PageUpdater.php

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<?php
namespace MediaWiki\Storage;

use AtomicSectionUpdate;
use ChangeTags;
use CommentStoreComment;
use Content;
use ContentHandler;
use DeferredUpdates;
use Hooks;
use LogicException;
use ManualLogEntry;
use MediaWiki\Linker\LinkTarget;
use MediaWiki\Revision\MutableRevisionRecord;
use MediaWiki\Revision\RevisionAccessException;
use MediaWiki\Revision\RevisionRecord;
use MediaWiki\Revision\RevisionStore;
use MediaWiki\Revision\SlotRoleRegistry;
use MediaWiki\Revision\SlotRecord;
use MWException;
use RecentChange;
use Revision;
use RuntimeException;
use Status;
use Title;
use User;
use Wikimedia\Assert\Assert;
use Wikimedia\Rdbms\DBConnRef;
use Wikimedia\Rdbms\DBUnexpectedError;
use Wikimedia\Rdbms\IDatabase;
use Wikimedia\Rdbms\ILoadBalancer;
use WikiPage;

class PageUpdater {

    private $user;

    private $wikiPage;

    private $derivedDataUpdater;

    private $loadBalancer;

    private $revisionStore;

    private $slotRoleRegistry;

    private $useAutomaticEditSummaries = true;

    private $rcPatrolStatus = RecentChange::PRC_UNPATROLLED;

    private $usePageCreationLog = true;

    private $ajaxEditStash = true;

    private $originalRevId = false;

    private $tags = [];

    private $undidRevId = 0;

    private $slotsUpdate;

    private $status = null;

    public function __construct(
        User $user,
        WikiPage $wikiPage,
        DerivedPageDataUpdater $derivedDataUpdater,
        ILoadBalancer $loadBalancer,
        RevisionStore $revisionStore,
        SlotRoleRegistry $slotRoleRegistry
    ) {
        $this->user = $user;
        $this->wikiPage = $wikiPage;
        $this->derivedDataUpdater = $derivedDataUpdater;

        $this->loadBalancer = $loadBalancer;
        $this->revisionStore = $revisionStore;
        $this->slotRoleRegistry = $slotRoleRegistry;

        $this->slotsUpdate = new RevisionSlotsUpdate();
    }

    public function setUseAutomaticEditSummaries( $useAutomaticEditSummaries ) {
        $this->useAutomaticEditSummaries = $useAutomaticEditSummaries;
    }

    public function setRcPatrolStatus( $status ) {
        $this->rcPatrolStatus = $status;
    }

    public function setUsePageCreationLog( $use ) {
        $this->usePageCreationLog = $use;
    }

    public function setAjaxEditStash( $ajaxEditStash ) {
        $this->ajaxEditStash = $ajaxEditStash;
    }

    private function getWikiId() {
        return false; // TODO: get from RevisionStore!
    }

    private function getDBConnectionRef( $mode ) {
        return $this->loadBalancer->getConnectionRef( $mode, [], $this->getWikiId() );
    }

    private function getLinkTarget() {
        // NOTE: eventually, we won't get a WikiPage passed into the constructor any more
        return $this->wikiPage->getTitle();
    }

    private function getTitle() {
        // NOTE: eventually, we won't get a WikiPage passed into the constructor any more
        return $this->wikiPage->getTitle();
    }

    private function getWikiPage() {
        // NOTE: eventually, we won't get a WikiPage passed into the constructor any more
        return $this->wikiPage;
    }

    public function hasEditConflict( $expectedParentRevision ) {
        $parent = $this->grabParentRevision();
        $parentId = $parent ? $parent->getId() : 0;

        return $parentId !== $expectedParentRevision;
    }

    public function grabParentRevision() {
        return $this->derivedDataUpdater->grabCurrentRevision();
    }

    private function checkFlags( $flags ) {
        if ( !( $flags & EDIT_NEW ) && !( $flags & EDIT_UPDATE ) ) {
            $flags |= ( $this->derivedDataUpdater->pageExisted() ) ? EDIT_UPDATE : EDIT_NEW;
        }

        return $flags;
    }

    public function setContent( $role, Content $content ) {
        $this->ensureRoleAllowed( $role );

