Implement extension registration from an extension.json file

[mediawiki.git] / includes / page / WikiPage.php

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

/**
 * Abstract class for type hinting (accepts WikiPage, Article, ImagePage, CategoryPage)
 */
interface Page {
}

/**
 * Class representing a MediaWiki article and history.
 *
 * Some fields are public only for backwards-compatibility. Use accessors.
 * In the past, this class was part of Article.php and everything was public.
 *
 * @internal documentation reviewed 15 Mar 2010
 */
class WikiPage implements Page, IDBAccessObject {
        // Constants for $mDataLoadedFrom and related

        /**
         * @var Title
         */
        public $mTitle = null;

        /**@{{
         * @protected
         */
        public $mDataLoaded = false;         // !< Boolean
        public $mIsRedirect = false;         // !< Boolean
        public $mLatest = false;             // !< Integer (false means "not loaded")
        /**@}}*/

        /** @var stdClass Map of cache fields (text, parser output, ect) for a proposed/new edit */
        public $mPreparedEdit = false;

        /**
         * @var int
         */
        protected $mId = null;

        /**
         * @var int One of the READ_* constants
         */
        protected $mDataLoadedFrom = self::READ_NONE;

        /**
         * @var Title
         */
        protected $mRedirectTarget = null;

        /**
         * @var Revision
         */
        protected $mLastRevision = null;

        /**
         * @var string Timestamp of the current revision or empty string if not loaded
         */
        protected $mTimestamp = '';

        /**
         * @var string
         */
        protected $mTouched = '19700101000000';

        /**
         * @var string
         */
        protected $mLinksUpdated = '19700101000000';

        /**
         * Constructor and clear the article
         * @param Title $title Reference to a Title object.
         */
        public function __construct( Title $title ) {
                $this->mTitle = $title;
        }

        /**
         * Create a WikiPage object of the appropriate class for the given title.
         *
         * @param Title $title
         *
         * @throws MWException
         * @return WikiPage Object of the appropriate type
         */
        public static function factory( Title $title ) {
                $ns = $title->getNamespace();

                if ( $ns == NS_MEDIA ) {
                        throw new MWException( "NS_MEDIA is a virtual namespace; use NS_FILE." );
                } elseif ( $ns < 0 ) {
                        throw new MWException( "Invalid or virtual namespace $ns given." );
                }

                switch ( $ns ) {
                        case NS_FILE:
                                $page = new WikiFilePage( $title );
                                break;
                        case NS_CATEGORY:
                                $page = new WikiCategoryPage( $title );
                                break;
                        default:
                                $page = new WikiPage( $title );
                }

                return $page;
        }

        /**
         * Constructor from a page id
         *
         * @param int $id Article ID to load
         * @param string|int $from One of the following values:
         *        - "fromdb" or WikiPage::READ_NORMAL to select from a slave database
         *        - "fromdbmaster" or WikiPage::READ_LATEST to select from the master database
         *
         * @return WikiPage|null
         */
        public static function newFromID( $id, $from = 'fromdb' ) {
                // page id's are never 0 or negative, see bug 61166
                if ( $id < 1 ) {
                        return null;
                }

                $from = self::convertSelectType( $from );
                $db = wfGetDB( $from === self::READ_LATEST ? DB_MASTER : DB_SLAVE );
                $row = $db->selectRow( 'page', self::selectFields(), array( 'page_id' => $id ), __METHOD__ );
                if ( !$row ) {
                        return null;
                }
                return self::newFromRow( $row, $from );
        }

        /**
         * Constructor from a database row
         *
         * @since 1.20
         * @param object $row Database row containing at least fields returned by selectFields().
         * @param string|int $from Source of $data:
         *        - "fromdb" or WikiPage::READ_NORMAL: from a slave DB
         *        - "fromdbmaster" or WikiPage::READ_LATEST: from the master DB
         *        - "forupdate" or WikiPage::READ_LOCKING: from the master DB using SELECT FOR UPDATE
         * @return WikiPage
         */
        public static function newFromRow( $row, $from = 'fromdb' ) {
                $page = self::factory( Title::newFromRow( $row ) );
                $page->loadFromRow( $row, $from );
                return $page;
        }

