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