        $this->slotsUpdate->modifyContent( $role, $content );
    }

    public function setSlot( SlotRecord $slot ) {
        $this->ensureRoleAllowed( $slot->getRole() );

        $this->slotsUpdate->modifySlot( $slot );
    }

    public function inheritSlot( SlotRecord $originalSlot ) {
        // NOTE: slots can be inherited even if the role is not "allowed" on the title.
        // NOTE: this slot is inherited from some other revision, but it's
        // a "modified" slot for the RevisionSlotsUpdate and DerivedPageDataUpdater,
        // since it's not implicitly inherited from the parent revision.
        $inheritedSlot = SlotRecord::newInherited( $originalSlot );
        $this->slotsUpdate->modifySlot( $inheritedSlot );
    }

    public function removeSlot( $role ) {
        $this->ensureRoleNotRequired( $role );

        $this->slotsUpdate->removeSlot( $role );
    }

    public function getOriginalRevisionId() {
        return $this->originalRevId;
    }

    public function setOriginalRevisionId( $originalRevId ) {
        Assert::parameterType( 'integer|boolean', $originalRevId, '$originalRevId' );
        $this->originalRevId = $originalRevId;
    }

    public function getUndidRevisionId() {
        return $this->undidRevId;
    }

    public function setUndidRevisionId( $undidRevId ) {
        Assert::parameterType( 'integer', $undidRevId, '$undidRevId' );
        $this->undidRevId = $undidRevId;
    }

    public function addTag( $tag ) {
        Assert::parameterType( 'string', $tag, '$tag' );
        $this->tags[] = trim( $tag );
    }

    public function addTags( array $tags ) {
        Assert::parameterElementType( 'string', $tags, '$tags' );
        foreach ( $tags as $tag ) {
            $this->addTag( $tag );
        }
    }

    public function getExplicitTags() {
        return $this->tags;
    }

    private function computeEffectiveTags( $flags ) {
        $tags = $this->tags;

        foreach ( $this->slotsUpdate->getModifiedRoles() as $role ) {
            $old_content = $this->getParentContent( $role );

            $handler = $this->getContentHandler( $role );
            $content = $this->slotsUpdate->getModifiedSlot( $role )->getContent();

            // TODO: MCR: Do this for all slots. Also add tags for removing roles!
            $tag = $handler->getChangeTag( $old_content, $content, $flags );
            // If there is no applicable tag, null is returned, so we need to check
            if ( $tag ) {
                $tags[] = $tag;
            }
        }

        // Check for undo tag
        if ( $this->undidRevId !== 0 && in_array( 'mw-undo', ChangeTags::getSoftwareTags() ) ) {
            $tags[] = 'mw-undo';
        }

        return array_unique( $tags );
    }

    private function getParentContent( $role ) {
        $parent = $this->grabParentRevision();

        if ( $parent && $parent->hasSlot( $role ) ) {
            return $parent->getContent( $role, RevisionRecord::RAW );
        }

        return null;
    }

    private function getContentHandler( $role ) {
        // TODO: inject something like a ContentHandlerRegistry
        if ( $this->slotsUpdate->isModifiedSlot( $role ) ) {
            $slot = $this->slotsUpdate->getModifiedSlot( $role );
        } else {
            $parent = $this->grabParentRevision();

            if ( $parent ) {
                $slot = $parent->getSlot( $role, RevisionRecord::RAW );
            } else {
                throw new RevisionAccessException( 'No such slot: ' . $role );
            }
        }

        return ContentHandler::getForModelID( $slot->getModel() );
    }

    private function makeAutoSummary( $flags ) {
        if ( !$this->useAutomaticEditSummaries || ( $flags & EDIT_AUTOSUMMARY ) === 0 ) {
            return CommentStoreComment::newUnsavedComment( '' );
        }

        // NOTE: this generates an auto-summary for SOME RANDOM changed slot!
        // TODO: combine auto-summaries for multiple slots!
        // XXX: this logic should not be in the storage layer!
        $roles = $this->slotsUpdate->getModifiedRoles();
        $role = reset( $roles );

        if ( $role === false ) {
            return CommentStoreComment::newUnsavedComment( '' );
        }