        /**
         * Convert 'fromdb', 'fromdbmaster' and 'forupdate' to READ_* constants.
         *
         * @param object|string|int $type
         * @return mixed
         */
        private static function convertSelectType( $type ) {
                switch ( $type ) {
                case 'fromdb':
                        return self::READ_NORMAL;
                case 'fromdbmaster':
                        return self::READ_LATEST;
                case 'forupdate':
                        return self::READ_LOCKING;
                default:
                        // It may already be an integer or whatever else
                        return $type;
                }
        }

        /**
         * Returns overrides for action handlers.
         * Classes listed here will be used instead of the default one when
         * (and only when) $wgActions[$action] === true. This allows subclasses
         * to override the default behavior.
         *
         * @todo Move this UI stuff somewhere else
         *
         * @return array
         */
        public function getActionOverrides() {
                $content_handler = $this->getContentHandler();
                return $content_handler->getActionOverrides();
        }

        /**
         * Returns the ContentHandler instance to be used to deal with the content of this WikiPage.
         *
         * Shorthand for ContentHandler::getForModelID( $this->getContentModel() );
         *
         * @return ContentHandler
         *
         * @since 1.21
         */
        public function getContentHandler() {
                return ContentHandler::getForModelID( $this->getContentModel() );
        }

        /**
         * Get the title object of the article
         * @return Title Title object of this page
         */
        public function getTitle() {
                return $this->mTitle;
        }

        /**
         * Clear the object
         * @return void
         */
        public function clear() {
                $this->mDataLoaded = false;
                $this->mDataLoadedFrom = self::READ_NONE;

                $this->clearCacheFields();
        }

        /**
         * Clear the object cache fields
         * @return void
         */
        protected function clearCacheFields() {
                $this->mId = null;
                $this->mRedirectTarget = null; // Title object if set
                $this->mLastRevision = null; // Latest revision
                $this->mTouched = '19700101000000';
                $this->mLinksUpdated = '19700101000000';
                $this->mTimestamp = '';
                $this->mIsRedirect = false;
                $this->mLatest = false;
                // Bug 57026: do not clear mPreparedEdit since prepareTextForEdit() already checks
                // the requested rev ID and content against the cached one for equality. For most
                // content types, the output should not change during the lifetime of this cache.
                // Clearing it can cause extra parses on edit for no reason.
        }

        /**
         * Clear the mPreparedEdit cache field, as may be needed by mutable content types
         * @return void
         * @since 1.23
         */
        public function clearPreparedEdit() {
                $this->mPreparedEdit = false;
        }

        /**
         * Return the list of revision fields that should be selected to create
         * a new page.
         *
         * @return array
         */
        public static function selectFields() {
                global $wgContentHandlerUseDB, $wgPageLanguageUseDB;

                $fields = array(
                        'page_id',
                        'page_namespace',
                        'page_title',
                        'page_restrictions',
                        'page_is_redirect',
                        'page_is_new',
                        'page_random',
                        'page_touched',
                        'page_links_updated',
                        'page_latest',
                        'page_len',
                );

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

                if ( $wgPageLanguageUseDB ) {
                        $fields[] = 'page_lang';
                }

                return $fields;
        }

        /**
         * Fetch a page record with the given conditions
         * @param DatabaseBase $dbr
         * @param array $conditions
         * @param array $options
         * @return object|bool Database result resource, or false on failure
         */
        protected function pageData( $dbr, $conditions, $options = array() ) {
                $fields = self::selectFields();

                Hooks::run( 'ArticlePageDataBefore', array( &$this, &$fields ) );

                $row = $dbr->selectRow( 'page', $fields, $conditions, __METHOD__, $options );

                Hooks::run( 'ArticlePageDataAfter', array( &$this, &$row ) );

                return $row;
        }

        /**
         * Fetch a page record matching the Title object's namespace and title
         * using a sanitized title string
         *
         * @param DatabaseBase $dbr
         * @param Title $title
         * @param array $options
         * @return object|bool Database result resource, or false on failure
         */
        public function pageDataFromTitle( $dbr, $title, $options = array() ) {
                return $this->pageData( $dbr, array(
                        'page_namespace' => $title->getNamespace(),
                        'page_title' => $title->getDBkey() ), $options );
        }

