<?php

/*

 * Enano - an open-source CMS capable of wiki functions, Drupal-like sidebar blocks, and everything in between

 * Copyright (C) 2006-2009 Dan Fuhry

 * search.php - algorithm used to search pages

 *

 * This program is Free Software; you can redistribute 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.

 *

 * 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 details.

 */

/**

 * In Enano versions prior to 1.0.2, this class provided a search function that was keyword-based and allowed boolean searches. It was

 * cut from Coblynau and replaced with perform_search(), later in this file, because of speed issues. Now mostly deprecated. The only

 * thing remaining is the buildIndex function, which is still used by the path manager and the new search framework.

 *

 * @package Enano

 * @subpackage Page management frontend

 * @license GNU General Public License <http://enanocms.org/Special:GNU_General_Public_License>

 */

class Searcher

{

	var $results;

	var $index;

	var $warnings;

	var $match_case = false;

	function buildIndex($texts)

	{

		$this->index = Array();

		$stopwords = get_stopwords();

		foreach($texts as $i => $l)

		{

			$seed = md5(microtime(true) . mt_rand());

			$texts[$i] = str_replace("'", 'xxxApoS'.$seed.'xxx', $texts[$i]);

			$texts[$i] = preg_replace('#([\W_]+)#i', ' ', $texts[$i]);

			$texts[$i] = preg_replace('#([ ]+?)#', ' ', $texts[$i]);

			$texts[$i] = preg_replace('#([\']*){2,}#s', '', $texts[$i]);

			$texts[$i] = str_replace('xxxApoS'.$seed.'xxx', "'", $texts[$i]);

			$l = $texts[$i];

			$words = Array();

			$good_chars = 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789\' ';

			$good_chars = enano_str_split($good_chars, 1);

			$letters = enano_str_split($l, 1);

			foreach($letters as $x => $t)

			{

				if(!in_array($t, $good_chars))

					unset($letters[$x]);

			}

			$letters = implode('', $letters);

			$words = explode(' ', $letters);

			foreach($words as $c => $w)

			{

				if(strlen($w) < 2 || in_array($w, $stopwords) || strlen($w) > 63 || preg_match('/[\']{2,}/', $w))

					unset($words[$c]);

				else

					$words[$c] = $w;

			}

			$words = array_values($words);

			foreach($words as $c => $w)

			{

				if(isset($this->index[$w]))

				{

					if(!in_array($i, $this->index[$w]))

						$this->index[$w][] = $i;

				}

				else

				{

					$this->index[$w] = Array();

					$this->index[$w][] = $i;

				}

			}

		}

		foreach($this->index as $k => $v)

		{

			$this->index[$k] = implode(',', $this->index[$k]);

		}

	}

}

/**

 * Searches the site for the specified string and returns an array with each value being an array filled with the following:

 *   page_id: string, self-explanatory

 *   namespace: string, self-explanatory

 *   page_length: integer, the length of the full page in bytes

 *   page_text: string, the contents of the page (trimmed to ~150 bytes if necessary)

 *   score: numerical relevance score, 1-100, rounded to 2 digits and calculated based on which terms were present and which were not

 * @param string Search query

 * @param string|reference Will be filled with any warnings encountered whilst parsing the query

 * @param bool Case sensitivity - defaults to false

 * @param array|reference Will be filled with the parsed list of words.

 * @return array

 */

function perform_search($query, &$warnings, $case_sensitive = false, &$word_list)

{

	global $db, $session, $paths, $template, $plugins; // Common objects

	global $lang;

	$warnings = array();

	//

	// STAGE 0: PARSE SEARCH QUERY

	// Identify all terms of the query. Separate between what is required and what is not, and what should be sent through the index as

	// opposed to straight-out LIKE-selected.

	//

	$query = parse_search_query($query, $warnings);

	// Segregate search terms containing spaces

	$query_phrase = array(

		'any' => array(),

		'req' => array()

		);

	foreach ( $query['any'] as $i => $_ )

	{

		$term =& $query['any'][$i];

		$term = trim($term);

		// the indexer only indexes words a-z with apostrophes

		if ( preg_match('/[^A-Za-z\']/', $term) )

		{

			$query_phrase['any'][] = $term;

			unset($term, $query['any'][$i]);

		}

	}

	unset($term);

	$query['any'] = array_values($query['any']);

	foreach ( $query['req'] as $i => $_ )

	{

		$term =& $query['req'][$i];

		$term = trim($term);

		if ( preg_match('/[^A-Za-z\']/', $term) )

		{

			$query_phrase['req'][] = $term;

			unset($term, $query['req'][$i]);

		}

	}

	unset($term);

	$query['req'] = array_values($query['req']);

	$results = array();

	$scores = array();

	$ns_list = '(' . implode('|', array_keys($paths->nslist)) . ')';

	// FIXME: Update to use FULLTEXT algo when available.

