Big cleanup to DifferenceEngine:
authorAlexandre Emsenhuber <ialex@users.mediawiki.org>
Wed, 5 Oct 2011 19:55:04 +0000 (19:55 +0000)
committerAlexandre Emsenhuber <ialex@users.mediawiki.org>
Wed, 5 Oct 2011 19:55:04 +0000 (19:55 +0000)
* Call Linker methods statically
* Factorised a lot of duplicate code, such as "Mark patrolled" links, revisions headers, etc.
* Removed showFirstRevision() and made that case be handled through the normal showDiffPage(). In such case, the header will look like a normal diff page, except it is centred. For this, addHeader() will now center the "new revision" header if the string passed to the "old revision" header and the diff is empty. getDiffBody() will also return an empty string if $mOldRev is false.
* Showing only one revision when the previous was not found will also ask to unhide the revision is deleted as in normal case
* Backed out code that generates the revision header from loadRevisionData() so that this function does not make a mix of backend and UI stuff. Factorised the code in getRevisionHeader().
* Lazy-load page's language and revisions IDs (in case of "prev", "next", etc. are passed) instead of doing that in constructor.
* Made a good part of links compatible with Special:ComparePages, such as navigation links, "undo", etc. that links to the title corresponding to the revision and not the given title in the constuctor.
* "Current revision as of" can also be displayed on the old revision, useful when comparing two current revisions in Special:ComparePages
* Removed navigation, undo and rollback links when comparing two different pages, this can confuses users thinking they are comparing two revisions of the same page. Also clicking on a "undo" link in such case will give "revision not found".
* Check if the user can read the revisions before sending a external editor file

includes/diff/DifferenceEngine.php

index 841a1e0..b03caff 100644 (file)
@@ -23,7 +23,6 @@ class DifferenceEngine {
         * @private
         */
        var $mOldid, $mNewid;
-       var $mOldtitle, $mNewtitle, $mPagetitle;
        var $mOldtext, $mNewtext;
        protected $mDiffLang;
 
@@ -37,6 +36,7 @@ class DifferenceEngine {
         * @var Revision
         */
        var $mOldRev, $mNewRev;
+       private $mRevisionsIdsLoaded = false; // Have the revisions IDs been loaded
        var $mRevisionsLoaded = false; // Have the revisions been loaded
        var $mTextLoaded = 0; // How many text blobs have been loaded, 0, 1 or 2?
        var $mCacheHit = false; // Was the diff fetched from cache?
@@ -52,6 +52,9 @@ class DifferenceEngine {
        // readability and conserve space with many small diffs.
        protected $mReducedLineNumbers = false;
 
+       // Link to action=markpatrolled
+       protected $mMarkPatrolledLink = null;
+
        protected $unhide = false; # show rev_deleted content if allowed
        /**#@-*/
 
@@ -75,29 +78,8 @@ class DifferenceEngine {
                }
                wfDebug( "DifferenceEngine old '$old' new '$new' rcid '$rcid'\n" );
 
-               # Default language in which the diff text is written.
-               $this->mDiffLang = $this->mTitle->getPageLanguage();
-
-               if ( 'prev' === $new ) {
-                       # Show diff between revision $old and the previous one.
-                       # Get previous one from DB.
-                       $this->mNewid = intval( $old );
-                       $this->mOldid = $this->mTitle->getPreviousRevisionID( $this->mNewid );
-               } elseif ( 'next' === $new ) {
-                       # Show diff between revision $old and the next one.
-                       # Get next one from DB.
-                       $this->mOldid = intval( $old );
-                       $this->mNewid = $this->mTitle->getNextRevisionID( $this->mOldid );
-                       if ( false === $this->mNewid ) {
-                               # if no result, NewId points to the newest old revision. The only newer
-                               # revision is cur, which is "0".
-                               $this->mNewid = 0;
-                       }
-               } else {
-                       $this->mOldid = intval( $old );
-                       $this->mNewid = intval( $new );
-                       wfRunHooks( 'NewDifferenceEngine', array( &$titleObj, &$this->mOldid, &$this->mNewid, $old, $new ) );
-               }
+               $this->mOldid = $old;
+               $this->mNewid = $new;
                $this->mRcidMarkPatrolled = intval( $rcid );  # force it to be an integer
                $this->mRefreshCache = $refreshCache;
                $this->unhide = $unhide;
@@ -110,6 +92,17 @@ class DifferenceEngine {
                $this->mReducedLineNumbers = $value;
        }
 
+       /**
+        * @return Language
+        */
+       function getDiffLang() {
+               if ( $this->mDiffLang === null ) {
+                       # Default language in which the diff text is written.
+                       $this->mDiffLang = $this->mTitle->getPageLanguage();
+               }
+               return $this->mDiffLang;
+       }
+
        /**
         * @return Title
         */
@@ -128,6 +121,7 @@ class DifferenceEngine {
         * @return int
         */
        function getOldid() {
+               $this->loadRevisionIds();
                return $this->mOldid;
        }
 
@@ -135,6 +129,7 @@ class DifferenceEngine {
         * @return Bool|int
         */
        function getNewid() {
+               $this->loadRevisionIds();
                return $this->mNewid;
        }
 
@@ -180,11 +175,33 @@ class DifferenceEngine {
        }
 
        function showDiffPage( $diffOnly = false ) {
-               global $wgUser, $wgOut, $wgUseExternalEditor, $wgUseRCPatrol;
+               global $wgUser, $wgOut, $wgRequest, $wgUseExternalEditor, $wgUseRCPatrol;
                wfProfileIn( __METHOD__ );
 
