SpecialUndelete.php

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<?php
class PageArchive {
    protected $title;

    protected $fileStatus;

    protected $revisionStatus;

    function __construct( $title ) {
        if ( is_null( $title ) ) {
            throw new MWException( __METHOD__ . ' given a null title.' );
        }
        $this->title = $title;
    }

    public static function listAllPages() {
        $dbr = wfGetDB( DB_SLAVE );

        return self::listPages( $dbr, '' );
    }

    public static function listPagesByPrefix( $prefix ) {
        $dbr = wfGetDB( DB_SLAVE );

        $title = Title::newFromText( $prefix );
        if ( $title ) {
            $ns = $title->getNamespace();
            $prefix = $title->getDBkey();
        } else {
            // Prolly won't work too good
            // @todo handle bare namespace names cleanly?
            $ns = 0;
        }

        $conds = array(
            'ar_namespace' => $ns,
            'ar_title' . $dbr->buildLike( $prefix, $dbr->anyString() ),
        );

        return self::listPages( $dbr, $conds );
    }

    protected static function listPages( $dbr, $condition ) {
        return $dbr->resultObject( $dbr->select(
            array( 'archive' ),
            array(
                'ar_namespace',
                'ar_title',
                'count' => 'COUNT(*)'
            ),
            $condition,
            __METHOD__,
            array(
                'GROUP BY' => array( 'ar_namespace', 'ar_title' ),
                'ORDER BY' => array( 'ar_namespace', 'ar_title' ),
                'LIMIT' => 100,
            )
        ) );
    }

    function listRevisions() {
        global $wgContentHandlerUseDB;

        $dbr = wfGetDB( DB_SLAVE );

        $tables = array( 'archive' );

        $fields = array(
            'ar_minor_edit', 'ar_timestamp', 'ar_user', 'ar_user_text',
            'ar_comment', 'ar_len', 'ar_deleted', 'ar_rev_id', 'ar_sha1',
        );

        if ( $wgContentHandlerUseDB ) {
            $fields[] = 'ar_content_format';
            $fields[] = 'ar_content_model';
        }

        $conds = array( 'ar_namespace' => $this->title->getNamespace(),
            'ar_title' => $this->title->getDBkey() );

        $options = array( 'ORDER BY' => 'ar_timestamp DESC' );

        $join_conds = array();

        ChangeTags::modifyDisplayQuery(
            $tables,
            $fields,
            $conds,
            $join_conds,
            $options
        );

        $res = $dbr->select( $tables,
            $fields,
            $conds,
            __METHOD__,
            $options,
            $join_conds
        );

        return $dbr->resultObject( $res );
    }

    function listFiles() {
        if ( $this->title->getNamespace() != NS_FILE ) {
            return null;
        }

        $dbr = wfGetDB( DB_SLAVE );
        $res = $dbr->select(
            'filearchive',
            ArchivedFile::selectFields(),
            array( 'fa_name' => $this->title->getDBkey() ),
            __METHOD__,
            array( 'ORDER BY' => 'fa_timestamp DESC' )
        );

        return $dbr->resultObject( $res );
    }

    function getRevision( $timestamp ) {
        global $wgContentHandlerUseDB;

        $dbr = wfGetDB( DB_SLAVE );

        $fields = array(
            'ar_rev_id',
            'ar_text',
            'ar_comment',
            'ar_user',
            'ar_user_text',
            'ar_timestamp',
            'ar_minor_edit',
            'ar_flags',
            'ar_text_id',
            'ar_deleted',
            'ar_len',
            'ar_sha1',
        );

        if ( $wgContentHandlerUseDB ) {
            $fields[] = 'ar_content_format';
            $fields[] = 'ar_content_model';
        }

        $row = $dbr->selectRow( 'archive',
            $fields,
            array( 'ar_namespace' => $this->title->getNamespace(),
                'ar_title' => $this->title->getDBkey(),
                'ar_timestamp' => $dbr->timestamp( $timestamp ) ),
            __METHOD__ );

        if ( $row ) {
            return Revision::newFromArchiveRow( $row, array( 'title' => $this->title ) );
        }

        return null;
    }

    function getPreviousRevision( $timestamp ) {
        $dbr = wfGetDB( DB_SLAVE );

        // Check the previous deleted revision...
        $row = $dbr->selectRow( 'archive',
            'ar_timestamp',
            array( 'ar_namespace' => $this->title->getNamespace(),
                'ar_title' => $this->title->getDBkey(),
                'ar_timestamp < ' .
                    $dbr->addQuotes( $dbr->timestamp( $timestamp ) ) ),
            __METHOD__,
            array(
                'ORDER BY' => 'ar_timestamp DESC',
                'LIMIT' => 1 ) );
        $prevDeleted = $row ? wfTimestamp( TS_MW, $row->ar_timestamp ) : false;

        $row = $dbr->selectRow( array( 'page', 'revision' ),
            array( 'rev_id', 'rev_timestamp' ),
            array(
                'page_namespace' => $this->title->getNamespace(),
                'page_title' => $this->title->getDBkey(),
                'page_id = rev_page',
                'rev_timestamp < ' .
                    $dbr->addQuotes( $dbr->timestamp( $timestamp ) ) ),
            __METHOD__,
            array(
                'ORDER BY' => 'rev_timestamp DESC',
                'LIMIT' => 1 ) );
        $prevLive = $row ? wfTimestamp( TS_MW, $row->rev_timestamp ) : false;
        $prevLiveId = $row ? intval( $row->rev_id ) : null;

        if ( $prevLive && $prevLive > $prevDeleted ) {
            // Most prior revision was live
            return Revision::newFromId( $prevLiveId );
        } elseif ( $prevDeleted ) {
            // Most prior revision was deleted
            return $this->getRevision( $prevDeleted );
        }

        // No prior revision on this page.
        return null;
    }

    function getTextFromRow( $row ) {
        if ( is_null( $row->ar_text_id ) ) {
            // An old row from MediaWiki 1.4 or previous.
            // Text is embedded in this row in classic compression format.
            return Revision::getRevisionText( $row, 'ar_' );
        }

