PageHistoryHandler.php

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<?php
 
namespace MediaWiki\Rest\Handler;
 
use ChangeTags;
use IDBAccessObject;
use MediaWiki\Page\ExistingPageRecord;
use MediaWiki\Page\PageLookup;
use MediaWiki\Permissions\GroupPermissionsLookup;
use MediaWiki\Rest\LocalizedHttpException;
use MediaWiki\Rest\Response;
use MediaWiki\Rest\SimpleHandler;
use MediaWiki\Revision\RevisionRecord;
use MediaWiki\Revision\RevisionStore;
use MediaWiki\Storage\NameTableAccessException;
use MediaWiki\Storage\NameTableStore;
use MediaWiki\Storage\NameTableStoreFactory;
use TitleFormatter;
use Wikimedia\Message\MessageValue;
use Wikimedia\Message\ParamType;
use Wikimedia\Message\ScalarParam;
use Wikimedia\ParamValidator\ParamValidator;
use Wikimedia\Rdbms\ILoadBalancer;
use Wikimedia\Rdbms\IResultWrapper;
 
class PageHistoryHandler extends SimpleHandler {
    private const REVISIONS_RETURN_LIMIT = 20;
    private const ALLOWED_FILTER_TYPES = [ 'anonymous', 'bot', 'reverted', 'minor' ];
 
    private $revisionStore;
 
    private $changeTagDefStore;
 
    private $groupPermissionsLookup;
 
    private $loadBalancer;
 
    private $pageLookup;
 
    private $titleFormatter;
 
    private $page = false;
 
    public function __construct(
        RevisionStore $revisionStore,
        NameTableStoreFactory $nameTableStoreFactory,
        GroupPermissionsLookup $groupPermissionsLookup,
        ILoadBalancer $loadBalancer,
        PageLookup $pageLookup,
        TitleFormatter $titleFormatter
    ) {
        $this->revisionStore = $revisionStore;
        $this->changeTagDefStore = $nameTableStoreFactory->getChangeTagDef();
        $this->groupPermissionsLookup = $groupPermissionsLookup;
        $this->loadBalancer = $loadBalancer;
        $this->pageLookup = $pageLookup;
        $this->titleFormatter = $titleFormatter;
    }
 
    private function getPage(): ?ExistingPageRecord {
        if ( $this->page === false ) {
            $this->page = $this->pageLookup->getExistingPageByText(
                    $this->getValidatedParams()['title']
                );
        }
        return $this->page;
    }
 
    public function run( $title ) {
        $params = $this->getValidatedParams();
        if ( $params['older_than'] !== null && $params['newer_than'] !== null ) {
            throw new LocalizedHttpException(
                new MessageValue( 'rest-pagehistory-incompatible-params' ), 400 );
        }
 
        if ( ( $params['older_than'] !== null && $params['older_than'] < 1 ) ||
            ( $params['newer_than'] !== null && $params['newer_than'] < 1 )
        ) {
            throw new LocalizedHttpException(
                new MessageValue( 'rest-pagehistory-param-range-error' ), 400 );
        }
 
        $tagIds = [];
        if ( $params['filter'] === 'reverted' ) {
            foreach ( ChangeTags::REVERT_TAGS as $tagName ) {
                try {
                    $tagIds[] = $this->changeTagDefStore->getId( $tagName );
                } catch ( NameTableAccessException $exception ) {
                    // If no revisions are tagged with a name, no tag id will be present
                }
            }
        }
 
        $page = $this->getPage();
        if ( !$page ) {
            throw new LocalizedHttpException(
                new MessageValue( 'rest-nonexistent-title',
                    [ new ScalarParam( ParamType::PLAINTEXT, $title ) ]
                ),
                404
            );
        }
        if ( !$this->getAuthority()->authorizeRead( 'read', $page ) ) {
            throw new LocalizedHttpException(
                new MessageValue( 'rest-permission-denied-title',
                    [ new ScalarParam( ParamType::PLAINTEXT, $title ) ] ),
                403
            );
        }
 
        $relativeRevId = $params['older_than'] ?? $params['newer_than'] ?? 0;
        if ( $relativeRevId ) {
            // Confirm the relative revision exists for this page. If so, get its timestamp.
            $rev = $this->revisionStore->getRevisionByPageId(
                $page->getId(),
                $relativeRevId
            );
            if ( !$rev ) {
                throw new LocalizedHttpException(
                    new MessageValue( 'rest-nonexistent-title-revision',
                        [ $relativeRevId, new ScalarParam( ParamType::PLAINTEXT, $title ) ]
                    ),
                    404
                );
            }
            $ts = $rev->getTimestamp();
            if ( $ts === null ) {
                throw new LocalizedHttpException(
                    new MessageValue( 'rest-pagehistory-timestamp-error',
                        [ $relativeRevId ]
                    ),
                    500
                );
            }
        } else {
            $ts = 0;
        }
 
