1 files changed, 233 insertions, 0 deletions
diff --git a/www/wiki/includes/specials/SpecialDoubleRedirects.php b/www/wiki/includes/specials/SpecialDoubleRedirects.php
new file mode 100644
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+++ b/www/wiki/includes/specials/SpecialDoubleRedirects.php
@@ -0,0 +1,233 @@
+<?php
+/**
+ * Implements Special:DoubleRedirects
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+ * http://www.gnu.org/copyleft/gpl.html
+ *
+ * @file
+ * @ingroup SpecialPage
+ */
+
+use Wikimedia\Rdbms\IResultWrapper;
+use Wikimedia\Rdbms\IDatabase;
+
+/**
+ * A special page listing redirects to redirecting page.
+ * The software will automatically not follow double redirects, to prevent loops.
+ *
+ * @ingroup SpecialPage
+ */
+class DoubleRedirectsPage extends QueryPage {
+	function __construct( $name = 'DoubleRedirects' ) {
+		parent::__construct( $name );
+	}
+
+	public function isExpensive() {
+		return true;
+	}
+
+	function isSyndicated() {
+		return false;
+	}
+
+	function sortDescending() {
+		return false;
+	}
+
+	function getPageHeader() {
+		return $this->msg( 'doubleredirectstext' )->parseAsBlock();
+	}
+
+	function reallyGetQueryInfo( $namespace = null, $title = null ) {
+		$limitToTitle = !( $namespace === null && $title === null );
+		$dbr = wfGetDB( DB_REPLICA );
+		$retval = [
+			'tables' => [
+				'ra' => 'redirect',
+				'rb' => 'redirect',
+				'pa' => 'page',
+				'pb' => 'page'
+			],
+			'fields' => [
+				'namespace' => 'pa.page_namespace',
+				'title' => 'pa.page_title',
+				'value' => 'pa.page_title',
+
+				'b_namespace' => 'pb.page_namespace',
+				'b_title' => 'pb.page_title',
+
+				// Select fields from redirect instead of page. Because there may
+				// not actually be a page table row for this target (e.g. for interwiki redirects)
+				'c_namespace' => 'rb.rd_namespace',
+				'c_title' => 'rb.rd_title',
+				'c_fragment' => 'rb.rd_fragment',
+				'c_interwiki' => 'rb.rd_interwiki',
+			],
+			'conds' => [
+				'ra.rd_from = pa.page_id',
+
+				// Filter out redirects where the target goes interwiki (T42353).
+				// This isn't an optimization, it is required for correct results,
+				// otherwise a non-double redirect like Bar -> w:Foo will show up
+				// like "Bar -> Foo -> w:Foo".
+
+				// Need to check both NULL and "" for some reason,
+				// apparently either can be stored for non-iw entries.
+				'ra.rd_interwiki IS NULL OR ra.rd_interwiki = ' . $dbr->addQuotes( '' ),
+
+				'pb.page_namespace = ra.rd_namespace',
+				'pb.page_title = ra.rd_title',
+
+				'rb.rd_from = pb.page_id',
+			]
+		];
+
+		if ( $limitToTitle ) {
+			$retval['conds']['pa.page_namespace'] = $namespace;
+			$retval['conds']['pa.page_title'] = $title;
+		}
+
+		return $retval;
+	}
+
+	public function getQueryInfo() {
+		return $this->reallyGetQueryInfo();
+	}
+
+	function getOrderFields() {
+		return [ 'ra.rd_namespace', 'ra.rd_title' ];
+	}
+
+	/**
+	 * @param Skin $skin
+	 * @param object $result Result row
+	 * @return string
+	 */
+	function formatResult( $skin, $result ) {
+		// If no Title B or C is in the query, it means this came from
+		// querycache (which only saves the 3 columns for title A).
+		// That does save the bulk of the query cost, but now we need to
+		// get a little more detail about each individual entry quickly
+		// using the filter of reallyGetQueryInfo.
+		$deep = false;
+		if ( $result ) {
+			if ( isset( $result->b_namespace ) ) {
+				$deep = $result;
+			} else {
+				$dbr = wfGetDB( DB_REPLICA );
+				$qi = $this->reallyGetQueryInfo(
+					$result->namespace,
+					$result->title
+				);
+				$res = $dbr->select(
+					$qi['tables'],
+					$qi['fields'],
+					$qi['conds'],
+					__METHOD__
+				);
+
+				if ( $res ) {
+					$deep = $dbr->fetchObject( $res ) ?: false;
+				}
+			}
+		}
+
+		$titleA = Title::makeTitle( $result->namespace, $result->title );
+
+		$linkRenderer = $this->getLinkRenderer();
+		if ( !$deep ) {
+			return '<del>' . $linkRenderer->makeLink( $titleA, null, [], [ 'redirect' => 'no' ] ) . '</del>';
+		}
+
+		// if the page is editable, add an edit link
+		if (
+			// check user permissions
+			$this->getUser()->isAllowed( 'edit' ) &&
+			// check, if the content model is editable through action=edit
+			ContentHandler::getForTitle( $titleA )->supportsDirectEditing()
+		) {
+			$edit = $linkRenderer->makeKnownLink(
+				$titleA,
+				$this->msg( 'parentheses', $this->msg( 'editlink' )->text() )->text(),
+				[],
+				[ 'action' => 'edit' ]
+			);
+		} else {
+			$edit = '';
+		}
+
+		$linkA = $linkRenderer->makeKnownLink(
+			$titleA,
+			null,
+			[],
+			[ 'redirect' => 'no' ]
+		);
+
+		$titleB = Title::makeTitle( $deep->b_namespace, $deep->b_title );
+		$linkB = $linkRenderer->makeKnownLink(
+			$titleB,
+			null,
+			[],
+			[ 'redirect' => 'no' ]
+		);
+
+		$titleC = Title::makeTitle(
+			$deep->c_namespace,
+			$deep->c_title,
+			$deep->c_fragment,
+			$deep->c_interwiki
+		);
+		$linkC = $linkRenderer->makeKnownLink( $titleC, $titleC->getFullText() );
+
+		$lang = $this->getLanguage();
+		$arr = $lang->getArrow() . $lang->getDirMark();
+
+		return ( "{$linkA} {$edit} {$arr} {$linkB} {$arr} {$linkC}" );
+	}
+
+	/**
+	 * Cache page content model and gender distinction for performance
+	 *
+	 * @param IDatabase $db
+	 * @param IResultWrapper $res
+	 */
+	function preprocessResults( $db, $res ) {
+		if ( !$res->numRows() ) {
+			return;
+		}
+
+		$batch = new LinkBatch;
+		foreach ( $res as $row ) {
+			$batch->add( $row->namespace, $row->title );
+			if ( isset( $row->b_namespace ) ) {
+				// lazy loaded when using cached results
+				$batch->add( $row->b_namespace, $row->b_title );
+			}
+			if ( isset( $row->c_interwiki ) && !$row->c_interwiki ) {
+				// lazy loaded when using cached result, not added when interwiki link
+				$batch->add( $row->c_namespace, $row->c_title );
+			}
+		}
+		$batch->execute();
+
+		// Back to start for display
+		$res->seek( 0 );
+	}
+
+	protected function getGroupName() {
+		return 'maintenance';
+	}
+}