<?php
/**
 * PHPExcel
 *
 * Copyright (c) 2006 - 2015 PHPExcel
 *
 * 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., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
 *
 * @category   PHPExcel
 * @package    PHPExcel_Shared
 * @copyright  Copyright (c) 2006 - 2015 PHPExcel (http://www.codeplex.com/PHPExcel)
 * @license    http://www.gnu.org/licenses/old-licenses/lgpl-2.1.txt    LGPL
 * @version    ##VERSION##, ##DATE##
 */

defined('IDENTIFIER_OLE') ||
    define('IDENTIFIER_OLE', pack('CCCCCCCC', 0xd0, 0xcf, 0x11, 0xe0, 0xa1, 0xb1, 0x1a, 0xe1));

class PHPExcel_Shared_OLERead
{
    private $data = '';

    // OLE identifier
    const IDENTIFIER_OLE                    = IDENTIFIER_OLE;

    // Size of a sector = 512 bytes
    const BIG_BLOCK_SIZE                    = 0x200;

    // Size of a short sector = 64 bytes
    const SMALL_BLOCK_SIZE                  = 0x40;

    // Size of a directory entry always = 128 bytes
    const PROPERTY_STORAGE_BLOCK_SIZE       = 0x80;

    // Minimum size of a standard stream = 4096 bytes, streams smaller than this are stored as short streams
    const SMALL_BLOCK_THRESHOLD             = 0x1000;

    // header offsets
    const NUM_BIG_BLOCK_DEPOT_BLOCKS_POS    = 0x2c;
    const ROOT_START_BLOCK_POS              = 0x30;
    const SMALL_BLOCK_DEPOT_BLOCK_POS       = 0x3c;
    const EXTENSION_BLOCK_POS               = 0x44;
    const NUM_EXTENSION_BLOCK_POS           = 0x48;
    const BIG_BLOCK_DEPOT_BLOCKS_POS        = 0x4c;

    // property storage offsets (directory offsets)
    const SIZE_OF_NAME_POS                  = 0x40;
    const TYPE_POS                          = 0x42;
    const START_BLOCK_POS                   = 0x74;
    const SIZE_POS                          = 0x78;


    public $wrkbook                         = null;
    public $summaryInformation              = null;
    public $documentSummaryInformation      = null;


    /**
     * Read the file
     *
     * @param $sFileName string Filename
     * @throws PHPExcel_Reader_Exception
     */
    public function read($sFileName)
    {
        // Check if file exists and is readable
        if (!is_readable($sFileName)) {
            throw new PHPExcel_Reader_Exception("Could not open " . $sFileName . " for reading! File does not exist, or it is not readable.");
        }

        // Get the file identifier
        // Don't bother reading the whole file until we know it's a valid OLE file
        $this->data = file_get_contents($sFileName, false, null, 0, 8);

        // Check OLE identifier
        if ($this->data != self::IDENTIFIER_OLE) {
            throw new PHPExcel_Reader_Exception('The filename ' . $sFileName . ' is not recognised as an OLE file');
        }

        // Get the file data
        $this->data = file_get_contents($sFileName);

        // Total number of sectors used for the SAT
        $this->numBigBlockDepotBlocks = self::getInt4d($this->data, self::NUM_BIG_BLOCK_DEPOT_BLOCKS_POS);

        // SecID of the first sector of the directory stream
        $this->rootStartBlock = self::getInt4d($this->data, self::ROOT_START_BLOCK_POS);

        // SecID of the first sector of the SSAT (or -2 if not extant)
        $this->sbdStartBlock = self::getInt4d($this->data, self::SMALL_BLOCK_DEPOT_BLOCK_POS);

        // SecID of the first sector of the MSAT (or -2 if no additional sectors are used)
        $this->extensionBlock = self::getInt4d($this->data, self::EXTENSION_BLOCK_POS);

        // Total number of sectors used by MSAT
        $this->numExtensionBlocks = self::getInt4d($this->data, self::NUM_EXTENSION_BLOCK_POS);

        $bigBlockDepotBlocks = array();
        $pos = self::BIG_BLOCK_DEPOT_BLOCKS_POS;

        $bbdBlocks = $this->numBigBlockDepotBlocks;

        if ($this->numExtensionBlocks != 0) {
            $bbdBlocks = (self::BIG_BLOCK_SIZE - self::BIG_BLOCK_DEPOT_BLOCKS_POS)/4;
        }

        for ($i = 0; $i < $bbdBlocks; ++$i) {
              $bigBlockDepotBlocks[$i] = self::getInt4d($this->data, $pos);
              $pos += 4;
        }

        for ($j = 0; $j < $this->numExtensionBlocks; ++$j) {
            $pos = ($this->extensionBlock + 1) * self::BIG_BLOCK_SIZE;
            $blocksToRead = min($this->numBigBlockDepotBlocks - $bbdBlocks, self::BIG_BLOCK_SIZE / 4 - 1);

            for ($i = $bbdBlocks; $i < $bbdBlocks + $blocksToRead; ++$i) {
                $bigBlockDepotBlocks[$i] = self::getInt4d($this->data, $pos);
                $pos += 4;
            }

            $bbdBlocks += $blocksToRead;
            if ($bbdBlocks < $this->numBigBlockDepotBlocks) {
                $this->extensionBlock = self::getInt4d($this->data, $pos);
            }
        }

        $pos = 0;
        $this->bigBlockChain = '';
        $bbs = self::BIG_BLOCK_SIZE / 4;
        for ($i = 0; $i < $this->numBigBlockDepotBlocks; ++$i) {
            $pos = ($bigBlockDepotBlocks[$i] + 1) * self::BIG_BLOCK_SIZE;