        $res = $this->getDbResults( $page, $params, $relativeRevId, $ts, $tagIds );
        $response = $this->processDbResults( $res, $page, $params );
        return $this->getResponseFactory()->createJson( $response );
    }
 
    private function getDbResults( ExistingPageRecord $page, array $params, $relativeRevId, $ts, $tagIds ) {
        $dbr = $this->loadBalancer->getConnectionRef( DB_REPLICA );
        $revQuery = $this->revisionStore->getQueryInfo();
        $cond = [
            'rev_page' => $page->getId()
        ];
 
        if ( $params['filter'] ) {
            // This redundant join condition tells MySQL that rev_page and revactor_page are the
            // same, so it can propagate the condition
            if ( isset( $revQuery['tables']['temp_rev_user'] ) /* SCHEMA_COMPAT_READ_TEMP */ ) {
                $revQuery['joins']['temp_rev_user'][1] =
                    "temp_rev_user.revactor_rev = rev_id AND revactor_page = rev_page";
            }
 
            // The validator ensures this value, if present, is one of the expected values
            switch ( $params['filter'] ) {
                case 'bot':
                    $cond[] = 'EXISTS(' . $dbr->selectSQLText(
                            'user_groups',
                            '1',
                            [
                                'actor_rev_user.actor_user = ug_user',
                                'ug_group' => $this->groupPermissionsLookup->getGroupsWithPermission( 'bot' ),
                                'ug_expiry IS NULL OR ug_expiry >= ' . $dbr->addQuotes( $dbr->timestamp() )
                            ],
                            __METHOD__
                        ) . ')';
                    $bitmask = $this->getBitmask();
                    if ( $bitmask ) {
                        $cond[] = $dbr->bitAnd( 'rev_deleted', $bitmask ) . " != $bitmask";
                    }
                    break;
 
                case 'anonymous':
                    $cond[] = "actor_user IS NULL";
                    $bitmask = $this->getBitmask();
                    if ( $bitmask ) {
                        $cond[] = $dbr->bitAnd( 'rev_deleted', $bitmask ) . " != $bitmask";
                    }
                    break;
 
                case 'reverted':
                    if ( !$tagIds ) {
                        return false;
                    }
                    $cond[] = 'EXISTS(' . $dbr->selectSQLText(
                            'change_tag',
                            '1',
                            [ 'ct_rev_id = rev_id', 'ct_tag_id' => $tagIds ],
                            __METHOD__
                        ) . ')';
                    break;
 
                case 'minor':
                    $cond[] = 'rev_minor_edit != 0';
                    break;
            }
        }
 
        if ( $relativeRevId ) {
            $op = $params['older_than'] ? '<' : '>';
            $sort = $params['older_than'] ? 'DESC' : 'ASC';
            $ts = $dbr->addQuotes( $dbr->timestamp( $ts ) );
            $cond[] = "rev_timestamp $op $ts OR " .
                "(rev_timestamp = $ts AND rev_id $op $relativeRevId)";
            $orderBy = "rev_timestamp $sort, rev_id $sort";
        } else {
            $orderBy = "rev_timestamp DESC, rev_id DESC";
        }
 
        // Select one more than the return limit, to learn if there are additional revisions.
        $limit = self::REVISIONS_RETURN_LIMIT + 1;
 
        $res = $dbr->select(
            $revQuery['tables'],
            $revQuery['fields'],
            $cond,
            __METHOD__,
            [
                'ORDER BY' => $orderBy,
                'LIMIT' => $limit,
            ],
            $revQuery['joins']
        );
 
        return $res;
    }
 
    private function getBitmask() {
        if ( !$this->getAuthority()->isAllowed( 'deletedhistory' ) ) {
            $bitmask = RevisionRecord::DELETED_USER;
        } elseif ( !$this->getAuthority()->isAllowedAny( 'suppressrevision', 'viewsuppressed' ) ) {
            $bitmask = RevisionRecord::DELETED_USER | RevisionRecord::DELETED_RESTRICTED;
        } else {
            $bitmask = 0;
        }
        return $bitmask;
    }
 
    private function processDbResults( $res, $page, $params ) {
        $revisions = [];
 
        if ( $res ) {
            $sizes = [];
            foreach ( $res as $row ) {
                $rev = $this->revisionStore->newRevisionFromRow(
                    $row,
                    IDBAccessObject::READ_NORMAL,
                    $page
                );
                if ( !$revisions ) {
                    $firstRevId = $row->rev_id;
                }
                $lastRevId = $row->rev_id;
 
                $revision = [
                    'id' => $rev->getId(),
                    'timestamp' => wfTimestamp( TS_ISO_8601, $rev->getTimestamp() ),
                    'minor' => $rev->isMinor(),
                    'size' => $rev->getSize()
                ];
 
