1 files changed, 25 insertions, 13 deletions

diff --git a/includes/specials/SpecialComparePages.php b/includes/specials/SpecialComparePages.php
index 9e3c52b9..fc6b0c58 100644
--- a/includes/specials/SpecialComparePages.php
+++ b/includes/specials/SpecialComparePages.php
@@ -106,31 +106,37 @@ class SpecialComparePages extends SpecialPage {
 		$form->trySubmit();
 	}
 
-	public static function showDiff( $data, HTMLForm $form ){
+	public static function showDiff( $data, HTMLForm $form ) {
 		$rev1 = self::revOrTitle( $data['Revision1'], $data['Page1'] );
 		$rev2 = self::revOrTitle( $data['Revision2'], $data['Page2'] );
 
-		if( $rev1 && $rev2 ) {
-			$de = new DifferenceEngine( $form->getContext(),
-				$rev1,
-				$rev2,
-				null, // rcid
-				( $data['Action'] == 'purge' ),
-				( $data['Unhide'] == '1' )
-			);
-			$de->showDiffPage( true );
+		if ( $rev1 && $rev2 ) {
+			$revision = Revision::newFromId( $rev1 );
+
+			if ( $revision ) { // NOTE: $rev1 was already checked, should exist.
+				$contentHandler = $revision->getContentHandler();
+				$de = $contentHandler->createDifferenceEngine( $form->getContext(),
+					$rev1,
+					$rev2,
+					null, // rcid
+					( $data['Action'] == 'purge' ),
+					( $data['Unhide'] == '1' )
+				);
+				$de->showDiffPage( true );
+			}
 		}
 	}
 
 	public static function revOrTitle( $revision, $title ) {
-		if( $revision ){
+		if ( $revision ) {
 			return $revision;
-		} elseif( $title ) {
+		} elseif ( $title ) {
 			$title = Title::newFromText( $title );
-			if( $title instanceof Title ){
+			if ( $title instanceof Title ) {
 				return $title->getLatestRevID();
 			}
 		}
+
 		return null;
 	}
 
@@ -145,6 +151,7 @@ class SpecialComparePages extends SpecialPage {
 		if ( !$title->exists() ) {
 			return $this->msg( 'compare-title-not-exists' )->parseAsBlock();
 		}
+
 		return true;
 	}
 
@@ -156,6 +163,11 @@ class SpecialComparePages extends SpecialPage {
 		if ( $revision === null ) {
 			return $this->msg( 'compare-revision-not-exists' )->parseAsBlock();
 		}
+
 		return true;
 	}
+
+	protected function getGroupName() {
+		return 'pagetools';
+	}
 }