<?php
/**
 *
 *
 * Created on May 13, 2007
 *
 * Copyright © 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.,
 * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
 * http://www.gnu.org/copyleft/gpl.html
 *
 * @file
 */

/**
 * This query adds an "<images>" subelement to all pages with the list of
 * images embedded into those pages.
 *
 * @ingroup API
 */
class ApiQueryImages extends ApiQueryGeneratorBase {

	public function __construct( $query, $moduleName ) {
		parent::__construct( $query, $moduleName, 'im' );
	}

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

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

	/**
	 * @param $resultPageSet ApiPageSet
	 */
	private function run( $resultPageSet = null ) {
		if ( $this->getPageSet()->getGoodTitleCount() == 0 ) {
			return;	// nothing to do
		}

		$params = $this->extractRequestParams();
		$this->addFields( array(
			'il_from',
			'il_to'
		) );

		$this->addTables( 'imagelinks' );
		$this->addWhereFld( 'il_from', array_keys( $this->getPageSet()->getGoodTitles() ) );
		if ( !is_null( $params['continue'] ) ) {
			$cont = explode( '|', $params['continue'] );
			if ( count( $cont ) != 2 ) {
				$this->dieUsage( 'Invalid continue param. You should pass the ' .
					'original value returned by the previous query', '_badcontinue' );
			}
			$op = $params['dir'] == 'descending' ? '<' : '>';
			$ilfrom = intval( $cont[0] );
			$ilto = $this->getDB()->addQuotes( $cont[1] );
			$this->addWhere(
				"il_from $op $ilfrom OR " .
				"(il_from = $ilfrom AND " .
				"il_to $op= $ilto)"
			);
		}

		$sort = ( $params['dir'] == 'descending' ? ' DESC' : '' );
		// Don't order by il_from if it's constant in the WHERE clause
		if ( count( $this->getPageSet()->getGoodTitles() ) == 1 ) {
			$this->addOption( 'ORDER BY', 'il_to' . $sort );
		} else {
			$this->addOption( 'ORDER BY', array(
						'il_from' . $sort,
						'il_to' . $sort
			));
		}
		$this->addOption( 'LIMIT', $params['limit'] + 1 );

		if ( !is_null( $params['images'] ) ) {
			$images = array();
			foreach ( $params['images'] as $img ) {
				$title = Title::newFromText( $img );
				if ( !$title || $title->getNamespace() != NS_FILE ) {
					$this->setWarning( "\"$img\" is not a file" );
				} else {
					$images[] = $title->getDBkey();
				}
			}
			$this->addWhereFld( 'il_to', $images );
		}

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

		if ( is_null( $resultPageSet ) ) {
			$count = 0;
			foreach ( $res as $row ) {
				if ( ++$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->il_from . '|' . $row->il_to );
					break;
				}
				$vals = array();
				ApiQueryBase::addTitleInfo( $vals, Title::makeTitle( NS_FILE, $row->il_to ) );
				$fit = $this->addPageSubItem( $row->il_from, $vals );
				if ( !$fit ) {
					$this->setContinueEnumParameter( 'continue', $row->il_from . '|' . $row->il_to );
					break;
				}
			}
		} else {
			$titles = array();
			$count = 0;
			foreach ( $res as $row ) {
				if ( ++$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->il_from . '|' . $row->il_to );
					break;
				}
				$titles[] = Title::makeTitle( NS_FILE, $row->il_to );
			}
			$resultPageSet->populateFromTitles( $titles );
		}
	}

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

	public function getAllowedParams() {
		return array(
			'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,
			'images' => array(
				ApiBase::PARAM_ISMULTI => true,
			),
			'dir' => array(
				ApiBase::PARAM_DFLT => 'ascending',
				ApiBase::PARAM_TYPE => array(
					'ascending',
					'descending'
				)
			),
		);
	}

	public function getParamDescription() {
		return array(
			'limit' => 'How many images to return',
			'continue' => 'When more results are available, use this to continue',
			'images' => 'Only list these images. Useful for checking whether a certain page has a certain Image.',
			'dir' => 'The direction in which to list',
		);
	}

	public function getResultProperties() {
		return array(
			'' => array(
				'ns' => 'namespace',
				'title' => 'string'
			)
		);
	}

	public function getDescription() {
		return 'Returns all images contained on the given page(s)';
	}

	public function getPossibleErrors() {
		return array_merge( parent::getPossibleErrors(), array(
			array( 'code' => '_badcontinue', 'info' => 'Invalid continue param. You should pass the original value returned by the previous query' ),
		) );
	}

	public function getExamples() {
		return array(
			'api.php?action=query&prop=images&titles=Main%20Page' => 'Get a list of images used in the [[Main Page]]',
			'api.php?action=query&generator=images&titles=Main%20Page&prop=info' => 'Get information about all images used in the [[Main Page]]',
		);
	}

	public function getHelpUrls() {
		return 'https://www.mediawiki.org/wiki/API:Properties#images_.2F_im';
	}

	public function getVersion() {
		return __CLASS__ . ': $Id$';
	}
}