            $this->bigBlockChain .= substr($this->data, $pos, 4*$bbs);
            $pos += 4*$bbs;
        }

        $pos = 0;
        $sbdBlock = $this->sbdStartBlock;
        $this->smallBlockChain = '';
        while ($sbdBlock != -2) {
            $pos = ($sbdBlock + 1) * self::BIG_BLOCK_SIZE;

            $this->smallBlockChain .= substr($this->data, $pos, 4*$bbs);
            $pos += 4*$bbs;

            $sbdBlock = self::getInt4d($this->bigBlockChain, $sbdBlock*4);
        }

        // read the directory stream
        $block = $this->rootStartBlock;
        $this->entry = $this->_readData($block);

        $this->readPropertySets();
    }

    /**
     * Extract binary stream data
     *
     * @return string
     */
    public function getStream($stream)
    {
        if ($stream === null) {
            return null;
        }

        $streamData = '';

        if ($this->props[$stream]['size'] < self::SMALL_BLOCK_THRESHOLD) {
            $rootdata = $this->_readData($this->props[$this->rootentry]['startBlock']);

            $block = $this->props[$stream]['startBlock'];

            while ($block != -2) {
                  $pos = $block * self::SMALL_BLOCK_SIZE;
                $streamData .= substr($rootdata, $pos, self::SMALL_BLOCK_SIZE);

                $block = self::getInt4d($this->smallBlockChain, $block*4);
            }

            return $streamData;
        } else {
            $numBlocks = $this->props[$stream]['size'] / self::BIG_BLOCK_SIZE;
            if ($this->props[$stream]['size'] % self::BIG_BLOCK_SIZE != 0) {
                ++$numBlocks;
            }

            if ($numBlocks == 0) {
                return '';
            }

            $block = $this->props[$stream]['startBlock'];

            while ($block != -2) {
                $pos = ($block + 1) * self::BIG_BLOCK_SIZE;
                $streamData .= substr($this->data, $pos, self::BIG_BLOCK_SIZE);
                $block = self::getInt4d($this->bigBlockChain, $block*4);
            }

            return $streamData;
        }
    }

    /**
     * Read a standard stream (by joining sectors using information from SAT)
     *
     * @param int $bl Sector ID where the stream starts
     * @return string Data for standard stream
     */
    private function _readData($bl)
    {
        $block = $bl;
        $data = '';

        while ($block != -2) {
            $pos = ($block + 1) * self::BIG_BLOCK_SIZE;
            $data .= substr($this->data, $pos, self::BIG_BLOCK_SIZE);
            $block = self::getInt4d($this->bigBlockChain, $block*4);
        }
        return $data;
    }

    /**
     * Read entries in the directory stream.
     */
    private function readPropertySets()
    {
        $offset = 0;

        // loop through entires, each entry is 128 bytes
        $entryLen = strlen($this->entry);
        while ($offset < $entryLen) {
            // entry data (128 bytes)
            $d = substr($this->entry, $offset, self::PROPERTY_STORAGE_BLOCK_SIZE);

            // size in bytes of name
            $nameSize = ord($d[self::SIZE_OF_NAME_POS]) | (ord($d[self::SIZE_OF_NAME_POS+1]) << 8);

            // type of entry
            $type = ord($d[self::TYPE_POS]);

            // sectorID of first sector or short sector, if this entry refers to a stream (the case with workbook)
            // sectorID of first sector of the short-stream container stream, if this entry is root entry
            $startBlock = self::getInt4d($d, self::START_BLOCK_POS);

            $size = self::getInt4d($d, self::SIZE_POS);

            $name = str_replace("\x00", "", substr($d, 0, $nameSize));

            $this->props[] = array(
                'name' => $name,
                'type' => $type,
                'startBlock' => $startBlock,
                'size' => $size
            );

            // tmp helper to simplify checks
            $upName = strtoupper($name);

            // Workbook directory entry (BIFF5 uses Book, BIFF8 uses Workbook)
            if (($upName === 'WORKBOOK') || ($upName === 'BOOK')) {
                $this->wrkbook = count($this->props) - 1;
            } elseif ($upName === 'ROOT ENTRY' || $upName === 'R') {
                // Root entry
                $this->rootentry = count($this->props) - 1;
            }

            // Summary information
            if ($name == chr(5) . 'SummaryInformation') {
//                echo 'Summary Information<br />';
                $this->summaryInformation = count($this->props) - 1;
            }

            // Additional Document Summary information
            if ($name == chr(5) . 'DocumentSummaryInformation') {
//                echo 'Document Summary Information<br />';
                $this->documentSummaryInformation = count($this->props) - 1;
            }

            $offset += self::PROPERTY_STORAGE_BLOCK_SIZE;
        }
    }

    /**
     * Read 4 bytes of data at specified position
     *
     * @param string $data
     * @param int $pos
     * @return int
     */
    private static function getInt4d($data, $pos)
    {
        // FIX: represent numbers correctly on 64-bit system
        // http://sourceforge.net/tracker/index.php?func=detail&aid=1487372&group_id=99160&atid=623334
        // Hacked by Andreas Rehm 2006 to ensure correct result of the <<24 block on 32 and 64bit systems
        $_or_24 = ord($data[$pos + 3]);
        if ($_or_24 >= 128) {
            // negative number
            $_ord_24 = -abs((256 - $_or_24) << 24);
        } else {
            $_ord_24 = ($_or_24 & 127) << 24;
        }
        return ord($data[$pos]) | (ord($data[$pos + 1]) << 8) | (ord($data[$pos + 2]) << 16) | $_ord_24;
    }
}