                # Allow frames except in certain special cases
                $wgOut->allowClickjacking();
+               $wgOut->setRobotPolicy( 'noindex,nofollow' );
+
+               if ( !$this->loadRevisionData() ) {
+                       // Sounds like a deleted revision... Let's see what we can do.
+                       $t = $this->mTitle->getPrefixedText();
+                       $d = wfMsgExt( 'missingarticle-diff', array( 'escape' ),
+                               $this->deletedIdMarker( $this->mOldid ),
+                               $this->deletedIdMarker( $this->mNewid ) );
+                       $wgOut->setPagetitle( wfMsg( 'errorpagetitle' ) );
+                       $wgOut->addWikiMsg( 'missing-article', "<nowiki>$t</nowiki>", "<span class='plainlinks'>$d</span>" );
+                       wfProfileOut( __METHOD__ );
+                       return;
+               }
+
+               # mOldPage might not be set, see below.
+               if ( !$this->mNewPage->userCanRead() || ( $this->mOldPage && !$this->mOldPage->userCanRead() ) ) {
+                       $wgOut->loginToUse();
+                       $wgOut->output();
+                       $wgOut->disable();
+                       wfProfileOut( __METHOD__ );
+                       return;
+               }
 
                # If external diffs are enabled both globally and for the user,
                # we'll use the application/x-external-editor interface to call
@@ -193,11 +210,12 @@ class DifferenceEngine {
                        global $wgCanonicalServer, $wgScript, $wgLang;
                        $wgOut->disable();
                        header ( "Content-type: application/x-external-editor; charset=UTF-8" );
-                       $url1 = $this->mTitle->getCanonical( array(
+                       # This should be mOldPage, but it may not be set, see below.
+                       $url1 = $this->mNewPage->getCanonicalURL( array(
                                'action' => 'raw',
                                'oldid' => $this->mOldid
                        ) );
-                       $url2 = $this->mTitle->getCanonical( array(
+                       $url2 = $this->mNewPage->getCanonicalURL( array(
                                'action' => 'raw',
                                'oldid' => $this->mNewid
                        ) );
@@ -223,213 +241,142 @@ CONTROL;
                        return;
                }
 
-               if ( !$this->loadRevisionData() ) {
-                       // Sounds like a deleted revision... Let's see what we can do.
-                       $t = $this->mTitle->getPrefixedText();
-                       $d = wfMsgExt( 'missingarticle-diff', array( 'escape' ),
-                               $this->deletedIdMarker( $this->mOldid ),
-                               $this->deletedIdMarker( $this->mNewid ) );
-                       $wgOut->setPagetitle( wfMsg( 'errorpagetitle' ) );
-                       $wgOut->addWikiMsg( 'missing-article', "<nowiki>$t</nowiki>", "<span class='plainlinks'>$d</span>" );
-                       wfProfileOut( __METHOD__ );
-                       return;
+               $rollback = '';
+               $undoLink = '';
+
+               $query = array();
+               # Carry over 'diffonly' param via navigation links
+               if ( $diffOnly != $wgUser->getBoolOption( 'diffonly' ) ) {
+                       $query['diffonly'] = $diffOnly;
+               }
+               # Cascade unhide param in links for easy deletion browsing
+               if ( $this->unhide ) {
+                       $query['unhide'] = 1;
                }
 
-               wfRunHooks( 'DiffViewHeader', array( $this, $this->mOldRev, $this->mNewRev ) );
+               # Check if one of the revisions is deleted/suppressed
+               $deleted = $suppressed = false;
+               $allowed = $this->mNewRev->userCan( Revision::DELETED_TEXT );
 
-               # mOldid is false if the difference engine is called with a "vague" query for
+               # mOldRev is false if the difference engine is called with a "vague" query for
                # a diff between a version V and its previous version V' AND the version V
                # is the first version of that article. In that case, V' does not exist.
-               if ( $this->mOldid === false ) {
-                       $this->showFirstRevision();
-                       $this->renderNewRevision();  // should we respect $diffOnly here or not?
-                       wfProfileOut( __METHOD__ );
-                       return;
-               }
+               if ( $this->mOldRev === false ) {
+                       wfRunHooks( 'DiffViewHeader', array( $this, $this->mOldRev, $this->mNewRev ) );
 
-               $oldTitle = $this->mOldPage->getPrefixedText();
-               $newTitle = $this->mNewPage->getPrefixedText();
-               if ( $oldTitle == $newTitle ) {
-                       $wgOut->setPageTitle( $newTitle );
-               } else {
-                       $wgOut->setPageTitle( $oldTitle . ', ' . $newTitle );
-               }
-               if ( $this->mNewPage->equals( $this->mOldPage ) ) {
+                       $sk = $wgUser->getSkin();
+                       if ( method_exists( $sk, 'suppressQuickbar' ) ) {
+                               $sk->suppressQuickbar();
+                       }
+
+                       $wgOut->setPageTitle( $this->mNewPage->getPrefixedText() );
                        $wgOut->setSubtitle( wfMsgExt( 'difference', array( 'parseinline' ) ) );
+                       $samePage = true;
+                       $oldHeader = '';
                } else {
-                       $wgOut->setSubtitle( wfMsgExt( 'difference-multipage', array( 'parseinline' ) ) );
-               }
-               $wgOut->setRobotPolicy( 'noindex,nofollow' );
-
-               if ( !$this->mOldPage->userCanRead() || !$this->mNewPage->userCanRead() ) {
-                       $wgOut->loginToUse();
-                       $wgOut->output();
-                       $wgOut->disable();
-                       wfProfileOut( __METHOD__ );
-                       return;
-               }
-
-               $sk = $wgUser->getSkin();
-               if ( method_exists( $sk, 'suppressQuickbar' ) ) {
-                       $sk->suppressQuickbar();
-               }
+                       if ( $this->mNewPage->equals( $this->mOldPage ) ) {
+                               $wgOut->setPageTitle( $this->mNewPage->getPrefixedText() );
+                               $wgOut->setSubtitle( wfMsgExt( 'difference', array( 'parseinline' ) ) );
+                               $samePage = true;
+                       } else {
+                               $wgOut->setPageTitle( $this->mOldPage->getPrefixedText() . ', ' . $this->mNewPage->getPrefixedText() );
+                               $wgOut->setSubtitle( wfMsgExt( 'difference-multipage', array( 'parseinline' ) ) );
+                               $samePage = false;
+                       }
 
