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         $rnd->setNamespace( $wgContLang->getNsIndex( $par ) );
  20         $rnd->setRedirect( false );
  21
  22         $title = $rnd->getRandomTitle();
  23
  24         if( is_null( $title ) ) {
  25                 $wgOut->addWikiText( wfMsg( 'randompage-nopages' ) );
  26                 return;
  27         }
  28
  29         $wgOut->reportTime();
  30         $wgOut->redirect( $title->getFullUrl() );
  31 }
  32
  33
  34 class RandomPage {
  35         private $namespace = NS_MAIN;  // namespace to select pages from
  36         private $redirect = false;     // select redirects instead of normal pages?
  37
  38         public function getNamespace ( ) {
  39                 return $this->namespace;
  40         }
  41         public function setNamespace ( $ns ) {
  42                 if( $ns < NS_MAIN ) $ns = NS_MAIN;
  43                 $this->namespace = $ns;
  44         }
  45         public function getRedirect ( ) {
  46                 return $this->redirect;
  47         }
  48         public function setRedirect ( $redirect ) {
  49                 $this->redirect = $redirect;
  50         }
  51
  52         /**
  53          * Choose a random title.
  54          * @return Title object (or null if nothing to choose from)
  55          */
  56         public function getRandomTitle ( ) {
  57                 $randstr = wfRandom();
  58                 $row = $this->selectRandomPageFromDB( $randstr );
  59
  60                 if( !$row ) {
  61                         // Try again with a normalized value
  62                         $randstr = wfRandom( $this->getMaxPageRandom() );
  63                         $row = $this->selectRandomPageFromDB( $randstr );
  64                 }
  65
  66                 if( $row )
  67                         return Title::makeTitleSafe( $this->namespace, $row->page_title );
  68                 else
  69                         return null;
  70         }
  71
  72         private function selectRandomPageFromDB ( $randstr ) {
  73                 global $wgExtraRandompageSQL;
  74                 $fname = 'RandomPage::selectRandomPageFromDB';
  75
  76                 $dbr = wfGetDB( DB_SLAVE );
  77
  78                 $from = $this->getSQLFrom( $dbr );
  79                 $where = $this->getSQLWhere( $dbr );
  80
  81                 $sql = "SELECT page_title FROM $from
  82                         WHERE $where AND page_random > $randstr
  83                         ORDER BY page_random";
  84
  85                 $sql = $dbr->limitResult( $sql, 1, 0 );
  86                 $res = $dbr->query( $sql, $fname );
  87                 return $dbr->fetchObject( $res );
  88         }
  89
  90         private function getMaxPageRandom () {
  91                 $fname = 'RandomPage::getMaxPageRandom';
  92
  93                 $dbr = wfGetDB( DB_SLAVE );
  94
  95                 $from = $this->getSQLFrom( $dbr );
  96                 $where = $this->getSQLWhere( $dbr );
  97
  98                 $sql = "SELECT MAX(page_random) AS max FROM $from WHERE $where";
  99
 100                 $sql = $dbr->limitResult( $sql, 1, 0 );
 101                 $res = $dbr->query( $sql, $fname );
 102                 $row = $dbr->fetchObject( $res );
 103
 104                 return $row ? $row->max : 0;
 105         }
 106
 107         private function getSQLFrom ( $dbr ) {
 108                 $use_index = $dbr->useIndexClause( 'page_random' );
 109                 $page = $dbr->tableName( 'page' );
 110                 return "$page $use_index";
 111         }
 112
 113         private function getSQLWhere ( $dbr ) {
 114                 global $wgExtraRandompageSQL;
 115                 $ns = (int) $this->namespace;
 116                 $redirect = $this->redirect ? 1 : 0;
 117                 $extra = $wgExtraRandompageSQL ? " AND ($wgExtraRandompageSQL)" : "";
 118                 return "page_namespace = $ns AND page_is_redirect = $redirect" . $extra;
 119         }
 120 }
 121
 122 ?>