<?php
# Copyright (C) 2006-2007 Greg Sabino Mullane <greg@turnstep.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

## XXX Better catching of SELECT to_tsquery('the')

/**
 * Search engine hook base class for Postgres
 * @addtogroup Search
 */

class SearchPostgres extends SearchEngine {

	function SearchPostgres( $db ) {
		$this->db = $db;
	}

	/**
	 * Perform a full text search query via tsearch2 and return a result set.
	 * Currently searches a page's current title (p.page_title) and text (t.old_text)
	 *
	 * @param string $term - Raw search term
	 * @return PostgresSearchResultSet
	 * @access public
	 */
	function searchText( $term ) {
		$resultSet = $this->db->resultObject( $this->db->query( $this->searchQuery( $term, 'textvector' ) ) );
		return new PostgresSearchResultSet( $resultSet, $this->searchTerms );
	}
	function searchTitle( $term ) {
		$resultSet = $this->db->resultObject( $this->db->query( $this->searchQuery( $term , 'titlevector' ) ) );
		return new PostgresSearchResultSet( $resultSet, $this->searchTerms );
	}


	/*
	 * Transform the user's search string into a better form for tsearch2
	*/
	function parseQuery( $filteredText, $fulltext ) {
		global $wgContLang;
		$lc = SearchEngine::legalSearchChars();
		$searchon = '';
		$searchconst = '';
		$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 $terms ) {
				switch ($terms[1]) {
					case '~': // negate but do not exclude like "-" for now, simply negate
					case '-': $searchconst.= '&!' . $wgContLang->stripForSearch( $terms[2] );
						break;
					case '+': $searchconst.= '&' . $wgContLang->stripForSearch( $terms[2] );
						break;
					case '<': // decrease priority of word - not implemented
					case '>': // increase priority of word - not implemented
					default : $searchon.= '|' . $wgContLang->stripForSearch( $terms[2] );
				}
				if( !empty( $terms[3] ) ) {
					$regexp = preg_quote( $terms[3], '/' );
					if( $terms[4] ) $regexp .= "[0-9A-Za-z_]+";
				} else {
					$regexp = preg_quote( str_replace( '"', '', $terms[2] ), '/' );
				}
				$this->searchTerms[] = $regexp;
			}
			wfDebug( "Would search with '$searchon'\n" );
			wfDebug( 'Match with /\b' . implode( '\b|\b', $this->searchTerms ) . "\b/\n" );
		} else {
			wfDebug( "Can't understand search query '{$this->filteredText}'\n" );
		}

		if (substr_count($searchon,'|')==1) {
			$searchon = str_replace ('|','&',$searchon);
		}
		$searchon = substr($searchconst . $searchon, 1) ;
		$searchon = preg_replace('/(\s+)/','&',$searchon);
		$searchon = $this->db->strencode( $searchon );
		return $searchon;
	}

	/**
	 * Construct the full SQL query to do the search.
	 * @param string $filteredTerm
	 * @param string $fulltext
	 * @private
	 */
	function searchQuery( $filteredTerm, $fulltext ) {

		$match = $this->parseQuery( $filteredTerm, $fulltext );

		## We need a separate query here so gin does not complain about empty searches
		$dbw = wfGetDB( DB_MASTER );
		$SQL = "SELECT to_tsquery('default','$match')";
		$res = $dbw->doQuery($SQL);
		if (!$res) {
			## TODO: Catch better than this e.g. "one 'two"
			die ("Sorry, that was not a valid search string. Please go back and try again");
		}
		$top = $dbw->addQuotes(pg_fetch_result($res,0,0));

		$query = "SELECT page_id, page_namespace, page_title, old_text AS page_text, ".
			"rank(titlevector, $top) AS rnk ".
			"FROM page p, revision r, pagecontent c WHERE p.page_latest = r.rev_id " .
			"AND r.rev_text_id = c.old_id AND $fulltext @@ $top";

		if ($top === "''") { ## e.g. if only stopwords are used
			$query = "SELECT page_id, page_namespace, page_title, old_text AS page_text, 0 AS rnk ".
				"FROM page p, revision r, pagecontent c WHERE p.page_latest = r.rev_id " .
				"AND r.rev_text_id = c.old_id AND 1=0";
		}

		## Redirects
		if (! $this->showRedirects)
			$query .= ' AND page_is_redirect = 0'; ## IS FALSE

		## Namespaces - defaults to 0
		if ( count($this->namespaces) < 1)
			$query .= ' AND page_namespace = 0';
		else {
			$namespaces = implode( ',', $this->namespaces );
			$query .= " AND page_namespace IN ($namespaces)";
		}

		$query .= " ORDER BY rnk DESC, page_id DESC";

		$query .= $this->db->limitResult( '', $this->limit, $this->offset );

		return $query;
	}

	## Most of the work of these two functions are done automatically via triggers

	function update( $pageid, $title, $text ) {
		$dbw = wfGetDB( DB_MASTER );
		## We don't want to index older revisions
		$SQL = "UPDATE pagecontent SET textvector = NULL WHERE old_id = ".
				"(SELECT rev_text_id FROM revision WHERE rev_page = $pageid ".
				"ORDER BY rev_text_id DESC LIMIT 1 OFFSET 1)";
		$dbw->doQuery($SQL);
		return true;
	}
	function updateTitle( $id, $title ) { return true; }

} ## end of the SearchPostgres class


class PostgresSearchResultSet extends SearchResultSet {
	function PostgresSearchResultSet( $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 );
		}
	}
}

?>