-               // Check if page is editable
-               $editable = $this->mNewRev->getTitle()->userCan( 'edit' );
-               if ( $editable && $this->mNewRev->isCurrent() && $wgUser->isAllowed( 'rollback' ) ) {
-                       $wgOut->preventClickjacking();
-                       $rollback = '&#160;&#160;&#160;' . $sk->generateRollback( $this->mNewRev );
-               } else {
-                       $rollback = '';
-               }
+                       if ( $samePage && $this->mNewPage->userCan( 'edit' ) ) {
+                               if ( $this->mNewRev->isCurrent() && $this->mNewPage->userCan( 'rollback' ) ) {
+                                       $wgOut->preventClickjacking();
+                                       $rollback = '&#160;&#160;&#160;' . Linker::generateRollback( $this->mNewRev );
+                               }
+                               if ( !$this->mOldRev->isDeleted( Revision::DELETED_TEXT ) && !$this->mNewRev->isDeleted( Revision::DELETED_TEXT ) ) {
+                                       $undoLink = ' ' . wfMsgHtml( 'parentheses', Html::element( 'a', array(
+                                               'href' => $this->mNewPage->getLocalUrl( array(
+                                                       'action' => 'edit',
+                                                       'undoafter' => $this->mOldid,
+                                                       'undo' => $this->mNewid ) ),
+                                               'title' => Linker::titleAttrib( 'undo' )
+                                       ), wfMsg( 'editundo' ) ) );
+                               }
+                       }
 
-               // Prepare a change patrol link, if applicable
-               if ( $wgUseRCPatrol && $this->mTitle->userCan( 'patrol' ) ) {
-                       // If we've been given an explicit change identifier, use it; saves time
-                       if ( $this->mRcidMarkPatrolled ) {
-                               $rcid = $this->mRcidMarkPatrolled;
-                               $rc = RecentChange::newFromId( $rcid );
-                               // Already patrolled?
-                               $rcid = is_object( $rc ) && !$rc->getAttribute( 'rc_patrolled' ) ? $rcid : 0;
-                       } else {
-                               // Look for an unpatrolled change corresponding to this diff
-                               $db = wfGetDB( DB_SLAVE );
-                               $change = RecentChange::newFromConds(
-                                       array(
-                                       // Redundant user,timestamp condition so we can use the existing index
-                                               'rc_user_text'  => $this->mNewRev->getRawUserText(),
-                                               'rc_timestamp'  => $db->timestamp( $this->mNewRev->getTimestamp() ),
-                                               'rc_this_oldid' => $this->mNewid,
-                                               'rc_last_oldid' => $this->mOldid,
-                                               'rc_patrolled'  => 0
-                                       ),
-                                       __METHOD__
+                       # Make "previous revision link"
+                       if ( $samePage && $this->mOldRev->getPrevious() ) {
+                               $prevlink = Linker::linkKnown(
+                                       $this->mOldPage,
+                                       wfMsgHtml( 'previousdiff' ),
+                                       array( 'id' => 'differences-prevlink' ),
+                                       array( 'diff' => 'prev', 'oldid' => $this->mOldid ) + $query
                                );
-                               if ( $change instanceof RecentChange ) {
-                                       $rcid = $change->mAttribs['rc_id'];
-                                       $this->mRcidMarkPatrolled = $rcid;
-                               } else {
-                                       // None found
-                                       $rcid = 0;
-                               }
+                       } else {
+                               $prevlink = '&#160;';
                        }
-                       // Build the link
-                       if ( $rcid ) {
-                               $wgOut->preventClickjacking();
-                               $token = $wgUser->editToken( $rcid );
-                               $patrol = ' <span class="patrollink">[' . $sk->link(
-                                       $this->mTitle,
-                                       wfMsgHtml( 'markaspatrolleddiff' ),
-                                       array(),
-                                       array(
-                                               'action' => 'markpatrolled',
-                                               'rcid' => $rcid,
-                                               'token' => $token,
-                                       ),
-                                       array(
-                                               'known',
-                                               'noclasses'
-                                       )
-                               ) . ']</span>';
+
+                       if ( $this->mOldRev->isMinor() ) {
+                               $oldminor = ChangesList::flag( 'minor' );
                        } else {
-                               $patrol = '';
+                               $oldminor = '';
                        }
-               } else {
-                       $patrol = '';
-               }
 
-               # Carry over 'diffonly' param via navigation links
-               if ( $diffOnly != $wgUser->getBoolOption( 'diffonly' ) ) {
-                       $query['diffonly'] = $diffOnly;
-               }
+                       $ldel = $this->revisionDeleteLink( $this->mOldRev );
+                       $oldRevisionHeader = $this->getRevisionHeader( $this->mOldRev, 'complete' );
 
