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  * Main execution point
  13  * @param $par Namespace to select the page from
  14  */
  15 function wfSpecialRandompage( $par = null ) {
  16         global $wgOut, $wgContLang;
  17
  18         $rnd = new RandomPage();
  19
  20         if ( $par == null ) {
  21                 // Select a random content namespace to use.
  22                 global $wgContentNamespaces;
  23                 $n = array_rand( $wgContentNamespaces );
  24                 $rnd->setNamespace( $wgContentNamespaces[$n] );
  25         }
  26         else {
  27                 $rnd->setNamespace( $wgContLang->getNsIndex( $par ) );
  28         }
  29
  30         $rnd->setRedirect( false );
  31
  32         $title = $rnd->getRandomTitle();
  33
  34         if( is_null( $title ) ) {
  35                 $wgOut->addWikiText( wfMsg( 'randompage-nopages' ) );
  36                 return;
  37         }
  38
  39         $wgOut->reportTime();
  40         $wgOut->redirect( $title->getFullUrl() );
  41 }
  42
  43
  44 /**
  45  * Special page to direct the user to a random page
  46  *
  47  * @addtogroup SpecialPage
  48  */
  49 class RandomPage {
  50         private $namespace = NS_MAIN;  // namespace to select pages from
  51         private $redirect = false;     // select redirects instead of normal pages?
  52
  53         public function getNamespace ( ) {
  54                 return $this->namespace;
  55         }
  56         public function setNamespace ( $ns ) {
  57                 if( $ns < NS_MAIN ) $ns = NS_MAIN;
  58                 $this->namespace = $ns;
  59         }
  60         public function getRedirect ( ) {
  61                 return $this->redirect;
  62         }
  63         public function setRedirect ( $redirect ) {
  64                 $this->redirect = $redirect;
  65         }
  66
  67         /**
  68          * Choose a random title.
  69          * @return Title object (or null if nothing to choose from)
  70          */
  71         public function getRandomTitle ( ) {
  72                 $randstr = wfRandom();
  73                 $row = $this->selectRandomPageFromDB( $randstr );
  74
  75                 /* If we picked a value that was higher than any in
  76                  * the DB, wrap around and select the page with the
  77                  * lowest value instead!  One might think this would
  78                  * skew the distribution, but in fact it won't cause
  79                  * any more bias than what the page_random scheme
  80                  * causes anyway.  Trust me, I'm a mathematician. :)
  81                  */
  82                 if( !$row )
  83                         $row = $this->selectRandomPageFromDB( "0" );
  84
  85                 if( $row )
  86                         return Title::makeTitleSafe( $this->namespace, $row->page_title );
  87                 else
  88                         return null;
  89         }
  90
  91         private function selectRandomPageFromDB ( $randstr ) {
  92                 global $wgExtraRandompageSQL;
  93                 $fname = 'RandomPage::selectRandomPageFromDB';
  94
  95                 $dbr = wfGetDB( DB_SLAVE );
  96
  97                 $use_index = $dbr->useIndexClause( 'page_random' );
  98                 $page = $dbr->tableName( 'page' );
  99
 100                 $ns = (int) $this->namespace;
 101                 $redirect = $this->redirect ? 1 : 0;
 102
 103                 $extra = $wgExtraRandompageSQL ? "AND ($wgExtraRandompageSQL)" : "";
 104                 $sql = "SELECT page_title
 105                         FROM $page $use_index
 106                         WHERE page_namespace = $ns
 107                         AND page_is_redirect = $redirect
 108                         AND page_random >= $randstr
 109                         $extra
 110                         ORDER BY page_random";
 111
 112                 $sql = $dbr->limitResult( $sql, 1, 0 );
 113                 $res = $dbr->query( $sql, $fname );
 114                 return $dbr->fetchObject( $res );
 115         }
 116 }
 117
 118 ?>