        $handler = $this->getContentHandler( $role );
        $content = $this->slotsUpdate->getModifiedSlot( $role )->getContent();
        $old_content = $this->getParentContent( $role );
        $summary = $handler->getAutosummary( $old_content, $content, $flags );

        return CommentStoreComment::newUnsavedComment( $summary );
    }

    public function saveRevision( CommentStoreComment $summary, $flags = 0 ) {
        // Defend against mistakes caused by differences with the
        // signature of WikiPage::doEditContent.
        Assert::parameterType( 'integer', $flags, '$flags' );

        if ( $this->wasCommitted() ) {
            throw new RuntimeException( 'saveRevision() has already been called on this PageUpdater!' );
        }

        // Low-level sanity check
        if ( $this->getLinkTarget()->getText() === '' ) {
            throw new RuntimeException( 'Something is trying to edit an article with an empty title' );
        }

        // NOTE: slots can be inherited even if the role is not "allowed" on the title.
        $status = Status::newGood();
        $this->checkAllRolesAllowed(
            $this->slotsUpdate->getModifiedRoles(),
            $status
        );
        $this->checkNoRolesRequired(
            $this->slotsUpdate->getRemovedRoles(),
            $status
        );

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

        // Make sure the given content is allowed in the respective slots of this page
        foreach ( $this->slotsUpdate->getModifiedRoles() as $role ) {
            $slot = $this->slotsUpdate->getModifiedSlot( $role );
            $roleHandler = $this->slotRoleRegistry->getRoleHandler( $role );

            if ( !$roleHandler->isAllowedModel( $slot->getModel(), $this->getTitle() ) ) {
                $contentHandler = ContentHandler::getForModelID( $slot->getModel() );
                $this->status = Status::newFatal( 'content-not-allowed-here',
                    ContentHandler::getLocalizedName( $contentHandler->getModelID() ),
                    $this->getTitle()->getPrefixedText(),
                    wfMessage( $roleHandler->getNameMessageKey() )
                    // TODO: defer message lookup to caller
                );
                return null;
            }
        }

        // Load the data from the master database if needed. Needed to check flags.
        // NOTE: This grabs the parent revision as the CAS token, if grabParentRevision
        // wasn't called yet. If the page is modified by another process before we are done with
        // it, this method must fail (with status 'edit-conflict')!
        // NOTE: The parent revision may be different from $this->originalRevisionId.
        $this->grabParentRevision();
        $flags = $this->checkFlags( $flags );

        // Avoid statsd noise and wasted cycles check the edit stash (T136678)
        if ( ( $flags & EDIT_INTERNAL ) || ( $flags & EDIT_FORCE_BOT ) ) {
            $useStashed = false;
        } else {
            $useStashed = $this->ajaxEditStash;
        }

        // TODO: use this only for the legacy hook, and only if something uses the legacy hook
        $wikiPage = $this->getWikiPage();

        $user = $this->user;

        // Prepare the update. This performs PST and generates the canonical ParserOutput.
        $this->derivedDataUpdater->prepareContent(
            $this->user,
            $this->slotsUpdate,
            $useStashed
        );

        // TODO: don't force initialization here!
        // This is a hack to work around the fact that late initialization of the ParserOutput
        // causes ApiFlowEditHeaderTest::testCache to fail. Whether that failure indicates an
        // actual problem, or is just an issue with the test setup, remains to be determined
        // [dk, 2018-03].
        // Anomie said in 2018-03:
        /*
            I suspect that what's breaking is this:

            The old version of WikiPage::doEditContent() called prepareContentForEdit() which
            generated the ParserOutput right then, so when doEditUpdates() gets called from the
            DeferredUpdate scheduled by WikiPage::doCreate() there's no need to parse. I note
            there's a comment there that says "Get the pre-save transform content and final
            parser output".
            The new version of WikiPage::doEditContent() makes a PageUpdater and calls its
            saveRevision(), which calls DerivedPageDataUpdater::prepareContent() and
            PageUpdater::doCreate() without ever having to actually generate a ParserOutput.
            Thus, when DerivedPageDataUpdater::doUpdates() is called from the DeferredUpdate
            scheduled by PageUpdater::doCreate(), it does find that it needs to parse at that point.

