Revision.php

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<?php
class Revision implements IDBAccessObject {
        protected $mId;

        protected $mPage;
        protected $mUserText;
        protected $mOrigUserText;
        protected $mUser;
        protected $mMinorEdit;
        protected $mTimestamp;
        protected $mDeleted;
        protected $mSize;
        protected $mSha1;
        protected $mParentId;
        protected $mComment;
        protected $mText;
        protected $mTextRow;

        protected $mTitle;
        protected $mCurrent;
        protected $mContentModel;
        protected $mContentFormat;

        protected $mContent;

        protected $mContentHandler;

        // Revision deletion constants
        const DELETED_TEXT = 1;
        const DELETED_COMMENT = 2;
        const DELETED_USER = 4;
        const DELETED_RESTRICTED = 8;
        const SUPPRESSED_USER = 12; // convenience

        // Audience options for accessors
        const FOR_PUBLIC = 1;
        const FOR_THIS_USER = 2;
        const RAW = 3;

        public static function newFromId( $id, $flags = 0 ) {
                return self::newFromConds( array( 'rev_id' => intval( $id ) ), $flags );
        }

        public static function newFromTitle( $title, $id = 0, $flags = 0 ) {
                $conds = array(
                        'page_namespace' => $title->getNamespace(),
                        'page_title'     => $title->getDBkey()
                );
                if ( $id ) {
                        // Use the specified ID
                        $conds['rev_id'] = $id;
                } else {
                        // Use a join to get the latest revision
                        $conds[] = 'rev_id=page_latest';
                }
                return self::newFromConds( $conds, (int)$flags );
        }

        public static function newFromPageId( $pageId, $revId = 0, $flags = 0 ) {
                $conds = array( 'page_id' => $pageId );
                if ( $revId ) {
                        $conds['rev_id'] = $revId;
                } else {
                        // Use a join to get the latest revision
                        $conds[] = 'rev_id = page_latest';
                }
                return self::newFromConds( $conds, (int)$flags );
        }

        public static function newFromArchiveRow( $row, $overrides = array() ) {
                global $wgContentHandlerUseDB;

                $attribs = $overrides + array(
                        'page'       => isset( $row->ar_page_id ) ? $row->ar_page_id : null,
                        'id'         => isset( $row->ar_rev_id ) ? $row->ar_rev_id : null,
                        'comment'    => $row->ar_comment,
                        'user'       => $row->ar_user,
                        'user_text'  => $row->ar_user_text,
                        'timestamp'  => $row->ar_timestamp,
                        'minor_edit' => $row->ar_minor_edit,
                        'text_id'    => isset( $row->ar_text_id ) ? $row->ar_text_id : null,
                        'deleted'    => $row->ar_deleted,
                        'len'        => $row->ar_len,
                        'sha1'       => isset( $row->ar_sha1 ) ? $row->ar_sha1 : null,
                        'content_model'   => isset( $row->ar_content_model ) ? $row->ar_content_model : null,
                        'content_format'  => isset( $row->ar_content_format ) ? $row->ar_content_format : null,
                );

                if ( !$wgContentHandlerUseDB ) {
                        unset( $attribs['content_model'] );
                        unset( $attribs['content_format'] );
                }

                if ( !isset( $attribs['title'] )
                        && isset( $row->ar_namespace )
                        && isset( $row->ar_title ) ) {

                        $attribs['title'] = Title::makeTitle( $row->ar_namespace, $row->ar_title );
                }

                if ( isset( $row->ar_text ) && !$row->ar_text_id ) {
                        // Pre-1.5 ar_text row
                        $attribs['text'] = self::getRevisionText( $row, 'ar_' );
                        if ( $attribs['text'] === false ) {
                                throw new MWException( 'Unable to load text from archive row (possibly bug 22624)' );
                        }
                }
                return new self( $attribs );
        }

        public static function newFromRow( $row ) {
                return new self( $row );
        }

        public static function loadFromId( $db, $id ) {
                return self::loadFromConds( $db, array( 'rev_id' => intval( $id ) ) );
        }

        public static function loadFromPageId( $db, $pageid, $id = 0 ) {
                $conds = array( 'rev_page' => intval( $pageid ), 'page_id'  => intval( $pageid ) );
                if( $id ) {
                        $conds['rev_id'] = intval( $id );
                } else {
                        $conds[] = 'rev_id=page_latest';
                }
                return self::loadFromConds( $db, $conds );
        }

        public static function loadFromTitle( $db, $title, $id = 0 ) {
                if( $id ) {
                        $matchId = intval( $id );
                } else {
                        $matchId = 'page_latest';
                }
                return self::loadFromConds( $db,
                        array(
                                "rev_id=$matchId",
                                'page_namespace' => $title->getNamespace(),
                                'page_title'     => $title->getDBkey()
                        )
                );
        }

