<?php
/**
 * SeekQuarry/Yioop --
 * Open Source Pure PHP Search Engine, Crawler, and Indexer
 *
 * Copyright (C) 2009 - 2026  Chris Pollett chris@pollett.org
 *
 * LICENSE:
 *
 * This program 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 3 of the License, or
 * (at your option) any later version.
 *
 * This program 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 this program.  If not, see <https://www.gnu.org/licenses/>.
 *
 * END LICENSE
 *
 * @author Chris Pollett chris@pollett.org
 * @license https://www.gnu.org/licenses/ GPL3
 * @link https://www.seekquarry.com/
 * @copyright 2009 - 2026
 * @filesource
 */
namespace seekquarry\yioop\library\processors;

/**
 * Used to create crawl summary information
 * for binary DOC files
 *
 * @author Chris Pollett
 */
class DocProcessor extends TextProcessor
{
    /**
     * Set-ups the any indexing plugins associated with this page
     * processor
     *
     * @param array $plugins an array of indexing plugins which might
     *     do further processing on the data handles by this page
     *     processor
     * @param int $max_description_len maximal length of a page summary
     * @param int $max_links_to_extract maximum number of links to extract
     *      from a single document
     * @param string $summarizer_option CRAWL_CONSTANT specifying what kind
     *      of summarizer to use self::BASIC_SUMMARIZER,
     *      self::GRAPH_BASED_SUMMARIZER and self::CENTROID_SUMMARIZER
     *      self::CENTROID_SUMMARIZER
     */
    public function __construct($plugins = [], $max_description_len = null,
        $max_links_to_extract = null,
        $summarizer_option = self::BASIC_SUMMARIZER)
    {
        parent::__construct($plugins, $max_description_len,
            $max_links_to_extract, $summarizer_option);
        /** Register File Types We Handle*/
        self::$indexed_file_types[] = "doc";
        self::$mime_processor["application/msword"] = "DocProcessor";
    }
    /**
     * Used to extract the title, description and links from
     * a string consisting of Word Doc data (2004 or earlier).
     *
     * @param string $page  the web-page contents
     * @param string $url  the url where the page contents came from,
     *    used to canonicalize relative links
     *
     * @return array  a summary of the contents of the page
     *
     */
    public function process($page, $url)
    {
        $text = "";
        if (is_string($page)) {
            $text = self::extractASCIIText($page);
        }
        if ($text == "") {
            $text = $url;
        }
        $summary = parent::process($text, $url);
        return $summary;
    }
    /**
     * This is the main text from Word doc extractor
     * A Word Doc consists of a FIB, Piece Table, and
     * DocumentStream. The last contains the text.
     * The piece table is supposed to be used to reconstruct
     * the order of the text from the DocumentStream and the FIB, file
     * information block,is supposed to tell us where the piece table is.
     * I am not using any of this for now. I am just brute
     * force looking for the text which I know has to be at a page (256 byte)
     * boundary. I then go until I no longer see ASCII. So the order
     * of text extracted might be screwed up right now.
     *
     * @param string $doc string data of a 2004 or earlier Word doc
     * @return string the heuristically-extracted ASCII text from the
     *      document body (the order may be off because text is pulled
     *      page by page)
     */
    public static function extractASCIIText($doc) {
        $len = strlen($doc);
        $text = "";
        $boundary_change = 0;
        $text_state = false;
        $start_text = 0;
        $end_text = 0;
        for ($i = 0; $i < $len; $i+= 256) {
             if (self::checkPageForText($doc, $i)) {
                $start_text = $i;
                break;
             }
        }
        for ($i = $start_text; $i < $len; $i += 8) {
            if (self::checkAllZeros($doc, $i)) {
                 $end_text =  $i;
                 break;
            }
            $text .= self::cleanTextBlock($doc, $i);
        }
        return $text;
    }
    /**
     * Scans document starting at given position and looking forward eight
     * character to see if these are ASCII printable or not.
     *
     * @param string $doc document to scan
     * @param int $pos position to start scanning
     * @return whether the eight next characters were ASCII printable
     */
    public static function checkPageForText($doc, $pos)
    {
        $is_text = true;
        for ($i = 0; $i < 8; $i++) {
            $ascii = ord($doc[$pos]);
            if (!((9 <= $ascii && $ascii <= 13) ||
                (32 <= $ascii && $ascii <= 126)) ){
                $is_text = false;
                break;
            }
            $pos++;
        }
        return $is_text;
    }
    /**
     * Scans document starting at given position and looking forward eight
     * character to see if these are all \0 or not.
     *
     * @param string $doc document to scan
     * @param int $pos position to start scanning
     * @return whether the eight next characters were \0
     */
    public static function checkAllZeros($doc, $pos)
    {
        $is_zero = true;
        for ($i = 0; $i < 8; $i++) {
            $ascii = ord($doc[$pos]);
            if ($ascii != 0 ){
                $is_zero = false;
                break;
            }
            $pos++;
        }
        return $is_zero;
    }
    /**
     * Scans document starting at given position forward eight
     * character returning those characters which are ASCII printable
     *
     * @param string $doc document to scan
     * @param int $pos position to start scanning
     * @return substring of ASCII printable characters
     */
    public static function cleanTextBlock($doc, $pos)
    {
        $text = "";
        for ($i = 0; $i < 8; $i++) {
            if (isset($doc[$pos])) {
                $ascii = ord($doc[$pos]);
                if ((9<= $ascii && $ascii <= 13) ||
                    (32<= $ascii && $ascii <= 126) ) {
                    $text .= chr($ascii);
                }
            }
            $pos++;
        }
        return $text;
    }
}