        // New-style: keyed to the text storage backend.
        $dbr = wfGetDB( DB_SLAVE );
        $text = $dbr->selectRow( 'text',
            array( 'old_text', 'old_flags' ),
            array( 'old_id' => $row->ar_text_id ),
            __METHOD__ );

        return Revision::getRevisionText( $text );
    }

    function getLastRevisionText() {
        $dbr = wfGetDB( DB_SLAVE );
        $row = $dbr->selectRow( 'archive',
            array( 'ar_text', 'ar_flags', 'ar_text_id' ),
            array( 'ar_namespace' => $this->title->getNamespace(),
                'ar_title' => $this->title->getDBkey() ),
            __METHOD__,
            array( 'ORDER BY' => 'ar_timestamp DESC' ) );

        if ( $row ) {
            return $this->getTextFromRow( $row );
        }

        return null;
    }

    function isDeleted() {
        $dbr = wfGetDB( DB_SLAVE );
        $n = $dbr->selectField( 'archive', 'COUNT(ar_title)',
            array( 'ar_namespace' => $this->title->getNamespace(),
                'ar_title' => $this->title->getDBkey() ),
            __METHOD__
        );

        return ( $n > 0 );
    }

    function undelete( $timestamps, $comment = '', $fileVersions = array(),
        $unsuppress = false, User $user = null
    ) {
        // If both the set of text revisions and file revisions are empty,
        // restore everything. Otherwise, just restore the requested items.
        $restoreAll = empty( $timestamps ) && empty( $fileVersions );

        $restoreText = $restoreAll || !empty( $timestamps );
        $restoreFiles = $restoreAll || !empty( $fileVersions );

        if ( $restoreFiles && $this->title->getNamespace() == NS_FILE ) {
            $img = wfLocalFile( $this->title );
            $this->fileStatus = $img->restore( $fileVersions, $unsuppress );
            if ( !$this->fileStatus->isOK() ) {
                return false;
            }
            $filesRestored = $this->fileStatus->successCount;
        } else {
            $filesRestored = 0;
        }

        if ( $restoreText ) {
            $this->revisionStatus = $this->undeleteRevisions( $timestamps, $unsuppress, $comment );
            if ( !$this->revisionStatus->isOK() ) {
                return false;
            }

            $textRestored = $this->revisionStatus->getValue();
        } else {
            $textRestored = 0;
        }

        // Touch the log!

        if ( $textRestored && $filesRestored ) {
            $reason = wfMessage( 'undeletedrevisions-files' )
                ->numParams( $textRestored, $filesRestored )->inContentLanguage()->text();
        } elseif ( $textRestored ) {
            $reason = wfMessage( 'undeletedrevisions' )->numParams( $textRestored )
                ->inContentLanguage()->text();
        } elseif ( $filesRestored ) {
            $reason = wfMessage( 'undeletedfiles' )->numParams( $filesRestored )
                ->inContentLanguage()->text();
        } else {
            wfDebug( "Undelete: nothing undeleted...\n" );

            return false;
        }

        if ( trim( $comment ) != '' ) {
            $reason .= wfMessage( 'colon-separator' )->inContentLanguage()->text() . $comment;
        }

        if ( $user === null ) {
            global $wgUser;
            $user = $wgUser;
        }

        $logEntry = new ManualLogEntry( 'delete', 'restore' );
        $logEntry->setPerformer( $user );
        $logEntry->setTarget( $this->title );
        $logEntry->setComment( $reason );

        wfRunHooks( 'ArticleUndeleteLogEntry', array( $this, &$logEntry, $user ) );

        $logid = $logEntry->insert();
        $logEntry->publish( $logid );

        return array( $textRestored, $filesRestored, $reason );
    }

    private function undeleteRevisions( $timestamps, $unsuppress = false, $comment = '' ) {
        global $wgContentHandlerUseDB;

        if ( wfReadOnly() ) {
            throw new ReadOnlyError();
        }

        $restoreAll = empty( $timestamps );
        $dbw = wfGetDB( DB_MASTER );

        # Does this page already exist? We'll have to update it...
        $article = WikiPage::factory( $this->title );
        # Load latest data for the current page (bug 31179)
        $article->loadPageData( 'fromdbmaster' );
        $oldcountable = $article->isCountable();

        $page = $dbw->selectRow( 'page',
            array( 'page_id', 'page_latest' ),
            array( 'page_namespace' => $this->title->getNamespace(),
                'page_title' => $this->title->getDBkey() ),
            __METHOD__,
            array( 'FOR UPDATE' ) // lock page
        );

        if ( $page ) {
            $makepage = false;
            # Page already exists. Import the history, and if necessary
            # we'll update the latest revision field in the record.

            $previousRevId = $page->page_latest;

            # Get the time span of this page
            $previousTimestamp = $dbw->selectField( 'revision', 'rev_timestamp',
                array( 'rev_id' => $previousRevId ),
                __METHOD__ );

            if ( $previousTimestamp === false ) {
                wfDebug( __METHOD__ . ": existing page refers to a page_latest that does not exist\n" );

                $status = Status::newGood( 0 );
                $status->warning( 'undeleterevision-missing' );

                return $status;
            }
        } else {
            # Have to create a new article...
            $makepage = true;
            $previousRevId = 0;
            $previousTimestamp = 0;
        }

        if ( $restoreAll ) {
            $oldones = '1 = 1'; # All revisions...
        } else {
            $oldts = implode( ',',
                array_map( array( &$dbw, 'addQuotes' ),
                    array_map( array( &$dbw, 'timestamp' ),
                        $timestamps ) ) );

            $oldones = "ar_timestamp IN ( {$oldts} )";
        }

        $fields = array(
            'ar_rev_id',
            'ar_text',
            'ar_comment',
            'ar_user',
            'ar_user_text',
            'ar_timestamp',
            'ar_minor_edit',
            'ar_flags',
            'ar_text_id',
            'ar_deleted',
            'ar_page_id',
            'ar_len',
            'ar_sha1'
        );

        if ( $wgContentHandlerUseDB ) {
            $fields[] = 'ar_content_format';
            $fields[] = 'ar_content_model';
        }

        $result = $dbw->select( 'archive',
            $fields,
            /* WHERE */ array(
                'ar_namespace' => $this->title->getNamespace(),
                'ar_title' => $this->title->getDBkey(),
                $oldones ),
            __METHOD__,
            /* options */ array( 'ORDER BY' => 'ar_timestamp' )
        );
        $ret = $dbw->resultObject( $result );
        $rev_count = $dbw->numRows( $result );

        if ( !$rev_count ) {
            wfDebug( __METHOD__ . ": no revisions to restore\n" );