        public static function loadFromTimestamp( $db, $title, $timestamp ) {
                return self::loadFromConds( $db,
                        array(
                                'rev_timestamp'  => $db->timestamp( $timestamp ),
                                'page_namespace' => $title->getNamespace(),
                                'page_title'     => $title->getDBkey()
                        )
                );
        }

        private static function newFromConds( $conditions, $flags = 0 ) {
                $db = wfGetDB( ( $flags & self::READ_LATEST ) ? DB_MASTER : DB_SLAVE );
                $rev = self::loadFromConds( $db, $conditions, $flags );
                if ( is_null( $rev ) && wfGetLB()->getServerCount() > 1 ) {
                        if ( !( $flags & self::READ_LATEST ) ) {
                                $dbw = wfGetDB( DB_MASTER );
                                $rev = self::loadFromConds( $dbw, $conditions, $flags );
                        }
                }
                return $rev;
        }

        private static function loadFromConds( $db, $conditions, $flags = 0 ) {
                $res = self::fetchFromConds( $db, $conditions, $flags );
                if( $res ) {
                        $row = $res->fetchObject();
                        if( $row ) {
                                $ret = new Revision( $row );
                                return $ret;
                        }
                }
                $ret = null;
                return $ret;
        }

        public static function fetchRevision( $title ) {
                return self::fetchFromConds(
                        wfGetDB( DB_SLAVE ),
                        array(
                                'rev_id=page_latest',
                                'page_namespace' => $title->getNamespace(),
                                'page_title'     => $title->getDBkey()
                        )
                );
        }

        private static function fetchFromConds( $db, $conditions, $flags = 0 ) {
                $fields = array_merge(
                        self::selectFields(),
                        self::selectPageFields(),
                        self::selectUserFields()
                );
                $options = array( 'LIMIT' => 1 );
                if ( ( $flags & self::READ_LOCKING ) == self::READ_LOCKING ) {
                        $options[] = 'FOR UPDATE';
                }
                return $db->select(
                        array( 'revision', 'page', 'user' ),
                        $fields,
                        $conditions,
                        __METHOD__,
                        $options,
                        array( 'page' => self::pageJoinCond(), 'user' => self::userJoinCond() )
                );
        }

        public static function userJoinCond() {
                return array( 'LEFT JOIN', array( 'rev_user != 0', 'user_id = rev_user' ) );
        }

        public static function pageJoinCond() {
                return array( 'INNER JOIN', array( 'page_id = rev_page' ) );
        }

        public static function selectFields() {
                global $wgContentHandlerUseDB;

                $fields = array(
                        'rev_id',
                        'rev_page',
                        'rev_text_id',
                        'rev_timestamp',
                        'rev_comment',
                        'rev_user_text',
                        'rev_user',
                        'rev_minor_edit',
                        'rev_deleted',
                        'rev_len',
                        'rev_parent_id',
                        'rev_sha1',
                );

                if ( $wgContentHandlerUseDB ) {
                        $fields[] = 'rev_content_format';
                        $fields[] = 'rev_content_model';
                }

                return $fields;
        }

        public static function selectTextFields() {
                return array(
                        'old_text',
                        'old_flags'
                );
        }

        public static function selectPageFields() {
                return array(
                        'page_namespace',
                        'page_title',
                        'page_id',
                        'page_latest',
                        'page_is_redirect',
                        'page_len',
                );
        }

        public static function selectUserFields() {
                return array( 'user_name' );
        }

        public static function getParentLengths( $db, array $revIds ) {
                $revLens = array();
                if ( !$revIds ) {
                        return $revLens; // empty
                }
                wfProfileIn( __METHOD__ );
                $res = $db->select( 'revision',
                        array( 'rev_id', 'rev_len' ),
                        array( 'rev_id' => $revIds ),
                        __METHOD__ );
                foreach ( $res as $row ) {
                        $revLens[$row->rev_id] = $row->rev_len;
                }
                wfProfileOut( __METHOD__ );
                return $revLens;
        }

        function __construct( $row ) {
                if( is_object( $row ) ) {
                        $this->mId        = intval( $row->rev_id );
                        $this->mPage      = intval( $row->rev_page );
                        $this->mTextId    = intval( $row->rev_text_id );
                        $this->mComment   =         $row->rev_comment;
                        $this->mUser      = intval( $row->rev_user );
                        $this->mMinorEdit = intval( $row->rev_minor_edit );
                        $this->mTimestamp =         $row->rev_timestamp;
                        $this->mDeleted   = intval( $row->rev_deleted );

                        if ( !isset( $row->rev_parent_id ) ) {
                                $this->mParentId = null;
                        } else {
                                $this->mParentId = intval( $row->rev_parent_id );
                        }

