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 = []; // 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 = [ $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 ( is_string( $par ) ) {
  60                         // Testing for stringiness since we want to catch
  61                         // the empty string to mean main namespace only.
  62                         $this->setNamespace( $wgContLang->getNsIndex( $par ) );
  63                 }
  64
  65                 $title = $this->getRandomTitle();
  66
  67                 if ( is_null( $title ) ) {
  68                         $this->setHeaders();
  69                         // Message: randompage-nopages, randomredirect-nopages
  70                         $this->getOutput()->addWikiMsg( strtolower( $this->getName() ) . '-nopages',
  71                                 $this->getNsList(), count( $this->namespaces ) );
  72
  73                         return;
  74                 }
  75
  76                 $redirectParam = $this->isRedirect() ? [ 'redirect' => 'no' ] : [];
  77                 $query = array_merge( $this->getRequest()->getValues(), $redirectParam );
  78                 unset( $query['title'] );
  79                 $this->getOutput()->redirect( $title->getFullURL( $query ) );
  80         }
  81
  82         /**
  83          * Get a comma-delimited list of namespaces we don't have
  84          * any pages in
  85          * @return string
  86          */
  87         private function getNsList() {
  88                 global $wgContLang;
  89                 $nsNames = [];
  90                 foreach ( $this->namespaces as $n ) {
  91                         if ( $n === NS_MAIN ) {
  92                                 $nsNames[] = $this->msg( 'blanknamespace' )->plain();
  93                         } else {
  94                                 $nsNames[] = $wgContLang->getNsText( $n );
  95                         }
  96                 }
  97
  98                 return $wgContLang->commaList( $nsNames );
  99         }
 100
 101         /**
 102          * Choose a random title.
 103          * @return Title|null Title object (or null if nothing to choose from)
 104          */
 105         public function getRandomTitle() {
 106                 $randstr = wfRandom();
 107                 $title = null;
 108
 109                 if ( !Hooks::run(
 110                         'SpecialRandomGetRandomTitle',
 111                         [ &$randstr, &$this->isRedir, &$this->namespaces, &$this->extra, &$title ]
 112                 ) ) {
 113                         return $title;
 114                 }
 115
 116                 $row = $this->selectRandomPageFromDB( $randstr );
 117
 118                 /* If we picked a value that was higher than any in
 119                  * the DB, wrap around and select the page with the
 120                  * lowest value instead!  One might think this would
 121                  * skew the distribution, but in fact it won't cause
 122                  * any more bias than what the page_random scheme
 123                  * causes anyway.  Trust me, I'm a mathematician. :)
 124                  */
 125                 if ( !$row ) {
 126                         $row = $this->selectRandomPageFromDB( "0" );
 127                 }
 128
 129                 if ( $row ) {
 130                         return Title::makeTitleSafe( $row->page_namespace, $row->page_title );
 131                 }
 132
 133                 return null;
 134         }
 135
 136         protected function getQueryInfo( $randstr ) {
 137                 $redirect = $this->isRedirect() ? 1 : 0;
 138                 $tables = [ 'page' ];
 139                 $conds = array_merge( [
 140                         'page_namespace' => $this->namespaces,
 141                         'page_is_redirect' => $redirect,
 142                         'page_random >= ' . $randstr
 143                 ], $this->extra );
 144                 $joinConds = [];
 145
 146                 // Allow extensions to modify the query
 147                 Hooks::run( 'RandomPageQuery', [ &$tables, &$conds, &$joinConds ] );
 148
 149                 return [
 150                         'tables' => $tables,
 151                         'fields' => [ 'page_title', 'page_namespace' ],
 152                         'conds' => $conds,
 153                         'options' => [
 154                                 'ORDER BY' => 'page_random',
 155                                 'LIMIT' => 1,
 156                         ],
 157                         'join_conds' => $joinConds
 158                 ];
 159         }
 160
 161         private function selectRandomPageFromDB( $randstr, $fname = __METHOD__ ) {
 162                 $dbr = wfGetDB( DB_REPLICA );
 163
 164                 $query = $this->getQueryInfo( $randstr );
 165                 $res = $dbr->select(
 166                         $query['tables'],
 167                         $query['fields'],
 168                         $query['conds'],
 169                         $fname,
 170                         $query['options'],
 171                         $query['join_conds']
 172                 );
 173
 174                 return $dbr->fetchObject( $res );
 175         }
 176
 177         protected function getGroupName() {
 178                 return 'redirects';
 179         }
 180 }