            And the order of operations in that Flow test is presumably:

            - Create a page with a call to WikiPage::doEditContent(), in a way that somehow avoids
            processing the DeferredUpdate.
            - Set up the "no set!" mock cache in Flow\Tests\Api\ApiTestCase::expectCacheInvalidate()
            - Then, during the course of doing that test, a $db->commit() results in the
            DeferredUpdates being run.
         */
        $this->derivedDataUpdater->getCanonicalParserOutput();

        $mainContent = $this->derivedDataUpdater->getSlots()->getContent( SlotRecord::MAIN );

        // Trigger pre-save hook (using provided edit summary)
        $hookStatus = Status::newGood( [] );
        // TODO: replace legacy hook!
        // TODO: avoid pass-by-reference, see T193950
        $hook_args = [ &$wikiPage, &$user, &$mainContent, &$summary,
            $flags & EDIT_MINOR, null, null, &$flags, &$hookStatus ];
        // Check if the hook rejected the attempted save
        if ( !Hooks::run( 'PageContentSave', $hook_args ) ) {
            if ( $hookStatus->isOK() ) {
                // Hook returned false but didn't call fatal(); use generic message
                $hookStatus->fatal( 'edit-hook-aborted' );
            }

            $this->status = $hookStatus;
            return null;
        }

        // Provide autosummaries if one is not provided and autosummaries are enabled
        // XXX: $summary == null seems logical, but the empty string may actually come from the user
        // XXX: Move this logic out of the storage layer! It does not belong here! Use a callback?
        if ( $summary->text === '' && $summary->data === null ) {
            $summary = $this->makeAutoSummary( $flags );
        }

        // Actually create the revision and create/update the page.
        // Do NOT yet set $this->status!
        if ( $flags & EDIT_UPDATE ) {
            $status = $this->doModify( $summary, $this->user, $flags );
        } else {
            $status = $this->doCreate( $summary, $this->user, $flags );
        }

        // Promote user to any groups they meet the criteria for
        DeferredUpdates::addCallableUpdate( function () use ( $user ) {
            $user->addAutopromoteOnceGroups( 'onEdit' );
            $user->addAutopromoteOnceGroups( 'onView' ); // b/c
        } );

        // NOTE: set $this->status only after all hooks have been called,
        // so wasCommitted doesn't return true wehn called indirectly from a hook handler!
        $this->status = $status;

        // TODO: replace bad status with Exceptions!
        return ( $this->status && $this->status->isOK() )
            ? $this->status->value['revision-record']
            : null;
    }

    public function wasCommitted() {
        return $this->status !== null;
    }

    public function getStatus() {
        return $this->status;
    }

    public function wasSuccessful() {
        return $this->status && $this->status->isOK();
    }

    public function isNew() {
        return $this->status && $this->status->isOK() && $this->status->value['new'];
    }

    public function isUnchanged() {
        return $this->status
            && $this->status->isOK()
            && $this->status->value['revision-record'] === null;
    }

    public function getNewRevision() {
        return ( $this->status && $this->status->isOK() )
            ? $this->status->value['revision-record']
            : null;
    }

    private function makeNewRevision(
        CommentStoreComment $comment,
        User $user,
        $flags,
        Status $status
    ) {
        $wikiPage = $this->getWikiPage();
        $title = $this->getTitle();
        $parent = $this->grabParentRevision();

        // XXX: we expect to get a MutableRevisionRecord here, but that's a bit brittle!
        // TODO: introduce something like an UnsavedRevisionFactory service instead!
        $rev = $this->derivedDataUpdater->getRevision();
        '@phan-var MutableRevisionRecord $rev';

        $rev->setPageId( $title->getArticleID() );

        if ( $parent ) {
            $oldid = $parent->getId();
            $rev->setParentId( $oldid );
        } else {
            $oldid = 0;
        }

        $rev->setComment( $comment );
        $rev->setUser( $user );
        $rev->setMinorEdit( ( $flags & EDIT_MINOR ) > 0 );

        foreach ( $rev->getSlots()->getSlots() as $slot ) {
            $content = $slot->getContent();

            // XXX: We may push this up to the "edit controller" level, see T192777.
            // XXX: prepareSave() and isValid() could live in SlotRoleHandler
            // XXX: PrepareSave should not take a WikiPage!
            $prepStatus = $content->prepareSave( $wikiPage, $flags, $oldid, $user );

            // TODO: MCR: record which problem arose in which slot.
            $status->merge( $prepStatus );
        }

        $this->checkAllRequiredRoles(
            $rev->getSlotRoles(),
            $status
        );

        return $rev;
    }

    private function doModify( CommentStoreComment $summary, User $user, $flags ) {
        $wikiPage = $this->getWikiPage(); // TODO: use for legacy hooks only!