                        if ( !isset( $row->rev_len ) ) {
                                $this->mSize = null;
                        } else {
                                $this->mSize = intval( $row->rev_len );
                        }

                        if ( !isset( $row->rev_sha1 ) ) {
                                $this->mSha1 = null;
                        } else {
                                $this->mSha1 = $row->rev_sha1;
                        }

                        if( isset( $row->page_latest ) ) {
                                $this->mCurrent = ( $row->rev_id == $row->page_latest );
                                $this->mTitle = Title::newFromRow( $row );
                        } else {
                                $this->mCurrent = false;
                                $this->mTitle = null;
                        }

                        if( !isset( $row->rev_content_model ) || is_null( $row->rev_content_model ) ) {
                                $this->mContentModel = null; # determine on demand if needed
                        } else {
                                $this->mContentModel = strval( $row->rev_content_model );
                        }

                        if( !isset( $row->rev_content_format ) || is_null( $row->rev_content_format ) ) {
                                $this->mContentFormat = null; # determine on demand if needed
                        } else {
                                $this->mContentFormat = strval( $row->rev_content_format );
                        }

                        // Lazy extraction...
                        $this->mText = null;
                        if( isset( $row->old_text ) ) {
                                $this->mTextRow = $row;
                        } else {
                                // 'text' table row entry will be lazy-loaded
                                $this->mTextRow = null;
                        }

                        // Use user_name for users and rev_user_text for IPs...
                        $this->mUserText = null; // lazy load if left null
                        if ( $this->mUser == 0 ) {
                                $this->mUserText = $row->rev_user_text; // IP user
                        } elseif ( isset( $row->user_name ) ) {
                                $this->mUserText = $row->user_name; // logged-in user
                        }
                        $this->mOrigUserText = $row->rev_user_text;
                } elseif( is_array( $row ) ) {
                        // Build a new revision to be saved...
                        global $wgUser; // ugh

                        # if we have a content object, use it to set the model and type
                        if ( !empty( $row['content'] ) ) {
                                //@todo: when is that set? test with external store setup! check out insertOn() [dk]
                                if ( !empty( $row['text_id'] ) ) {
                                        throw new MWException( "Text already stored in external store (id {$row['text_id']}), " .
                                                "can't serialize content object" );
                                }

                                $row['content_model'] = $row['content']->getModel();
                                # note: mContentFormat is initializes later accordingly
                                # note: content is serialized later in this method!
                                # also set text to null?
                        }

                        $this->mId        = isset( $row['id']         ) ? intval( $row['id']         ) : null;
                        $this->mPage      = isset( $row['page']       ) ? intval( $row['page']       ) : null;
                        $this->mTextId    = isset( $row['text_id']    ) ? intval( $row['text_id']    ) : null;
                        $this->mUserText  = isset( $row['user_text']  ) ? strval( $row['user_text']  ) : $wgUser->getName();
                        $this->mUser      = isset( $row['user']       ) ? intval( $row['user']       ) : $wgUser->getId();
                        $this->mMinorEdit = isset( $row['minor_edit'] ) ? intval( $row['minor_edit'] ) : 0;
                        $this->mTimestamp = isset( $row['timestamp']  ) ? strval( $row['timestamp']  ) : wfTimestampNow();
                        $this->mDeleted   = isset( $row['deleted']    ) ? intval( $row['deleted']    ) : 0;
                        $this->mSize      = isset( $row['len']        ) ? intval( $row['len']        ) : null;
                        $this->mParentId  = isset( $row['parent_id']  ) ? intval( $row['parent_id']  ) : null;
                        $this->mSha1      = isset( $row['sha1']  )      ? strval( $row['sha1']  )      : null;

                        $this->mContentModel   = isset( $row['content_model']  )  ? strval( $row['content_model'] )  : null;
                        $this->mContentFormat  = isset( $row['content_format']  ) ? strval( $row['content_format'] ) : null;

                        // Enforce spacing trimming on supplied text
                        $this->mComment   = isset( $row['comment']    ) ?  trim( strval( $row['comment'] ) ) : null;
                        $this->mText      = isset( $row['text']       ) ? rtrim( strval( $row['text']    ) ) : null;
                        $this->mTextRow   = null;

                        $this->mTitle     = isset( $row['title']      ) ? $row['title'] : null;

                        // if we have a Content object, override mText and mContentModel
                        if ( !empty( $row['content'] ) ) {
                                if ( !( $row['content'] instanceof Content ) ) {
                                        throw new MWException( '`content` field must contain a Content object.' );
                                }

                                $handler = $this->getContentHandler();
                                $this->mContent = $row['content'];

                                $this->mContentModel = $this->mContent->getModel();
                                $this->mContentHandler = null;

