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          * Choose a random title.
  99          * @return Title object (or null if nothing to choose from)
 100          */
 101         public function getRandomTitle() {
 102                 $randstr = wfRandom();
 103                 $title = null;
 104                 if ( !wfRunHooks( 'SpecialRandomGetRandomTitle', array( &$randstr, &$this->isRedir, &$this->namespaces,
 105                         &$this->extra, &$title ) ) ) {
 106                         return $title;
 107                 }
 108                 $row = $this->selectRandomPageFromDB( $randstr );
 109
 110                 /* If we picked a value that was higher than any in
 111                  * the DB, wrap around and select the page with the
 112                  * lowest value instead!  One might think this would
 113                  * skew the distribution, but in fact it won't cause
 114                  * any more bias than what the page_random scheme
 115                  * causes anyway.  Trust me, I'm a mathematician. :)
 116                  */
 117                 if( !$row ) {
 118                         $row = $this->selectRandomPageFromDB( "0" );
 119                 }
 120
 121                 if( $row ) {
 122                         return Title::makeTitleSafe( $row->page_namespace, $row->page_title );
 123                 } else {
 124                         return null;
 125                 }
 126         }
 127
 128         protected function getQueryInfo( $randstr ) {
 129                 global $wgExtraRandompageSQL;
 130                 $redirect = $this->isRedirect() ? 1 : 0;
 131
 132                 if ( $wgExtraRandompageSQL ) {
 133                         $this->extra[] = $wgExtraRandompageSQL;
 134                 }
 135                 if ( $this->addExtraSQL() ) {
 136                         $this->extra[] = $this->addExtraSQL();
 137                 }
 138
 139                 return array(
 140                         'tables' => array( 'page' ),
 141                         'fields' => array( 'page_title', 'page_namespace' ),
 142                         'conds' => array_merge( array(
 143                                 'page_namespace' => $this->namespaces,
 144                                 'page_is_redirect' => $redirect,
 145                                 'page_random >= ' . $randstr
 146                         ), $this->extra ),
 147                         'options' => array(
 148                                 'ORDER BY' => 'page_random',
 149                                 'USE INDEX' => 'page_random',
 150                                 'LIMIT' => 1,
 151                         ),
 152                         'join_conds' => array()
 153                 );
 154         }
 155
 156         private function selectRandomPageFromDB( $randstr, $fname = __METHOD__ ) {
 157                 $dbr = wfGetDB( DB_SLAVE );
 158
 159                 $query = $this->getQueryInfo( $randstr );
 160                 $res = $dbr->select(
 161                         $query['tables'],
 162                         $query['fields'],
 163                         $query['conds'],
 164                         $fname,
 165                         $query['options'],
 166                         $query['join_conds']
 167                 );
 168
 169                 return $dbr->fetchObject( $res );
 170         }
 171
 172         /* an alternative to $wgExtraRandompageSQL so subclasses
 173          * can add their own SQL by overriding this function
 174          * @deprecated, append to $this->extra instead
 175          */
 176         public function addExtraSQL() {
 177                 return '';
 178         }
 179 }