    
  /**
   * Reads a 32bit Integer from the Stream
   * 
   * @access private
   * @return Integer from the Stream
   */
  function readint() {
      if ($this->BYTEORDER == 0) {
        // low endian
		$_var=unpack('V', $this->STREAM->read(4));
		return array_shift($_var);
        //return array_shift(unpack('V', $this->STREAM->read(4)));
      } else {
        // big endian
		$_var=unpack('N', $this->STREAM->read(4));
		return array_shift($_var);
        //return array_shift(unpack('N', $this->STREAM->read(4)));
      }
    }

  /**
   * Reads an array of Integers from the Stream
   * 
   * @param int count How many elements should be read
   * @return Array of Integers
   */
  function readintarray($count) {
    if ($this->BYTEORDER == 0) {
        // low endian
        return unpack('V'.$count, $this->STREAM->read(4 * $count));
      } else {
        // big endian
        return unpack('N'.$count, $this->STREAM->read(4 * $count));
      }
  }
  
  /**
   * Constructor
   * 
   * @param object Reader the StreamReader object
   * @param boolean enable_cache Enable or disable caching of strings (default on)
   */
  function __construct($Reader, $enable_cache = true) {
  	$machine = php_uname("m");
  	
  	$enabled64Bits = false;
	if (preg_match('/64/', $machine)) {
  		$enabled64Bits = true;
  	}
  	
    // If there isn't a StreamReader, turn on short circuit mode.
    if (! $Reader || isset($Reader->error) ) {
      $this->short_circuit = true;
      return;
    }
    
    // Caching can be turned off
    $this->enable_cache = $enable_cache;

    // $MAGIC1 = (int)0x950412de; //bug in PHP 5
    $MAGIC1 = (int) - 1794895138;
    // $MAGIC2 = (int)0xde120495; //bug
    $MAGIC2 = (int) - 569244523;

    // Applied patch for 64bit systems
    // http://source.ibiblio.org/trac/lyceum/attachment/ticket/652/gettext-64bit-fix.diff

    $this->STREAM = $Reader;
    $magic = $this->readint();
    
    if ($enabled64Bits) {
	    if ($magic == ($MAGIC1 & 0xFFFFFFFF) || $magic == $MAGIC1) {
	        $this->BYTEORDER = 0;
	    } elseif ($magic == ($MAGIC2 & 0xFFFFFFFF) || $magic == $MAGIC2) {
	      $this->BYTEORDER = 1;
	    } else {
	      $this->error = 1; // not MO file
	      return false;
	    }
    }
    else {
    	if ($magic == $MAGIC1) {
	        $this->BYTEORDER = 0;
	    } elseif ($magic == $MAGIC2) {
	      $this->BYTEORDER = 1;
	    } else {
	      $this->error = 1; // not MO file
	      return false;
	    }
    }
    
    // FIXME: Do we care about revision? We should.
    $revision = $this->readint();
    
    $this->total = $this->readint();
    $this->originals = $this->readint();
    $this->translations = $this->readint();
  }
  
  /**
   * Loads the translation tables from the MO file into the cache
   * If caching is enabled, also loads all strings into a cache
   * to speed up translation lookups
   * 
   * @access private
   */
  function load_tables() {
    if (is_array($this->cache_translations) &&
      is_array($this->table_originals) &&
      is_array($this->table_translations))
      return;
    
    /* get original and translations tables */
    $this->STREAM->seekto($this->originals);
    $this->table_originals = $this->readintarray($this->total * 2);
    $this->STREAM->seekto($this->translations);
    $this->table_translations = $this->readintarray($this->total * 2);
    
    if ($this->enable_cache) {
      $this->cache_translations = array ();
      /* read all strings in the cache */
      for ($i = 0; $i < $this->total; $i++) {
        $this->STREAM->seekto($this->table_originals[$i * 2 + 2]);
        $original = $this->STREAM->read($this->table_originals[$i * 2 + 1]);
        $this->STREAM->seekto($this->table_translations[$i * 2 + 2]);
        $translation = $this->STREAM->read($this->table_translations[$i * 2 + 1]);
        $this->cache_translations[$original] = $translation;
      }
    }
  }
  
  /**
   * Returns a string from the "originals" table
   * 
   * @access private
   * @param int num Offset number of original string
   * @return string Requested string if found, otherwise ''
   */
  function get_original_string($num) {
    $length = $this->table_originals[$num * 2 + 1];
    $offset = $this->table_originals[$num * 2 + 2];
    if (! $length)
      return '';
    $this->STREAM->seekto($offset);
    $data = $this->STREAM->read($length);
    return (string)$data;
  }
  
  /**
   * Returns a string from the "translations" table
   * 
   * @access private
   * @param int num Offset number of original string
   * @return string Requested string if found, otherwise ''
   */
  function get_translation_string($num) {
    $length = $this->table_translations[$num * 2 + 1];
    $offset = $this->table_translations[$num * 2 + 2];
    if (! $length)
      return '';
    $this->STREAM->seekto($offset);
    $data = $this->STREAM->read($length);
    return (string)$data;
  }
  
  /**
   * Binary search for string
   * 
   * @access private
   * @param string string
   * @param int start (internally used in recursive function)
   * @param int end (internally used in recursive function)
   * @return int string number (offset in originals table)
   */
  function find_string($string, $start = -1, $end = -1) {
    if (($start == -1) or ($end == -1)) {
      // find_string is called with only one parameter, set start end end
      $start = 0;
      $end = $this->total;
    }
    if (abs($start - $end) <= 1) {
      // We're done, now we either found the string, or it doesn't exist
      $txt = $this->get_original_string($start);
      if ($string == $txt)
        return $start;
      else
        return -1;
    } else if ($start > $end) {
      // start > end -> turn around and start over
      return $this->find_string($string, $end, $start);
    } else {
      // Divide table in two parts
      $half = (int)(($start + $end) / 2);
      $cmp = strcmp($string, $this->get_original_string($half));
      if ($cmp == 0)
        // string is exactly in the middle => return it
        return $half;
      else if ($cmp < 0)
        // The string is in the upper half
        return $this->find_string($string, $start, $half);
      else
        // The string is in the lower half
        return $this->find_string($string, $half, $end);
    }
  }

  /**
   * Translates a string
   * @access public
   * @param string string to be translated
   * @return string translated string (or original, if not found)
   */
  function translate($string) {
    if ($this->short_circuit)
      return $string;
    $this->load_tables();

    if ($this->enable_cache) {
      // Caching enabled, get translated string from cache
      if (array_key_exists($string, $this->cache_translations))
        return $this->cache_translations[$string];
      else
        return $string;
    } else {
      // Caching not enabled, try to find string
      $num = $this->find_string($string);
      if ($num == -1)
        return $string;
      else
        return $this->get_translation_string($num);
    }
  }
}

?>