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<?php
/**
* Special page to direct the user to a random page
*
* @ingroup SpecialPage
* @author Rob Church <robchur@gmail.com>, Ilmari Karonen
* @license GNU General Public Licence 2.0 or later
*/
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, $wgContLang;
if ($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;
}
$query = $this->isRedirect() ? 'redirect=no' : '';
$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[] = wfMsgForContent( '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;
}
private function selectRandomPageFromDB( $randstr ) {
global $wgExtraRandompageSQL;
$dbr = wfGetDB( DB_SLAVE );
$use_index = $dbr->useIndexClause( 'page_random' );
$page = $dbr->tableName( 'page' );
$ns = implode( ",", $this->namespaces );
$redirect = $this->isRedirect() ? 1 : 0;
if ( $wgExtraRandompageSQL ) {
$this->extra[] = $wgExtraRandompageSQL;
}
if ( $this->addExtraSQL() ) {
$this->extra[] = $this->addExtraSQL();
}
$extra = '';
if ( $this->extra ) {
$extra = 'AND (' . implode( ') AND (', $this->extra ) . ')';
}
$sql = "SELECT page_title, page_namespace
FROM $page $use_index
WHERE page_namespace IN ( $ns )
AND page_is_redirect = $redirect
AND page_random >= $randstr
$extra
ORDER BY page_random";
$sql = $dbr->limitResult( $sql, 1, 0 );
$res = $dbr->query( $sql, __METHOD__ );
return $dbr->fetchObject( $res );
}
/* an alternative to $wgExtraRandompageSQL so subclasses
* can add their own SQL by overriding this function
* @deprecated, append to $this->extra instead
*/
public function addExtraSQL() {
return '';
}
}
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