            $status = Status::newGood( 0 );
            $status->warning( "undelete-no-results" );

            return $status;
        }

        $ret->seek( $rev_count - 1 ); // move to last
        $row = $ret->fetchObject(); // get newest archived rev
        $ret->seek( 0 ); // move back

        // grab the content to check consistency with global state before restoring the page.
        $revision = Revision::newFromArchiveRow( $row,
            array(
                'title' => $article->getTitle(), // used to derive default content model
            )
        );
        $user = User::newFromName( $revision->getRawUserText(), false );
        $content = $revision->getContent( Revision::RAW );

        //NOTE: article ID may not be known yet. prepareSave() should not modify the database.
        $status = $content->prepareSave( $article, 0, -1, $user );

        if ( !$status->isOK() ) {
            return $status;
        }

        if ( $makepage ) {
            // Check the state of the newest to-be version...
            if ( !$unsuppress && ( $row->ar_deleted & Revision::DELETED_TEXT ) ) {
                return Status::newFatal( "undeleterevdel" );
            }
            // Safe to insert now...
            $newid = $article->insertOn( $dbw );
            $pageId = $newid;
        } else {
            // Check if a deleted revision will become the current revision...
            if ( $row->ar_timestamp > $previousTimestamp ) {
                // Check the state of the newest to-be version...
                if ( !$unsuppress && ( $row->ar_deleted & Revision::DELETED_TEXT ) ) {
                    return Status::newFatal( "undeleterevdel" );
                }
            }

            $newid = false;
            $pageId = $article->getId();
        }

        $revision = null;
        $restored = 0;

        foreach ( $ret as $row ) {
            // Check for key dupes due to shitty archive integrity.
            if ( $row->ar_rev_id ) {
                $exists = $dbw->selectField( 'revision', '1',
                    array( 'rev_id' => $row->ar_rev_id ), __METHOD__ );
                if ( $exists ) {
                    continue; // don't throw DB errors
                }
            }
            // Insert one revision at a time...maintaining deletion status
            // unless we are specifically removing all restrictions...
            $revision = Revision::newFromArchiveRow( $row,
                array(
                    'page' => $pageId,
                    'title' => $this->title,
                    'deleted' => $unsuppress ? 0 : $row->ar_deleted
                ) );

            $revision->insertOn( $dbw );
            $restored++;

            wfRunHooks( 'ArticleRevisionUndeleted', array( &$this->title, $revision, $row->ar_page_id ) );
        }
        # Now that it's safely stored, take it out of the archive
        $dbw->delete( 'archive',
            /* WHERE */ array(
                'ar_namespace' => $this->title->getNamespace(),
                'ar_title' => $this->title->getDBkey(),
                $oldones ),
            __METHOD__ );

        // Was anything restored at all?
        if ( $restored == 0 ) {
            return Status::newGood( 0 );
        }

        $created = (bool)$newid;

        // Attach the latest revision to the page...
        $wasnew = $article->updateIfNewerOn( $dbw, $revision, $previousRevId );
        if ( $created || $wasnew ) {
            // Update site stats, link tables, etc
            $user = User::newFromName( $revision->getRawUserText(), false );
            $article->doEditUpdates(
                $revision,
                $user,
                array( 'created' => $created, 'oldcountable' => $oldcountable )
            );
        }

        wfRunHooks( 'ArticleUndelete', array( &$this->title, $created, $comment ) );

        if ( $this->title->getNamespace() == NS_FILE ) {
            $update = new HTMLCacheUpdate( $this->title, 'imagelinks' );
            $update->doUpdate();
        }

        return Status::newGood( $restored );
    }

    function getFileStatus() {
        return $this->fileStatus;
    }

    function getRevisionStatus() {
        return $this->revisionStatus;
    }
}

class SpecialUndelete extends SpecialPage {
    private $mAction;
    private $mTarget;
    private $mTimestamp;
    private $mRestore;
    private $mInvert;
    private $mFilename;
    private $mTargetTimestamp;
    private $mAllowed;
    private $mCanView;
    private $mComment;
    private $mToken;

    private $mTargetObj;

    function __construct() {
        parent::__construct( 'Undelete', 'deletedhistory' );
    }

    function loadRequest( $par ) {
        $request = $this->getRequest();
        $user = $this->getUser();

        $this->mAction = $request->getVal( 'action' );
        if ( $par !== null && $par !== '' ) {
            $this->mTarget = $par;
        } else {
            $this->mTarget = $request->getVal( 'target' );
        }

        $this->mTargetObj = null;

        if ( $this->mTarget !== null && $this->mTarget !== '' ) {
            $this->mTargetObj = Title::newFromURL( $this->mTarget );
        }

        $this->mSearchPrefix = $request->getText( 'prefix' );
        $time = $request->getVal( 'timestamp' );
        $this->mTimestamp = $time ? wfTimestamp( TS_MW, $time ) : '';
        $this->mFilename = $request->getVal( 'file' );

        $posted = $request->wasPosted() &&
            $user->matchEditToken( $request->getVal( 'wpEditToken' ) );
        $this->mRestore = $request->getCheck( 'restore' ) && $posted;
        $this->mInvert = $request->getCheck( 'invert' ) && $posted;
        $this->mPreview = $request->getCheck( 'preview' ) && $posted;
        $this->mDiff = $request->getCheck( 'diff' );
        $this->mDiffOnly = $request->getBool( 'diffonly', $this->getUser()->getOption( 'diffonly' ) );
        $this->mComment = $request->getText( 'wpComment' );
        $this->mUnsuppress = $request->getVal( 'wpUnsuppress' ) && $user->isAllowed( 'suppressrevision' );
        $this->mToken = $request->getVal( 'token' );

        if ( $user->isAllowed( 'undelete' ) && !$user->isBlocked() ) {
            $this->mAllowed = true; // user can restore
            $this->mCanView = true; // user can view content
        } elseif ( $user->isAllowed( 'deletedtext' ) ) {
            $this->mAllowed = false; // user cannot restore
            $this->mCanView = true; // user can view content
            $this->mRestore = false;
        } else { // user can only view the list of revisions
            $this->mAllowed = false;
            $this->mCanView = false;
            $this->mTimestamp = '';
            $this->mRestore = false;
        }

        if ( $this->mRestore || $this->mInvert ) {
            $timestamps = array();
            $this->mFileVersions = array();
            foreach ( $request->getValues() as $key => $val ) {
                $matches = array();
                if ( preg_match( '/^ts(\d{14})$/', $key, $matches ) ) {
                    array_push( $timestamps, $matches[1] );
                }

                if ( preg_match( '/^fileid(\d+)$/', $key, $matches ) ) {
                    $this->mFileVersions[] = intval( $matches[1] );
                }
            }
            rsort( $timestamps );
            $this->mTargetTimestamp = $timestamps;
        }
    }

    function execute( $par ) {
        $this->checkPermissions();
        $user = $this->getUser();

