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 use MediaWiki\MediaWikiServices;
  26
  27 /**
  28  * Special page to direct the user to a random page
  29  *
  30  * @ingroup SpecialPage
  31  */
  32 class RandomPage extends SpecialPage {
  33         private $namespaces; // namespaces to select pages from
  34         protected $isRedir = false; // should the result be a redirect?
  35         protected $extra = []; // Extra SQL statements
  36
  37         public function __construct( $name = 'Randompage' ) {
  38                 $this->namespaces = MediaWikiServices::getInstance()->getNamespaceInfo()->
  39                         getContentNamespaces();
  40                 parent::__construct( $name );
  41         }
  42
  43         public function getNamespaces() {
  44                 return $this->namespaces;
  45         }
  46
  47         public function setNamespace( $ns ) {
  48                 if ( !$ns || $ns < NS_MAIN ) {
  49                         $ns = NS_MAIN;
  50                 }
  51                 $this->namespaces = [ $ns ];
  52         }
  53
  54         // select redirects instead of normal pages?
  55         public function isRedirect() {
  56                 return $this->isRedir;
  57         }
  58
  59         public function execute( $par ) {
  60                 if ( is_string( $par ) ) {
  61                         // Testing for stringiness since we want to catch
  62                         // the empty string to mean main namespace only.
  63                         $this->setNamespace(
  64                                 MediaWikiServices::getInstance()->getContentLanguage()->getNsIndex( $par ) );
  65                 }
  66
  67                 $title = $this->getRandomTitle();
  68
  69                 if ( is_null( $title ) ) {
  70                         $this->setHeaders();
  71                         // Message: randompage-nopages, randomredirect-nopages
  72                         $this->getOutput()->addWikiMsg( strtolower( $this->getName() ) . '-nopages',
  73                                 $this->getNsList(), count( $this->namespaces ) );
  74
  75                         return;
  76                 }
  77
  78                 $redirectParam = $this->isRedirect() ? [ 'redirect' => 'no' ] : [];
  79                 $query = array_merge( $this->getRequest()->getValues(), $redirectParam );
  80                 unset( $query['title'] );
  81                 $this->getOutput()->redirect( $title->getFullURL( $query ) );
  82         }
  83
  84         /**
  85          * Get a comma-delimited list of namespaces we don't have
  86          * any pages in
  87          * @return string
  88          */
  89         private function getNsList() {
  90                 $contLang = MediaWikiServices::getInstance()->getContentLanguage();
  91                 $nsNames = [];
  92                 foreach ( $this->namespaces as $n ) {
  93                         if ( $n === NS_MAIN ) {
  94                                 $nsNames[] = $this->msg( 'blanknamespace' )->plain();
  95                         } else {
  96                                 $nsNames[] = $contLang->getNsText( $n );
  97                         }
  98                 }
  99
 100                 return $contLang->commaList( $nsNames );
 101         }
 102
 103         /**
 104          * Choose a random title.
 105          * @return Title|null Title object (or null if nothing to choose from)
 106          */
 107         public function getRandomTitle() {
 108                 $randstr = wfRandom();
 109                 $title = null;
 110
 111                 if ( !Hooks::run(
 112                         'SpecialRandomGetRandomTitle',
 113                         [ &$randstr, &$this->isRedir, &$this->namespaces, &$this->extra, &$title ]
 114                 ) ) {
 115                         return $title;
 116                 }
 117
 118                 $row = $this->selectRandomPageFromDB( $randstr );
 119
 120                 /* If we picked a value that was higher than any in
 121                  * the DB, wrap around and select the page with the
 122                  * lowest value instead!  One might think this would
 123                  * skew the distribution, but in fact it won't cause
 124                  * any more bias than what the page_random scheme
 125                  * causes anyway.  Trust me, I'm a mathematician. :)
 126                  */
 127                 if ( !$row ) {
 128                         $row = $this->selectRandomPageFromDB( "0" );
 129                 }
 130
 131                 if ( $row ) {
 132                         return Title::makeTitleSafe( $row->page_namespace, $row->page_title );
 133                 }
 134
 135                 return null;
 136         }
 137
 138         protected function getQueryInfo( $randstr ) {
 139                 $redirect = $this->isRedirect() ? 1 : 0;
 140                 $tables = [ 'page' ];
 141                 $conds = array_merge( [
 142                         'page_namespace' => $this->namespaces,
 143                         'page_is_redirect' => $redirect,
 144                         'page_random >= ' . $randstr
 145                 ], $this->extra );
 146                 $joinConds = [];
 147
 148                 // Allow extensions to modify the query
 149                 Hooks::run( 'RandomPageQuery', [ &$tables, &$conds, &$joinConds ] );
 150
 151                 return [
 152                         'tables' => $tables,
 153                         'fields' => [ 'page_title', 'page_namespace' ],
 154                         'conds' => $conds,
 155                         'options' => [
 156                                 'ORDER BY' => 'page_random',
 157                                 'LIMIT' => 1,
 158                         ],
 159                         'join_conds' => $joinConds
 160                 ];
 161         }
 162
 163         private function selectRandomPageFromDB( $randstr, $fname = __METHOD__ ) {
 164                 $dbr = wfGetDB( DB_REPLICA );
 165
 166                 $query = $this->getQueryInfo( $randstr );
 167                 $res = $dbr->select(
 168                         $query['tables'],
 169                         $query['fields'],
 170                         $query['conds'],
 171                         $fname,
 172                         $query['options'],
 173                         $query['join_conds']
 174                 );
 175
 176                 return $dbr->fetchObject( $res );
 177         }
 178
 179         protected function getGroupName() {
 180                 return 'redirects';
 181         }
 182 }