-               # Make "previous revision link"
-               $query['diff'] = 'prev';
-               $query['oldid'] = $this->mOldid;
-               # Cascade unhide param in links for easy deletion browsing
-               if ( $this->unhide ) {
-                       $query['unhide'] = 1;
-               }
-               if ( !$this->mOldRev->getPrevious() ) {
-                       $prevlink = '&#160;';
-               } else {
-                       $prevlink = $sk->link(
-                               $this->mTitle,
-                               wfMsgHtml( 'previousdiff' ),
-                               array(
-                                       'id' => 'differences-prevlink'
-                               ),
-                               $query,
-                               array(
-                                       'known',
-                                       'noclasses'
-                               )
-                       );
+                       $oldHeader = '<div id="mw-diff-otitle1"><strong>' . $oldRevisionHeader . '</strong></div>' .
+                               '<div id="mw-diff-otitle2">' .
+                                       Linker::revUserTools( $this->mOldRev, !$this->unhide ) . '</div>' .
+                               '<div id="mw-diff-otitle3">' . $oldminor .
+                                       Linker::revComment( $this->mOldRev, !$diffOnly, !$this->unhide ) . $ldel . '</div>' .
+                               '<div id="mw-diff-otitle4">' . $prevlink . '</div>';
+
+                       if ( $this->mOldRev->isDeleted( Revision::DELETED_TEXT ) ) {
+                               $deleted = true; // old revisions text is hidden
+                               if ( $this->mOldRev->isDeleted( Revision::DELETED_RESTRICTED ) ) {
+                                       $suppressed = true; // also suppressed
+                               }
+                       }
+
+                       # Check if this user can see the revisions
+                       if ( !$this->mOldRev->userCan( Revision::DELETED_TEXT ) ) {
+                               $allowed = false;
+                       }
                }
 
                # Make "next revision link"
-               $query['diff'] = 'next';
-               $query['oldid'] = $this->mNewid;
                # Skip next link on the top revision
-               if ( $this->mNewRev->isCurrent() ) {
-                       $nextlink = '&#160;';
-               } else {
-                       $nextlink = $sk->link(
-                               $this->mTitle,
+               if ( $samePage && !$this->mNewRev->isCurrent() ) {
+                       $nextlink = Linker::linkKnown(
+                               $this->mNewPage,
                                wfMsgHtml( 'nextdiff' ),
-                               array(
-                                       'id' => 'differences-nextlink'
-                               ),
-                               $query,
-                               array(
-                                       'known',
-                                       'noclasses'
-                               )
+                               array( 'id' => 'differences-nextlink' ),
+                               array( 'diff' => 'next', 'oldid' => $this->mNewid ) + $query
                        );
+               } else {
+                       $nextlink = '&#160;';
                }
 
-               $oldminor = '';
-               $newminor = '';
-
-               if ( $this->mOldRev->isMinor() ) {
-                       $oldminor = ChangesList::flag( 'minor' );
-               }
                if ( $this->mNewRev->isMinor() ) {
                        $newminor = ChangesList::flag( 'minor' );
+               } else {
+                       $newminor = '';
                }
 
                # Handle RevisionDelete links...
-               $ldel = $this->revisionDeleteLink( $this->mOldRev );
                $rdel = $this->revisionDeleteLink( $this->mNewRev );
+               $newRevisionHeader = $this->getRevisionHeader( $this->mNewRev, 'complete' ) . $undoLink;
 
-               $oldHeader = '<div id="mw-diff-otitle1"><strong>' . $this->mOldtitle . '</strong></div>' .
-                       '<div id="mw-diff-otitle2">' .
-                               $sk->revUserTools( $this->mOldRev, !$this->unhide ) . '</div>' .
-                       '<div id="mw-diff-otitle3">' . $oldminor .
-                               $sk->revComment( $this->mOldRev, !$diffOnly, !$this->unhide ) . $ldel . '</div>' .
-                       '<div id="mw-diff-otitle4">' . $prevlink . '</div>';
-               $newHeader = '<div id="mw-diff-ntitle1"><strong>' . $this->mNewtitle . '</strong></div>' .
-                       '<div id="mw-diff-ntitle2">' . $sk->revUserTools( $this->mNewRev, !$this->unhide ) .
+               $newHeader = '<div id="mw-diff-ntitle1"><strong>' . $newRevisionHeader . '</strong></div>' .
+                       '<div id="mw-diff-ntitle2">' . Linker::revUserTools( $this->mNewRev, !$this->unhide ) .
                                " $rollback</div>" .
                        '<div id="mw-diff-ntitle3">' . $newminor .
-                               $sk->revComment( $this->mNewRev, !$diffOnly, !$this->unhide ) . $rdel . '</div>' .
-                       '<div id="mw-diff-ntitle4">' . $nextlink . $patrol . '</div>';
+                               Linker::revComment( $this->mNewRev, !$diffOnly, !$this->unhide ) . $rdel . '</div>' .
+                       '<div id="mw-diff-ntitle4">' . $nextlink . $this->markPatrolledLink() . '</div>';
 
-               # Check if this user can see the revisions
-               $allowed = $this->mOldRev->userCan( Revision::DELETED_TEXT )
-                       && $this->mNewRev->userCan( Revision::DELETED_TEXT );
-               # Check if one of the revisions is deleted/suppressed
-               $deleted = $suppressed = false;
-               if ( $this->mOldRev->isDeleted( Revision::DELETED_TEXT ) ) {
-                       $deleted = true; // old revisions text is hidden
-                       if ( $this->mOldRev->isDeleted( Revision::DELETED_RESTRICTED ) )
-                               $suppressed = true; // also suppressed
-               }
                if ( $this->mNewRev->isDeleted( Revision::DELETED_TEXT ) ) {
                        $deleted = true; // new revisions text is hidden
                        if ( $this->mNewRev->isDeleted( Revision::DELETED_RESTRICTED ) )
                                $suppressed = true; // also suppressed
                }
+
                # If the diff cannot be shown due to a deleted revision, then output
                # the diff header and links to unhide (if available)...
                if ( $deleted && ( !$this->unhide || !$allowed ) ) {
@@ -443,11 +390,7 @@ CONTROL;
                                        array( $msg ) );
                        } else {
                                # Give explanation and add a link to view the diff...
-                               $link = $this->mTitle->getFullUrl( array(
-                                       'diff' => $this->mNewid,
-                                       'oldid' => $this->mOldid,
-                                       'unhide' => 1
-                               ) );
+                               $link = $this->mTitle->getFullUrl( $wgRequest->appendQueryValue( 'unhide', '1', true ) );
                                $msg = $suppressed ? 'rev-suppressed-unhide-diff' : 'rev-deleted-unhide-diff';
                                $wgOut->wrapWikiMsg( "<div id='mw-$msg' class='mw-warning plainlinks'>\n$1\n</div>\n", array( $msg, $link ) );
                        }
@@ -467,6 +410,73 @@ CONTROL;
                wfProfileOut( __METHOD__ );
        }
 