        /**
         * Fetch a page record matching the requested ID
         *
         * @param DatabaseBase $dbr
         * @param int $id
         * @param array $options
         * @return object|bool Database result resource, or false on failure
         */
        public function pageDataFromId( $dbr, $id, $options = array() ) {
                return $this->pageData( $dbr, array( 'page_id' => $id ), $options );
        }

        /**
         * Load the object from a given source by title
         *
         * @param object|string|int $from One of the following:
         *   - A DB query result object.
         *   - "fromdb" or WikiPage::READ_NORMAL to get from a slave DB.
         *   - "fromdbmaster" or WikiPage::READ_LATEST to get from the master DB.
         *   - "forupdate"  or WikiPage::READ_LOCKING to get from the master DB
         *     using SELECT FOR UPDATE.
         *
         * @return void
         */
        public function loadPageData( $from = 'fromdb' ) {
                $from = self::convertSelectType( $from );
                if ( is_int( $from ) && $from <= $this->mDataLoadedFrom ) {
                        // We already have the data from the correct location, no need to load it twice.
                        return;
                }

                if ( $from === self::READ_LOCKING ) {
                        $data = $this->pageDataFromTitle( wfGetDB( DB_MASTER ), $this->mTitle, array( 'FOR UPDATE' ) );
                } elseif ( $from === self::READ_LATEST ) {
                        $data = $this->pageDataFromTitle( wfGetDB( DB_MASTER ), $this->mTitle );
                } elseif ( $from === self::READ_NORMAL ) {
                        $data = $this->pageDataFromTitle( wfGetDB( DB_SLAVE ), $this->mTitle );
                        // Use a "last rev inserted" timestamp key to diminish the issue of slave lag.
                        // Note that DB also stores the master position in the session and checks it.
                        $touched = $this->getCachedLastEditTime();
                        if ( $touched ) { // key set
                                if ( !$data || $touched > wfTimestamp( TS_MW, $data->page_touched ) ) {
                                        $from = self::READ_LATEST;
                                        $data = $this->pageDataFromTitle( wfGetDB( DB_MASTER ), $this->mTitle );
                                }
                        }
                } else {
                        // No idea from where the caller got this data, assume slave database.
                        $data = $from;
                        $from = self::READ_NORMAL;
                }

                $this->loadFromRow( $data, $from );
        }

        /**
         * Load the object from a database row
         *
         * @since 1.20
         * @param object $data Database row containing at least fields returned by selectFields()
         * @param string|int $from One of the following:
         *        - "fromdb" or WikiPage::READ_NORMAL if the data comes from a slave DB
         *        - "fromdbmaster" or WikiPage::READ_LATEST if the data comes from the master DB
         *        - "forupdate"  or WikiPage::READ_LOCKING if the data comes from
         *          the master DB using SELECT FOR UPDATE
         */
        public function loadFromRow( $data, $from ) {
                $lc = LinkCache::singleton();
                $lc->clearLink( $this->mTitle );

                if ( $data ) {
                        $lc->addGoodLinkObjFromRow( $this->mTitle, $data );

                        $this->mTitle->loadFromRow( $data );

                        // Old-fashioned restrictions
                        $this->mTitle->loadRestrictions( $data->page_restrictions );

                        $this->mId = intval( $data->page_id );
                        $this->mTouched = wfTimestamp( TS_MW, $data->page_touched );
                        $this->mLinksUpdated = wfTimestampOrNull( TS_MW, $data->page_links_updated );
                        $this->mIsRedirect = intval( $data->page_is_redirect );
                        $this->mLatest = intval( $data->page_latest );
                        // Bug 37225: $latest may no longer match the cached latest Revision object.
                        // Double-check the ID of any cached latest Revision object for consistency.
                        if ( $this->mLastRevision && $this->mLastRevision->getId() != $this->mLatest ) {
                                $this->mLastRevision = null;
                                $this->mTimestamp = '';
                        }
                } else {
                        $lc->addBadLinkObj( $this->mTitle );

                        $this->mTitle->loadFromRow( false );

                        $this->clearCacheFields();

                        $this->mId = 0;
                }

                $this->mDataLoaded = true;
                $this->mDataLoadedFrom = self::convertSelectType( $from );
        }

