Merge "Update docs/hooks.txt for ShowSearchHitTitle"

[mediawiki.git] / includes / MergeHistory.php

<?php

/**
 *
 *
 * Created on Dec 29, 2015
 *
 * Copyright © 2015 Geoffrey Mon <geofbot@gmail.com>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License along
 * with this program; if not, write to the Free Software Foundation, Inc.,
 * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
 * http://www.gnu.org/copyleft/gpl.html
 *
 * @file
 */

/**
 * Handles the backend logic of merging the histories of two
 * pages.
 *
 * @since 1.27
 */
class MergeHistory {

        /** @const int Maximum number of revisions that can be merged at once */
        const REVISION_LIMIT = 5000;

        /** @var Title Page from which history will be merged */
        protected $source;

        /** @var Title Page to which history will be merged */
        protected $dest;

        /** @var IDatabase Database that we are using */
        protected $dbw;

        /** @var MWTimestamp Maximum timestamp that we can use (oldest timestamp of dest) */
        protected $maxTimestamp;

        /** @var string SQL WHERE condition that selects source revisions to insert into destination */
        protected $timeWhere;

        /** @var MWTimestamp|bool Timestamp upto which history from the source will be merged */
        protected $timestampLimit;

        /** @var integer Number of revisions merged (for Special:MergeHistory success message) */
        protected $revisionsMerged;

        /**
         * MergeHistory constructor.
         * @param Title $source Page from which history will be merged
         * @param Title $dest Page to which history will be merged
         * @param string|bool $timestamp Timestamp up to which history from the source will be merged
         */
        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;
                }
        }

        /**
         * Get the number of revisions that will be moved
         * @return int
         */
        public function getRevisionCount() {
                $count = $this->dbw->selectRowCount( 'revision', '1',
                        [ 'rev_page' => $this->source->getArticleID(), $this->timeWhere ],
                        __METHOD__,
                        [ 'LIMIT' => self::REVISION_LIMIT + 1 ]
                );

                return $count;
        }

        /**
         * Get the number of revisions that were moved
         * Used in the SpecialMergeHistory success message
         * @return int
         */
        public function getMergedRevisionCount() {
                return $this->revisionsMerged;
        }

        /**
         * Check if the merge is possible
         * @param User $user
         * @param string $reason
         * @return Status
         */
        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;
        }

        /**
         * Does various sanity checks that the merge is
         * valid. Only things based on the two pages
         * should be checked here.
         *
         * @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;
        }

        /**
         * Actually attempt the history move
         *
         * @todo if all versions of page A are moved to B and then a user
         * tries to do a reverse-merge via the "unmerge" log link, then page
         * A will still be a redirect (as it was after the original merge),
         * though it will have the old revisions back from before (as expected).
         * The user may have to "undo" the redirect manually to finish the "unmerge".
         * Maybe this should delete redirects at the source page of merges?
         *
         * @param User $user
         * @param string $reason
         * @return Status status of the history merge
         */
        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;
        }
}