        // Update article, but only if changed.
        $status = Status::newGood( [ 'new' => false, 'revision' => null, 'revision-record' => null ] );

        $oldRev = $this->grabParentRevision();
        $oldid = $oldRev ? $oldRev->getId() : 0;

        if ( !$oldRev ) {
            // Article gone missing
            $status->fatal( 'edit-gone-missing' );

            return $status;
        }

        $newRevisionRecord = $this->makeNewRevision(
            $summary,
            $user,
            $flags,
            $status
        );

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

        $now = $newRevisionRecord->getTimestamp();

        // XXX: we may want a flag that allows a null revision to be forced!
        $changed = $this->derivedDataUpdater->isChange();

        $dbw = $this->getDBConnectionRef( DB_MASTER );

        if ( $changed ) {
            $dbw->startAtomic( __METHOD__ );

            // Get the latest page_latest value while locking it.
            // Do a CAS style check to see if it's the same as when this method
            // started. If it changed then bail out before touching the DB.
            $latestNow = $wikiPage->lockAndGetLatest(); // TODO: move to storage service, pass DB
            if ( $latestNow != $oldid ) {
                // We don't need to roll back, since we did not modify the database yet.
                // XXX: Or do we want to rollback, any transaction started by calling
                // code will fail? If we want that, we should probably throw an exception.
                $dbw->endAtomic( __METHOD__ );
                // Page updated or deleted in the mean time
                $status->fatal( 'edit-conflict' );

                return $status;
            }

            // At this point we are now comitted to returning an OK
            // status unless some DB query error or other exception comes up.
            // This way callers don't have to call rollback() if $status is bad
            // unless they actually try to catch exceptions (which is rare).

            // Save revision content and meta-data
            $newRevisionRecord = $this->revisionStore->insertRevisionOn( $newRevisionRecord, $dbw );
            $newLegacyRevision = new Revision( $newRevisionRecord );

            // Update page_latest and friends to reflect the new revision
            // TODO: move to storage service
            $wasRedirect = $this->derivedDataUpdater->wasRedirect();
            if ( !$wikiPage->updateRevisionOn( $dbw, $newLegacyRevision, null, $wasRedirect ) ) {
                throw new PageUpdateException( "Failed to update page row to use new revision." );
            }

            // TODO: replace legacy hook!
            $tags = $this->computeEffectiveTags( $flags );
            Hooks::run(
                'NewRevisionFromEditComplete',
                [ $wikiPage, $newLegacyRevision, $this->getOriginalRevisionId(), $user, &$tags ]
            );

            // Update recentchanges
            if ( !( $flags & EDIT_SUPPRESS_RC ) ) {
                // Add RC row to the DB
                RecentChange::notifyEdit(
                    $now,
                    $this->getTitle(),
                    $newRevisionRecord->isMinor(),
                    $user,
                    $summary->text, // TODO: pass object when that becomes possible
                    $oldid,
                    $newRevisionRecord->getTimestamp(),
                    ( $flags & EDIT_FORCE_BOT ) > 0,
                    '',
                    $oldRev->getSize(),
                    $newRevisionRecord->getSize(),
                    $newRevisionRecord->getId(),
                    $this->rcPatrolStatus,
                    $tags
                );
            }

            $user->incEditCount();

            $dbw->endAtomic( __METHOD__ );

            // Return the new revision to the caller
            $status->value['revision-record'] = $newRevisionRecord;

            // TODO: globally replace usages of 'revision' with getNewRevision()
            $status->value['revision'] = $newLegacyRevision;
        } else {
            // T34948: revision ID must be set to page {{REVISIONID}} and
            // related variables correctly. Likewise for {{REVISIONUSER}} (T135261).
            // Since we don't insert a new revision into the database, the least
            // error-prone way is to reuse given old revision.
            $newRevisionRecord = $oldRev;