+       /**
+        * Get a link to mark the change as patrolled, or '' if there's either no
+        * revision to patrol or the user is not allowed to to it.
+        * Side effect: this method will call OutputPage::preventClickjacking()
+        * when a link is builded.
+        *
+        * @return String
+        */
+       protected function markPatrolledLink() {
+               global $wgUseRCPatrol, $wgUser, $wgOut;
+
+               if ( $this->mMarkPatrolledLink === null ) {
+                       // Prepare a change patrol link, if applicable
+                       if ( $wgUseRCPatrol && $this->mNewPage->userCan( 'patrol' ) ) {
+                               // If we've been given an explicit change identifier, use it; saves time
+                               if ( $this->mRcidMarkPatrolled ) {
+                                       $rcid = $this->mRcidMarkPatrolled;
+                                       $rc = RecentChange::newFromId( $rcid );
+                                       // Already patrolled?
+                                       $rcid = is_object( $rc ) && !$rc->getAttribute( 'rc_patrolled' ) ? $rcid : 0;
+                               } else {
+                                       // Look for an unpatrolled change corresponding to this diff
+                                       $db = wfGetDB( DB_SLAVE );
+                                       $change = RecentChange::newFromConds(
+                                               array(
+                                               // Redundant user,timestamp condition so we can use the existing index
+                                                       'rc_user_text'  => $this->mNewRev->getRawUserText(),
+                                                       'rc_timestamp'  => $db->timestamp( $this->mNewRev->getTimestamp() ),
+                                                       'rc_this_oldid' => $this->mNewid,
+                                                       'rc_last_oldid' => $this->mOldid,
+                                                       'rc_patrolled'  => 0
+                                               ),
+                                               __METHOD__
+                                       );
+                                       if ( $change instanceof RecentChange ) {
+                                               $rcid = $change->mAttribs['rc_id'];
+                                               $this->mRcidMarkPatrolled = $rcid;
+                                       } else {
+                                               // None found
+                                               $rcid = 0;
+                                       }
+                               }
+                               // Build the link
+                               if ( $rcid ) {
+                                       $wgOut->preventClickjacking();
+                                       $token = $wgUser->editToken( $rcid );
+                                       $this->mMarkPatrolledLink = ' <span class="patrollink">[' . Linker::linkKnown(
+                                               $this->mNewPage,
+                                               wfMsgHtml( 'markaspatrolleddiff' ),
+                                               array(),
+                                               array(
+                                                       'action' => 'markpatrolled',
+                                                       'rcid' => $rcid,
+                                                       'token' => $token,
+                                               )
+                                       ) . ']</span>';
+                               } else {
+                                       $this->mMarkPatrolledLink = '';
+                               }
+                       } else {
+                               $this->mMarkPatrolledLink = '';
+                       }
+               }
+
+               return $this->mMarkPatrolledLink;
+       }
+
        /**
         * @param $rev Revision
         * @return String
@@ -479,16 +489,15 @@ CONTROL;
                // (a) the user can delete revisions, or
                // (b) the user can view deleted revision *and* this one is deleted
                if ( $canHide || ( $rev->getVisibility() && $wgUser->isAllowed( 'deletedhistory' ) ) ) {
-                       $sk = $wgUser->getSkin();
                        if ( !$rev->userCan( Revision::DELETED_RESTRICTED ) ) {
-                               $link = $sk->revDeleteLinkDisabled( $canHide ); // revision was hidden from sysops
+                               $link = Linker::revDeleteLinkDisabled( $canHide ); // revision was hidden from sysops
                        } else {
                                $query = array(
                                        'type'   => 'revision',
-                                       'target' => $rev->mTitle->getPrefixedDbkey(),
+                                       'target' => $rev->getTitle()->getPrefixedDBkey(),
                                        'ids'    => $rev->getId()
                                );
-                               $link = $sk->revDeleteLink( $query,
+                               $link = Linker::revDeleteLink( $query,
                                        $rev->isDeleted( Revision::DELETED_RESTRICTED ), $canHide );
                        }
                        $link = '&#160;&#160;&#160;' . $link . ' ';
@@ -502,9 +511,10 @@ CONTROL;
        function renderNewRevision() {
                global $wgOut, $wgUser;
                wfProfileIn( __METHOD__ );
+               $revHeader = $this->getRevisionHeader( $this->mNewRev );
                # Add "current version as of X" title
                $wgOut->addHTML( "<hr class='diff-hr' />
-               <h2 class='diff-currentversion-title'>{$this->mPagetitle}</h2>\n" );
+               <h2 class='diff-currentversion-title'>{$revHeader}</h2>\n" );
                # Page content may be handled by a hooked call instead...
                if ( wfRunHooks( 'ArticleContentOnDiff', array( $this, $wgOut ) ) ) {
                        # Use the current version parser cache if applicable
@@ -518,20 +528,20 @@ CONTROL;
                        $wgOut->setRevisionId( $this->mNewRev->getId() );
                        $wgOut->setArticleFlag( true );
 