        $this->setHeaders();
        $this->outputHeader();

        $this->loadRequest( $par );

        $out = $this->getOutput();

        if ( is_null( $this->mTargetObj ) ) {
            $out->addWikiMsg( 'undelete-header' );

            # Not all users can just browse every deleted page from the list
            if ( $user->isAllowed( 'browsearchive' ) ) {
                $this->showSearchForm();
            }

            return;
        }

        if ( $this->mAllowed ) {
            $out->setPageTitle( $this->msg( 'undeletepage' ) );
        } else {
            $out->setPageTitle( $this->msg( 'viewdeletedpage' ) );
        }

        $this->getSkin()->setRelevantTitle( $this->mTargetObj );

        if ( $this->mTimestamp !== '' ) {
            $this->showRevision( $this->mTimestamp );
        } elseif ( $this->mFilename !== null && $this->mTargetObj->inNamespace( NS_FILE ) ) {
            $file = new ArchivedFile( $this->mTargetObj, '', $this->mFilename );
            // Check if user is allowed to see this file
            if ( !$file->exists() ) {
                $out->addWikiMsg( 'filedelete-nofile', $this->mFilename );
            } elseif ( !$file->userCan( File::DELETED_FILE, $user ) ) {
                if ( $file->isDeleted( File::DELETED_RESTRICTED ) ) {
                    throw new PermissionsError( 'suppressrevision' );
                } else {
                    throw new PermissionsError( 'deletedtext' );
                }
            } elseif ( !$user->matchEditToken( $this->mToken, $this->mFilename ) ) {
                $this->showFileConfirmationForm( $this->mFilename );
            } else {
                $this->showFile( $this->mFilename );
            }
        } elseif ( $this->mRestore && $this->mAction == 'submit' ) {
            $this->undelete();
        } else {
            $this->showHistory();
        }
    }

    function showSearchForm() {
        global $wgScript;

        $out = $this->getOutput();
        $out->setPageTitle( $this->msg( 'undelete-search-title' ) );
        $out->addHTML(
            Xml::openElement( 'form', array( 'method' => 'get', 'action' => $wgScript ) ) .
                Xml::fieldset( $this->msg( 'undelete-search-box' )->text() ) .
                Html::hidden( 'title', $this->getPageTitle()->getPrefixedDBkey() ) .
                Html::rawElement(
                    'label',
                    array( 'for' => 'prefix' ),
                    $this->msg( 'undelete-search-prefix' )->parse()
                ) .
                Xml::input(
                    'prefix',
                    20,
                    $this->mSearchPrefix,
                    array( 'id' => 'prefix', 'autofocus' => true )
                ) . ' ' .
                Xml::submitButton( $this->msg( 'undelete-search-submit' )->text() ) .
                Xml::closeElement( 'fieldset' ) .
                Xml::closeElement( 'form' )
        );

        # List undeletable articles
        if ( $this->mSearchPrefix ) {
            $result = PageArchive::listPagesByPrefix( $this->mSearchPrefix );
            $this->showList( $result );
        }
    }

    private function showList( $result ) {
        $out = $this->getOutput();

        if ( $result->numRows() == 0 ) {
            $out->addWikiMsg( 'undelete-no-results' );

            return false;
        }

        $out->addWikiMsg( 'undeletepagetext', $this->getLanguage()->formatNum( $result->numRows() ) );

        $undelete = $this->getPageTitle();
        $out->addHTML( "<ul>\n" );
        foreach ( $result as $row ) {
            $title = Title::makeTitleSafe( $row->ar_namespace, $row->ar_title );
            if ( $title !== null ) {
                $item = Linker::linkKnown(
                    $undelete,
                    htmlspecialchars( $title->getPrefixedText() ),
                    array(),
                    array( 'target' => $title->getPrefixedText() )
                );
            } else {
                // The title is no longer valid, show as text
                $item = Html::element(
                    'span',
                    array( 'class' => 'mw-invalidtitle' ),
                    Linker::getInvalidTitleDescription(
                        $this->getContext(),
                        $row->ar_namespace,
                        $row->ar_title
                    )
                );
            }
            $revs = $this->msg( 'undeleterevisions' )->numParams( $row->count )->parse();
            $out->addHTML( "<li>{$item} ({$revs})</li>\n" );
        }
        $result->free();
        $out->addHTML( "</ul>\n" );

        return true;
    }

    private function showRevision( $timestamp ) {
        if ( !preg_match( '/[0-9]{14}/', $timestamp ) ) {
            return;
        }

        $archive = new PageArchive( $this->mTargetObj );
        if ( !wfRunHooks( 'UndeleteForm::showRevision', array( &$archive, $this->mTargetObj ) ) ) {
            return;
        }
        $rev = $archive->getRevision( $timestamp );

        $out = $this->getOutput();
        $user = $this->getUser();

        if ( !$rev ) {
            $out->addWikiMsg( 'undeleterevision-missing' );

            return;
        }

        if ( $rev->isDeleted( Revision::DELETED_TEXT ) ) {
            if ( !$rev->userCan( Revision::DELETED_TEXT, $user ) ) {
                $out->wrapWikiMsg(
                    "<div class='mw-warning plainlinks'>\n$1\n</div>\n",
                    'rev-deleted-text-permission'
                );

                return;
            }

            $out->wrapWikiMsg(
                "<div class='mw-warning plainlinks'>\n$1\n</div>\n",
                'rev-deleted-text-view'
            );
            $out->addHTML( '<br />' );
            // and we are allowed to see...
        }

        if ( $this->mDiff ) {
            $previousRev = $archive->getPreviousRevision( $timestamp );
            if ( $previousRev ) {
                $this->showDiff( $previousRev, $rev );
                if ( $this->mDiffOnly ) {
                    return;
                }

