MergeHistory.php

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<?php

class MergeHistory {

    const REVISION_LIMIT = 5000;

    protected $source;

    protected $dest;

    protected $dbw;

    protected $maxTimestamp;

    protected $timeWhere;

    protected $timestampLimit;

    protected $revisionsMerged;

    public function __construct( Title $source, Title $dest, $timestamp = false ) {
        // Save the parameters
        $this->source = $source;
        $this->dest = $dest;

        // Get the database
        $this->dbw = wfGetDB( DB_MASTER );

        // Max timestamp should be min of destination page
        $firstDestTimestamp = $this->dbw->selectField(
            'revision',
            'MIN(rev_timestamp)',
            [ 'rev_page' => $this->dest->getArticleID() ],
            __METHOD__
        );
        $this->maxTimestamp = new MWTimestamp( $firstDestTimestamp );

        // Get the timestamp pivot condition
        try {
            if ( $timestamp ) {
                // If we have a requested timestamp, use the
                // latest revision up to that point as the insertion point
                $mwTimestamp = new MWTimestamp( $timestamp );
                $lastWorkingTimestamp = $this->dbw->selectField(
                    'revision',
                    'MAX(rev_timestamp)',
                    [
                        'rev_timestamp <= ' .
                            $this->dbw->addQuotes( $this->dbw->timestamp( $mwTimestamp ) ),
                        'rev_page' => $this->source->getArticleID()
                    ],
                    __METHOD__
                );
                $mwLastWorkingTimestamp = new MWTimestamp( $lastWorkingTimestamp );

                $timeInsert = $mwLastWorkingTimestamp;
                $this->timestampLimit = $mwLastWorkingTimestamp;
            } else {
                // If we don't, merge entire source page history into the
                // beginning of destination page history

                // Get the latest timestamp of the source
                $lastSourceTimestamp = $this->dbw->selectField(
                    [ 'page', 'revision' ],
                    'rev_timestamp',
                    [ 'page_id' => $this->source->getArticleID(),
                        'page_latest = rev_id'
                    ],
                    __METHOD__
                );
                $lasttimestamp = new MWTimestamp( $lastSourceTimestamp );

                $timeInsert = $this->maxTimestamp;
                $this->timestampLimit = $lasttimestamp;
            }

            $this->timeWhere = "rev_timestamp <= " .
                $this->dbw->addQuotes( $this->dbw->timestamp( $timeInsert ) );
        } catch ( TimestampException $ex ) {
            // The timestamp we got is screwed up and merge cannot continue
            // This should be detected by $this->isValidMerge()
            $this->timestampLimit = false;
        }
    }

    public function getRevisionCount() {
        $count = $this->dbw->selectRowCount( 'revision', '1',
            [ 'rev_page' => $this->source->getArticleID(), $this->timeWhere ],
            __METHOD__,
            [ 'LIMIT' => self::REVISION_LIMIT + 1 ]
        );

        return $count;
    }

    public function getMergedRevisionCount() {
        return $this->revisionsMerged;
    }

    public function checkPermissions( User $user, $reason ) {
        $status = new Status();

        // Check if user can edit both pages
        $errors = wfMergeErrorArrays(
            $this->source->getUserPermissionsErrors( 'edit', $user ),
            $this->dest->getUserPermissionsErrors( 'edit', $user )
        );

        // Convert into a Status object
        if ( $errors ) {
            foreach ( $errors as $error ) {
                call_user_func_array( [ $status, 'fatal' ], $error );
            }
        }

        // Anti-spam
        if ( EditPage::matchSummarySpamRegex( $reason ) !== false ) {
            // This is kind of lame, won't display nice
            $status->fatal( 'spamprotectiontext' );
        }

        // Check mergehistory permission
        if ( !$user->isAllowed( 'mergehistory' ) ) {
            // User doesn't have the right to merge histories
            $status->fatal( 'mergehistory-fail-permission' );
        }

        return $status;
    }

    public function isValidMerge() {
        $status = new Status();

        // If either article ID is 0, then revisions cannot be reliably selected
        if ( $this->source->getArticleID() === 0 ) {
            $status->fatal( 'mergehistory-fail-invalid-source' );
        }
        if ( $this->dest->getArticleID() === 0 ) {
            $status->fatal( 'mergehistory-fail-invalid-dest' );
        }

        // Make sure page aren't the same
        if ( $this->source->equals( $this->dest ) ) {
            $status->fatal( 'mergehistory-fail-self-merge' );
        }