        /**
         * @return int Page ID
         */
        public function getId() {
                if ( !$this->mDataLoaded ) {
                        $this->loadPageData();
                }
                return $this->mId;
        }

        /**
         * @return bool Whether or not the page exists in the database
         */
        public function exists() {
                if ( !$this->mDataLoaded ) {
                        $this->loadPageData();
                }
                return $this->mId > 0;
        }

        /**
         * Check if this page is something we're going to be showing
         * some sort of sensible content for. If we return false, page
         * views (plain action=view) will return an HTTP 404 response,
         * so spiders and robots can know they're following a bad link.
         *
         * @return bool
         */
        public function hasViewableContent() {
                return $this->exists() || $this->mTitle->isAlwaysKnown();
        }

        /**
         * Tests if the article content represents a redirect
         *
         * @return bool
         */
        public function isRedirect() {
                $content = $this->getContent();
                if ( !$content ) {
                        return false;
                }

                return $content->isRedirect();
        }

        /**
         * Returns the page's content model id (see the CONTENT_MODEL_XXX constants).
         *
         * Will use the revisions actual content model if the page exists,
         * and the page's default if the page doesn't exist yet.
         *
         * @return string
         *
         * @since 1.21
         */
        public function getContentModel() {
                if ( $this->exists() ) {
                        // look at the revision's actual content model
                        $rev = $this->getRevision();

                        if ( $rev !== null ) {
                                return $rev->getContentModel();
                        } else {
                                $title = $this->mTitle->getPrefixedDBkey();
                                wfWarn( "Page $title exists but has no (visible) revisions!" );
                        }
                }

                // use the default model for this page
                return $this->mTitle->getContentModel();
        }

        /**
         * Loads page_touched and returns a value indicating if it should be used
         * @return bool True if not a redirect
         */
        public function checkTouched() {
                if ( !$this->mDataLoaded ) {
                        $this->loadPageData();
                }
                return !$this->mIsRedirect;
        }

        /**
         * Get the page_touched field
         * @return string Containing GMT timestamp
         */
        public function getTouched() {
                if ( !$this->mDataLoaded ) {
                        $this->loadPageData();
                }
                return $this->mTouched;
        }

        /**
         * Get the page_links_updated field
         * @return string|null Containing GMT timestamp
         */
        public function getLinksTimestamp() {
                if ( !$this->mDataLoaded ) {
                        $this->loadPageData();
                }
                return $this->mLinksUpdated;
        }

        /**
         * Get the page_latest field
         * @return int The rev_id of current revision
         */
        public function getLatest() {
                if ( !$this->mDataLoaded ) {
                        $this->loadPageData();
                }
                return (int)$this->mLatest;
        }

        /**
         * Get the Revision object of the oldest revision
         * @return Revision|null
         */
        public function getOldestRevision() {

                // Try using the slave database first, then try the master
                $continue = 2;
                $db = wfGetDB( DB_SLAVE );
                $revSelectFields = Revision::selectFields();

                $row = null;
                while ( $continue ) {
                        $row = $db->selectRow(
                                array( 'page', 'revision' ),
                                $revSelectFields,
                                array(
                                        'page_namespace' => $this->mTitle->getNamespace(),
                                        'page_title' => $this->mTitle->getDBkey(),
                                        'rev_page = page_id'
                                ),
                                __METHOD__,
                                array(
                                        'ORDER BY' => 'rev_timestamp ASC'
                                )
                        );

                        if ( $row ) {
                                $continue = 0;
                        } else {
                                $db = wfGetDB( DB_MASTER );
                                $continue--;
                        }
                }

                return $row ? Revision::newFromRow( $row ) : null;
        }

        /**
         * Loads everything except the text
         * This isn't necessary for all uses, so it's only done if needed.
         */
        protected function loadLastEdit() {
                if ( $this->mLastRevision !== null ) {
                        return; // already loaded
                }

                $latest = $this->getLatest();
                if ( !$latest ) {
                        return; // page doesn't exist or is missing page_latest info
                }

