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 $namespaces;  // namespaces to select pages from
  12         protected $isRedir = false; // should the result be a redirect?
  13         protected $extra = array(); // Extra SQL statements
  14
  15         public function __construct( $name = 'Randompage' ){
  16                 global $wgContentNamespaces;
  17                 $this->namespaces = $wgContentNamespaces;
  18                 parent::__construct( $name );
  19         }
  20
  21         public function getNamespaces() {
  22                 return $this->namespaces;
  23         }
  24
  25         public function setNamespace ( $ns ) {
  26                 if( !$ns || $ns < NS_MAIN ) $ns = NS_MAIN;
  27                 $this->namespaces = array( $ns );
  28         }
  29
  30         // select redirects instead of normal pages?
  31         public function isRedirect(){
  32                 return $this->isRedir;
  33         }
  34
  35         public function execute( $par ) {
  36                 global $wgOut, $wgContLang;
  37
  38                 if ($par) {
  39                         $this->setNamespace( $wgContLang->getNsIndex( $par ) );
  40                 }
  41
  42                 $title = $this->getRandomTitle();
  43
  44                 if( is_null( $title ) ) {
  45                         $this->setHeaders();
  46                         $wgOut->addWikiMsg( strtolower( $this->mName ) . '-nopages',
  47                                 $this->getNsList(), count( $this->namespaces ) );
  48                         return;
  49                 }
  50
  51                 $query = $this->isRedirect() ? 'redirect=no' : '';
  52                 $wgOut->redirect( $title->getFullUrl( $query ) );
  53         }
  54
  55         /**
  56          * Get a comma-delimited list of namespaces we don't have
  57          * any pages in
  58          * @return String
  59          */
  60         private function getNsList() {
  61                 global $wgContLang;
  62                 $nsNames = array();
  63                 foreach( $this->namespaces as $n ) {
  64                         if( $n === NS_MAIN )
  65                                 $nsNames[] = wfMsgForContent( 'blanknamespace' );
  66                         else
  67                                 $nsNames[] = $wgContLang->getNsText( $n );
  68                 }
  69                 return $wgContLang->commaList( $nsNames );
  70         }
  71
  72
  73         /**
  74          * Choose a random title.
  75          * @return Title object (or null if nothing to choose from)
  76          */
  77         public function getRandomTitle() {
  78                 $randstr = wfRandom();
  79                 $title = null;
  80                 if ( !wfRunHooks( 'SpecialRandomGetRandomTitle', array( &$randstr, &$this->isRedir, &$this->namespaces, &$this->extra, &$title ) ) ) {
  81                         return $title;
  82                 }
  83                 $row = $this->selectRandomPageFromDB( $randstr );
  84
  85                 /* If we picked a value that was higher than any in
  86                  * the DB, wrap around and select the page with the
  87                  * lowest value instead!  One might think this would
  88                  * skew the distribution, but in fact it won't cause
  89                  * any more bias than what the page_random scheme
  90                  * causes anyway.  Trust me, I'm a mathematician. :)
  91                  */
  92                 if( !$row )
  93                         $row = $this->selectRandomPageFromDB( "0" );
  94
  95                 if( $row )
  96                         return Title::makeTitleSafe( $row->page_namespace, $row->page_title );
  97                 else
  98                         return null;
  99         }
 100
 101         private function selectRandomPageFromDB( $randstr ) {
 102                 global $wgExtraRandompageSQL;
 103                 $dbr = wfGetDB( DB_SLAVE );
 104
 105                 $use_index = $dbr->useIndexClause( 'page_random' );
 106                 $page = $dbr->tableName( 'page' );
 107
 108                 $ns = implode( ",", $this->namespaces );
 109                 $redirect = $this->isRedirect() ? 1 : 0;
 110
 111                 if ( $wgExtraRandompageSQL ) {
 112                         $this->extra[] = $wgExtraRandompageSQL;
 113                 }
 114                 if ( $this->addExtraSQL() ) {
 115                         $this->extra[] = $this->addExtraSQL();
 116                 }
 117                 $extra = '';
 118                 if ( $this->extra ) {
 119                         $extra = 'AND (' . implode( ') AND (', $this->extra ) . ')';
 120                 }
 121                 $sql = "SELECT page_title, page_namespace
 122                         FROM $page $use_index
 123                         WHERE page_namespace IN ( $ns )
 124                         AND page_is_redirect = $redirect
 125                         AND page_random >= $randstr
 126                         $extra
 127                         ORDER BY page_random";
 128
 129                 $sql = $dbr->limitResult( $sql, 1, 0 );
 130                 $res = $dbr->query( $sql, __METHOD__ );
 131                 return $dbr->fetchObject( $res );
 132         }
 133
 134         /* an alternative to $wgExtraRandompageSQL so subclasses
 135          * can add their own SQL by overriding this function
 136          * @deprecated, append to $this->extra instead
 137          */
 138         public function addExtraSQL() {
 139                 return '';
 140         }
 141 }