	// Build an SQL query to load from the index table

	if ( count($query['any']) < 1 && count($query['req']) < 1 && count($query_phrase['any']) < 1 && count($query_phrase['req']) < 1 )

	{

		// This is both because of technical restrictions and devastation that would occur on shared servers/large sites.

		$warnings[] = $lang->get('search_err_query_no_positive');

		return array();

	}

	//

	// STAGE 1

	// Get all possible result pages from the search index. Tally which pages have the most words, and later sort them by boolean relevance

	//

	// Skip this if no indexable words are included

	if ( count($query['any']) > 0 || count($query['req']) > 0 )

	{

		$where_any = array();

		foreach ( $query['any'] as $term )

		{

			$term = escape_string_like($term);

			if ( !$case_sensitive )

				$term = strtolower($term);

			$where_any[] = $term;

		}

		foreach ( $query['req'] as $term )

		{

			$term = escape_string_like($term);

			if ( !$case_sensitive )

				$term = strtolower($term);

			$where_any[] = $term;

		}

		$col_word = ( $case_sensitive ) ? 'word' : 'word_lcase';

		$where_any_str = ( count($where_any) > 0 ) ? '( ' . $col_word . ' LIKE \'%' . implode('%\' OR ' . $col_word . ' LIKE \'%', $where_any) . '%\' )' : '';

		// generate query

		$sql = "SELECT word, page_names FROM " . table_prefix . "search_index WHERE {$where_any_str}";

		if ( !($q = $db->sql_query($sql)) )

			$db->_die('Error is in perform_search(), includes/search.php, query 1');

		$word_tracking = array();

		if ( $row = $db->fetchrow($q) )

		{

			do

			{

				// get page list

				$pages =& $row['page_names'];

				// Find page IDs that contain commas

				// This should never happen because commas are escaped by sanitize_page_id(). Nevertheless for compatibility with older

				// databases, and to alleviate the concerns of hackers, we'll accommodate for page IDs with commas here by checking for

				// IDs that don't match the pattern for stringified page ID + namespace. If it doesn't match, that means it's a continuation

				// of the previous ID and should be concatenated to the previous entry.

				$matches = strpos($pages, ',') ? explode(',', $pages) : array($pages);

				$prev = false;

				foreach ( $matches as $i => $_ )

				{

					$match =& $matches[$i];

					if ( !preg_match("/^ns=$ns_list;pid=(.+)$/", $match) && $prev )

					{

						$matches[$prev] .= ',' . $match;

						unset($match, $matches[$i]);

						continue;

					}

					$prev = $i;

				}

				unset($match);

				// Iterate through each of the results, assigning scores based on how many times the page has shown up.

				// This works because this phase of the search is strongly word-based not page-based. If a page shows up

				// multiple times while fetching the result rows from the search_index table, it simply means that page

				// contains more than one of the terms the user searched for.

				foreach ( $matches as $match )

				{

					$word_cs = (( $case_sensitive ) ? $row['word'] : strtolower($row['word']));

					if ( isset($word_tracking[$match]) && in_array($word_cs, $word_tracking[$match]) )

					{

						continue;

					}

					if ( isset($word_tracking[$match]) )

					{

						if ( isset($word_tracking[$match]) )

						{

							$word_tracking[$match][] = $word_cs;

						}

					}

					else

					{

						$word_tracking[$match] = array($word_cs);

					}

					// echo '<pre>' . print_r($word_tracking, true) . '</pre>';

					$inc = 1;

					// Is this search term present in the page's title? If so, give extra points

					preg_match("/^ns=$ns_list;pid=(.+)$/", $match, $piecesparts);

					$title = get_page_title_ns($piecesparts[2], $piecesparts[1]);

					$test_func = ( $case_sensitive ) ? 'strstr' : 'stristr';

					if ( $test_func($title, $row['word']) || $test_func($piecesparts[2], $row['word']) )

					{

						$inc = 1.5;

					}

					// increase points if 2 or more words match a phrase in the title

					for ( $i = 0; $i < count($where_any) - 1; $i++ )

					{

						$phrase = "{$where_any[$i]} {$where_any[$i + 1]}";

						if ( $test_func($title, $phrase) )

						{

							$inc *= 1.25;

						}

					}

					// Deduct points if there are few similarities between the words

					$lev_array = array();

					foreach ( $where_any as $qword )

					{

						if ( strstr($word_cs, $qword) )

							$lev_array[ $qword ] = levenshtein($qword, $word_cs);

