<?php
/**
 *
 *
 * Created on July 7, 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
 */

/**
 * @ingroup API
 */
class ApiQueryExtLinksUsage extends ApiQueryGeneratorBase {

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

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

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

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

	/**
	 * @param $resultPageSet ApiPageSet
	 * @return void
	 */
	private function run( $resultPageSet = null ) {
		$params = $this->extractRequestParams();

		$query = $params['query'];
		$protocol = self::getProtocolPrefix( $params['protocol'] );

		$this->addTables( array( 'page', 'externallinks' ) ); // must be in this order for 'USE INDEX'
		$this->addOption( 'USE INDEX', 'el_index' );
		$this->addWhere( 'page_id=el_from' );

		global $wgMiserMode;
		$miser_ns = array();
		if ( $wgMiserMode ) {
			$miser_ns = $params['namespace'];
		} else {
			$this->addWhereFld( 'page_namespace', $params['namespace'] );
		}

		$whereQuery = $this->prepareUrlQuerySearchString( $query, $protocol );

		if ( $whereQuery !== null ) {
			$this->addWhere( $whereQuery );
		}

		$prop = array_flip( $params['prop'] );
		$fld_ids = isset( $prop['ids'] );
		$fld_title = isset( $prop['title'] );
		$fld_url = isset( $prop['url'] );

		if ( is_null( $resultPageSet ) ) {
			$this->addFields( array(
				'page_id',
				'page_namespace',
				'page_title'
			) );
			$this->addFieldsIf( 'el_to', $fld_url );
		} else {
			$this->addFields( $resultPageSet->getPageTableFields() );
		}

		$limit = $params['limit'];
		$offset = $params['offset'];
		$this->addOption( 'LIMIT', $limit + 1 );
		if ( isset( $offset ) ) {
			$this->addOption( 'OFFSET', $offset );
		}

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

		$result = $this->getResult();
		$count = 0;
		foreach ( $res as $row ) {
			if ( ++ $count > $limit ) {
				// We've reached the one extra which shows that there are additional pages to be had. Stop here...
				$this->setContinueEnumParameter( 'offset', $offset + $limit );
				break;
			}

			if ( count( $miser_ns ) && !in_array( $row->page_namespace, $miser_ns ) ) {
				continue;
			}

			if ( is_null( $resultPageSet ) ) {
				$vals = array();
				if ( $fld_ids ) {
					$vals['pageid'] = intval( $row->page_id );
				}
				if ( $fld_title ) {
					$title = Title::makeTitle( $row->page_namespace, $row->page_title );
					ApiQueryBase::addTitleInfo( $vals, $title );
				}
				if ( $fld_url ) {
					$to = $row->el_to;
					// expand protocol-relative urls
					if ( $params['expandurl'] ) {
						$to = wfExpandUrl( $to, PROTO_CANONICAL );
					}
					$vals['url'] = $to;
				}
				$fit = $result->addValue( array( 'query', $this->getModuleName() ), null, $vals );
				if ( !$fit ) {
					$this->setContinueEnumParameter( 'offset', $offset + $count - 1 );
					break;
				}
			} else {
				$resultPageSet->processDbRow( $row );
			}
		}

		if ( is_null( $resultPageSet ) ) {
			$result->setIndexedTagName_internal( array( 'query', $this->getModuleName() ),
					$this->getModulePrefix() );
		}
	}

	public function getAllowedParams() {
		return array(
			'prop' => array(
				ApiBase::PARAM_ISMULTI => true,
				ApiBase::PARAM_DFLT => 'ids|title|url',
				ApiBase::PARAM_TYPE => array(
					'ids',
					'title',
					'url'
				)
			),
			'offset' => array(
				ApiBase::PARAM_TYPE => 'integer'
			),
			'protocol' => array(
				ApiBase::PARAM_TYPE => self::prepareProtocols(),
				ApiBase::PARAM_DFLT => '',
			),
			'query' => null,
			'namespace' => array(
				ApiBase::PARAM_ISMULTI => true,
				ApiBase::PARAM_TYPE => 'namespace'
			),
			'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
			),
			'expandurl' => false,
		);
	}

	public static function prepareProtocols() {
		global $wgUrlProtocols;
		$protocols = array( '' );
		foreach ( $wgUrlProtocols as $p ) {
			if ( $p !== '//' ) {
				$protocols[] = substr( $p, 0, strpos( $p, ':' ) );
			}
		}
		return $protocols;
	}

	public static function getProtocolPrefix( $protocol ) {
		// Find the right prefix
		global $wgUrlProtocols;
		if ( $protocol && !in_array( $protocol, $wgUrlProtocols ) ) {
			foreach ( $wgUrlProtocols as $p ) {
				if ( substr( $p, 0, strlen( $protocol ) ) === $protocol ) {
					$protocol = $p;
					break;
				}
			}

			return $protocol;
		} else {
			return null;
		}
	}

	public function getParamDescription() {
		global $wgMiserMode;
		$p = $this->getModulePrefix();
		$desc = array(
			'prop' => array(
				'What pieces of information to include',
				' ids    - Adds the ID of page',
				' title  - Adds the title and namespace ID of the page',
				' url    - Adds the URL used in the page',
			),
			'offset' => 'Used for paging. Use the value returned for "continue"',
			'protocol' => array(
				"Protocol of the URL. If empty and {$p}query set, the protocol is http.",
				"Leave both this and {$p}query empty to list all external links"
			),
			'query' => 'Search string without protocol. See [[Special:LinkSearch]]. Leave empty to list all external links',
			'namespace' => 'The page namespace(s) to enumerate.',
			'limit' => 'How many pages to return.',
			'expandurl' => 'Expand protocol-relative URLs with the canonical protocol',
		);

		if ( $wgMiserMode ) {
			$desc['namespace'] = array(
				$desc['namespace'],
				"NOTE: Due to \$wgMiserMode, using this may result in fewer than \"{$p}limit\" results",
				'returned before continuing; in extreme cases, zero results may be returned',
			);
		}

		return $desc;
	}

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

	public function getDescription() {
		return 'Enumerate pages that contain a given URL';
	}

	public function getPossibleErrors() {
		return array_merge( parent::getPossibleErrors(), array(
			array( 'code' => 'bad_query', 'info' => 'Invalid query' ),
		) );
	}

	public function getExamples() {
		return array(
			'api.php?action=query&list=exturlusage&euquery=www.mediawiki.org'
		);
	}

	public function getHelpUrls() {
		return 'https://www.mediawiki.org/wiki/API:Exturlusage';
	}
}
