<?php
# Copyright (C) 2004 Brion Vibber <brion@pobox.com>
# http://www.mediawiki.org/
#
# 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 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 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.,
# 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
# http://www.gnu.org/copyleft/gpl.html

/**
 * @file
 * @ingroup Search
 */

/**
 * Search engine hook for MySQL 4+
 * @ingroup Search
 */
class SearchMySQL extends SearchEngine {
	var $strictMatching = true;

	/** @todo document */
	function __construct( $db ) {
		$this->db = $db;
	}

	/** 
	 * Parse the user's query and transform it into an SQL fragment which will 
	 * become part of a WHERE clause
	 */
	function parseQuery( $filteredText, $fulltext ) {
		global $wgContLang;
		$lc = SearchEngine::legalSearchChars(); // Minus format chars
		$searchon = '';
		$this->searchTerms = array();

		# FIXME: This doesn't handle parenthetical expressions.
		$m = array();
		if( preg_match_all( '/([-+<>~]?)(([' . $lc . ']+)(\*?)|"[^"]*")/',
			  $filteredText, $m, PREG_SET_ORDER ) ) {
			foreach( $m as $terms ) {
				if( $searchon !== '' ) $searchon .= ' ';
				if( $this->strictMatching && ($terms[1] == '') ) {
					$terms[1] = '+';
				}
				$searchon .= $terms[1] . $wgContLang->stripForSearch( $terms[2] );
				if( !empty( $terms[3] ) ) {
					// Match individual terms in result highlighting...
					$regexp = preg_quote( $terms[3], '/' );
					if( $terms[4] ) {
						$regexp = "\b$regexp"; // foo*
					} else {
						$regexp = "\b$regexp\b";
					}
				} else {
					// Match the quoted term in result highlighting...
					$regexp = preg_quote( str_replace( '"', '', $terms[2] ), '/' );
				}
				$this->searchTerms[] = $regexp;
			}
			wfDebug( "Would search with '$searchon'\n" );
			wfDebug( 'Match with /' . implode( '|', $this->searchTerms ) . "/\n" );
		} else {
			wfDebug( "Can't understand search query '{$filteredText}'\n" );
		}

		$searchon = $this->db->strencode( $searchon );
		$field = $this->getIndexField( $fulltext );
		return " MATCH($field) AGAINST('$searchon' IN BOOLEAN MODE) ";
	}

	public static function legalSearchChars() {
		return "\"*" . parent::legalSearchChars();
	}

	/**
	 * Perform a full text search query and return a result set.
	 *
	 * @param string $term - Raw search term
	 * @return MySQLSearchResultSet
	 * @access public
	 */
	function searchText( $term ) {
		$resultSet = $this->db->resultObject( $this->db->query( $this->getQuery( $this->filter( $term ), true ) ) );
		return new MySQLSearchResultSet( $resultSet, $this->searchTerms );
	}

	/**
	 * Perform a title-only search query and return a result set.
	 *
	 * @param string $term - Raw search term
	 * @return MySQLSearchResultSet
	 * @access public
	 */
	function searchTitle( $term ) {
		$resultSet = $this->db->resultObject( $this->db->query( $this->getQuery( $this->filter( $term ), false ) ) );
		return new MySQLSearchResultSet( $resultSet, $this->searchTerms );
	}


	/**
	 * Return a partial WHERE clause to exclude redirects, if so set
	 * @return string
	 * @private
	 */
	function queryRedirect() {
		if( $this->showRedirects ) {
			return '';
		} else {
			return 'AND page_is_redirect=0';
		}
	}

	/**
	 * Return a partial WHERE clause to limit the search to the given namespaces
	 * @return string
	 * @private
	 */
	function queryNamespaces() {
		if( is_null($this->namespaces) )
			return '';  # search all
		if ( !count( $this->namespaces ) ) {
			$namespaces = '0';
		} else {
			$namespaces = $this->db->makeList( $this->namespaces );
		}
		return 'AND page_namespace IN (' . $namespaces . ')';
	}

	/**
	 * Return a LIMIT clause to limit results on the query.
	 * @return string
	 * @private
	 */
	function queryLimit() {
		return $this->db->limitResult( '', $this->limit, $this->offset );
	}

	/**
	 * Does not do anything for generic search engine
	 * subclasses may define this though
	 * @return string
	 * @private
	 */
	function queryRanking( $filteredTerm, $fulltext ) {
		return '';
	}

	/**
	 * Construct the full SQL query to do the search.
	 * The guts shoulds be constructed in queryMain()
	 * @param string $filteredTerm
	 * @param bool $fulltext
	 * @private
	 */
	function getQuery( $filteredTerm, $fulltext ) {
		return $this->queryMain( $filteredTerm, $fulltext ) . ' ' .
			$this->queryRedirect() . ' ' .
			$this->queryNamespaces() . ' ' .
			$this->queryRanking( $filteredTerm, $fulltext ) . ' ' .
			$this->queryLimit();
	}


	/**
	 * Picks which field to index on, depending on what type of query.
	 * @param bool $fulltext
	 * @return string
	 */
	function getIndexField( $fulltext ) {
		return $fulltext ? 'si_text' : 'si_title';
	}

	/**
	 * Get the base part of the search query.
	 * The actual match syntax will depend on the server
	 * version; MySQL 3 and MySQL 4 have different capabilities
	 * in their fulltext search indexes.
	 *
	 * @param string $filteredTerm
	 * @param bool $fulltext
	 * @return string
	 * @private
	 */
	function queryMain( $filteredTerm, $fulltext ) {
		$match = $this->parseQuery( $filteredTerm, $fulltext );
		$page        = $this->db->tableName( 'page' );
		$searchindex = $this->db->tableName( 'searchindex' );
		return 'SELECT page_id, page_namespace, page_title ' .
			"FROM $page,$searchindex " .
			'WHERE page_id=si_page AND ' . $match;
	}

	/**
	 * Create or update the search index record for the given page.
	 * Title and text should be pre-processed.
	 *
	 * @param int $id
	 * @param string $title
	 * @param string $text
	 */
	function update( $id, $title, $text ) {
		$dbw = wfGetDB( DB_MASTER );
		$dbw->replace( 'searchindex',
			array( 'si_page' ),
			array(
				'si_page' => $id,
				'si_title' => $title,
				'si_text' => $text
			), __METHOD__ );
	}

	/**
	 * Update a search index record's title only.
	 * Title should be pre-processed.
	 *
	 * @param int $id
	 * @param string $title
	 */
    function updateTitle( $id, $title ) {
		$dbw = wfGetDB( DB_MASTER );

		$dbw->update( 'searchindex',
			array( 'si_title' => $title ),
			array( 'si_page'  => $id ),
			__METHOD__,
			array( $dbw->lowPriorityOption() ) );
	}
}

/**
 * @ingroup Search
 */
class MySQLSearchResultSet extends SearchResultSet {
	function MySQLSearchResultSet( $resultSet, $terms ) {
		$this->mResultSet = $resultSet;
		$this->mTerms = $terms;
	}

	function termMatches() {
		return $this->mTerms;
	}

	function numRows() {
		return $this->mResultSet->numRows();
	}

	function next() {
		$row = $this->mResultSet->fetchObject();
		if( $row === false ) {
			return false;
		} else {
			return new SearchResult( $row );
		}
	}

	function free() {
		$this->mResultSet->free();
	}
}
