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<?php
/**
* Implements Special:Randompage
*
* 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
* @author Rob Church <robchur@gmail.com>, Ilmari Karonen
*/
/**
* Special page to direct the user to a random page
*
* @ingroup SpecialPage
*/
class RandomPage extends SpecialPage {
private $namespaces; // namespaces to select pages from
protected $isRedir = false; // should the result be a redirect?
protected $extra = array(); // Extra SQL statements
public function __construct( $name = 'Randompage' ){
global $wgContentNamespaces;
$this->namespaces = $wgContentNamespaces;
parent::__construct( $name );
}
public function getNamespaces() {
return $this->namespaces;
}
public function setNamespace ( $ns ) {
if( !$ns || $ns < NS_MAIN ) {
$ns = NS_MAIN;
}
$this->namespaces = array( $ns );
}
// select redirects instead of normal pages?
public function isRedirect(){
return $this->isRedir;
}
public function execute( $par ) {
global $wgOut, $wgContLang, $wgRequest;
if ($par) {
$this->setNamespace( $wgContLang->getNsIndex( $par ) );
}
$title = $this->getRandomTitle();
if( is_null( $title ) ) {
$this->setHeaders();
$wgOut->addWikiMsg( strtolower( $this->mName ) . '-nopages',
$this->getNsList(), count( $this->namespaces ) );
return;
}
$redirectParam = $this->isRedirect() ? array( 'redirect' => 'no' ) : array();
$query = array_merge( $wgRequest->getValues(), $redirectParam );
unset( $query['title'] );
$wgOut->redirect( $title->getFullUrl( $query ) );
}
/**
* Get a comma-delimited list of namespaces we don't have
* any pages in
* @return String
*/
private function getNsList() {
global $wgContLang;
$nsNames = array();
foreach( $this->namespaces as $n ) {
if( $n === NS_MAIN ) {
$nsNames[] = wfMsgNoTrans( 'blanknamespace' );
} else {
$nsNames[] = $wgContLang->getNsText( $n );
}
}
return $wgContLang->commaList( $nsNames );
}
/**
* Choose a random title.
* @return Title object (or null if nothing to choose from)
*/
public function getRandomTitle() {
$randstr = wfRandom();
$title = null;
if ( !wfRunHooks( 'SpecialRandomGetRandomTitle', array( &$randstr, &$this->isRedir, &$this->namespaces,
&$this->extra, &$title ) ) ) {
return $title;
}
$row = $this->selectRandomPageFromDB( $randstr );
/* If we picked a value that was higher than any in
* the DB, wrap around and select the page with the
* lowest value instead! One might think this would
* skew the distribution, but in fact it won't cause
* any more bias than what the page_random scheme
* causes anyway. Trust me, I'm a mathematician. :)
*/
if( !$row ) {
$row = $this->selectRandomPageFromDB( "0" );
}
if( $row ) {
return Title::makeTitleSafe( $row->page_namespace, $row->page_title );
} else {
return null;
}
}
protected function getQueryInfo( $randstr ) {
$redirect = $this->isRedirect() ? 1 : 0;
return array(
'tables' => array( 'page' ),
'fields' => array( 'page_title', 'page_namespace' ),
'conds' => array_merge( array(
'page_namespace' => $this->namespaces,
'page_is_redirect' => $redirect,
'page_random >= ' . $randstr
), $this->extra ),
'options' => array(
'ORDER BY' => 'page_random',
'USE INDEX' => 'page_random',
'LIMIT' => 1,
),
'join_conds' => array()
);
}
private function selectRandomPageFromDB( $randstr, $fname = __METHOD__ ) {
$dbr = wfGetDB( DB_SLAVE );
$query = $this->getQueryInfo( $randstr );
$res = $dbr->select(
$query['tables'],
$query['fields'],
$query['conds'],
$fname,
$query['options'],
$query['join_conds']
);
return $dbr->fetchObject( $res );
}
}
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