            $status->warning( 'edit-no-change' );
            // Update page_touched as updateRevisionOn() was not called.
            // Other cache updates are managed in WikiPage::onArticleEdit()
            // via WikiPage::doEditUpdates().
            $this->getTitle()->invalidateCache( $now );
        }

        // Do secondary updates once the main changes have been committed...
        // NOTE: the updates have to be processed before sending the response to the client
        // (DeferredUpdates::PRESEND), otherwise the client may already be following the
        // HTTP redirect to the standard view before dervide data has been created - most
        // importantly, before the parser cache has been updated. This would cause the
        // content to be parsed a second time, or may cause stale content to be shown.
        DeferredUpdates::addUpdate(
            $this->getAtomicSectionUpdate(
                $dbw,
                $wikiPage,
                $newRevisionRecord,
                $user,
                $summary,
                $flags,
                $status,
                [ 'changed' => $changed, ]
            ),
            DeferredUpdates::PRESEND
        );

        return $status;
    }

    private function doCreate( CommentStoreComment $summary, User $user, $flags ) {
        $wikiPage = $this->getWikiPage(); // TODO: use for legacy hooks only!

        if ( !$this->derivedDataUpdater->getSlots()->hasSlot( SlotRecord::MAIN ) ) {
            throw new PageUpdateException( 'Must provide a main slot when creating a page!' );
        }

        $status = Status::newGood( [ 'new' => true, 'revision' => null, 'revision-record' => null ] );

        $newRevisionRecord = $this->makeNewRevision(
            $summary,
            $user,
            $flags,
            $status
        );

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

        $now = $newRevisionRecord->getTimestamp();

        $dbw = $this->getDBConnectionRef( DB_MASTER );
        $dbw->startAtomic( __METHOD__ );

        // Add the page record unless one already exists for the title
        // TODO: move to storage service
        $newid = $wikiPage->insertOn( $dbw );
        if ( $newid === false ) {
            $dbw->endAtomic( __METHOD__ );
            $status->fatal( 'edit-already-exists' );

            return $status;
        }

        // At this point we are now comitted to returning an OK
        // status unless some DB query error or other exception comes up.
        // This way callers don't have to call rollback() if $status is bad
        // unless they actually try to catch exceptions (which is rare).
        $newRevisionRecord->setPageId( $newid );

        // Save the revision text...
        $newRevisionRecord = $this->revisionStore->insertRevisionOn( $newRevisionRecord, $dbw );
        $newLegacyRevision = new Revision( $newRevisionRecord );

        // Update the page record with revision data
        // TODO: move to storage service
        if ( !$wikiPage->updateRevisionOn( $dbw, $newLegacyRevision, 0 ) ) {
            throw new PageUpdateException( "Failed to update page row to use new revision." );
        }

        // TODO: replace legacy hook!
        $tags = $this->computeEffectiveTags( $flags );
        Hooks::run(
            'NewRevisionFromEditComplete',
            [ $wikiPage, $newLegacyRevision, false, $user, &$tags ]
        );

        // Update recentchanges
        if ( !( $flags & EDIT_SUPPRESS_RC ) ) {
            // Add RC row to the DB
            RecentChange::notifyNew(
                $now,
                $this->getTitle(),
                $newRevisionRecord->isMinor(),
                $user,
                $summary->text, // TODO: pass object when that becomes possible
                ( $flags & EDIT_FORCE_BOT ) > 0,
                '',
                $newRevisionRecord->getSize(),
                $newRevisionRecord->getId(),
                $this->rcPatrolStatus,
                $tags
            );
        }

        $user->incEditCount();

        if ( $this->usePageCreationLog ) {
            // Log the page creation
            // @TODO: Do we want a 'recreate' action?
            $logEntry = new ManualLogEntry( 'create', 'create' );
            $logEntry->setPerformer( $user );
            $logEntry->setTarget( $this->getTitle() );
            $logEntry->setComment( $summary->text );
            $logEntry->setTimestamp( $now );
            $logEntry->setAssociatedRevId( $newRevisionRecord->getId() );
            $logEntry->insert();
            // Note that we don't publish page creation events to recentchanges
            // (i.e. $logEntry->publish()) since this would create duplicate entries,
            // one for the edit and one for the page creation.
        }

        $dbw->endAtomic( __METHOD__ );