					}

					if ( count($lev_array) && min($lev_array) > 3 )

					{

						$inc /= array_sum($lev_array) / count($lev_array);

					}

					if ( isset($scores[$match]) )

					{

						$scores[$match] = $scores[$match] + $inc;

					}

					else

					{

						$scores[$match] = $inc;

					}

				}

			}

			while ( $row = $db->fetchrow($q) );

		}

		$db->free_result($q);

		//

		// STAGE 2: FIRST ELIMINATION ROUND

		// Iterate through the list of required terms. If a given page is not found to have the required term, eliminate it

		//

		foreach ( $query['req'] as $term )

		{

			foreach ( $word_tracking as $i => $page )

			{

				if ( !in_array($term, $page) )

				{

					unset($word_tracking[$i], $scores[$i]);

				}

			}

		}

	}

	//

	// STAGE 3: PHRASE SEARCHING

	// Use LIKE to find pages with specified phrases. We can do a super-picky single query without another elimination round because

	// at this stage we can search the full page_text column instead of relying on a word list.

	//

	// We can skip this stage if none of these special terms apply

	$text_col = ( $case_sensitive ) ? 'page_text' : ENANO_SQLFUNC_LOWERCASE . '(page_text)';

	$name_col = ( $case_sensitive ) ? 'name' : ENANO_SQLFUNC_LOWERCASE . '(name)';

	$text_col_join = ( $case_sensitive ) ? 't.page_text' : ENANO_SQLFUNC_LOWERCASE . '(t.page_text)';

	$name_col_join = ( $case_sensitive ) ? 'p.name' : ENANO_SQLFUNC_LOWERCASE . '(p.name)';

	$concat_column = ( ENANO_DBLAYER == 'MYSQL' ) ?

		'CONCAT(\'ns=\',t.namespace,\';pid=\',t.page_id)' :

		"'ns=' || t.namespace || ';pid=' || t.page_id";

	if ( count($query_phrase['any']) > 0 || count($query_phrase['req']) > 0 )

	{

		$where_any = array();

		foreach ( $query_phrase['any'] as $term )

		{

			$term = escape_string_like($term);

			if ( !$case_sensitive )

				$term = strtolower($term);

			$where_any[] = "( $text_col LIKE '%$term%' OR $name_col LIKE '%$term%' )";

		}

		$where_any = ( count($where_any) > 0 ) ? implode(" OR\n  ", $where_any) : '';

		// Also do required terms, but use AND to ensure that all required terms are included

		$where_req = array();

		foreach ( $query_phrase['req'] as $term )

		{

			$term = escape_string_like($term);

			if ( !$case_sensitive )

				$term = strtolower($term);

			$where_req[] = "( $text_col LIKE '%$term%' OR $name_col LIKE '%$term%' )";

		}

		$and_clause = ( $where_any != '' ) ? 'AND ' : '';

		$where_req = ( count($where_req) > 0 ) ? "{$and_clause}" . implode(" AND\n  ", $where_req) : '';

		$sql = 'SELECT ' . $concat_column . ' AS id, p.name, t.page_text FROM ' . table_prefix . "page_text AS t\n"

						. "  LEFT JOIN " . table_prefix . "pages AS p\n"

						. "    ON ( p.urlname = t.page_id AND p.namespace = t.namespace )\n"

						. "  WHERE p.visible = 1 AND (\n    $where_any\n    $where_req\n  );";

		if ( !($q = $db->sql_query($sql)) )

			$db->_die('Error is in perform_search(), includes/search.php, query 2. Parsed query dump follows:<pre>(indexable) ' . htmlspecialchars(print_r($query, true)) . '(non-indexable) ' . htmlspecialchars(print_r($query_phrase, true)) . '</pre>');

		if ( $row = $db->fetchrow() )

		{

			do

			{

				$id =& $row['id'];

				$inc = 0.0;

				$title = $row['name'];

				$test_func = ( $case_sensitive ) ? 'strstr' : 'stristr';

				// Is this search term present in the page's title? If so, give extra points

				$word_list = array_merge($query_phrase['any'], $query_phrase['req']);

				foreach ( $word_list as $word )

				{

					if ( $test_func($title, $word) )

						$inc += 1.5;

					else if ( $test_func($row['page_text'], $word) )

						$inc += 1.0;

				}

				// increase points if 2 or more words match a phrase in the title

				for ( $i = 0; $i < count($word_list) - 1; $i++ )

				{

					$phrase = "{$word_list[$i]} {$word_list[$i + 1]}";

					if ( $test_func($title, $phrase) )

						$inc *= 1.25;

					else if ( $test_func($row['page_text'], $phrase) )

						$inc *= 1.125;

				}