                // Remember revision sizes and parent ids for calculating deltas. If a revision's
                // parent id is unknown, we will be unable to supply the delta for that revision.
                $sizes[$rev->getId()] = $rev->getSize();
                $parentId = $rev->getParentId();
                if ( $parentId ) {
                    $revision['parent_id'] = $parentId;
                }
 
                $comment = $rev->getComment( RevisionRecord::FOR_THIS_USER, $this->getAuthority() );
                $revision['comment'] = $comment ? $comment->text : null;
 
                $revUser = $rev->getUser( RevisionRecord::FOR_THIS_USER, $this->getAuthority() );
                if ( $revUser ) {
                    $revision['user'] = [
                        'id' => $revUser->isRegistered() ? $revUser->getId() : null,
                        'name' => $revUser->getName()
                    ];
                } else {
                    $revision['user'] = null;
                }
 
                $revisions[] = $revision;
 
                // Break manually at the return limit. We may have more results than we can return.
                if ( count( $revisions ) == self::REVISIONS_RETURN_LIMIT ) {
                    break;
                }
            }
 
            // Request any parent sizes that we do not already know, then calculate deltas
            $unknownSizes = [];
            foreach ( $revisions as $revision ) {
                if ( isset( $revision['parent_id'] ) && !isset( $sizes[$revision['parent_id']] ) ) {
                    $unknownSizes[] = $revision['parent_id'];
                }
            }
            if ( $unknownSizes ) {
                $sizes += $this->revisionStore->getRevisionSizes( $unknownSizes );
            }
            foreach ( $revisions as &$revision ) {
                $revision['delta'] = null;
                if ( isset( $revision['parent_id'] ) ) {
                    if ( isset( $sizes[$revision['parent_id']] ) ) {
                        $revision['delta'] = $revision['size'] - $sizes[$revision['parent_id']];
                    }
 
                    // We only remembered this for delta calculations. We do not want to return it.
                    unset( $revision['parent_id'] );
                }
            }
 
            if ( $revisions && $params['newer_than'] ) {
                $revisions = array_reverse( $revisions );
                $temp = $lastRevId;
                $lastRevId = $firstRevId;
                $firstRevId = $temp;
            }
        }
 
        $response = [
            'revisions' => $revisions
        ];
 
        // Omit newer/older if there are no additional corresponding revisions.
        // This facilitates clients doing "paging" style api operations.
        if ( $revisions ) {
            if ( $params['newer_than'] || $res->numRows() > self::REVISIONS_RETURN_LIMIT ) {
                $older = $lastRevId;
            }
            if ( $params['older_than'] ||
                ( $params['newer_than'] && $res->numRows() > self::REVISIONS_RETURN_LIMIT )
            ) {
                $newer = $firstRevId;
            }
        }
 
        $queryParts = [];
 
        if ( isset( $params['filter'] ) ) {
            $queryParts['filter'] = $params['filter'];
        }
 
        $pathParams = [ 'title' => $this->titleFormatter->getPrefixedDBkey( $page ) ];
 
        $response['latest'] = $this->getRouteUrl( $pathParams, $queryParts );
 
        if ( isset( $older ) ) {
            $response['older'] =
                $this->getRouteUrl( $pathParams, $queryParts + [ 'older_than' => $older ] );
        }
        if ( isset( $newer ) ) {
            $response['newer'] =
                $this->getRouteUrl( $pathParams, $queryParts + [ 'newer_than' => $newer ] );
        }
 
        return $response;
    }
 
    public function needsWriteAccess() {
        return false;
    }
 
    public function getParamSettings() {
        return [
            'title' => [
                self::PARAM_SOURCE => 'path',
                ParamValidator::PARAM_TYPE => 'string',
                ParamValidator::PARAM_REQUIRED => true,
            ],
            'older_than' => [
                self::PARAM_SOURCE => 'query',
                ParamValidator::PARAM_TYPE => 'integer',
                ParamValidator::PARAM_REQUIRED => false,
            ],
            'newer_than' => [
                self::PARAM_SOURCE => 'query',
                ParamValidator::PARAM_TYPE => 'integer',
                ParamValidator::PARAM_REQUIRED => false,
            ],
            'filter' => [
                self::PARAM_SOURCE => 'query',
                ParamValidator::PARAM_TYPE => self::ALLOWED_FILTER_TYPES,
                ParamValidator::PARAM_REQUIRED => false,
            ],
        ];
    }
 
    protected function getETag(): ?string {
        $page = $this->getPage();
        if ( !$page ) {
            return null;
        }
 
        return '"' . $page->getLatest() . '"';
    }
 
    protected function getLastModified(): ?string {
        $page = $this->getPage();
        if ( !$page ) {
            return null;
        }
 
        $rev = $this->revisionStore->getKnownCurrentRevision( $page );
        return $rev->getTimestamp();
    }
 
    protected function hasRepresentation() {
        return (bool)$this->getPage();
    }
}