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 ) {
  47                         $ns = NS_MAIN;
  48                 }
  49                 $this->namespaces = array( $ns );
  50         }
  51
  52         // select redirects instead of normal pages?
  53         public function isRedirect(){
  54                 return $this->isRedir;
  55         }
  56
  57         public function execute( $par ) {
  58                 global $wgOut, $wgContLang, $wgRequest;
  59
  60                 if ($par) {
  61                         $this->setNamespace( $wgContLang->getNsIndex( $par ) );
  62                 }
  63
  64                 $title = $this->getRandomTitle();
  65
  66                 if( is_null( $title ) ) {
  67                         $this->setHeaders();
  68                         $wgOut->addWikiMsg( strtolower( $this->mName ) . '-nopages',
  69                                 $this->getNsList(), count( $this->namespaces ) );
  70                         return;
  71                 }
  72
  73                 $redirectParam = $this->isRedirect() ? array( 'redirect' => 'no' ) : array();
  74                 $query = array_merge( $wgRequest->getValues(), $redirectParam );
  75                 unset( $query['title'] );
  76                 $wgOut->redirect( $title->getFullUrl( $query ) );
  77         }
  78
  79         /**
  80          * Get a comma-delimited list of namespaces we don't have
  81          * any pages in
  82          * @return String
  83          */
  84         private function getNsList() {
  85                 global $wgContLang;
  86                 $nsNames = array();
  87                 foreach( $this->namespaces as $n ) {
  88                         if( $n === NS_MAIN ) {
  89                                 $nsNames[] = wfMsgForContent( 'blanknamespace' );
  90                         } else {
  91                                 $nsNames[] = $wgContLang->getNsText( $n );
  92                         }
  93                 }
  94                 return $wgContLang->commaList( $nsNames );
  95         }
  96
  97
  98         /**
  99          * Choose a random title.
 100          * @return Title object (or null if nothing to choose from)
 101          */
 102         public function getRandomTitle() {
 103                 $randstr = wfRandom();
 104                 $title = null;
 105                 if ( !wfRunHooks( 'SpecialRandomGetRandomTitle', array( &$randstr, &$this->isRedir, &$this->namespaces,
 106                         &$this->extra, &$title ) ) ) {
 107                         return $title;
 108                 }
 109                 $row = $this->selectRandomPageFromDB( $randstr );
 110
 111                 /* If we picked a value that was higher than any in
 112                  * the DB, wrap around and select the page with the
 113                  * lowest value instead!  One might think this would
 114                  * skew the distribution, but in fact it won't cause
 115                  * any more bias than what the page_random scheme
 116                  * causes anyway.  Trust me, I'm a mathematician. :)
 117                  */
 118                 if( !$row ) {
 119                         $row = $this->selectRandomPageFromDB( "0" );
 120                 }
 121
 122                 if( $row ) {
 123                         return Title::makeTitleSafe( $row->page_namespace, $row->page_title );
 124                 } else {
 125                         return null;
 126                 }
 127         }
 128
 129         private function selectRandomPageFromDB( $randstr ) {
 130                 global $wgExtraRandompageSQL;
 131                 $dbr = wfGetDB( DB_SLAVE );
 132
 133                 $redirect = $this->isRedirect() ? 1 : 0;
 134
 135                 if ( $wgExtraRandompageSQL ) {
 136                         $this->extra[] = $wgExtraRandompageSQL;
 137                 }
 138                 if ( $this->addExtraSQL() ) {
 139                         $this->extra[] = $this->addExtraSQL();
 140                 }
 141
 142                 $res = $dbr->doQuery(
 143                         'page',
 144                         array( 'page_title', 'page_namespace' ),
 145                         array_merge( array(
 146                                 'page_namespace' => $this->namespaces,
 147                                 'page_is_redirect' => $redirect,
 148                                 'page_random >= ' . $randstr
 149                         ), $this->extra ),
 150                         __METHOD__,
 151                         array(
 152                                 'ORDER BY' => 'page_random',
 153                                 'USE INDEX' => 'page_random'
 154                         )
 155                 );
 156
 157                 return $dbr->fetchObject( $res );
 158         }
 159
 160         /* an alternative to $wgExtraRandompageSQL so subclasses
 161          * can add their own SQL by overriding this function
 162          * @deprecated, append to $this->extra instead
 163          */
 164         public function addExtraSQL() {
 165                 return '';
 166         }
 167 }