                                $this->mText = $handler->serializeContent( $row['content'], $this->getContentFormat() );
                        } elseif ( !is_null( $this->mText ) ) {
                                $handler = $this->getContentHandler();
                                $this->mContent = $handler->unserializeContent( $this->mText );
                        }

                        // If we have a Title object, make sure it is consistent with mPage.
                        if ( $this->mTitle && $this->mTitle->exists() ) {
                                if ( $this->mPage === null ) {
                                        // if the page ID wasn't known, set it now
                                        $this->mPage = $this->mTitle->getArticleID();
                                } elseif ( $this->mTitle->getArticleID() !== $this->mPage ) {
                                        // Got different page IDs. This may be legit (e.g. during undeletion),
                                        // but it seems worth mentioning it in the log.
                                        wfDebug( "Page ID " . $this->mPage . " mismatches the ID " .
                                                $this->mTitle->getArticleID() . " provided by the Title object." );
                                }
                        }

                        $this->mCurrent = false;

                        // If we still have no length, see it we have the text to figure it out
                        if ( !$this->mSize ) {
                                if ( !is_null( $this->mContent ) ) {
                                        $this->mSize = $this->mContent->getSize();
                                } else {
                                        #NOTE: this should never happen if we have either text or content object!
                                        $this->mSize = null;
                                }
                        }

                        // Same for sha1
                        if ( $this->mSha1 === null ) {
                                $this->mSha1 = is_null( $this->mText ) ? null : self::base36Sha1( $this->mText );
                        }

                        // force lazy init
                        $this->getContentModel();
                        $this->getContentFormat();
                } else {
                        throw new MWException( 'Revision constructor passed invalid row format.' );
                }
                $this->mUnpatrolled = null;
        }

        public function getId() {
                return $this->mId;
        }

        public function setId( $id ) {
                $this->mId = $id;
        }

        public function getTextId() {
                return $this->mTextId;
        }

        public function getParentId() {
                return $this->mParentId;
        }

        public function getSize() {
                return $this->mSize;
        }

        public function getSha1() {
                return $this->mSha1;
        }

        public function getTitle() {
                if( isset( $this->mTitle ) ) {
                        return $this->mTitle;
                }
                if( !is_null( $this->mId ) ) { //rev_id is defined as NOT NULL, but this revision may not yet have been inserted.
                        $dbr = wfGetDB( DB_SLAVE );
                        $row = $dbr->selectRow(
                                array( 'page', 'revision' ),
                                self::selectPageFields(),
                                array( 'page_id=rev_page',
                                        'rev_id' => $this->mId ),
                                __METHOD__ );
                        if ( $row ) {
                                $this->mTitle = Title::newFromRow( $row );
                        }
                }

                if ( !$this->mTitle && !is_null( $this->mPage ) && $this->mPage > 0 ) {
                        $this->mTitle = Title::newFromID( $this->mPage );
                }

                return $this->mTitle;
        }

        public function setTitle( $title ) {
                $this->mTitle = $title;
        }

        public function getPage() {
                return $this->mPage;
        }

        public function getUser( $audience = self::FOR_PUBLIC, User $user = null ) {
                if( $audience == self::FOR_PUBLIC && $this->isDeleted( self::DELETED_USER ) ) {
                        return 0;
                } elseif( $audience == self::FOR_THIS_USER && !$this->userCan( self::DELETED_USER, $user ) ) {
                        return 0;
                } else {
                        return $this->mUser;
                }
        }

        public function getRawUser() {
                return $this->mUser;
        }

        public function getUserText( $audience = self::FOR_PUBLIC, User $user = null ) {
                if( $audience == self::FOR_PUBLIC && $this->isDeleted( self::DELETED_USER ) ) {
                        return '';
                } elseif( $audience == self::FOR_THIS_USER && !$this->userCan( self::DELETED_USER, $user ) ) {
                        return '';
                } else {
                        return $this->getRawUserText();
                }
        }

        public function getRawUserText() {
                if ( $this->mUserText === null ) {
                        $this->mUserText = User::whoIs( $this->mUser ); // load on demand
                        if ( $this->mUserText === false ) {
                                # This shouldn't happen, but it can if the wiki was recovered
                                # via importing revs and there is no user table entry yet.
                                $this->mUserText = $this->mOrigUserText;
                        }
                }
                return $this->mUserText;
        }

        function getComment( $audience = self::FOR_PUBLIC, User $user = null ) {
                if( $audience == self::FOR_PUBLIC && $this->isDeleted( self::DELETED_COMMENT ) ) {
                        return '';
                } elseif( $audience == self::FOR_THIS_USER && !$this->userCan( self::DELETED_COMMENT, $user ) ) {
                        return '';
                } else {
                        return $this->mComment;
                }
        }

        public function getRawComment() {
                return $this->mComment;
        }