-                       if ( $this->mTitle->isCssJsSubpage() || $this->mTitle->isCssOrJsPage() ) {
+                       if ( $this->mNewPage->isCssJsSubpage() || $this->mNewPage->isCssOrJsPage() ) {
                                // Stolen from Article::view --AG 2007-10-11
                                // Give hooks a chance to customise the output
                                // @TODO: standardize this crap into one function
-                               if ( wfRunHooks( 'ShowRawCssJs', array( $this->mNewtext, $this->mTitle, $wgOut ) ) ) {
+                               if ( wfRunHooks( 'ShowRawCssJs', array( $this->mNewtext, $this->mNewPage, $wgOut ) ) ) {
                                        // Wrap the whole lot in a <pre> and don't parse
                                        $m = array();
-                                       preg_match( '!\.(css|js)$!u', $this->mTitle->getText(), $m );
+                                       preg_match( '!\.(css|js)$!u', $this->mNewPage->getText(), $m );
                                        $wgOut->addHTML( "<pre class=\"mw-code mw-{$m[1]}\" dir=\"ltr\">\n" );
                                        $wgOut->addHTML( htmlspecialchars( $this->mNewtext ) );
                                        $wgOut->addHTML( "\n</pre>\n" );
                                }
                        } elseif ( $pCache ) {
-                               $article = new Article( $this->mTitle, 0 );
+                               $article = new Article( $this->mNewPage, 0 );
                                $pOutput = ParserCache::singleton()->get( $article, $wgOut->parserOptions() );
                                if( $pOutput ) {
                                        $wgOut->addParserOutput( $pOutput );
@@ -547,87 +557,7 @@ CONTROL;
                        }
                }
                # Add redundant patrol link on bottom...
-               if ( $this->mRcidMarkPatrolled && $this->mTitle->quickUserCan( 'patrol' ) ) {
-                       $sk = $wgUser->getSkin();
-                       $token = $wgUser->editToken( $this->mRcidMarkPatrolled );
-                       $wgOut->preventClickjacking();
-                       $wgOut->addHTML(
-                               "<div class='patrollink'>[" . $sk->link(
-                                       $this->mTitle,
-                                       wfMsgHtml( 'markaspatrolleddiff' ),
-                                       array(),
-                                       array(
-                                               'action'        => 'markpatrolled',
-                                               'rcid'          => $this->mRcidMarkPatrolled,
-                                               'token'         => $token,
-                                       )
-                               ) . ']</div>'
-                        );
-               }
-
-               wfProfileOut( __METHOD__ );
-       }
-
-       /**
-        * Show the first revision of an article. Uses normal diff headers in
-        * contrast to normal "old revision" display style.
-        */
-       function showFirstRevision() {
-               global $wgOut, $wgUser;
-               wfProfileIn( __METHOD__ );
-
-               # Get article text from the DB
-               #
-               if ( ! $this->loadNewText() ) {
-                       $t = $this->mTitle->getPrefixedText();
-                       $d = wfMsgExt( 'missingarticle-diff', array( 'escape' ),
-                                       $this->deletedIdMarker( $this->mOldid ),
-                                       $this->deletedIdMarker( $this->mNewid ) );
-                       $wgOut->setPagetitle( wfMsg( 'errorpagetitle' ) );
-                       $wgOut->addWikiMsg( 'missing-article', "<nowiki>$t</nowiki>", "<span class='plainlinks'>$d</span>" );
-                       wfProfileOut( __METHOD__ );
-                       return;
-               }
-
-               # Check if user is allowed to look at this page. If not, bail out.
-               if ( !$this->mTitle->userCanRead() ) {
-                       $wgOut->loginToUse();
-                       $wgOut->output();
-                       wfProfileOut( __METHOD__ );
-                       throw new MWException( "Permission Error: you do not have access to view this page" );
-               }
-
-               # Prepare the header box
-               #
-               $sk = $wgUser->getSkin();
-
-               $next = $this->mTitle->getNextRevisionID( $this->mNewid );
-               if ( !$next ) {
-                       $nextlink = '';
-               } else {
-                       $nextlink = '<br />' . $sk->link(
-                               $this->mTitle,
-                               wfMsgHtml( 'nextdiff' ),
-                               array(
-                                       'id' => 'differences-nextlink'
-                               ),
-                               array(
-                                       'diff' => 'next',
-                                       'oldid' => $this->mNewid,
-                               ),
-                               array(
-                                       'known',
-                                       'noclasses'
-                               )
-                       );
-               }
-               $header = "<div class=\"firstrevisionheader\" style=\"text-align: center\">" .
-                       $sk->revUserTools( $this->mNewRev ) . "<br />" . $sk->revComment( $this->mNewRev ) . $nextlink . "</div>\n";
-
-               $wgOut->addHTML( $header );
-
-               $wgOut->setSubtitle( wfMsgExt( 'difference', array( 'parseinline' ) ) );
-               $wgOut->setRobotPolicy( 'noindex,nofollow' );
+               $wgOut->addHTML( $this->markPatrolledLink() );
 
                wfProfileOut( __METHOD__ );
        }
@@ -698,8 +628,9 @@ CONTROL;
                        return false;
                }
                // Short-circuit
-               if ( $this->mOldRev && $this->mNewRev
-                       && $this->mOldRev->getID() == $this->mNewRev->getID() )
+               // If mOldRev is false, it means that the 
+               if ( $this->mOldRev === false || ( $this->mOldRev && $this->mNewRev
+                       && $this->mOldRev->getID() == $this->mNewRev->getID() ) )
                {
                        wfProfileOut( __METHOD__ );
                        return '';
@@ -900,10 +831,10 @@ CONTROL;
                        $newRev = $this->mNewRev;
                }
 
-               $nEdits = $this->mTitle->countRevisionsBetween( $oldRev, $newRev );
+               $nEdits = $this->mNewPage->countRevisionsBetween( $oldRev, $newRev );
                if ( $nEdits > 0 ) {
                        $limit = 100; // use diff-multi-manyusers if too many users
-                       $numUsers = $this->mTitle->countAuthorsBetween( $oldRev, $newRev, $limit );
+                       $numUsers = $this->mNewPage->countAuthorsBetween( $oldRev, $newRev, $limit );
                        return self::intermediateEditsMsg( $nEdits, $numUsers, $limit );
                }
                return ''; // nothing
@@ -928,6 +859,56 @@ CONTROL;
                        $wgLang->formatnum( $numEdits ), $wgLang->formatnum( $numUsers ) );
        }
 