                $out->addHTML( '<hr />' );
            } else {
                $out->addWikiMsg( 'undelete-nodiff' );
            }
        }

        $link = Linker::linkKnown(
            $this->getPageTitle( $this->mTargetObj->getPrefixedDBkey() ),
            htmlspecialchars( $this->mTargetObj->getPrefixedText() )
        );

        $lang = $this->getLanguage();

        // date and time are separate parameters to facilitate localisation.
        // $time is kept for backward compat reasons.
        $time = $lang->userTimeAndDate( $timestamp, $user );
        $d = $lang->userDate( $timestamp, $user );
        $t = $lang->userTime( $timestamp, $user );
        $userLink = Linker::revUserTools( $rev );

        $content = $rev->getContent( Revision::FOR_THIS_USER, $user );

        $isText = ( $content instanceof TextContent );

        if ( $this->mPreview || $isText ) {
            $openDiv = '<div id="mw-undelete-revision" class="mw-warning">';
        } else {
            $openDiv = '<div id="mw-undelete-revision">';
        }
        $out->addHTML( $openDiv );

        // Revision delete links
        if ( !$this->mDiff ) {
            $revdel = Linker::getRevDeleteLink( $user, $rev, $this->mTargetObj );
            if ( $revdel ) {
                $out->addHTML( "$revdel " );
            }
        }

        $out->addHTML( $this->msg( 'undelete-revision' )->rawParams( $link )->params(
            $time )->rawParams( $userLink )->params( $d, $t )->parse() . '</div>' );

        if ( !wfRunHooks( 'UndeleteShowRevision', array( $this->mTargetObj, $rev ) ) ) {
            return;
        }

        if ( $this->mPreview || !$isText ) {
            // NOTE: non-text content has no source view, so always use rendered preview

            // Hide [edit]s
            $popts = $out->parserOptions();
            $popts->setEditSection( false );

            $pout = $content->getParserOutput( $this->mTargetObj, $rev->getId(), $popts, true );
            $out->addParserOutput( $pout );
        }

        if ( $isText ) {
            // source view for textual content
            $sourceView = Xml::element(
                'textarea',
                array(
                    'readonly' => 'readonly',
                    'cols' => $user->getIntOption( 'cols' ),
                    'rows' => $user->getIntOption( 'rows' )
                ),
                $content->getNativeData() . "\n"
            );

            $previewButton = Xml::element( 'input', array(
                'type' => 'submit',
                'name' => 'preview',
                'value' => $this->msg( 'showpreview' )->text()
            ) );
        } else {
            $sourceView = '';
            $previewButton = '';
        }

        $diffButton = Xml::element( 'input', array(
            'name' => 'diff',
            'type' => 'submit',
            'value' => $this->msg( 'showdiff' )->text() ) );

        $out->addHTML(
            $sourceView .
                Xml::openElement( 'div', array(
                    'style' => 'clear: both' ) ) .
                Xml::openElement( 'form', array(
                    'method' => 'post',
                    'action' => $this->getPageTitle()->getLocalURL( array( 'action' => 'submit' ) ) ) ) .
                Xml::element( 'input', array(
                    'type' => 'hidden',
                    'name' => 'target',
                    'value' => $this->mTargetObj->getPrefixedDBkey() ) ) .
                Xml::element( 'input', array(
                    'type' => 'hidden',
                    'name' => 'timestamp',
                    'value' => $timestamp ) ) .
                Xml::element( 'input', array(
                    'type' => 'hidden',
                    'name' => 'wpEditToken',
                    'value' => $user->getEditToken() ) ) .
                $previewButton .
                $diffButton .
                Xml::closeElement( 'form' ) .
                Xml::closeElement( 'div' )
        );
    }

    function showDiff( $previousRev, $currentRev ) {
        $diffContext = clone $this->getContext();
        $diffContext->setTitle( $currentRev->getTitle() );
        $diffContext->setWikiPage( WikiPage::factory( $currentRev->getTitle() ) );

        $diffEngine = $currentRev->getContentHandler()->createDifferenceEngine( $diffContext );
        $diffEngine->showDiffStyle();

        $formattedDiff = $diffEngine->generateContentDiffBody(
            $previousRev->getContent( Revision::FOR_THIS_USER, $this->getUser() ),
            $currentRev->getContent( Revision::FOR_THIS_USER, $this->getUser() )
        );

        $formattedDiff = $diffEngine->addHeader(
            $formattedDiff,
            $this->diffHeader( $previousRev, 'o' ),
            $this->diffHeader( $currentRev, 'n' )
        );

        $this->getOutput()->addHTML( "<div>$formattedDiff</div>\n" );
    }

    private function diffHeader( $rev, $prefix ) {
        $isDeleted = !( $rev->getId() && $rev->getTitle() );
        if ( $isDeleted ) {
            $targetPage = $this->getPageTitle();
            $targetQuery = array(
                'target' => $this->mTargetObj->getPrefixedText(),
                'timestamp' => wfTimestamp( TS_MW, $rev->getTimestamp() )
            );
        } else {
            $targetPage = $rev->getTitle();
            $targetQuery = array( 'oldid' => $rev->getId() );
        }

        // Add show/hide deletion links if available
        $user = $this->getUser();
        $lang = $this->getLanguage();
        $rdel = Linker::getRevDeleteLink( $user, $rev, $this->mTargetObj );

        if ( $rdel ) {
            $rdel = " $rdel";
        }

        $minor = $rev->isMinor() ? ChangesList::flag( 'minor' ) : '';

        $tags = wfGetDB( DB_SLAVE )->selectField(
            'tag_summary',
            'ts_tags',
            array( 'ts_rev_id' => $rev->getId() ),
            __METHOD__
        );
        $tagSummary = ChangeTags::formatSummaryRow( $tags, 'deleteddiff' );

