<?php
/***********************************************************************

  Copyright (C) 2002, 2003  Rickard Andersson (punbb@telia.com)

  This file is part of PunBB.

  PunBB 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.

  PunBB 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, write to the Free Software
  Foundation, Inc., 59 Temple Place, Suite 330, Boston,
  MA  02111-1307  USA

************************************************************************/


// The contents of this file are very much inspired by the file functions_search.php
// from the phpBB Group forum software phpBB2 (http://www.phpbb.com).


// Make sure no one attempts to run this script "directly"
if (!defined('PUN'))
	exit;


//
// "Cleans up" a text string and returns an array of unique words
// This function depends on the current locale setting
//
function split_words($text)
{
	global $language;
	static $noise_match, $noise_replace, $stopwords;

	if (empty($noise_match))
	{
		$noise_match = array('^', '$', '&', '(', ')', '<', '>', '`', '\'', '"', '|', ',', '@', '_', '?', '%', '-', '~', '+', '.', '[', ']', '{', '}', ':', '\\', '/', '=', '#', ';', '!', '*');
		$noise_replace = array(' ', ' ', ' ', ' ', ' ', ' ', ' ', '',  '',   ' ', ' ', ' ', ' ', '',  ' ', ' ', '',  ' ', ' ', ' ', ' ', ' ', ' ', ' ', ' ', '' ,  ' ', ' ', ' ', ' ', ' ', ' ');

		$stopwords = @file('lang/'.$language.'/'.$language.'_stopwords.txt');
	}

	// Clean up
	$patterns[] = "#[\n\r]+#";
	$patterns[] = '#&[\#a-z0-9]+?;#i';
	$patterns[] = '#\b[\w]+:\/\/[a-z0-9\.\-]+(\/[a-z0-9\?\.%_\-\+=&\/]+)?#';
	$patterns[] = '#\[img:[a-z0-9]{10,}\].*?\[\/img:[a-z0-9]{10,}\]#';
	$patterns[] = '#\[\/?url(=.*?)?\]#';
	$patterns[] = '#\[\/?[a-z\*=\+\-]+(\:?[0-9a-z]+)?:[a-z0-9]{10,}(\:[a-z0-9]+)?=?.*?\]#';
	$text = preg_replace($patterns, ' ', ' '.strtolower($text).' ');

	// Filter out non-alphabetical chars
	$text = str_replace($noise_match, $noise_replace, $text);

	// Strip out too long and too short words
	$text = preg_replace('#\b([\w]{1,2}|[\w]{21,})\b#is', ' ', $text);

	if (!empty($stopwords))
	{
		@reset($stopwords);
		foreach ($stopwords as $word)
			$text = preg_replace('#\b'.preg_quote(trim($word)).'\b#', ' ', $text);
	}

	preg_match_all('#\b([\w]+)\b#', $text, $components);
	return array_unique($components[1]);
}


//
// Updates the search index with the contents of $post_id (and $subject)
//
function update_search_index($mode, $post_id, $message, $subject = null)
{
	global $db_type, $db;

	// Split old and new post/subject to obtain array of 'words'
	$words_message = split_words($message);
	$words_subject = ($subject) ? split_words($subject) : array();

	if ($mode == 'edit')
	{
		$result = $db->query('SELECT w.id, w.word, m.subject_match FROM '.$db->prefix.'search_words AS w INNER JOIN '.$db->prefix.'search_matches AS m ON w.id=m.word_id WHERE m.post_id='.$post_id) or error('Unable to fetch search index words', __FILE__, __LINE__, $db->error());

		// Declare here to stop array_keys() and array_diff() from complaining if not set
		$cur_words['post'] = array();
		$cur_words['subject'] = array();

		while ($row = $db->fetch_row($result))
		{
			$match_in = ($row[2]) ? 'subject' : 'post';
			$cur_words[$match_in][$row[1]] = $row[0];
		}

		$db->free_result($result);

		$words['add']['post'] = array_diff($words_message, array_keys($cur_words['post']));
		$words['add']['subject'] = array_diff($words_subject, array_keys($cur_words['subject']));
		$words['del']['post'] = array_diff(array_keys($cur_words['post']), $words_message);
		$words['del']['subject'] = array_diff(array_keys($cur_words['subject']), $words_subject);
	}
	else
	{
		$words['add']['post'] = $words_message;
		$words['add']['subject'] = $words_subject;
		$words['del']['post'] = array();
		$words['del']['subject'] = array();
	}

	unset($words_message);
	unset($words_subject);

