<?php

/*
 * Created on May 12, 2007
 *
 * API for MediaWiki 1.8+
 *
 * Copyright (C) 2006 Yuri Astrakhan <Firstname><Lastname>@gmail.com
 *
 * 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.,
 * 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
 * http://www.gnu.org/copyleft/gpl.html
 */

if ( !defined( 'MEDIAWIKI' ) ) {
	// Eclipse helper - will be ignored in production
	require_once ( "ApiQueryBase.php" );
}

/**
 * A query module to list all wiki links on a given set of pages.
 *
 * @ingroup API
 */
class ApiQueryLinks extends ApiQueryGeneratorBase {

	const LINKS = 'links';
	const TEMPLATES = 'templates';

	private $table, $prefix, $description;

	public function __construct( $query, $moduleName ) {

		switch ( $moduleName ) {
			case self::LINKS :
				$this->table = 'pagelinks';
				$this->prefix = 'pl';
				$this->description = 'link';
				break;
			case self::TEMPLATES :
				$this->table = 'templatelinks';
				$this->prefix = 'tl';
				$this->description = 'template';
				break;
			default :
				ApiBase :: dieDebug( __METHOD__, 'Unknown module name' );
		}

		parent :: __construct( $query, $moduleName, $this->prefix );
	}

	public function execute() {
		$this->run();
	}

	public function getCacheMode( $params ) {
		return 'public';
	}

	public function executeGenerator( $resultPageSet ) {
		$this->run( $resultPageSet );
	}

	private function run( $resultPageSet = null ) {

		if ( $this->getPageSet()->getGoodTitleCount() == 0 )
			return;	// nothing to do

		$params = $this->extractRequestParams();

		$this->addFields( array (
			$this->prefix . '_from AS pl_from',
			$this->prefix . '_namespace AS pl_namespace',
			$this->prefix . '_title AS pl_title'
		) );

		$this->addTables( $this->table );
		$this->addWhereFld( $this->prefix . '_from', array_keys( $this->getPageSet()->getGoodTitles() ) );
		$this->addWhereFld( $this->prefix . '_namespace', $params['namespace'] );

		if ( !is_null( $params['continue'] ) ) {
			$cont = explode( '|', $params['continue'] );
			if ( count( $cont ) != 3 )
				$this->dieUsage( "Invalid continue param. You should pass the " .
					"original value returned by the previous query", "_badcontinue" );
			$plfrom = intval( $cont[0] );
			$plns = intval( $cont[1] );
			$pltitle = $this->getDB()->strencode( $this->titleToKey( $cont[2] ) );
			$this->addWhere( "{$this->prefix}_from > $plfrom OR " .
					"({$this->prefix}_from = $plfrom AND " .
					"({$this->prefix}_namespace > $plns OR " .
					"({$this->prefix}_namespace = $plns AND " .
					"{$this->prefix}_title >= '$pltitle')))" );
		}

		// Here's some MySQL craziness going on: if you use WHERE foo='bar'
		// and later ORDER BY foo MySQL doesn't notice the ORDER BY is pointless
		// but instead goes and filesorts, because the index for foo was used
		// already. To work around this, we drop constant fields in the WHERE
		// clause from the ORDER BY clause
		$order = array();
		if ( count( $this->getPageSet()->getGoodTitles() ) != 1 )
			$order[] = "{$this->prefix}_from";
		if ( count( $params['namespace'] ) != 1 )
			$order[] = "{$this->prefix}_namespace";

		$order[] = "{$this->prefix}_title";
		$this->addOption( 'ORDER BY', implode( ", ", $order ) );
		$this->addOption( 'USE INDEX', "{$this->prefix}_from" );
		$this->addOption( 'LIMIT', $params['limit'] + 1 );

		$db = $this->getDB();
		$res = $this->select( __METHOD__ );

		if ( is_null( $resultPageSet ) ) {
			$count = 0;
			while ( $row = $db->fetchObject( $res ) ) {
				if ( ++$count > $params['limit'] ) {
					// We've reached the one extra which shows that
					// there are additional pages to be had. Stop here...
					$this->setContinueEnumParameter( 'continue',
						"{$row->pl_from}|{$row->pl_namespace}|" .
						$this->keyToTitle( $row->pl_title ) );
					break;
				}
				$vals = array();
				ApiQueryBase :: addTitleInfo( $vals, Title :: makeTitle( $row->pl_namespace, $row->pl_title ) );
				$fit = $this->addPageSubItem( $row->pl_from, $vals );
				if ( !$fit )
				{
					$this->setContinueEnumParameter( 'continue',
						"{$row->pl_from}|{$row->pl_namespace}|" .
						$this->keyToTitle( $row->pl_title ) );
					break;
				}
			}
		} else {
			$titles = array();
			$count = 0;
			while ( $row = $db->fetchObject( $res ) ) {
				if ( ++$count > $params['limit'] ) {
					// We've reached the one extra which shows that
					// there are additional pages to be had. Stop here...
					$this->setContinueEnumParameter( 'continue',
						"{$row->pl_from}|{$row->pl_namespace}|" .
						$this->keyToTitle( $row->pl_title ) );
					break;
				}
				$titles[] = Title :: makeTitle( $row->pl_namespace, $row->pl_title );
			}
			$resultPageSet->populateFromTitles( $titles );
		}

		$db->freeResult( $res );
	}

	public function getAllowedParams()
	{
		return array(
				'namespace' => array(
					ApiBase :: PARAM_TYPE => 'namespace',
					ApiBase :: PARAM_ISMULTI => true
				),
				'limit' => array(
					ApiBase :: PARAM_DFLT => 10,
					ApiBase :: PARAM_TYPE => 'limit',
					ApiBase :: PARAM_MIN => 1,
					ApiBase :: PARAM_MAX => ApiBase :: LIMIT_BIG1,
					ApiBase :: PARAM_MAX2 => ApiBase :: LIMIT_BIG2
				),
				'continue' => null,
			);
	}

	public function getParamDescription()
	{
		return array(
				'namespace' => "Show {$this->description}s in this namespace(s) only",
				'limit' => "How many {$this->description}s to return",
				'continue' => 'When more results are available, use this to continue',
		);
	}

	public function getDescription() {
		return "Returns all {$this->description}s from the given page(s)";
	}

	protected function getExamples() {
		return array (
				"Get {$this->description}s from the [[Main Page]]:",
				"  api.php?action=query&prop={$this->getModuleName()}&titles=Main%20Page",
				"Get information about the {$this->description} pages in the [[Main Page]]:",
				"  api.php?action=query&generator={$this->getModuleName()}&titles=Main%20Page&prop=info",
				"Get {$this->description}s from the Main Page in the User and Template namespaces:",
				"  api.php?action=query&prop={$this->getModuleName()}&titles=Main%20Page&{$this->prefix}namespace=2|10"
			);
	}

	public function getVersion() {
		return __CLASS__ . ': $Id: ApiQueryLinks.php 69932 2010-07-26 08:03:21Z tstarling $';
	}
}