        // FIXME This is reimplementing DifferenceEngine#getRevisionHeader
        // and partially #showDiffPage, but worse
        return '<div id="mw-diff-' . $prefix . 'title1"><strong>' .
            Linker::link(
                $targetPage,
                $this->msg(
                    'revisionasof',
                    $lang->userTimeAndDate( $rev->getTimestamp(), $user ),
                    $lang->userDate( $rev->getTimestamp(), $user ),
                    $lang->userTime( $rev->getTimestamp(), $user )
                )->escaped(),
                array(),
                $targetQuery
            ) .
            '</strong></div>' .
            '<div id="mw-diff-' . $prefix . 'title2">' .
            Linker::revUserTools( $rev ) . '<br />' .
            '</div>' .
            '<div id="mw-diff-' . $prefix . 'title3">' .
            $minor . Linker::revComment( $rev ) . $rdel . '<br />' .
            '</div>' .
            '<div id="mw-diff-' . $prefix . 'title5">' .
            $tagSummary[0] . '<br />' .
            '</div>';
    }

    private function showFileConfirmationForm( $key ) {
        $out = $this->getOutput();
        $lang = $this->getLanguage();
        $user = $this->getUser();
        $file = new ArchivedFile( $this->mTargetObj, '', $this->mFilename );
        $out->addWikiMsg( 'undelete-show-file-confirm',
            $this->mTargetObj->getText(),
            $lang->userDate( $file->getTimestamp(), $user ),
            $lang->userTime( $file->getTimestamp(), $user ) );
        $out->addHTML(
            Xml::openElement( 'form', array(
                    'method' => 'POST',
                    'action' => $this->getPageTitle()->getLocalURL( array(
                        'target' => $this->mTarget,
                        'file' => $key,
                        'token' => $user->getEditToken( $key ),
                    ) ),
                )
            ) .
                Xml::submitButton( $this->msg( 'undelete-show-file-submit' )->text() ) .
                '</form>'
        );
    }

    private function showFile( $key ) {
        $this->getOutput()->disable();

        # We mustn't allow the output to be Squid cached, otherwise
        # if an admin previews a deleted image, and it's cached, then
        # a user without appropriate permissions can toddle off and
        # nab the image, and Squid will serve it
        $response = $this->getRequest()->response();
        $response->header( 'Expires: ' . gmdate( 'D, d M Y H:i:s', 0 ) . ' GMT' );
        $response->header( 'Cache-Control: no-cache, no-store, max-age=0, must-revalidate' );
        $response->header( 'Pragma: no-cache' );

        $repo = RepoGroup::singleton()->getLocalRepo();
        $path = $repo->getZonePath( 'deleted' ) . '/' . $repo->getDeletedHashPath( $key ) . $key;
        $repo->streamFile( $path );
    }

    private function showHistory() {
        $out = $this->getOutput();
        if ( $this->mAllowed ) {
            $out->addModules( 'mediawiki.special.undelete' );
        }
        $out->wrapWikiMsg(
            "<div class='mw-undelete-pagetitle'>\n$1\n</div>\n",
            array( 'undeletepagetitle', wfEscapeWikiText( $this->mTargetObj->getPrefixedText() ) )
        );

        $archive = new PageArchive( $this->mTargetObj );
        wfRunHooks( 'UndeleteForm::showHistory', array( &$archive, $this->mTargetObj ) );
        /*
        $text = $archive->getLastRevisionText();
        if( is_null( $text ) ) {
            $out->addWikiMsg( 'nohistory' );
            return;
        }
        */
        $out->addHTML( '<div class="mw-undelete-history">' );
        if ( $this->mAllowed ) {
            $out->addWikiMsg( 'undeletehistory' );
            $out->addWikiMsg( 'undeleterevdel' );
        } else {
            $out->addWikiMsg( 'undeletehistorynoadmin' );
        }
        $out->addHTML( '</div>' );

        # List all stored revisions
        $revisions = $archive->listRevisions();
        $files = $archive->listFiles();

        $haveRevisions = $revisions && $revisions->numRows() > 0;
        $haveFiles = $files && $files->numRows() > 0;

        # Batch existence check on user and talk pages
        if ( $haveRevisions ) {
            $batch = new LinkBatch();
            foreach ( $revisions as $row ) {
                $batch->addObj( Title::makeTitleSafe( NS_USER, $row->ar_user_text ) );
                $batch->addObj( Title::makeTitleSafe( NS_USER_TALK, $row->ar_user_text ) );
            }
            $batch->execute();
            $revisions->seek( 0 );
        }
        if ( $haveFiles ) {
            $batch = new LinkBatch();
            foreach ( $files as $row ) {
                $batch->addObj( Title::makeTitleSafe( NS_USER, $row->fa_user_text ) );
                $batch->addObj( Title::makeTitleSafe( NS_USER_TALK, $row->fa_user_text ) );
            }
            $batch->execute();
            $files->seek( 0 );
        }

        if ( $this->mAllowed ) {
            $action = $this->getPageTitle()->getLocalURL( array( 'action' => 'submit' ) );
            # Start the form here
            $top = Xml::openElement(
                'form',
                array( 'method' => 'post', 'action' => $action, 'id' => 'undelete' )
            );
            $out->addHTML( $top );
        }

        # Show relevant lines from the deletion log:
        $deleteLogPage = new LogPage( 'delete' );
        $out->addHTML( Xml::element( 'h2', null, $deleteLogPage->getName()->text() ) . "\n" );
        LogEventsList::showLogExtract( $out, 'delete', $this->mTargetObj );
        # Show relevant lines from the suppression log:
        $suppressLogPage = new LogPage( 'suppress' );
        if ( $this->getUser()->isAllowed( 'suppressionlog' ) ) {
            $out->addHTML( Xml::element( 'h2', null, $suppressLogPage->getName()->text() ) . "\n" );
            LogEventsList::showLogExtract( $out, 'suppress', $this->mTargetObj );
        }

        if ( $this->mAllowed && ( $haveRevisions || $haveFiles ) ) {
            # Format the user-visible controls (comment field, submission button)
            # in a nice little table
            if ( $this->getUser()->isAllowed( 'suppressrevision' ) ) {
                $unsuppressBox =
                    "<tr>
                        <td>&#160;</td>
                        <td class='mw-input'>" .
                        Xml::checkLabel( $this->msg( 'revdelete-unsuppress' )->text(),
                            'wpUnsuppress', 'mw-undelete-unsuppress', $this->mUnsuppress ) .
                        "</td>
                    </tr>";
            } else {
                $unsuppressBox = '';
            }

