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