        public function isMinor() {
                return (bool)$this->mMinorEdit;
        }

        public function isUnpatrolled() {
                if( $this->mUnpatrolled !== null ) {
                        return $this->mUnpatrolled;
                }
                $dbr = wfGetDB( DB_SLAVE );
                $this->mUnpatrolled = $dbr->selectField( 'recentchanges',
                        'rc_id',
                        array( // Add redundant user,timestamp condition so we can use the existing index
                                'rc_user_text'  => $this->getRawUserText(),
                                'rc_timestamp'  => $dbr->timestamp( $this->getTimestamp() ),
                                'rc_this_oldid' => $this->getId(),
                                'rc_patrolled'  => 0
                        ),
                        __METHOD__
                );
                return (int)$this->mUnpatrolled;
        }

        public function isDeleted( $field ) {
                return ( $this->mDeleted & $field ) == $field;
        }

        public function getVisibility() {
                return (int)$this->mDeleted;
        }

        public function getText( $audience = self::FOR_PUBLIC, User $user = null ) {
                ContentHandler::deprecated( __METHOD__, '1.21' );

                $content = $this->getContent( $audience, $user );
                return ContentHandler::getContentText( $content ); # returns the raw content text, if applicable
        }

        public function getContent( $audience = self::FOR_PUBLIC, User $user = null ) {
                if( $audience == self::FOR_PUBLIC && $this->isDeleted( self::DELETED_TEXT ) ) {
                        return null;
                } elseif( $audience == self::FOR_THIS_USER && !$this->userCan( self::DELETED_TEXT, $user ) ) {
                        return null;
                } else {
                        return $this->getContentInternal();
                }
        }

        public function revText() {
                wfDeprecated( __METHOD__, '1.17' );
                return $this->getText( self::FOR_THIS_USER );
        }

        public function getRawText() {
                ContentHandler::deprecated( __METHOD__, "1.21" );
                return $this->getText( self::RAW );
        }

        public function getSerializedData() {
                return $this->mText;
        }

        protected function getContentInternal() {
                if( is_null( $this->mContent ) ) {
                        // Revision is immutable. Load on demand:
                        if( is_null( $this->mText ) ) {
                                $this->mText = $this->loadText();
                        }

                        if ( $this->mText !== null && $this->mText !== false ) {
                                // Unserialize content
                                $handler = $this->getContentHandler();
                                $format = $this->getContentFormat();

                                $this->mContent = $handler->unserializeContent( $this->mText, $format );
                        } else {
                                $this->mContent = false; // negative caching!
                        }
                }

                // NOTE: copy() will return $this for immutable content objects
                return $this->mContent ? $this->mContent->copy() : null;
        }

        public function getContentModel() {
                if ( !$this->mContentModel ) {
                        $title = $this->getTitle();
                        $this->mContentModel = ( $title ? $title->getContentModel() : CONTENT_MODEL_WIKITEXT );

                        assert( !empty( $this->mContentModel ) );
                }

                return $this->mContentModel;
        }

        public function getContentFormat() {
                if ( !$this->mContentFormat ) {
                        $handler = $this->getContentHandler();
                        $this->mContentFormat = $handler->getDefaultFormat();

                        assert( !empty( $this->mContentFormat ) );
                }

                return $this->mContentFormat;
        }

        public function getContentHandler() {
                if ( !$this->mContentHandler ) {
                        $model = $this->getContentModel();
                        $this->mContentHandler = ContentHandler::getForModelID( $model );

                        $format = $this->getContentFormat();

                        if ( !$this->mContentHandler->isSupportedFormat( $format ) ) {
                                throw new MWException( "Oops, the content format $format is not supported for this content model, $model" );
                        }
                }

                return $this->mContentHandler;
        }

        public function getTimestamp() {
                return wfTimestamp( TS_MW, $this->mTimestamp );
        }

        public function isCurrent() {
                return $this->mCurrent;
        }

        public function getPrevious() {
                if( $this->getTitle() ) {
                        $prev = $this->getTitle()->getPreviousRevisionID( $this->getId() );
                        if( $prev ) {
                                return self::newFromTitle( $this->getTitle(), $prev );
                        }
                }
                return null;
        }

        public function getNext() {
                if( $this->getTitle() ) {
                        $next = $this->getTitle()->getNextRevisionID( $this->getId() );
                        if ( $next ) {
                                return self::newFromTitle( $this->getTitle(), $next );
                        }
                }
                return null;
        }

        private function getPreviousRevisionId( $db ) {
                if( is_null( $this->mPage ) ) {
                        return 0;
                }
                # Use page_latest if ID is not given
                if( !$this->mId ) {
                        $prevId = $db->selectField( 'page', 'page_latest',
                                array( 'page_id' => $this->mPage ),
                                __METHOD__ );
                } else {
                        $prevId = $db->selectField( 'revision', 'rev_id',
                                array( 'rev_page' => $this->mPage, 'rev_id < ' . $this->mId ),
                                __METHOD__,
                                array( 'ORDER BY' => 'rev_id DESC' ) );
                }
                return intval( $prevId );
        }

        public static function getRevisionText( $row, $prefix = 'old_', $wiki = false ) {
                wfProfileIn( __METHOD__ );

