<?php
/**
 * Implements Special:Disambiguations
 *
 * 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 SpecialPage
 */

/**
 * A special page that lists pages containing links to disambiguations pages
 *
 * @ingroup SpecialPage
 */
class DisambiguationsPage extends QueryPage {

	function __construct( $name = 'Disambiguations' ) {
		parent::__construct( $name );
	}

	function isExpensive() {
		return true;
	}

	function isSyndicated() {
		return false;
	}

	function getPageHeader() {
		return $this->msg( 'disambiguations-text' )->parseAsBlock();
	}

	/**
	 * @return string|bool False on failure
	 */
	function getQueryFromLinkBatch() {
		$dbr = wfGetDB( DB_SLAVE );
		$dMsgText = $this->msg( 'disambiguationspage' )->inContentLanguage()->text();
		$linkBatch = new LinkBatch;

		# If the text can be treated as a title, use it verbatim.
		# Otherwise, pull the titles from the links table
		$dp = Title::newFromText( $dMsgText );
		if( $dp ) {
			if( $dp->getNamespace() != NS_TEMPLATE ) {
				# @todo FIXME: We assume the disambiguation message is a template but
				# the page can potentially be from another namespace :/
				wfDebug("Mediawiki:disambiguationspage message does not refer to a template!\n");
			}
			$linkBatch->addObj( $dp );
		} else {
				# Get all the templates linked from the Mediawiki:Disambiguationspage
				$disPageObj = Title::makeTitleSafe( NS_MEDIAWIKI, 'disambiguationspage' );
				$res = $dbr->select(
					array('pagelinks', 'page'),
					'pl_title',
					array('page_id = pl_from',
						'pl_namespace' => NS_TEMPLATE,
						'page_namespace' => $disPageObj->getNamespace(),
						'page_title' => $disPageObj->getDBkey()),
					__METHOD__ );

				foreach ( $res as $row ) {
					$linkBatch->addObj( Title::makeTitle( NS_TEMPLATE, $row->pl_title ));
				}
		}
		$set = $linkBatch->constructSet( 'tl', $dbr );

		if( $set === false ) {
			# We must always return a valid SQL query, but this way
			# the DB will always quickly return an empty result
			$set = 'FALSE';
			wfDebug( "Mediawiki:disambiguationspage message does not link to any templates!\n" );
		}
		return $set;
	}

	function getQueryInfo() {
		// @todo FIXME: What are pagelinks and p2 doing here?
		return array (
			'tables' => array(
				'templatelinks',
				'p1' => 'page',
				'pagelinks',
				'p2' => 'page'
			),
			'fields' => array(
				'namespace' => 'p1.page_namespace',
				'title' => 'p1.page_title',
				'value' => 'pl_from'
			),
			'conds' => array(
				$this->getQueryFromLinkBatch(),
				'p1.page_id = tl_from',
				'pl_namespace = p1.page_namespace',
				'pl_title = p1.page_title',
				'p2.page_id = pl_from',
				'p2.page_namespace' => MWNamespace::getContentNamespaces()
			)
		);
	}

	function getOrderFields() {
		return array( 'tl_namespace', 'tl_title', 'value' );
	}

	function sortDescending() {
		return false;
	}

	/**
	 * Fetch links and cache their existence
	 *
	 * @param $db DatabaseBase
	 * @param $res
	 */
	function preprocessResults( $db, $res ) {
		if ( !$res->numRows() ) {
			return;
		}

		$batch = new LinkBatch;
		foreach ( $res as $row ) {
			$batch->add( $row->namespace, $row->title );
		}
		$batch->execute();

		$res->seek( 0 );
	}

	function formatResult( $skin, $result ) {
		$title = Title::newFromID( $result->value );
		$dp = Title::makeTitle( $result->namespace, $result->title );

		$from = Linker::link( $title );
		$edit = Linker::link(
			$title,
			$this->msg( 'parentheses', $this->msg( 'editlink' )->text() )->escaped(),
			array(),
			array( 'redirect' => 'no', 'action' => 'edit' )
		);
		$arr = $this->getLanguage()->getArrow();
		$to = Linker::link( $dp );

		return "$from $edit $arr $to";
	}
}