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, $wgRequest;
  37
  38                 if ($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                 $redirectParam = $this->isRedirect() ? array( 'redirect' => 'no' ) : array();
  52                 $query = array_merge( $wgRequest->getValues(), $redirectParam );
  53                 unset( $query['title'] );
  54                 $wgOut->redirect( $title->getFullUrl( $query ) );
  55         }
  56
  57         /**
  58          * Get a comma-delimited list of namespaces we don't have
  59          * any pages in
  60          * @return String
  61          */
  62         private function getNsList() {
  63                 global $wgContLang;
  64                 $nsNames = array();
  65                 foreach( $this->namespaces as $n ) {
  66                         if( $n === NS_MAIN )
  67                                 $nsNames[] = wfMsgForContent( 'blanknamespace' );
  68                         else
  69                                 $nsNames[] = $wgContLang->getNsText( $n );
  70                 }
  71                 return $wgContLang->commaList( $nsNames );
  72         }
  73
  74
  75         /**
  76          * Choose a random title.
  77          * @return Title object (or null if nothing to choose from)
  78          */
  79         public function getRandomTitle() {
  80                 $randstr = wfRandom();
  81                 $title = null;
  82                 if ( !wfRunHooks( 'SpecialRandomGetRandomTitle', array( &$randstr, &$this->isRedir, &$this->namespaces, &$this->extra, &$title ) ) ) {
  83                         return $title;
  84                 }
  85                 $row = $this->selectRandomPageFromDB( $randstr );
  86
  87                 /* If we picked a value that was higher than any in
  88                  * the DB, wrap around and select the page with the
  89                  * lowest value instead!  One might think this would
  90                  * skew the distribution, but in fact it won't cause
  91                  * any more bias than what the page_random scheme
  92                  * causes anyway.  Trust me, I'm a mathematician. :)
  93                  */
  94                 if( !$row )
  95                         $row = $this->selectRandomPageFromDB( "0" );
  96
  97                 if( $row )
  98                         return Title::makeTitleSafe( $row->page_namespace, $row->page_title );
  99                 else
 100                         return null;
 101         }
 102
 103         private function selectRandomPageFromDB( $randstr ) {
 104                 global $wgExtraRandompageSQL;
 105                 $dbr = wfGetDB( DB_SLAVE );
 106
 107                 $use_index = $dbr->useIndexClause( 'page_random' );
 108                 $page = $dbr->tableName( 'page' );
 109
 110                 $ns = implode( ",", $this->namespaces );
 111                 $redirect = $this->isRedirect() ? 1 : 0;
 112
 113                 if ( $wgExtraRandompageSQL ) {
 114                         $this->extra[] = $wgExtraRandompageSQL;
 115                 }
 116                 if ( $this->addExtraSQL() ) {
 117                         $this->extra[] = $this->addExtraSQL();
 118                 }
 119                 $extra = '';
 120                 if ( $this->extra ) {
 121                         $extra = 'AND (' . implode( ') AND (', $this->extra ) . ')';
 122                 }
 123                 $sql = "SELECT page_title, page_namespace
 124                         FROM $page $use_index
 125                         WHERE page_namespace IN ( $ns )
 126                         AND page_is_redirect = $redirect
 127                         AND page_random >= $randstr
 128                         $extra
 129                         ORDER BY page_random";
 130
 131                 $sql = $dbr->limitResult( $sql, 1, 0 );
 132                 $res = $dbr->query( $sql, __METHOD__ );
 133                 return $dbr->fetchObject( $res );
 134         }
 135
 136         /* an alternative to $wgExtraRandompageSQL so subclasses
 137          * can add their own SQL by overriding this function
 138          * @deprecated, append to $this->extra instead
 139          */
 140         public function addExtraSQL() {
 141                 return '';
 142         }
 143 }