                # Get data
                $textField = $prefix . 'text';
                $flagsField = $prefix . 'flags';

                if( isset( $row->$flagsField ) ) {
                        $flags = explode( ',', $row->$flagsField );
                } else {
                        $flags = array();
                }

                if( isset( $row->$textField ) ) {
                        $text = $row->$textField;
                } else {
                        wfProfileOut( __METHOD__ );
                        return false;
                }

                # Use external methods for external objects, text in table is URL-only then
                if ( in_array( 'external', $flags ) ) {
                        $url = $text;
                        $parts = explode( '://', $url, 2 );
                        if( count( $parts ) == 1 || $parts[1] == '' ) {
                                wfProfileOut( __METHOD__ );
                                return false;
                        }
                        $text = ExternalStore::fetchFromURL( $url, array( 'wiki' => $wiki ) );
                }

                // If the text was fetched without an error, convert it
                if ( $text !== false ) {
                        if( in_array( 'gzip', $flags ) ) {
                                # Deal with optional compression of archived pages.
                                # This can be done periodically via maintenance/compressOld.php, and
                                # as pages are saved if $wgCompressRevisions is set.
                                $text = gzinflate( $text );
                        }

                        if( in_array( 'object', $flags ) ) {
                                # Generic compressed storage
                                $obj = unserialize( $text );
                                if ( !is_object( $obj ) ) {
                                        // Invalid object
                                        wfProfileOut( __METHOD__ );
                                        return false;
                                }
                                $text = $obj->getText();
                        }

                        global $wgLegacyEncoding;
                        if( $text !== false && $wgLegacyEncoding
                                && !in_array( 'utf-8', $flags ) && !in_array( 'utf8', $flags ) )
                        {
                                # Old revisions kept around in a legacy encoding?
                                # Upconvert on demand.
                                # ("utf8" checked for compatibility with some broken
                                #  conversion scripts 2008-12-30)
                                global $wgContLang;
                                $text = $wgContLang->iconv( $wgLegacyEncoding, 'UTF-8', $text );
                        }
                }
                wfProfileOut( __METHOD__ );
                return $text;
        }

        public static function compressRevisionText( &$text ) {
                global $wgCompressRevisions;
                $flags = array();

                # Revisions not marked this way will be converted
                # on load if $wgLegacyCharset is set in the future.
                $flags[] = 'utf-8';

                if( $wgCompressRevisions ) {
                        if( function_exists( 'gzdeflate' ) ) {
                                $text = gzdeflate( $text );
                                $flags[] = 'gzip';
                        } else {
                                wfDebug( __METHOD__ . " -- no zlib support, not compressing\n" );
                        }
                }
                return implode( ',', $flags );
        }

        public function insertOn( $dbw ) {
                global $wgDefaultExternalStore, $wgContentHandlerUseDB;

                wfProfileIn( __METHOD__ );

                $this->checkContentModel();

                $data = $this->mText;
                $flags = self::compressRevisionText( $data );

                # Write to external storage if required
                if( $wgDefaultExternalStore ) {
                        // Store and get the URL
                        $data = ExternalStore::insertToDefault( $data );
                        if( !$data ) {
                                throw new MWException( "Unable to store text to external storage" );
                        }
                        if( $flags ) {
                                $flags .= ',';
                        }
                        $flags .= 'external';
                }

                # Record the text (or external storage URL) to the text table
                if( !isset( $this->mTextId ) ) {
                        $old_id = $dbw->nextSequenceValue( 'text_old_id_seq' );
                        $dbw->insert( 'text',
                                array(
                                        'old_id'    => $old_id,
                                        'old_text'  => $data,
                                        'old_flags' => $flags,
                                ), __METHOD__
                        );
                        $this->mTextId = $dbw->insertId();
                }

                if ( $this->mComment === null ) $this->mComment = "";