            $table = Xml::fieldset( $this->msg( 'undelete-fieldset-title' )->text() ) .
                Xml::openElement( 'table', array( 'id' => 'mw-undelete-table' ) ) .
                "<tr>
                    <td colspan='2' class='mw-undelete-extrahelp'>" .
                $this->msg( 'undeleteextrahelp' )->parseAsBlock() .
                "</td>
            </tr>
            <tr>
                <td class='mw-label'>" .
                Xml::label( $this->msg( 'undeletecomment' )->text(), 'wpComment' ) .
                "</td>
                <td class='mw-input'>" .
                Xml::input(
                    'wpComment',
                    50,
                    $this->mComment,
                    array( 'id' => 'wpComment', 'autofocus' => true )
                ) .
                "</td>
            </tr>
            <tr>
                <td>&#160;</td>
                <td class='mw-submit'>" .
                Xml::submitButton(
                    $this->msg( 'undeletebtn' )->text(),
                    array( 'name' => 'restore', 'id' => 'mw-undelete-submit' )
                ) . ' ' .
                Xml::submitButton(
                    $this->msg( 'undeleteinvert' )->text(),
                    array( 'name' => 'invert', 'id' => 'mw-undelete-invert' )
                ) .
                "</td>
            </tr>" .
                $unsuppressBox .
                Xml::closeElement( 'table' ) .
                Xml::closeElement( 'fieldset' );

            $out->addHTML( $table );
        }

        $out->addHTML( Xml::element( 'h2', null, $this->msg( 'history' )->text() ) . "\n" );

        if ( $haveRevisions ) {
            # The page's stored (deleted) history:
            $out->addHTML( '<ul>' );
            $remaining = $revisions->numRows();
            $earliestLiveTime = $this->mTargetObj->getEarliestRevTime();

            foreach ( $revisions as $row ) {
                $remaining--;
                $out->addHTML( $this->formatRevisionRow( $row, $earliestLiveTime, $remaining ) );
            }
            $revisions->free();
            $out->addHTML( '</ul>' );
        } else {
            $out->addWikiMsg( 'nohistory' );
        }

        if ( $haveFiles ) {
            $out->addHTML( Xml::element( 'h2', null, $this->msg( 'filehist' )->text() ) . "\n" );
            $out->addHTML( '<ul>' );
            foreach ( $files as $row ) {
                $out->addHTML( $this->formatFileRow( $row ) );
            }
            $files->free();
            $out->addHTML( '</ul>' );
        }

        if ( $this->mAllowed ) {
            # Slip in the hidden controls here
            $misc = Html::hidden( 'target', $this->mTarget );
            $misc .= Html::hidden( 'wpEditToken', $this->getUser()->getEditToken() );
            $misc .= Xml::closeElement( 'form' );
            $out->addHTML( $misc );
        }

        return true;
    }

    private function formatRevisionRow( $row, $earliestLiveTime, $remaining ) {
        $rev = Revision::newFromArchiveRow( $row,
            array(
                'title' => $this->mTargetObj
            ) );

        $revTextSize = '';
        $ts = wfTimestamp( TS_MW, $row->ar_timestamp );
        // Build checkboxen...
        if ( $this->mAllowed ) {
            if ( $this->mInvert ) {
                if ( in_array( $ts, $this->mTargetTimestamp ) ) {
                    $checkBox = Xml::check( "ts$ts" );
                } else {
                    $checkBox = Xml::check( "ts$ts", true );
                }
            } else {
                $checkBox = Xml::check( "ts$ts" );
            }
        } else {
            $checkBox = '';
        }

        // Build page & diff links...
        $user = $this->getUser();
        if ( $this->mCanView ) {
            $titleObj = $this->getPageTitle();
            # Last link
            if ( !$rev->userCan( Revision::DELETED_TEXT, $this->getUser() ) ) {
                $pageLink = htmlspecialchars( $this->getLanguage()->userTimeAndDate( $ts, $user ) );
                $last = $this->msg( 'diff' )->escaped();
            } elseif ( $remaining > 0 || ( $earliestLiveTime && $ts > $earliestLiveTime ) ) {
                $pageLink = $this->getPageLink( $rev, $titleObj, $ts );
                $last = Linker::linkKnown(
                    $titleObj,
                    $this->msg( 'diff' )->escaped(),
                    array(),
                    array(
                        'target' => $this->mTargetObj->getPrefixedText(),
                        'timestamp' => $ts,
                        'diff' => 'prev'
                    )
                );
            } else {
                $pageLink = $this->getPageLink( $rev, $titleObj, $ts );
                $last = $this->msg( 'diff' )->escaped();
            }
        } else {
            $pageLink = htmlspecialchars( $this->getLanguage()->userTimeAndDate( $ts, $user ) );
            $last = $this->msg( 'diff' )->escaped();
        }

        // User links
        $userLink = Linker::revUserTools( $rev );

        // Minor edit
        $minor = $rev->isMinor() ? ChangesList::flag( 'minor' ) : '';

        // Revision text size
        $size = $row->ar_len;
        if ( !is_null( $size ) ) {
            $revTextSize = Linker::formatRevisionSize( $size );
        }

        // Edit summary
        $comment = Linker::revComment( $rev );

        // Tags
        $attribs = array();
        list( $tagSummary, $classes ) = ChangeTags::formatSummaryRow( $row->ts_tags, 'deletedhistory' );
        if ( $classes ) {
            $attribs['class'] = implode( ' ', $classes );
        }

        // Revision delete links
        $revdlink = Linker::getRevDeleteLink( $user, $rev, $this->mTargetObj );

