includes/specials/SpecialRandompage.php

   1 <?php
   2
   3 /**
   4  * Special page to direct the user to a random page
   5  *
   6  * @ingroup SpecialPage
   7  * @author Rob Church <robchur@gmail.com>, Ilmari Karonen
   8  * @license GNU General Public Licence 2.0 or later
   9  */
  10 class RandomPage extends SpecialPage {
  11         private $namespace = NS_MAIN;  // namespace to select pages from
  12
  13         function __construct( $name = 'Randompage' ){
  14                 parent::__construct( $name );
  15         }
  16
  17         public function getNamespace() {
  18                 return $this->namespace;
  19         }
  20
  21         public function setNamespace ( $ns ) {
  22                 if( $ns < NS_MAIN ) $ns = NS_MAIN;
  23                 $this->namespace = $ns;
  24         }
  25
  26         // select redirects instead of normal pages?
  27         // Overriden by SpecialRandomredirect
  28         public function isRedirect(){
  29                 return false;
  30         }
  31
  32         public function execute( $par ) {
  33                 global $wgOut, $wgContLang;
  34
  35                 if ($par)
  36                         $this->setNamespace( $wgContLang->getNsIndex( $par ) );
  37
  38                 $title = $this->getRandomTitle();
  39
  40                 if( is_null( $title ) ) {
  41                         $this->setHeaders();
  42                         $wgOut->addWikiMsg( strtolower( $this->mName ) . '-nopages' );
  43                         return;
  44                 }
  45
  46                 $query = $this->isRedirect() ? 'redirect=no' : '';
  47                 $wgOut->redirect( $title->getFullUrl( $query ) );
  48         }
  49
  50
  51         /**
  52          * Choose a random title.
  53          * @return Title object (or null if nothing to choose from)
  54          */
  55         public function getRandomTitle() {
  56                 $randstr = wfRandom();
  57                 $row = $this->selectRandomPageFromDB( $randstr );
  58
  59                 /* If we picked a value that was higher than any in
  60                  * the DB, wrap around and select the page with the
  61                  * lowest value instead!  One might think this would
  62                  * skew the distribution, but in fact it won't cause
  63                  * any more bias than what the page_random scheme
  64                  * causes anyway.  Trust me, I'm a mathematician. :)
  65                  */
  66                 if( !$row )
  67                         $row = $this->selectRandomPageFromDB( "0" );
  68
  69                 if( $row )
  70                         return Title::makeTitleSafe( $this->namespace, $row->page_title );
  71                 else
  72                         return null;
  73         }
  74
  75         private function selectRandomPageFromDB( $randstr ) {
  76                 global $wgExtraRandompageSQL;
  77                 $fname = 'RandomPage::selectRandomPageFromDB';
  78
  79                 $dbr = wfGetDB( DB_SLAVE );
  80
  81                 $use_index = $dbr->useIndexClause( 'page_random' );
  82                 $page = $dbr->tableName( 'page' );
  83
  84                 $ns = (int) $this->namespace;
  85                 $redirect = $this->isRedirect() ? 1 : 0;
  86
  87                 $extra = $wgExtraRandompageSQL ? "AND ($wgExtraRandompageSQL)" : "";
  88                 $sql = "SELECT page_title
  89                         FROM $page $use_index
  90                         WHERE page_namespace = $ns
  91                         AND page_is_redirect = $redirect
  92                         AND page_random >= $randstr
  93                         $extra
  94                         ORDER BY page_random";
  95
  96                 $sql = $dbr->limitResult( $sql, 1, 0 );
  97                 $res = $dbr->query( $sql, $fname );
  98                 return $dbr->fetchObject( $res );
  99         }
 100 }