        // Return the new revision to the caller
        // TODO: globally replace usages of 'revision' with getNewRevision()
        $status->value['revision'] = $newLegacyRevision;
        $status->value['revision-record'] = $newRevisionRecord;

        // Do secondary updates once the main changes have been committed...
        DeferredUpdates::addUpdate(
            $this->getAtomicSectionUpdate(
                $dbw,
                $wikiPage,
                $newRevisionRecord,
                $user,
                $summary,
                $flags,
                $status,
                [ 'created' => true ]
            ),
            DeferredUpdates::PRESEND
        );

        return $status;
    }

    private function getAtomicSectionUpdate(
        IDatabase $dbw,
        WikiPage $wikiPage,
        RevisionRecord $newRevisionRecord,
        User $user,
        CommentStoreComment $summary,
        $flags,
        Status $status,
        $hints = []
    ) {
        return new AtomicSectionUpdate(
            $dbw,
            __METHOD__,
            function () use (
                $wikiPage, $newRevisionRecord, $user,
                $summary, $flags, $status, $hints
            ) {
                // set debug data
                $hints['causeAction'] = 'edit-page';
                $hints['causeAgent'] = $user->getName();

                $newLegacyRevision = new Revision( $newRevisionRecord );
                $mainContent = $newRevisionRecord->getContent( SlotRecord::MAIN, RevisionRecord::RAW );

                // Update links tables, site stats, etc.
                $this->derivedDataUpdater->prepareUpdate( $newRevisionRecord, $hints );
                $this->derivedDataUpdater->doUpdates();

                // TODO: replace legacy hook!
                // TODO: avoid pass-by-reference, see T193950

                if ( $hints['created'] ?? false ) {
                    // Trigger post-create hook
                    $params = [ &$wikiPage, &$user, $mainContent, $summary->text,
                        $flags & EDIT_MINOR, null, null, &$flags, $newLegacyRevision ];
                    Hooks::run( 'PageContentInsertComplete', $params );
                }

                // Trigger post-save hook
                $params = [ &$wikiPage, &$user, $mainContent, $summary->text,
                        $flags & EDIT_MINOR, null, null, &$flags, $newLegacyRevision,
                        &$status, $this->getOriginalRevisionId(), $this->undidRevId ];
                Hooks::run( 'PageContentSaveComplete', $params );
            }
        );
    }

    private function getRequiredSlotRoles() {
        return $this->slotRoleRegistry->getRequiredRoles( $this->getTitle() );
    }

    private function getAllowedSlotRoles() {
        return $this->slotRoleRegistry->getAllowedRoles( $this->getTitle() );
    }

    private function ensureRoleAllowed( $role ) {
        $allowedRoles = $this->getAllowedSlotRoles();
        if ( !in_array( $role, $allowedRoles ) ) {
            throw new PageUpdateException( "Slot role `$role` is not allowed." );
        }
    }

    private function ensureRoleNotRequired( $role ) {
        $requiredRoles = $this->getRequiredSlotRoles();
        if ( in_array( $role, $requiredRoles ) ) {
            throw new PageUpdateException( "Slot role `$role` is required." );
        }
    }

    private function checkAllRolesAllowed( array $roles, Status $status ) {
        $allowedRoles = $this->getAllowedSlotRoles();

        $forbidden = array_diff( $roles, $allowedRoles );
        if ( !empty( $forbidden ) ) {
            $status->error(
                'edit-slots-cannot-add',
                count( $forbidden ),
                implode( ', ', $forbidden )
            );
        }
    }

    private function checkNoRolesRequired( array $roles, Status $status ) {
        $requiredRoles = $this->getRequiredSlotRoles();

        $needed = array_diff( $roles, $requiredRoles );
        if ( !empty( $needed ) ) {
            $status->error(
                'edit-slots-cannot-remove',
                count( $needed ),
                implode( ', ', $needed )
            );
        }
    }

    private function checkAllRequiredRoles( array $roles, Status $status ) {
        $requiredRoles = $this->getRequiredSlotRoles();

        $missing = array_diff( $requiredRoles, $roles );
        if ( !empty( $missing ) ) {
            $status->error(
                'edit-slots-missing',
                count( $missing ),
                implode( ', ', $missing )
            );
        }
    }

}