        $revisionRow = $this->msg( 'undelete-revision-row' )
            ->rawParams(
                $checkBox,
                $revdlink,
                $last,
                $pageLink,
                $userLink,
                $minor,
                $revTextSize,
                $comment,
                $tagSummary
            )
            ->escaped();

        return Xml::tags( 'li', $attribs, $revisionRow ) . "\n";
    }

    private function formatFileRow( $row ) {
        $file = ArchivedFile::newFromRow( $row );
        $ts = wfTimestamp( TS_MW, $row->fa_timestamp );
        $user = $this->getUser();

        if ( $this->mAllowed && $row->fa_storage_key ) {
            $checkBox = Xml::check( 'fileid' . $row->fa_id );
            $key = urlencode( $row->fa_storage_key );
            $pageLink = $this->getFileLink( $file, $this->getPageTitle(), $ts, $key );
        } else {
            $checkBox = '';
            $pageLink = $this->getLanguage()->userTimeAndDate( $ts, $user );
        }
        $userLink = $this->getFileUser( $file );
        $data = $this->msg( 'widthheight' )->numParams( $row->fa_width, $row->fa_height )->text();
        $bytes = $this->msg( 'parentheses' )
            ->rawParams( $this->msg( 'nbytes' )->numParams( $row->fa_size )->text() )
            ->plain();
        $data = htmlspecialchars( $data . ' ' . $bytes );
        $comment = $this->getFileComment( $file );

        // Add show/hide deletion links if available
        $canHide = $user->isAllowed( 'deleterevision' );
        if ( $canHide || ( $file->getVisibility() && $user->isAllowed( 'deletedhistory' ) ) ) {
            if ( !$file->userCan( File::DELETED_RESTRICTED, $user ) ) {
                // Revision was hidden from sysops
                $revdlink = Linker::revDeleteLinkDisabled( $canHide );
            } else {
                $query = array(
                    'type' => 'filearchive',
                    'target' => $this->mTargetObj->getPrefixedDBkey(),
                    'ids' => $row->fa_id
                );
                $revdlink = Linker::revDeleteLink( $query,
                    $file->isDeleted( File::DELETED_RESTRICTED ), $canHide );
            }
        } else {
            $revdlink = '';
        }

        return "<li>$checkBox $revdlink $pageLink . . $userLink $data $comment</li>\n";
    }

    function getPageLink( $rev, $titleObj, $ts ) {
        $user = $this->getUser();
        $time = $this->getLanguage()->userTimeAndDate( $ts, $user );

        if ( !$rev->userCan( Revision::DELETED_TEXT, $user ) ) {
            return '<span class="history-deleted">' . $time . '</span>';
        }

        $link = Linker::linkKnown(
            $titleObj,
            htmlspecialchars( $time ),
            array(),
            array(
                'target' => $this->mTargetObj->getPrefixedText(),
                'timestamp' => $ts
            )
        );

        if ( $rev->isDeleted( Revision::DELETED_TEXT ) ) {
            $link = '<span class="history-deleted">' . $link . '</span>';
        }

        return $link;
    }

    function getFileLink( $file, $titleObj, $ts, $key ) {
        $user = $this->getUser();
        $time = $this->getLanguage()->userTimeAndDate( $ts, $user );

        if ( !$file->userCan( File::DELETED_FILE, $user ) ) {
            return '<span class="history-deleted">' . $time . '</span>';
        }

        $link = Linker::linkKnown(
            $titleObj,
            htmlspecialchars( $time ),
            array(),
            array(
                'target' => $this->mTargetObj->getPrefixedText(),
                'file' => $key,
                'token' => $user->getEditToken( $key )
            )
        );

        if ( $file->isDeleted( File::DELETED_FILE ) ) {
            $link = '<span class="history-deleted">' . $link . '</span>';
        }

        return $link;
    }

    function getFileUser( $file ) {
        if ( !$file->userCan( File::DELETED_USER, $this->getUser() ) ) {
            return '<span class="history-deleted">' .
                $this->msg( 'rev-deleted-user' )->escaped() .
                '</span>';
        }

        $link = Linker::userLink( $file->getRawUser(), $file->getRawUserText() ) .
            Linker::userToolLinks( $file->getRawUser(), $file->getRawUserText() );

        if ( $file->isDeleted( File::DELETED_USER ) ) {
            $link = '<span class="history-deleted">' . $link . '</span>';
        }

        return $link;
    }

    function getFileComment( $file ) {
        if ( !$file->userCan( File::DELETED_COMMENT, $this->getUser() ) ) {
            return '<span class="history-deleted"><span class="comment">' .
                $this->msg( 'rev-deleted-comment' )->escaped() . '</span></span>';
        }

        $link = Linker::commentBlock( $file->getRawDescription() );

        if ( $file->isDeleted( File::DELETED_COMMENT ) ) {
            $link = '<span class="history-deleted">' . $link . '</span>';
        }

        return $link;
    }

    function undelete() {
        global $wgUploadMaintenance;

        if ( $wgUploadMaintenance && $this->mTargetObj->getNamespace() == NS_FILE ) {
            throw new ErrorPageError( 'undelete-error', 'filedelete-maintenance' );
        }

        if ( wfReadOnly() ) {
            throw new ReadOnlyError;
        }

        $out = $this->getOutput();
        $archive = new PageArchive( $this->mTargetObj );
        wfRunHooks( 'UndeleteForm::undelete', array( &$archive, $this->mTargetObj ) );
        $ok = $archive->undelete(
            $this->mTargetTimestamp,
            $this->mComment,
            $this->mFileVersions,
            $this->mUnsuppress,
            $this->getUser()
        );

        if ( is_array( $ok ) ) {
            if ( $ok[1] ) { // Undeleted file count
                wfRunHooks( 'FileUndeleteComplete', array(
                    $this->mTargetObj, $this->mFileVersions,
                    $this->getUser(), $this->mComment ) );
            }

            $link = Linker::linkKnown( $this->mTargetObj );
            $out->addHTML( $this->msg( 'undeletedpage' )->rawParams( $link )->parse() );
        } else {
            $out->setPageTitle( $this->msg( 'undelete-error' ) );
        }

        // Show revision undeletion warnings and errors
        $status = $archive->getRevisionStatus();
        if ( $status && !$status->isGood() ) {
            $out->addWikiText( '<div class="error">' .
                $status->getWikiText(
                    'cannotundelete',
                    'cannotundelete'
                ) . '</div>'
            );
        }

        // Show file undeletion warnings and errors
        $status = $archive->getFileStatus();
        if ( $status && !$status->isGood() ) {
            $out->addWikiText( '<div class="error">' .
                $status->getWikiText(
                    'undelete-error-short',
                    'undelete-error-long'
                ) . '</div>'
            );
        }
    }

    protected function getGroupName() {
        return 'pagetools';
    }
}