        // Make sure the timestamp is valid
        if ( !$this->timestampLimit ) {
            $status->fatal( 'mergehistory-fail-bad-timestamp' );
        }

        // $this->timestampLimit must be older than $this->maxTimestamp
        if ( $this->timestampLimit > $this->maxTimestamp ) {
            $status->fatal( 'mergehistory-fail-timestamps-overlap' );
        }

        // Check that there are not too many revisions to move
        if ( $this->timestampLimit && $this->getRevisionCount() > self::REVISION_LIMIT ) {
            $status->fatal( 'mergehistory-fail-toobig', Message::numParam( self::REVISION_LIMIT ) );
        }

        return $status;
    }

    public function merge( User $user, $reason = '' ) {
        $status = new Status();

        // Check validity and permissions required for merge
        $validCheck = $this->isValidMerge(); // Check this first to check for null pages
        if ( !$validCheck->isOK() ) {
            return $validCheck;
        }
        $permCheck = $this->checkPermissions( $user, $reason );
        if ( !$permCheck->isOK() ) {
            return $permCheck;
        }

        $this->dbw->update(
            'revision',
            [ 'rev_page' => $this->dest->getArticleID() ],
            [ 'rev_page' => $this->source->getArticleID(), $this->timeWhere ],
            __METHOD__
        );

        // Check if this did anything
        $this->revisionsMerged = $this->dbw->affectedRows();
        if ( $this->revisionsMerged < 1 ) {
            $status->fatal( 'mergehistory-fail-no-change' );
            return $status;
        }

        // Make the source page a redirect if no revisions are left
        $haveRevisions = $this->dbw->selectField(
            'revision',
            'rev_timestamp',
            [ 'rev_page' => $this->source->getArticleID() ],
            __METHOD__,
            [ 'FOR UPDATE' ]
        );
        if ( !$haveRevisions ) {
            if ( $reason ) {
                $reason = wfMessage(
                    'mergehistory-comment',
                    $this->source->getPrefixedText(),
                    $this->dest->getPrefixedText(),
                    $reason
                )->inContentLanguage()->text();
            } else {
                $reason = wfMessage(
                    'mergehistory-autocomment',
                    $this->source->getPrefixedText(),
                    $this->dest->getPrefixedText()
                )->inContentLanguage()->text();
            }

            $contentHandler = ContentHandler::getForTitle( $this->source );
            $redirectContent = $contentHandler->makeRedirectContent(
                $this->dest,
                wfMessage( 'mergehistory-redirect-text' )->inContentLanguage()->plain()
            );

            if ( $redirectContent ) {
                $redirectPage = WikiPage::factory( $this->source );
                $redirectRevision = new Revision( [
                    'title' => $this->source,
                    'page' => $this->source->getArticleID(),
                    'comment' => $reason,
                    'content' => $redirectContent ] );
                $redirectRevision->insertOn( $this->dbw );
                $redirectPage->updateRevisionOn( $this->dbw, $redirectRevision );

                // Now, we record the link from the redirect to the new title.
                // It should have no other outgoing links...
                $this->dbw->delete(
                    'pagelinks',
                    [ 'pl_from' => $this->dest->getArticleID() ],
                    __METHOD__
                );
                $this->dbw->insert( 'pagelinks',
                    [
                        'pl_from' => $this->dest->getArticleID(),
                        'pl_from_namespace' => $this->dest->getNamespace(),
                        'pl_namespace' => $this->dest->getNamespace(),
                        'pl_title' => $this->dest->getDBkey() ],
                    __METHOD__
                );
            } else {
                // Warning if we couldn't create the redirect
                $status->warning( 'mergehistory-warning-redirect-not-created' );
            }
        } else {
            $this->source->invalidateCache(); // update histories
        }
        $this->dest->invalidateCache(); // update histories

        // Update our logs
        $logEntry = new ManualLogEntry( 'merge', 'merge' );
        $logEntry->setPerformer( $user );
        $logEntry->setComment( $reason );
        $logEntry->setTarget( $this->source );
        $logEntry->setParameters( [
            '4::dest' => $this->dest->getPrefixedText(),
            '5::mergepoint' => $this->timestampLimit->getTimestamp( TS_MW )
        ] );
        $logId = $logEntry->insert();
        $logEntry->publish( $logId );

        Hooks::run( 'ArticleMergeComplete', [ $this->source, $this->dest ] );

        return $status;
    }
}