	// Get unique words from the above arrays
	$unique_words = array_unique(array_merge($words['add']['post'], $words['add']['subject']));

	if (!empty($unique_words))
	{
		$result = $db->query('SELECT id, word FROM '.$db->prefix.'search_words WHERE word IN('.implode(',', preg_replace('#^(.*)$#', '\'\1\'', $unique_words)).')') or error('Unable to fetch search index words', __FILE__, __LINE__, $db->error());

		$word_ids = array();
		while ($row = $db->fetch_row($result))
			$word_ids[$row[1]] = $row[0];

		$db->free_result($result);

		$new_words = array_diff($unique_words, array_keys($word_ids));
		unset($unique_words);

		if (!empty($new_words))
		{
			switch ($db_type)
			{
				case 'mysql':
					$result = $db->query('INSERT INTO '.$db->prefix.'search_words (word) VALUES'.implode(',', preg_replace('#^(.*)$#', '(\'\1\')', $new_words))) or error('Unable to insert search index words', __FILE__, __LINE__, $db->error());
					break;

				default:
					foreach ($new_words as $word)
						$result = $db->query('INSERT INTO '.$db->prefix.'search_words (word) VALUES(\''.$word.'\')') or error('Unable to insert search index words', __FILE__, __LINE__, $db->error());
					break;
			}
		}

		unset($new_words);
	}

	// Delete matches (only if editing a post)
	foreach ($words['del'] as $match_in => $wordlist)
	{
		$subject_match = ($match_in == 'subject') ? 1 : 0;

		if (!empty($wordlist))
		{
			foreach ($wordlist as $word)
				$sql .= (($sql != '') ? ',' : '').$cur_words[$match_in][$word];

			$db->query('DELETE FROM '.$db->prefix.'search_matches WHERE word_id IN('.$sql.') AND post_id='.$post_id.' AND subject_match='.$subject_match) or error('Unable to delete search index word matches', __FILE__, __LINE__, $db->error());
		}
	}

	// Add new matches
	foreach ($words['add'] as $match_in => $wordlist)
	{
		$subject_match = ($match_in == 'subject') ? 1 : 0;

		if (!empty($wordlist))
			$result = $db->query('INSERT INTO '.$db->prefix.'search_matches (post_id, word_id, subject_match) SELECT '.$post_id.', id, '.$subject_match.' FROM '.$db->prefix.'search_words WHERE word IN('.implode(',', preg_replace('#^(.*)$#', '\'\1\'', $wordlist)).')') or error('Unable to insert search index word matches', __FILE__, __LINE__, $db->error());
	}

	unset($words);
}


//
// Strip search index of indexed words in $post_ids
//
function strip_search_index($post_ids)
{
	global $db_type, $db;

	switch ($db_type)
	{
		case 'mysql':
		{
			$result = $db->query('SELECT word_id FROM '.$db->prefix.'search_matches WHERE post_id IN('.$post_ids.') GROUP BY word_id') or error('Unable to fetch search index word match', __FILE__, __LINE__, $db->error());

			if ($db->num_rows($result))
			{
				$word_ids = 0;
				while ($row = $db->fetch_row($result))
					$word_ids .= ($word_ids != '') ? ','.$row[0] : $row[0];

				$result = $db->query('SELECT word_id FROM '.$db->prefix.'search_matches WHERE word_id IN('.$word_ids.') GROUP BY word_id HAVING COUNT(word_id)=1') or error('Unable to fetch search index word match', __FILE__, __LINE__, $db->error());

				if ($db->num_rows($result))
				{
					$word_ids = '';

					while ($row = $db->fetch_row($result))
						$word_ids .= ($word_ids != '') ? ','.$row[0] : $row[0];

					if ($word_ids != '')
						$db->query('DELETE FROM '.$db->prefix.'search_words WHERE id IN('.$word_ids.')') or error('Unable to delete search index word', __FILE__, __LINE__, $db->error());
				}
			}

			break;
		}

		default:
			$db->query('DELETE FROM '.$db->prefix.'search_words WHERE id IN(SELECT word_id FROM '.$db->prefix.'search_matches WHERE word_id IN(SELECT word_id FROM '.$db->prefix.'search_matches WHERE post_id IN('.$post_ids.') GROUP BY word_id) GROUP BY word_id HAVING COUNT(word_id)=1)') or error('Unable to delete from search index', __FILE__, __LINE__, $db->error());
			break;
	}

	$db->query('DELETE FROM '.$db->prefix.'search_matches WHERE post_id IN('.$post_ids.')') or error('Unable to delete search index word match', __FILE__, __LINE__, $db->error());
}