                # Record the edit in revisions
                $rev_id = isset( $this->mId )
                        ? $this->mId
                        : $dbw->nextSequenceValue( 'revision_rev_id_seq' );
                $row = array(
                        'rev_id'         => $rev_id,
                        'rev_page'       => $this->mPage,
                        'rev_text_id'    => $this->mTextId,
                        'rev_comment'    => $this->mComment,
                        'rev_minor_edit' => $this->mMinorEdit ? 1 : 0,
                        'rev_user'       => $this->mUser,
                        'rev_user_text'  => $this->mUserText,
                        'rev_timestamp'  => $dbw->timestamp( $this->mTimestamp ),
                        'rev_deleted'    => $this->mDeleted,
                        'rev_len'        => $this->mSize,
                        'rev_parent_id'  => is_null( $this->mParentId )
                                ? $this->getPreviousRevisionId( $dbw )
                                : $this->mParentId,
                        'rev_sha1'       => is_null( $this->mSha1 )
                                ? Revision::base36Sha1( $this->mText )
                                : $this->mSha1,
                );

                if ( $wgContentHandlerUseDB ) {
                        //NOTE: Store null for the default model and format, to save space.
                        //XXX: Makes the DB sensitive to changed defaults. Make this behavior optional? Only in miser mode?

                        $model = $this->getContentModel();
                        $format = $this->getContentFormat();

                        $title = $this->getTitle();

                        if ( $title === null ) {
                                throw new MWException( "Insufficient information to determine the title of the revision's page!" );
                        }

                        $defaultModel = ContentHandler::getDefaultModelFor( $title );
                        $defaultFormat = ContentHandler::getForModelID( $defaultModel )->getDefaultFormat();

                        $row[ 'rev_content_model' ] = ( $model === $defaultModel ) ? null : $model;
                        $row[ 'rev_content_format' ] = ( $format === $defaultFormat ) ? null : $format;
                }

                $dbw->insert( 'revision', $row, __METHOD__ );

                $this->mId = !is_null( $rev_id ) ? $rev_id : $dbw->insertId();

                wfRunHooks( 'RevisionInsertComplete', array( &$this, $data, $flags ) );

                wfProfileOut( __METHOD__ );
                return $this->mId;
        }

        protected function checkContentModel() {
                global $wgContentHandlerUseDB;

                $title = $this->getTitle(); //note: may return null for revisions that have not yet been inserted.

                $model = $this->getContentModel();
                $format = $this->getContentFormat();
                $handler = $this->getContentHandler();

                if ( !$handler->isSupportedFormat( $format ) ) {
                        $t = $title->getPrefixedDBkey();

                        throw new MWException( "Can't use format $format with content model $model on $t" );
                }

                if ( !$wgContentHandlerUseDB && $title ) {
                        // if $wgContentHandlerUseDB is not set, all revisions must use the default content model and format.

                        $defaultModel = ContentHandler::getDefaultModelFor( $title );
                        $defaultHandler = ContentHandler::getForModelID( $defaultModel );
                        $defaultFormat = $defaultHandler->getDefaultFormat();

                        if ( $this->getContentModel() != $defaultModel ) {
                                $t = $title->getPrefixedDBkey();

                                throw new MWException( "Can't save non-default content model with \$wgContentHandlerUseDB disabled: "
                                                                                . "model is $model , default for $t is $defaultModel" );
                        }

                        if ( $this->getContentFormat() != $defaultFormat ) {
                                $t = $title->getPrefixedDBkey();

                                throw new MWException( "Can't use non-default content format with \$wgContentHandlerUseDB disabled: "
                                                                                . "format is $format, default for $t is $defaultFormat" );
                        }
                }

                $content = $this->getContent( Revision::RAW );

                if ( !$content || !$content->isValid() ) {
                        $t = $title->getPrefixedDBkey();

                        throw new MWException( "Content of $t is not valid! Content model is $model" );
                }
        }

        public static function base36Sha1( $text ) {
                return wfBaseConvert( sha1( $text ), 16, 36, 31 );
        }

        protected function loadText() {
                wfProfileIn( __METHOD__ );

                // Caching may be beneficial for massive use of external storage
                global $wgRevisionCacheExpiry, $wgMemc;
                $textId = $this->getTextId();
                $key = wfMemcKey( 'revisiontext', 'textid', $textId );
                if( $wgRevisionCacheExpiry ) {
                        $text = $wgMemc->get( $key );
                        if( is_string( $text ) ) {
                                wfDebug( __METHOD__ . ": got id $textId from cache\n" );
                                wfProfileOut( __METHOD__ );
                                return $text;
                        }
                }

                // If we kept data for lazy extraction, use it now...
                if ( isset( $this->mTextRow ) ) {
                        $row = $this->mTextRow;
                        $this->mTextRow = null;
                } else {
                        $row = null;
                }

                if( !$row ) {
                        // Text data is immutable; check slaves first.
                        $dbr = wfGetDB( DB_SLAVE );
                        $row = $dbr->selectRow( 'text',
                                array( 'old_text', 'old_flags' ),
                                array( 'old_id' => $this->getTextId() ),
                                __METHOD__ );
                }

                if( !$row && wfGetLB()->getServerCount() > 1 ) {
                        // Possible slave lag!
                        $dbw = wfGetDB( DB_MASTER );
                        $row = $dbw->selectRow( 'text',
                                array( 'old_text', 'old_flags' ),
                                array( 'old_id' => $this->getTextId() ),
                                __METHOD__ );
                }

