<?php

/**
 * PHPExcel_Shared_OLE_ChainedBlockStream
 *
 * 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_OLE
 * @copyright  Copyright (c) 2006 - 2007 Christian Schmidt
 * @license    http://www.gnu.org/licenses/old-licenses/lgpl-2.1.txt    LGPL
 * @version ##VERSION##, ##DATE##
 */
class PHPExcel_Shared_OLE_ChainedBlockStream
{
    /**
     * The OLE container of the file that is being read.
     * @var OLE
     */
    public $ole;

    /**
     * Parameters specified by fopen().
     * @var array
     */
    public $params;

    /**
     * The binary data of the file.
     * @var  string
     */
    public $data;

    /**
     * The file pointer.
     * @var  int  byte offset
     */
    public $pos;

    /**
     * Implements support for fopen().
     * For creating streams using this wrapper, use OLE_PPS_File::getStream().
     *
     * @param    string    $path            resource name including scheme, e.g.
     *                                    ole-chainedblockstream://oleInstanceId=1
     * @param    string    $mode            only "r" is supported
     * @param    int        $options        mask of STREAM_REPORT_ERRORS and STREAM_USE_PATH
     * @param    string  &$openedPath    absolute path of the opened stream (out parameter)
     * @return    bool    true on success
     */
    public function stream_open($path, $mode, $options, &$openedPath)
    {
        if ($mode != 'r') {
            if ($options & STREAM_REPORT_ERRORS) {
                trigger_error('Only reading is supported', E_USER_WARNING);
            }
            return false;
        }

        // 25 is length of "ole-chainedblockstream://"
        parse_str(substr($path, 25), $this->params);
        if (!isset($this->params['oleInstanceId'], $this->params['blockId'], $GLOBALS['_OLE_INSTANCES'][$this->params['oleInstanceId']])) {
            if ($options & STREAM_REPORT_ERRORS) {
                trigger_error('OLE stream not found', E_USER_WARNING);
            }
            return false;
        }
        $this->ole = $GLOBALS['_OLE_INSTANCES'][$this->params['oleInstanceId']];

        $blockId = $this->params['blockId'];
        $this->data = '';
        if (isset($this->params['size']) && $this->params['size'] < $this->ole->bigBlockThreshold && $blockId != $this->ole->root->_StartBlock) {
            // Block id refers to small blocks
            $rootPos = $this->ole->_getBlockOffset($this->ole->root->_StartBlock);
            while ($blockId != -2) {
                $pos = $rootPos + $blockId * $this->ole->bigBlockSize;
                $blockId = $this->ole->sbat[$blockId];
                fseek($this->ole->_file_handle, $pos);
                $this->data .= fread($this->ole->_file_handle, $this->ole->bigBlockSize);
            }
        } else {
            // Block id refers to big blocks
            while ($blockId != -2) {
                $pos = $this->ole->_getBlockOffset($blockId);
                fseek($this->ole->_file_handle, $pos);
                $this->data .= fread($this->ole->_file_handle, $this->ole->bigBlockSize);
                $blockId = $this->ole->bbat[$blockId];
            }
        }
        if (isset($this->params['size'])) {
            $this->data = substr($this->data, 0, $this->params['size']);
        }

        if ($options & STREAM_USE_PATH) {
            $openedPath = $path;
        }

        return true;
    }

    /**
     * Implements support for fclose().
     *
     */
    public function stream_close()
    {
        $this->ole = null;
        unset($GLOBALS['_OLE_INSTANCES']);
    }

    /**
     * Implements support for fread(), fgets() etc.
     *
     * @param   int        $count    maximum number of bytes to read
     * @return  string
     */
    public function stream_read($count)
    {
        if ($this->stream_eof()) {
            return false;
        }
        $s = substr($this->data, $this->pos, $count);
        $this->pos += $count;
        return $s;
    }

    /**
     * Implements support for feof().
     *
     * @return  bool  TRUE if the file pointer is at EOF; otherwise FALSE
     */
    public function stream_eof()
    {
        return $this->pos >= strlen($this->data);
    }

    /**
     * Returns the position of the file pointer, i.e. its offset into the file
     * stream. Implements support for ftell().
     *
     * @return  int
     */
    public function stream_tell()
    {
        return $this->pos;
    }

    /**
     * Implements support for fseek().
     *
     * @param    int        $offset    byte offset
     * @param    int        $whence    SEEK_SET, SEEK_CUR or SEEK_END
     * @return    bool
     */
    public function stream_seek($offset, $whence)
    {
        if ($whence == SEEK_SET && $offset >= 0) {
            $this->pos = $offset;
        } elseif ($whence == SEEK_CUR && -$offset <= $this->pos) {
            $this->pos += $offset;
        } elseif ($whence == SEEK_END && -$offset <= sizeof($this->data)) {
            $this->pos = strlen($this->data) + $offset;
        } else {
            return false;
        }
        return true;
    }

    /**
     * Implements support for fstat(). Currently the only supported field is
     * "size".
     * @return  array
     */
    public function stream_stat()
    {
        return array(
            'size' => strlen($this->data),
            );
    }

    // Methods used by stream_wrapper_register() that are not implemented:
    // bool stream_flush ( void )
    // int stream_write ( string data )
    // bool rename ( string path_from, string path_to )
    // bool mkdir ( string path, int mode, int options )
    // bool rmdir ( string path, int options )
    // bool dir_opendir ( string path, int options )
    // array url_stat ( string path, int flags )
    // string dir_readdir ( void )
    // bool dir_rewinddir ( void )
    // bool dir_closedir ( void )
}