                // Bug 37225: if session S1 loads the page row FOR UPDATE, the result always includes the
                // latest changes committed. This is true even within REPEATABLE-READ transactions, where
                // S1 normally only sees changes committed before the first S1 SELECT. Thus we need S1 to
                // also gets the revision row FOR UPDATE; otherwise, it may not find it since a page row
                // UPDATE and revision row INSERT by S2 may have happened after the first S1 SELECT.
                // http://dev.mysql.com/doc/refman/5.0/en/set-transaction.html#isolevel_repeatable-read.
                $flags = ( $this->mDataLoadedFrom == self::READ_LOCKING ) ? Revision::READ_LOCKING : 0;
                $revision = Revision::newFromPageId( $this->getId(), $latest, $flags );
                if ( $revision ) { // sanity
                        $this->setLastEdit( $revision );
                }
        }

        /**
         * Set the latest revision
         * @param Revision $revision
         */
        protected function setLastEdit( Revision $revision ) {
                $this->mLastRevision = $revision;
                $this->mTimestamp = $revision->getTimestamp();
        }

        /**
         * Get the latest revision
         * @return Revision|null
         */
        public function getRevision() {
                $this->loadLastEdit();
                if ( $this->mLastRevision ) {
                        return $this->mLastRevision;
                }
                return null;
        }

        /**
         * Get the content of the current revision. No side-effects...
         *
         * @param int $audience One of:
         *   Revision::FOR_PUBLIC       to be displayed to all users
         *   Revision::FOR_THIS_USER    to be displayed to $wgUser
         *   Revision::RAW              get the text regardless of permissions
         * @param User $user User object to check for, only if FOR_THIS_USER is passed
         *   to the $audience parameter
         * @return Content|null The content of the current revision
         *
         * @since 1.21
         */
        public function getContent( $audience = Revision::FOR_PUBLIC, User $user = null ) {
                $this->loadLastEdit();
                if ( $this->mLastRevision ) {
                        return $this->mLastRevision->getContent( $audience, $user );
                }
                return null;
        }

        /**
         * Get the text of the current revision. No side-effects...
         *
         * @param int $audience One of:
         *   Revision::FOR_PUBLIC       to be displayed to all users
         *   Revision::FOR_THIS_USER    to be displayed to the given user
         *   Revision::RAW              get the text regardless of permissions
         * @param User $user User object to check for, only if FOR_THIS_USER is passed
         *   to the $audience parameter
         * @return string|bool The text of the current revision
         * @deprecated since 1.21, getContent() should be used instead.
         */
        public function getText( $audience = Revision::FOR_PUBLIC, User $user = null ) {
                ContentHandler::deprecated( __METHOD__, '1.21' );

                $this->loadLastEdit();
                if ( $this->mLastRevision ) {
                        return $this->mLastRevision->getText( $audience, $user );
                }
                return false;
        }

        /**
         * Get the text of the current revision. No side-effects...
         *
         * @return string|bool The text of the current revision. False on failure
         * @deprecated since 1.21, getContent() should be used instead.
         */
        public function getRawText() {
                ContentHandler::deprecated( __METHOD__, '1.21' );

                return $this->getText( Revision::RAW );
        }

        /**
         * @return string MW timestamp of last article revision
         */
        public function getTimestamp() {
                // Check if the field has been filled by WikiPage::setTimestamp()
                if ( !$this->mTimestamp ) {
                        $this->loadLastEdit();
                }

                return wfTimestamp( TS_MW, $this->mTimestamp );
        }

        /**
         * Set the page timestamp (use only to avoid DB queries)
         * @param string $ts MW timestamp of last article revision
         * @return void
         */
        public function setTimestamp( $ts ) {
                $this->mTimestamp = wfTimestamp( TS_MW, $ts );
        }

        /**
         * @param int $audience One of:
         *   Revision::FOR_PUBLIC       to be displayed to all users
         *   Revision::FOR_THIS_USER    to be displayed to the given user
         *   Revision::RAW              get the text regardless of permissions
         * @param User $user User object to check for, only if FOR_THIS_USER is passed
         *   to the $audience parameter
         * @return int User ID for the user that made the last article revision
         */
        public function getUser( $audience = Revision::FOR_PUBLIC, User $user = null ) {
                $this->loadLastEdit();
                if ( $this->mLastRevision ) {
                        return $this->mLastRevision->getUser( $audience, $user );
                } else {
                        return -1;
                }
        }

