1 files changed, 100 insertions, 0 deletions
diff --git a/includes/specials/SpecialRandompage.php b/includes/specials/SpecialRandompage.php
new file mode 100644
index 00000000..0e7ada1d
--- /dev/null
+++ b/includes/specials/SpecialRandompage.php
@@ -0,0 +1,100 @@
+<?php
+
+/**
+ * Special page to direct the user to a random page
+ *
+ * @ingroup SpecialPage
+ * @author Rob Church <robchur@gmail.com>, Ilmari Karonen
+ * @license GNU General Public Licence 2.0 or later
+ */
+class RandomPage extends SpecialPage {
+	private $namespace = NS_MAIN;  // namespace to select pages from
+
+	function __construct( $name = 'Randompage' ){
+		parent::__construct( $name );
+	}
+
+	public function getNamespace() {
+		return $this->namespace;
+	}
+
+	public function setNamespace ( $ns ) {
+		if( $ns < NS_MAIN ) $ns = NS_MAIN;
+		$this->namespace = $ns;
+	}
+
+	// select redirects instead of normal pages?
+	// Overriden by SpecialRandomredirect
+	public function isRedirect(){
+		return false;
+	}
+
+	public function execute( $par ) {
+		global $wgOut, $wgContLang;
+
+		if ($par)
+			$this->setNamespace( $wgContLang->getNsIndex( $par ) );
+
+		$title = $this->getRandomTitle();
+
+		if( is_null( $title ) ) {
+			$this->setHeaders();
+			$wgOut->addWikiMsg( strtolower( $this->mName ) . '-nopages' );
+			return;
+		}
+
+		$query = $this->isRedirect() ? 'redirect=no' : '';
+		$wgOut->redirect( $title->getFullUrl( $query ) );
+	}
+
+
+	/**
+	 * Choose a random title.
+	 * @return Title object (or null if nothing to choose from)
+	 */
+	public function getRandomTitle() {
+		$randstr = wfRandom();
+		$row = $this->selectRandomPageFromDB( $randstr );
+
+		/* If we picked a value that was higher than any in
+		 * the DB, wrap around and select the page with the
+		 * lowest value instead!  One might think this would
+		 * skew the distribution, but in fact it won't cause
+		 * any more bias than what the page_random scheme
+		 * causes anyway.  Trust me, I'm a mathematician. :)
+		 */
+		if( !$row )
+			$row = $this->selectRandomPageFromDB( "0" );
+
+		if( $row )
+			return Title::makeTitleSafe( $this->namespace, $row->page_title );
+		else
+			return null;
+	}
+
+	private function selectRandomPageFromDB( $randstr ) {
+		global $wgExtraRandompageSQL;
+		$fname = 'RandomPage::selectRandomPageFromDB';
+
+		$dbr = wfGetDB( DB_SLAVE );
+
+		$use_index = $dbr->useIndexClause( 'page_random' );
+		$page = $dbr->tableName( 'page' );
+
+		$ns = (int) $this->namespace;
+		$redirect = $this->isRedirect() ? 1 : 0;
+
+		$extra = $wgExtraRandompageSQL ? "AND ($wgExtraRandompageSQL)" : "";
+		$sql = "SELECT page_title
+			FROM $page $use_index
+			WHERE page_namespace = $ns
+			AND page_is_redirect = $redirect
+			AND page_random >= $randstr
+			$extra
+			ORDER BY page_random";
+
+		$sql = $dbr->limitResult( $sql, 1, 0 );
+		$res = $dbr->query( $sql, $fname );
+		return $dbr->fetchObject( $res );
+	}
+}