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                 $this->namespaces = MWNamespace::getContentNamespaces();
  37                 parent::__construct( $name );
  38         }
  39
  40         public function getNamespaces() {
  41                 return $this->namespaces;
  42         }
  43
  44         public function setNamespace( $ns ) {
  45                 if ( !$ns || $ns < NS_MAIN ) {
  46                         $ns = NS_MAIN;
  47                 }
  48                 $this->namespaces = array( $ns );
  49         }
  50
  51         // select redirects instead of normal pages?
  52         public function isRedirect() {
  53                 return $this->isRedir;
  54         }
  55
  56         public function execute( $par ) {
  57                 global $wgContLang;
  58
  59                 if ( $par ) {
  60                         $this->setNamespace( $wgContLang->getNsIndex( $par ) );
  61                 }
  62
  63                 $title = $this->getRandomTitle();
  64
  65                 if ( is_null( $title ) ) {
  66                         $this->setHeaders();
  67                         // Message: randompage-nopages, randomredirect-nopages
  68                         $this->getOutput()->addWikiMsg( strtolower( $this->getName() ) . '-nopages',
  69                                 $this->getNsList(), count( $this->namespaces ) );
  70
  71                         return;
  72                 }
  73
  74                 $redirectParam = $this->isRedirect() ? array( 'redirect' => 'no' ) : array();
  75                 $query = array_merge( $this->getRequest()->getValues(), $redirectParam );
  76                 unset( $query['title'] );
  77                 $this->getOutput()->redirect( $title->getFullURL( $query ) );
  78         }
  79
  80         /**
  81          * Get a comma-delimited list of namespaces we don't have
  82          * any pages in
  83          * @return String
  84          */
  85         private function getNsList() {
  86                 global $wgContLang;
  87                 $nsNames = array();
  88                 foreach ( $this->namespaces as $n ) {
  89                         if ( $n === NS_MAIN ) {
  90                                 $nsNames[] = $this->msg( 'blanknamespace' )->plain();
  91                         } else {
  92                                 $nsNames[] = $wgContLang->getNsText( $n );
  93                         }
  94                 }
  95
  96                 return $wgContLang->commaList( $nsNames );
  97         }
  98
  99         /**
 100          * Choose a random title.
 101          * @return Title object (or null if nothing to choose from)
 102          */
 103         public function getRandomTitle() {
 104                 $randstr = wfRandom();
 105                 $title = null;
 106
 107                 if ( !wfRunHooks(
 108                         'SpecialRandomGetRandomTitle',
 109                         array( &$randstr, &$this->isRedir, &$this->namespaces, &$this->extra, &$title )
 110                 ) ) {
 111                         return $title;
 112                 }
 113
 114                 $row = $this->selectRandomPageFromDB( $randstr );
 115
 116                 /* If we picked a value that was higher than any in
 117                  * the DB, wrap around and select the page with the
 118                  * lowest value instead!  One might think this would
 119                  * skew the distribution, but in fact it won't cause
 120                  * any more bias than what the page_random scheme
 121                  * causes anyway.  Trust me, I'm a mathematician. :)
 122                  */
 123                 if ( !$row ) {
 124                         $row = $this->selectRandomPageFromDB( "0" );
 125                 }
 126
 127                 if ( $row ) {
 128                         return Title::makeTitleSafe( $row->page_namespace, $row->page_title );
 129                 }
 130
 131                 return null;
 132         }
 133
 134         protected function getQueryInfo( $randstr ) {
 135                 $redirect = $this->isRedirect() ? 1 : 0;
 136
 137                 return array(
 138                         'tables' => array( 'page' ),
 139                         'fields' => array( 'page_title', 'page_namespace' ),
 140                         'conds' => array_merge( array(
 141                                 'page_namespace' => $this->namespaces,
 142                                 'page_is_redirect' => $redirect,
 143                                 'page_random >= ' . $randstr
 144                         ), $this->extra ),
 145                         'options' => array(
 146                                 'ORDER BY' => 'page_random',
 147                                 'USE INDEX' => 'page_random',
 148                                 'LIMIT' => 1,
 149                         ),
 150                         'join_conds' => array()
 151                 );
 152         }
 153
 154         private function selectRandomPageFromDB( $randstr, $fname = __METHOD__ ) {
 155                 $dbr = wfGetDB( DB_SLAVE );
 156
 157                 $query = $this->getQueryInfo( $randstr );
 158                 $res = $dbr->select(
 159                         $query['tables'],
 160                         $query['fields'],
 161                         $query['conds'],
 162                         $fname,
 163                         $query['options'],
 164                         $query['join_conds']
 165                 );
 166
 167                 return $dbr->fetchObject( $res );
 168         }
 169
 170         protected function getGroupName() {
 171                 return 'redirects';
 172         }
 173 }