                $text = self::getRevisionText( $row );

                # No negative caching -- negative hits on text rows may be due to corrupted slave servers
                if( $wgRevisionCacheExpiry && $text !== false ) {
                        $wgMemc->set( $key, $text, $wgRevisionCacheExpiry );
                }

                wfProfileOut( __METHOD__ );

                return $text;
        }

        public static function newNullRevision( $dbw, $pageId, $summary, $minor ) {
                global $wgContentHandlerUseDB;

                wfProfileIn( __METHOD__ );

                $fields = array( 'page_latest', 'page_namespace', 'page_title',
                                                'rev_text_id', 'rev_len', 'rev_sha1' );

                if ( $wgContentHandlerUseDB ) {
                        $fields[] = 'rev_content_model';
                        $fields[] = 'rev_content_format';
                }

                $current = $dbw->selectRow(
                        array( 'page', 'revision' ),
                        $fields,
                        array(
                                'page_id' => $pageId,
                                'page_latest=rev_id',
                                ),
                        __METHOD__ );

                if( $current ) {
                        $row = array(
                                'page'       => $pageId,
                                'comment'    => $summary,
                                'minor_edit' => $minor,
                                'text_id'    => $current->rev_text_id,
                                'parent_id'  => $current->page_latest,
                                'len'        => $current->rev_len,
                                'sha1'       => $current->rev_sha1
                        );

                        if ( $wgContentHandlerUseDB ) {
                                $row[ 'content_model' ] = $current->rev_content_model;
                                $row[ 'content_format' ] = $current->rev_content_format;
                        }

                        $revision = new Revision( $row );
                        $revision->setTitle( Title::makeTitle( $current->page_namespace, $current->page_title ) );
                } else {
                        $revision = null;
                }

                wfProfileOut( __METHOD__ );
                return $revision;
        }

        public function userCan( $field, User $user = null ) {
                return self::userCanBitfield( $this->mDeleted, $field, $user );
        }

        public static function userCanBitfield( $bitfield, $field, User $user = null ) {
                if( $bitfield & $field ) { // aspect is deleted
                        if ( $bitfield & self::DELETED_RESTRICTED ) {
                                $permission = 'suppressrevision';
                        } elseif ( $field & self::DELETED_TEXT ) {
                                $permission = 'deletedtext';
                        } else {
                                $permission = 'deletedhistory';
                        }
                        wfDebug( "Checking for $permission due to $field match on $bitfield\n" );
                        if ( $user === null ) {
                                global $wgUser;
                                $user = $wgUser;
                        }
                        return $user->isAllowed( $permission );
                } else {
                        return true;
                }
        }

        static function getTimestampFromId( $title, $id ) {
                $dbr = wfGetDB( DB_SLAVE );
                // Casting fix for databases that can't take '' for rev_id
                if ( $id == '' ) {
                        $id = 0;
                }
                $conds = array( 'rev_id' => $id );
                $conds['rev_page'] = $title->getArticleID();
                $timestamp = $dbr->selectField( 'revision', 'rev_timestamp', $conds, __METHOD__ );
                if ( $timestamp === false && wfGetLB()->getServerCount() > 1 ) {
                        # Not in slave, try master
                        $dbw = wfGetDB( DB_MASTER );
                        $timestamp = $dbw->selectField( 'revision', 'rev_timestamp', $conds, __METHOD__ );
                }
                return wfTimestamp( TS_MW, $timestamp );
        }

        static function countByPageId( $db, $id ) {
                $row = $db->selectRow( 'revision', array( 'revCount' => 'COUNT(*)' ),
                        array( 'rev_page' => $id ), __METHOD__ );
                if( $row ) {
                        return $row->revCount;
                }
                return 0;
        }

        static function countByTitle( $db, $title ) {
                $id = $title->getArticleID();
                if( $id ) {
                        return self::countByPageId( $db, $id );
                }
                return 0;
        }

        public static function userWasLastToEdit( $db, $pageId, $userId, $since ) {
                if ( !$userId ) return false;

                if ( is_int( $db ) ) {
                        $db = wfGetDB( $db );
                }

                $res = $db->select( 'revision',
                        'rev_user',
                        array(
                                'rev_page' => $pageId,
                                'rev_timestamp > ' . $db->addQuotes( $db->timestamp( $since ) )
                        ),
                        __METHOD__,
                        array( 'ORDER BY' => 'rev_timestamp ASC', 'LIMIT' => 50 ) );
                foreach ( $res as $row ) {
                        if ( $row->rev_user != $userId ) {
                                return false;
                        }
                }
                return true;
        }
}