includes/SpecialRandompage.php

   1 <?php
   2
   3 /**
   4  * Special page to direct the user to a random page
   5  *
   6  * @addtogroup SpecialPage
   7  * @author Rob Church <robchur@gmail.com>, Ilmari Karonen
   8  * @license GNU General Public Licence 2.0 or later
   9  */
  10
  11 /**
  12  * Special page to direct the user to a random page
  13  *
  14  * @addtogroup SpecialPage
  15  */
  16 class RandomPage extends SpecialPage {
  17         private $namespace = NS_MAIN;  // namespace to select pages from
  18
  19         function __construct( $name = 'Randompage' ){
  20                 parent::__construct( $name );
  21         }
  22
  23         public function getNamespace() {
  24                 return $this->namespace;
  25         }
  26
  27         public function setNamespace ( $ns ) {
  28                 if( $ns < NS_MAIN ) $ns = NS_MAIN;
  29                 $this->namespace = $ns;
  30         }
  31
  32         // select redirects instead of normal pages?
  33         // Overriden by SpecialRandomredirect
  34         public function isRedirect(){
  35                 return false;
  36         }
  37
  38         public function execute( $par ) {
  39                 global $wgOut, $wgContLang;
  40
  41                 if ($par)
  42                         $this->setNamespace( $wgContLang->getNsIndex( $par ) );
  43
  44                 $title = $this->getRandomTitle();
  45
  46                 if( is_null( $title ) ) {
  47                         $this->setHeaders();
  48                         $wgOut->addWikiText( wfMsg( strtolower( $this->mName ) . '-nopages' ) );
  49                         return;
  50                 }
  51
  52                 $query = $this->isRedirect() ? 'redirect=no' : '';
  53                 $wgOut->redirect( $title->getFullUrl( $query ) );
  54         }
  55
  56
  57         /**
  58          * Choose a random title.
  59          * @return Title object (or null if nothing to choose from)
  60          */
  61         public function getRandomTitle() {
  62                 $randstr = wfRandom();
  63                 $row = $this->selectRandomPageFromDB( $randstr );
  64
  65                 /* If we picked a value that was higher than any in
  66                  * the DB, wrap around and select the page with the
  67                  * lowest value instead!  One might think this would
  68                  * skew the distribution, but in fact it won't cause
  69                  * any more bias than what the page_random scheme
  70                  * causes anyway.  Trust me, I'm a mathematician. :)
  71                  */
  72                 if( !$row )
  73                         $row = $this->selectRandomPageFromDB( "0" );
  74
  75                 if( $row )
  76                         return Title::makeTitleSafe( $this->namespace, $row->page_title );
  77                 else
  78                         return null;
  79         }
  80
  81         private function selectRandomPageFromDB( $randstr ) {
  82                 global $wgExtraRandompageSQL;
  83                 $fname = 'RandomPage::selectRandomPageFromDB';
  84
  85                 $dbr = wfGetDB( DB_SLAVE );
  86
  87                 $use_index = $dbr->useIndexClause( 'page_random' );
  88                 $page = $dbr->tableName( 'page' );
  89
  90                 $ns = (int) $this->namespace;
  91                 $redirect = $this->isRedirect() ? 1 : 0;
  92
  93                 $extra = $wgExtraRandompageSQL ? "AND ($wgExtraRandompageSQL)" : "";
  94                 $sql = "SELECT page_title
  95                         FROM $page $use_index
  96                         WHERE page_namespace = $ns
  97                         AND page_is_redirect = $redirect
  98                         AND page_random >= $randstr
  99                         $extra
 100                         ORDER BY page_random";
 101
 102                 $sql = $dbr->limitResult( $sql, 1, 0 );
 103                 $res = $dbr->query( $sql, $fname );
 104                 return $dbr->fetchObject( $res );
 105         }
 106 }
 107
 108