includes/specials/SpecialRandompage.php

   1 <?php
   2 /**
   3  * Implements Special:Randompage
   4  *
   5  * This program is free software; you can redistribute it and/or modify
   6  * it under the terms of the GNU General Public License as published by
   7  * the Free Software Foundation; either version 2 of the License, or
   8  * (at your option) any later version.
   9  *
  10  * This program is distributed in the hope that it will be useful,
  11  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
  13  * GNU General Public License for more details.
  14  *
  15  * You should have received a copy of the GNU General Public License along
  16  * with this program; if not, write to the Free Software Foundation, Inc.,
  17  * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
  18  * http://www.gnu.org/copyleft/gpl.html
  19  *
  20  * @file
  21  * @ingroup SpecialPage
  22  * @author Rob Church <robchur@gmail.com>, Ilmari Karonen
  23  */
  24
  25 /**
  26  * Special page to direct the user to a random page
  27  *
  28  * @ingroup SpecialPage
  29  */
  30 class RandomPage extends SpecialPage {
  31         private $namespaces;  // namespaces to select pages from
  32         protected $isRedir = false; // should the result be a redirect?
  33         protected $extra = array(); // Extra SQL statements
  34
  35         public function __construct( $name = 'Randompage' ){
  36                 global $wgContentNamespaces;
  37                 $this->namespaces = $wgContentNamespaces;
  38                 parent::__construct( $name );
  39         }
  40
  41         public function getNamespaces() {
  42                 return $this->namespaces;
  43         }
  44
  45         public function setNamespace ( $ns ) {
  46                 if( !$ns || $ns < NS_MAIN ) $ns = NS_MAIN;
  47                 $this->namespaces = array( $ns );
  48         }
  49
  50         // select redirects instead of normal pages?
  51         public function isRedirect(){
  52                 return $this->isRedir;
  53         }
  54
  55         public function execute( $par ) {
  56                 global $wgOut, $wgContLang, $wgRequest;
  57
  58                 if ($par) {
  59                         $this->setNamespace( $wgContLang->getNsIndex( $par ) );
  60                 }
  61
  62                 $title = $this->getRandomTitle();
  63
  64                 if( is_null( $title ) ) {
  65                         $this->setHeaders();
  66                         $wgOut->addWikiMsg( strtolower( $this->mName ) . '-nopages',
  67                                 $this->getNsList(), count( $this->namespaces ) );
  68                         return;
  69                 }
  70
  71                 $redirectParam = $this->isRedirect() ? array( 'redirect' => 'no' ) : array();
  72                 $query = array_merge( $wgRequest->getValues(), $redirectParam );
  73                 unset( $query['title'] );
  74                 $wgOut->redirect( $title->getFullUrl( $query ) );
  75         }
  76
  77         /**
  78          * Get a comma-delimited list of namespaces we don't have
  79          * any pages in
  80          * @return String
  81          */
  82         private function getNsList() {
  83                 global $wgContLang;
  84                 $nsNames = array();
  85                 foreach( $this->namespaces as $n ) {
  86                         if( $n === NS_MAIN )
  87                                 $nsNames[] = wfMsgForContent( 'blanknamespace' );
  88                         else
  89                                 $nsNames[] = $wgContLang->getNsText( $n );
  90                 }
  91                 return $wgContLang->commaList( $nsNames );
  92         }
  93
  94
  95         /**
  96          * Choose a random title.
  97          * @return Title object (or null if nothing to choose from)
  98          */
  99         public function getRandomTitle() {
 100                 $randstr = wfRandom();
 101                 $title = null;
 102                 if ( !wfRunHooks( 'SpecialRandomGetRandomTitle', array( &$randstr, &$this->isRedir, &$this->namespaces, &$this->extra, &$title ) ) ) {
 103                         return $title;
 104                 }
 105                 $row = $this->selectRandomPageFromDB( $randstr );
 106
 107                 /* If we picked a value that was higher than any in
 108                  * the DB, wrap around and select the page with the
 109                  * lowest value instead!  One might think this would
 110                  * skew the distribution, but in fact it won't cause
 111                  * any more bias than what the page_random scheme
 112                  * causes anyway.  Trust me, I'm a mathematician. :)
 113                  */
 114                 if( !$row )
 115                         $row = $this->selectRandomPageFromDB( "0" );
 116
 117                 if( $row )
 118                         return Title::makeTitleSafe( $row->page_namespace, $row->page_title );
 119                 else
 120                         return null;
 121         }
 122
 123         private function selectRandomPageFromDB( $randstr ) {
 124                 global $wgExtraRandompageSQL;
 125                 $dbr = wfGetDB( DB_SLAVE );
 126
 127                 $use_index = $dbr->useIndexClause( 'page_random' );
 128                 $page = $dbr->tableName( 'page' );
 129
 130                 $ns = implode( ",", $this->namespaces );
 131                 $redirect = $this->isRedirect() ? 1 : 0;
 132
 133                 if ( $wgExtraRandompageSQL ) {
 134                         $this->extra[] = $wgExtraRandompageSQL;
 135                 }
 136                 if ( $this->addExtraSQL() ) {
 137                         $this->extra[] = $this->addExtraSQL();
 138                 }
 139                 $extra = '';
 140                 if ( $this->extra ) {
 141                         $extra = 'AND (' . implode( ') AND (', $this->extra ) . ')';
 142                 }
 143                 $sql = "SELECT page_title, page_namespace
 144                         FROM $page $use_index
 145                         WHERE page_namespace IN ( $ns )
 146                         AND page_is_redirect = $redirect
 147                         AND page_random >= $randstr
 148                         $extra
 149                         ORDER BY page_random";
 150
 151                 $sql = $dbr->limitResult( $sql, 1, 0 );
 152                 $res = $dbr->query( $sql, __METHOD__ );
 153                 return $dbr->fetchObject( $res );
 154         }
 155
 156         /* an alternative to $wgExtraRandompageSQL so subclasses
 157          * can add their own SQL by overriding this function
 158          * @deprecated, append to $this->extra instead
 159          */
 160         public function addExtraSQL() {
 161                 return '';
 162         }
 163 }