includes/specials/SpecialRandompage.php

   1 <?php
   2 /**
   3  *
   4  * This program is free software; you can redistribute it and/or modify
   5  * it under the terms of the GNU General Public License as published by
   6  * the Free Software Foundation; either version 2 of the License, or
   7  * (at your option) any later version.
   8  *
   9  * This program is distributed in the hope that it will be useful,
  10  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
  12  * GNU General Public License for more details.
  13  *
  14  * You should have received a copy of the GNU General Public License along
  15  * with this program; if not, write to the Free Software Foundation, Inc.,
  16  * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
  17  * http://www.gnu.org/copyleft/gpl.html
  18  */
  19
  20 /**
  21  * Special page to direct the user to a random page
  22  *
  23  * @ingroup SpecialPage
  24  * @author Rob Church <robchur@gmail.com>, Ilmari Karonen
  25  * @license GNU General Public Licence 2.0 or later
  26  */
  27 class RandomPage extends SpecialPage {
  28         private $namespaces;  // namespaces to select pages from
  29         protected $isRedir = false; // should the result be a redirect?
  30         protected $extra = array(); // Extra SQL statements
  31
  32         public function __construct( $name = 'Randompage' ){
  33                 global $wgContentNamespaces;
  34                 $this->namespaces = $wgContentNamespaces;
  35                 parent::__construct( $name );
  36         }
  37
  38         public function getNamespaces() {
  39                 return $this->namespaces;
  40         }
  41
  42         public function setNamespace ( $ns ) {
  43                 if( !$ns || $ns < NS_MAIN ) $ns = NS_MAIN;
  44                 $this->namespaces = array( $ns );
  45         }
  46
  47         // select redirects instead of normal pages?
  48         public function isRedirect(){
  49                 return $this->isRedir;
  50         }
  51
  52         public function execute( $par ) {
  53                 global $wgOut, $wgContLang, $wgRequest;
  54
  55                 if ($par) {
  56                         $this->setNamespace( $wgContLang->getNsIndex( $par ) );
  57                 }
  58
  59                 $title = $this->getRandomTitle();
  60
  61                 if( is_null( $title ) ) {
  62                         $this->setHeaders();
  63                         $wgOut->addWikiMsg( strtolower( $this->mName ) . '-nopages',
  64                                 $this->getNsList(), count( $this->namespaces ) );
  65                         return;
  66                 }
  67
  68                 $redirectParam = $this->isRedirect() ? array( 'redirect' => 'no' ) : array();
  69                 $query = array_merge( $wgRequest->getValues(), $redirectParam );
  70                 unset( $query['title'] );
  71                 $wgOut->redirect( $title->getFullUrl( $query ) );
  72         }
  73
  74         /**
  75          * Get a comma-delimited list of namespaces we don't have
  76          * any pages in
  77          * @return String
  78          */
  79         private function getNsList() {
  80                 global $wgContLang;
  81                 $nsNames = array();
  82                 foreach( $this->namespaces as $n ) {
  83                         if( $n === NS_MAIN )
  84                                 $nsNames[] = wfMsgForContent( 'blanknamespace' );
  85                         else
  86                                 $nsNames[] = $wgContLang->getNsText( $n );
  87                 }
  88                 return $wgContLang->commaList( $nsNames );
  89         }
  90
  91
  92         /**
  93          * Choose a random title.
  94          * @return Title object (or null if nothing to choose from)
  95          */
  96         public function getRandomTitle() {
  97                 $randstr = wfRandom();
  98                 $title = null;
  99                 if ( !wfRunHooks( 'SpecialRandomGetRandomTitle', array( &$randstr, &$this->isRedir, &$this->namespaces, &$this->extra, &$title ) ) ) {
 100                         return $title;
 101                 }
 102                 $row = $this->selectRandomPageFromDB( $randstr );
 103
 104                 /* If we picked a value that was higher than any in
 105                  * the DB, wrap around and select the page with the
 106                  * lowest value instead!  One might think this would
 107                  * skew the distribution, but in fact it won't cause
 108                  * any more bias than what the page_random scheme
 109                  * causes anyway.  Trust me, I'm a mathematician. :)
 110                  */
 111                 if( !$row )
 112                         $row = $this->selectRandomPageFromDB( "0" );
 113
 114                 if( $row )
 115                         return Title::makeTitleSafe( $row->page_namespace, $row->page_title );
 116                 else
 117                         return null;
 118         }
 119
 120         private function selectRandomPageFromDB( $randstr ) {
 121                 global $wgExtraRandompageSQL;
 122                 $dbr = wfGetDB( DB_SLAVE );
 123
 124                 $use_index = $dbr->useIndexClause( 'page_random' );
 125                 $page = $dbr->tableName( 'page' );
 126
 127                 $ns = implode( ",", $this->namespaces );
 128                 $redirect = $this->isRedirect() ? 1 : 0;
 129
 130                 if ( $wgExtraRandompageSQL ) {
 131                         $this->extra[] = $wgExtraRandompageSQL;
 132                 }
 133                 if ( $this->addExtraSQL() ) {
 134                         $this->extra[] = $this->addExtraSQL();
 135                 }
 136                 $extra = '';
 137                 if ( $this->extra ) {
 138                         $extra = 'AND (' . implode( ') AND (', $this->extra ) . ')';
 139                 }
 140                 $sql = "SELECT page_title, page_namespace
 141                         FROM $page $use_index
 142                         WHERE page_namespace IN ( $ns )
 143                         AND page_is_redirect = $redirect
 144                         AND page_random >= $randstr
 145                         $extra
 146                         ORDER BY page_random";
 147
 148                 $sql = $dbr->limitResult( $sql, 1, 0 );
 149                 $res = $dbr->query( $sql, __METHOD__ );
 150                 return $dbr->fetchObject( $res );
 151         }
 152
 153         /* an alternative to $wgExtraRandompageSQL so subclasses
 154          * can add their own SQL by overriding this function
 155          * @deprecated, append to $this->extra instead
 156          */
 157         public function addExtraSQL() {
 158                 return '';
 159         }
 160 }