+       /**
+        * Get a header for a specified revision.
+        *
+        * @param $rev Revision
+        * @param $complete String: 'complete' to get the header wrapped depending
+        *        the visibility of the revision and a link to edit the page.
+        * @return String HTML fragment
+        */
+       private function getRevisionHeader( Revision $rev, $complete = '' ) {
+               global $wgLang;
+
+               $revtimestamp = $rev->getTimestamp();
+               $timestamp = $wgLang->timeanddate( $revtimestamp, true );
+               $dateofrev = $wgLang->date( $revtimestamp, true );
+               $timeofrev = $wgLang->time( $revtimestamp, true );
+
+               $header = htmlspecialchars( wfMsg(
+                       $rev->isCurrent() ? 'currentrev-asof' : 'revisionasof',
+                       $timestamp,
+                       $dateofrev,
+                       $timeofrev
+               ) );
+
+               if ( $complete !== 'complete' ) {
+                       return $header;
+               }
+
+               $title = $rev->getTitle();
+
+               $header = Linker::linkKnown( $title, $header, array(),
+                       array( 'oldid' => $rev->getID() ) );
+
+               if ( $rev->userCan( Revision::DELETED_TEXT ) ) {
+                       $editQuery = array( 'action' => 'edit' );
+                       if ( !$rev->isCurrent() ) {
+                               $editQuery['oldid'] = $rev->getID();
+                       }
+
+                       $msg = wfMsgHtml( $title->userCan( 'edit' ) ? 'editold' : 'viewsourceold' );
+                       $header .= ' (' . Linker::linkKnown( $title, $msg, array(), $editQuery ) . ')';
+                       if ( $rev->isDeleted( Revision::DELETED_TEXT ) ) {
+                               $header = Html::rawElement( 'span', array( 'class' => 'history-deleted' ), $header );
+                       }
+               } else {
+                       $header = Html::rawElement( 'span', array( 'class' => 'history-deleted' ), $header );
+               }
+
+               return $header;
+       }
+
        /**
         * Add the header to a diff body
         *
@@ -936,25 +917,34 @@ CONTROL;
        function addHeader( $diff, $otitle, $ntitle, $multi = '', $notice = '' ) {
                // shared.css sets diff in interface language/dir, but the actual content
                // is often in a different language, mostly the page content language/dir
-               $tableClass = 'diff diff-contentalign-' . htmlspecialchars( $this->mDiffLang->alignStart() );
+               $tableClass = 'diff diff-contentalign-' . htmlspecialchars( $this->getDiffLang()->alignStart() );
                $header = "<table class='$tableClass'>";
-               if ( $diff ) { // Safari/Chrome show broken output if cols not used
+
+               if ( !$diff && !$otitle ) {
                        $header .= "
-                       <col class='diff-marker' />
-                       <col class='diff-content' />
-                       <col class='diff-marker' />
-                       <col class='diff-content' />";
-                       $colspan = 2;
-                       $multiColspan = 4;
+                       <tr valign='top'>
+                       <td class='diff-ntitle'>{$ntitle}</td>
+                       </tr>";
+                       $multiColspan = 1;
                } else {
-                       $colspan = 1;
-                       $multiColspan = 2;
+                       if ( $diff ) { // Safari/Chrome show broken output if cols not used
+                               $header .= "
+                               <col class='diff-marker' />
+                               <col class='diff-content' />
+                               <col class='diff-marker' />
+                               <col class='diff-content' />";
+                               $colspan = 2;
+                               $multiColspan = 4;
+                       } else {
+                               $colspan = 1;
+                               $multiColspan = 2;
+                       }
+                       $header .= "
+                       <tr valign='top'>
+                       <td colspan='$colspan' class='diff-otitle'>{$otitle}</td>
+                       <td colspan='$colspan' class='diff-ntitle'>{$ntitle}</td>
+                       </tr>";
                }
-               $header .= "
-               <tr valign='top'>
-               <td colspan='$colspan' class='diff-otitle'>{$otitle}</td>
-               <td colspan='$colspan' class='diff-ntitle'>{$ntitle}</td>
-               </tr>";
 
                if ( $multi != '' ) {
                        $header .= "<tr><td colspan='{$multiColspan}' align='center' class='diff-multi'>{$multi}</td></tr>";
@@ -985,6 +975,41 @@ CONTROL;
                $this->mDiffLang = wfGetLangObj( $lang );
        }
 
+       /**
+        * Load revision IDs
+        */
+       private function loadRevisionIds() {
+               if ( $this->mRevisionsIdsLoaded ) {
+                       return;
+               }
+
+               $this->mRevisionsIdsLoaded = true;
+
+               $old = $this->mOldid;
+               $new = $this->mNewid;
+
+               if ( $new === 'prev' ) {
+                       # Show diff between revision $old and the previous one.
+                       # Get previous one from DB.
+                       $this->mNewid = intval( $old );
+                       $this->mOldid = $this->mTitle->getPreviousRevisionID( $this->mNewid );
+               } elseif ( $new === 'next' ) {
+                       # Show diff between revision $old and the next one.
+                       # Get next one from DB.
+                       $this->mOldid = intval( $old );
+                       $this->mNewid = $this->mTitle->getNextRevisionID( $this->mOldid );
+                       if ( $this->mNewid === false ) {
+                               # if no result, NewId points to the newest old revision. The only newer
+                               # revision is cur, which is "0".
+                               $this->mNewid = 0;
+                       }
+               } else {
+                       $this->mOldid = intval( $old );
+                       $this->mNewid = intval( $new );
+                       wfRunHooks( 'NewDifferenceEngine', array( &$this->mTitle, &$this->mOldid, &$this->mNewid, $old, $new ) );
+               }
+       }
+
        /**
         * Load revision metadata for the specified articles. If newid is 0, then compare
         * the old article in oldid to the current article; if oldid is 0, then
@@ -998,72 +1023,29 @@ CONTROL;
         * @return bool
         */
        function loadRevisionData() {
-               global $wgLang, $wgUser;
+               global $wgUser;
+
                if ( $this->mRevisionsLoaded ) {
                        return true;
-               } else {
-                       // Whether it succeeds or fails, we don't want to try again
-                       $this->mRevisionsLoaded = true;
                }
 