        /**
         * Get the User object of the user who created the page
         * @param int $audience One of:
         *   Revision::FOR_PUBLIC       to be displayed to all users
         *   Revision::FOR_THIS_USER    to be displayed to the given user
         *   Revision::RAW              get the text regardless of permissions
         * @param User $user User object to check for, only if FOR_THIS_USER is passed
         *   to the $audience parameter
         * @return User|null
         */
        public function getCreator( $audience = Revision::FOR_PUBLIC, User $user = null ) {
                $revision = $this->getOldestRevision();
                if ( $revision ) {
                        $userName = $revision->getUserText( $audience, $user );
                        return User::newFromName( $userName, false );
                } else {
                        return null;
                }
        }

        /**
         * @param int $audience One of:
         *   Revision::FOR_PUBLIC       to be displayed to all users
         *   Revision::FOR_THIS_USER    to be displayed to the given user
         *   Revision::RAW              get the text regardless of permissions
         * @param User $user User object to check for, only if FOR_THIS_USER is passed
         *   to the $audience parameter
         * @return string Username of the user that made the last article revision
         */
        public function getUserText( $audience = Revision::FOR_PUBLIC, User $user = null ) {
                $this->loadLastEdit();
                if ( $this->mLastRevision ) {
                        return $this->mLastRevision->getUserText( $audience, $user );
                } else {
                        return '';
                }
        }

        /**
         * @param int $audience One of:
         *   Revision::FOR_PUBLIC       to be displayed to all users
         *   Revision::FOR_THIS_USER    to be displayed to the given user
         *   Revision::RAW              get the text regardless of permissions
         * @param User $user User object to check for, only if FOR_THIS_USER is passed
         *   to the $audience parameter
         * @return string Comment stored for the last article revision
         */
        public function getComment( $audience = Revision::FOR_PUBLIC, User $user = null ) {
                $this->loadLastEdit();
                if ( $this->mLastRevision ) {
                        return $this->mLastRevision->getComment( $audience, $user );
                } else {
                        return '';
                }
        }

        /**
         * Returns true if last revision was marked as "minor edit"
         *
         * @return bool Minor edit indicator for the last article revision.
         */
        public function getMinorEdit() {
                $this->loadLastEdit();
                if ( $this->mLastRevision ) {
                        return $this->mLastRevision->isMinor();
                } else {
                        return false;
                }
        }

        /**
         * Get the cached timestamp for the last time the page changed.
         * This is only used to help handle slave lag by comparing to page_touched.
         * @return string MW timestamp
         */
        protected function getCachedLastEditTime() {
                global $wgMemc;
                $key = wfMemcKey( 'page-lastedit', md5( $this->mTitle->getPrefixedDBkey() ) );
                return $wgMemc->get( $key );
        }

        /**
         * Set the cached timestamp for the last time the page changed.
         * This is only used to help handle slave lag by comparing to page_touched.
         * @param string $timestamp
         * @return void
         */
        public function setCachedLastEditTime( $timestamp ) {
                global $wgMemc;
                $key = wfMemcKey( 'page-lastedit', md5( $this->mTitle->getPrefixedDBkey() ) );
                $wgMemc->set( $key, wfTimestamp( TS_MW, $timestamp ), 60 * 15 );
        }

        /**
         * Determine whether a page would be suitable for being counted as an
         * article in the site_stats table based on the title & its content
         *
         * @param object|bool $editInfo (false): object returned by prepareTextForEdit(),
         *   if false, the current database state will be used
         * @return bool
         */
        public function isCountable( $editInfo = false ) {
                global $wgArticleCountMethod;

                if ( !$this->mTitle->isContentPage() ) {
                        return false;
                }

                if ( $editInfo ) {
                        $content = $editInfo->pstContent;
                } else {
                        $content = $this->getContent();
                }

                if ( !$content || $content->isRedirect() ) {
                        return false;
                }

                $hasLinks = null;

                if ( $wgArticleCountMethod === 'link' ) {
                        // nasty special case to avoid re-parsing to detect links

