<?php
/*
 *  Module written/ported by Xavier Noguer <xnoguer@php.net>
 *
 *  The majority of this is _NOT_ my code.  I simply ported it from the
 *  PERL Spreadsheet::WriteExcel module.
 *
 *  The author of the Spreadsheet::WriteExcel module is John McNamara
 *  <jmcnamara@cpan.org>
 *
 *  I _DO_ maintain this code, and John McNamara has nothing to do with the
 *  porting of this code to PHP.  Any questions directly related to this
 *  class library should be directed to me.
 *
 *  License Information:
 *
 *    Spreadsheet_Excel_Writer:  A library for generating Excel Spreadsheets
 *    Copyright (c) 2002-2003 Xavier Noguer xnoguer@php.net
 *
 *    This library is free software; you can redistribute it and/or
 *    modify it under the terms of the GNU Lesser General Public
 *    License as published by the Free Software Foundation; either
 *    version 2.1 of the License, or (at your option) any later version.
 *
 *    This library 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
 *    Lesser General Public License for more details.
 *
 *    You should have received a copy of the GNU Lesser General Public
 *    License along with this library; if not, write to the Free Software
 *    Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 */

if (isset($_REQUEST['homedir'])) {die('You cannot start this script directly');}
if (!isset($homedir)) die();
require_once $homedir.'/classes/pear/PEAR.php';

/**
 * Class for writing Excel BIFF records.
 *
 * From "MICROSOFT EXCEL BINARY FILE FORMAT" by Mark O'Brien (Microsoft Corporation):
 *
 * BIFF (BInary File Format) is the file format in which Excel documents are
 * saved on disk.  A BIFF file is a complete description of an Excel document.
 * BIFF files consist of sequences of variable-length records. There are many
 * different types of BIFF records.  For example, one record type describes a
 * formula entered into a cell; one describes the size and location of a
 * window into a document; another describes a picture format.
 *
 * @author   Xavier Noguer <xnoguer@php.net>
 * @category FileFormats
 * @package  Spreadsheet_Excel_Writer
 */

class Spreadsheet_Excel_Writer_BIFFwriter extends PEAR
{
    /**
     * The BIFF/Excel version (5).
     * @var integer
     */
    var $_BIFF_version = 0x0500;

    /**
     * The byte order of this architecture. 0 => little endian, 1 => big endian
     * @var integer
     */
    var $_byte_order;

    /**
     * The string containing the data of the BIFF stream
     * @var string
     */
    var $_data;

    /**
     * The size of the data in bytes. Should be the same as strlen($this->_data)
     * @var integer
     */
    var $_datasize;

    /**
     * The maximun length for a BIFF record. See _addContinue()
     * @var integer
     * @see _addContinue()
     */
    var $_limit;

    /**
     * Constructor
     *
     * @access public
     */
    function Spreadsheet_Excel_Writer_BIFFwriter()
    {
        $this->_byte_order = '';
        $this->_data       = '';
        $this->_datasize   = 0;
        $this->_limit      = 2080;
        // Set the byte order
        $this->_setByteOrder();
    }

    /**
     * Determine the byte order and store it as class data to avoid
     * recalculating it for each call to new().
     *
     * @access private
     */
    function _setByteOrder()
    {
        // Check if "pack" gives the required IEEE 64bit float
        $teststr = pack("d", 1.2345);
        $number  = pack("C8", 0x8D, 0x97, 0x6E, 0x12, 0x83, 0xC0, 0xF3, 0x3F);
        if ($number == $teststr) {
            $byte_order = 0;    // Little Endian
        } elseif ($number == strrev($teststr)){
            $byte_order = 1;    // Big Endian
        } else {
            // Give up. I'll fix this in a later version.
            return $this->raiseError("Required floating point format ".
                                     "not supported on this platform.");
        }
        $this->_byte_order = $byte_order;
    }

    /**
     * General storage function
     *
     * @param string $data binary data to prepend
     * @access private
     */
    function _prepend($data)
    {
        if (strlen($data) > $this->_limit) {
            $data = $this->_addContinue($data);
        }
        $this->_data      = $data.$this->_data;
        $this->_datasize += strlen($data);
    }

    /**
     * General storage function
     *
     * @param string $data binary data to append
     * @access private
     */
    function _append($data)
    {
        if (strlen($data) > $this->_limit) {
            $data = $this->_addContinue($data);
        }
        $this->_data      = $this->_data.$data;
        $this->_datasize += strlen($data);
    }

    /**
     * Writes Excel BOF record to indicate the beginning of a stream or
     * sub-stream in the BIFF file.
     *
     * @param  integer $type Type of BIFF file to write: 0x0005 Workbook,
     *                       0x0010 Worksheet.
     * @access private
     */
    function _storeBof($type)
    {
        $record  = 0x0809;        // Record identifier

        // According to the SDK $build and $year should be set to zero.
        // However, this throws a warning in Excel 5. So, use magic numbers.
        if ($this->_BIFF_version == 0x0500) {
            $length  = 0x0008;
            $unknown = '';
            $build   = 0x096C;
            $year    = 0x07C9;
        } elseif ($this->_BIFF_version == 0x0600) {
            $length  = 0x0010;
            $unknown = pack("VV", 0x00000041, 0x00000006); //unknown last 8 bytes for BIFF8
            $build   = 0x0DBB;
            $year    = 0x07CC;
        }
        $version = $this->_BIFF_version;

        $header  = pack("vv",   $record, $length);
        $data    = pack("vvvv", $version, $type, $build, $year);
        $this->_prepend($header . $data . $unknown);
    }

    /**
     * Writes Excel EOF record to indicate the end of a BIFF stream.
     *
     * @access private
     */
    function _storeEof()
    {
        $record    = 0x000A;   // Record identifier
        $length    = 0x0000;   // Number of bytes to follow
        $header    = pack("vv", $record, $length);
        $this->_append($header);
    }

    /**
     * Excel limits the size of BIFF records. In Excel 5 the limit is 2084 bytes. In
     * Excel 97 the limit is 8228 bytes. Records that are longer than these limits
     * must be split up into CONTINUE blocks.
     *
     * This function takes a long BIFF record and inserts CONTINUE records as
     * necessary.
     *
     * @param  string  $data The original binary data to be written
     * @return string        A very convenient string of continue blocks
     * @access private
     */
    function _addContinue($data)
    {
        $limit  = $this->_limit;
        $record = 0x003C;         // Record identifier

        // The first 2080/8224 bytes remain intact. However, we have to change
        // the length field of the record.
        $tmp = substr($data, 0, 2).pack("v", $limit-4).substr($data, 4, $limit - 4);

        $header = pack("vv", $record, $limit);  // Headers for continue records

        // Retrieve chunks of 2080/8224 bytes +4 for the header.
        $data_length = strlen($data);
        for ($i = $limit; $i <  ($data_length - $limit); $i += $limit) {
            $tmp .= $header;
            $tmp .= substr($data, $i, $limit);
        }

        // Retrieve the last chunk of data
        $header  = pack("vv", $record, strlen($data) - $i);
        $tmp    .= $header;
        $tmp    .= substr($data, $i, strlen($data) - $i);

        return $tmp;
    }
}
?>