+               // Whether it succeeds or fails, we don't want to try again
+               $this->mRevisionsLoaded = true;
+
+               $this->loadRevisionIds();
+
                // Load the new revision object
                $this->mNewRev = $this->mNewid
                        ? Revision::newFromId( $this->mNewid )
                        : Revision::newFromTitle( $this->mTitle );
+
                if ( !$this->mNewRev instanceof Revision ) {
                        return false;
                }
 
                // Update the new revision ID in case it was 0 (makes life easier doing UI stuff)
                $this->mNewid = $this->mNewRev->getId();
-
-               // Check if page is editable
-               $editable = $this->mNewRev->getTitle()->userCan( 'edit' );
-
-               // Set assorted variables
-               $timestamp = $wgLang->timeanddate( $this->mNewRev->getTimestamp(), true );
-               $dateofrev = $wgLang->date( $this->mNewRev->getTimestamp(), true );
-               $timeofrev = $wgLang->time( $this->mNewRev->getTimestamp(), true );
                $this->mNewPage = $this->mNewRev->getTitle();
-               if ( $this->mNewRev->isCurrent() ) {
-                       $newLink = $this->mNewPage->escapeLocalUrl( array(
-                               'oldid' => $this->mNewid
-                       ) );
-                       $this->mPagetitle = htmlspecialchars( wfMsg(
-                               'currentrev-asof',
-                               $timestamp,
-                               $dateofrev,
-                               $timeofrev
-                       ) );
-                       $newEdit = $this->mNewPage->escapeLocalUrl( array(
-                               'action' => 'edit'
-                       ) );
-
-                       $this->mNewtitle = "<a href='$newLink'>{$this->mPagetitle}</a>";
-                       $this->mNewtitle .= " (<a href='$newEdit'>" . wfMsgHtml( $editable ? 'editold' : 'viewsourceold' ) . "</a>)";
-               } else {
-                       $newLink = $this->mNewPage->escapeLocalUrl( array(
-                               'oldid' => $this->mNewid
-                       ) );
-                       $newEdit = $this->mNewPage->escapeLocalUrl( array(
-                               'action' => 'edit',
-                               'oldid' => $this->mNewid
-                       ) );
-                       $this->mPagetitle = htmlspecialchars( wfMsg(
-                               'revisionasof',
-                               $timestamp,
-                               $dateofrev,
-                               $timeofrev
-                       ) );
-
-                       $this->mNewtitle = "<a href='$newLink'>{$this->mPagetitle}</a>";
-                       $this->mNewtitle .= " (<a href='$newEdit'>" . wfMsgHtml( $editable ? 'editold' : 'viewsourceold' ) . "</a>)";
-               }
-               if ( !$this->mNewRev->userCan( Revision::DELETED_TEXT ) ) {
-                       $this->mNewtitle = "<span class='history-deleted'>{$this->mPagetitle}</span>";
-               } elseif ( $this->mNewRev->isDeleted( Revision::DELETED_TEXT ) ) {
-                       $this->mNewtitle = "<span class='history-deleted'>{$this->mNewtitle}</span>";
-               }
 
                // Load the old revision object
                $this->mOldRev = false;
@@ -1087,38 +1069,6 @@ CONTROL;
 
                if ( $this->mOldRev ) {
                        $this->mOldPage = $this->mOldRev->getTitle();
-
-                       $t = $wgLang->timeanddate( $this->mOldRev->getTimestamp(), true );
-                       $dateofrev = $wgLang->date( $this->mOldRev->getTimestamp(), true );
-                       $timeofrev = $wgLang->time( $this->mOldRev->getTimestamp(), true );
-                       $oldLink = $this->mOldPage->escapeLocalUrl( array(
-                               'oldid' => $this->mOldid
-                       ) );
-                       $oldEdit = $this->mOldPage->escapeLocalUrl( array(
-                               'action' => 'edit',
-                               'oldid' => $this->mOldid
-                       ) );
-                       $this->mOldPagetitle = htmlspecialchars( wfMsg( 'revisionasof', $t, $dateofrev, $timeofrev ) );
-
-                       $this->mOldtitle = "<a href='$oldLink'>{$this->mOldPagetitle}</a>"
-                       . " (<a href='$oldEdit'>" . wfMsgHtml( $editable ? 'editold' : 'viewsourceold' ) . "</a>)";
-                       // Add an "undo" link
-                       if ( $editable && !$this->mOldRev->isDeleted( Revision::DELETED_TEXT ) && !$this->mNewRev->isDeleted( Revision::DELETED_TEXT ) ) {
-                               $undoLink = Html::element( 'a', array(
-                                       'href' => $this->mNewPage->getLocalUrl( array(
-                                               'action' => 'edit',
-                                               'undoafter' => $this->mOldid,
-                                               'undo' => $this->mNewid ) ),
-                                       'title' => $wgUser->getSkin()->titleAttrib( 'undo' )
-                               ), wfMsg( 'editundo' ) );
-                               $this->mNewtitle .= ' (' . $undoLink . ')';
-                       }
-
-                       if ( !$this->mOldRev->userCan( Revision::DELETED_TEXT ) ) {
-                               $this->mOldtitle = '<span class="history-deleted">' . $this->mOldPagetitle . '</span>';
-                       } elseif ( $this->mOldRev->isDeleted( Revision::DELETED_TEXT ) ) {
-                               $this->mOldtitle = '<span class="history-deleted">' . $this->mOldtitle . '</span>';
-                       }
                }
 
                return true;