                        if ( $editInfo ) {
                                // ParserOutput::getLinks() is a 2D array of page links, so
                                // to be really correct we would need to recurse in the array
                                // but the main array should only have items in it if there are
                                // links.
                                $hasLinks = (bool)count( $editInfo->output->getLinks() );
                        } else {
                                $hasLinks = (bool)wfGetDB( DB_SLAVE )->selectField( 'pagelinks', 1,
                                        array( 'pl_from' => $this->getId() ), __METHOD__ );
                        }
                }

                return $content->isCountable( $hasLinks );
        }

        /**
         * If this page is a redirect, get its target
         *
         * The target will be fetched from the redirect table if possible.
         * If this page doesn't have an entry there, call insertRedirect()
         * @return Title|null Title object, or null if this page is not a redirect
         */
        public function getRedirectTarget() {
                if ( !$this->mTitle->isRedirect() ) {
                        return null;
                }

                if ( $this->mRedirectTarget !== null ) {
                        return $this->mRedirectTarget;
                }

                // Query the redirect table
                $dbr = wfGetDB( DB_SLAVE );
                $row = $dbr->selectRow( 'redirect',
                        array( 'rd_namespace', 'rd_title', 'rd_fragment', 'rd_interwiki' ),
                        array( 'rd_from' => $this->getId() ),
                        __METHOD__
                );

                // rd_fragment and rd_interwiki were added later, populate them if empty
                if ( $row && !is_null( $row->rd_fragment ) && !is_null( $row->rd_interwiki ) ) {
                        $this->mRedirectTarget = Title::makeTitle(
                                $row->rd_namespace, $row->rd_title,
                                $row->rd_fragment, $row->rd_interwiki );
                        return $this->mRedirectTarget;
                }

                // This page doesn't have an entry in the redirect table
                $this->mRedirectTarget = $this->insertRedirect();
                return $this->mRedirectTarget;
        }

        /**
         * Insert an entry for this page into the redirect table.
         *
         * Don't call this function directly unless you know what you're doing.
         * @return Title|null Title object or null if not a redirect
         */
        public function insertRedirect() {
                // recurse through to only get the final target
                $content = $this->getContent();
                $retval = $content ? $content->getUltimateRedirectTarget() : null;
                if ( !$retval ) {
                        return null;
                }
                $this->insertRedirectEntry( $retval );
                return $retval;
        }

        /**
         * Insert or update the redirect table entry for this page to indicate
         * it redirects to $rt .
         * @param Title $rt Redirect target
         */
        public function insertRedirectEntry( $rt ) {
                $dbw = wfGetDB( DB_MASTER );
                $dbw->replace( 'redirect', array( 'rd_from' ),
                        array(
                                'rd_from' => $this->getId(),
                                'rd_namespace' => $rt->getNamespace(),
                                'rd_title' => $rt->getDBkey(),
                                'rd_fragment' => $rt->getFragment(),
                                'rd_interwiki' => $rt->getInterwiki(),
                        ),
                        __METHOD__
                );
        }

        /**
         * Get the Title object or URL this page redirects to
         *
         * @return bool|Title|string False, Title of in-wiki target, or string with URL
         */
        public function followRedirect() {
                return $this->getRedirectURL( $this->getRedirectTarget() );
        }

        /**
         * Get the Title object or URL to use for a redirect. We use Title
         * objects for same-wiki, non-special redirects and URLs for everything
         * else.
         * @param Title $rt Redirect target
         * @return bool|Title|string False, Title object of local target, or string with URL
         */
        public function getRedirectURL( $rt ) {
                if ( !$rt ) {
                        return false;
                }

                if ( $rt->isExternal() ) {
                        if ( $rt->isLocal() ) {
                                // Offsite wikis need an HTTP redirect.
                                //
                                // This can be hard to reverse and may produce loops,
                                // so they may be disabled in the site configuration.
                                $source = $this->mTitle->getFullURL( 'redirect=no' );
                                return $rt->getFullURL( array( 'rdfrom' => $source ) );
                        } else {
                                // External pages without "local" bit set are not valid
                                // redirect targets
                                return false;
                        }
                }

                if ( $rt->isSpecialPage() ) {
                        // Gotta handle redirects to special pages differently:
                        // Fill the HTTP response "Location" header and ignore
                        // the rest of the page we're on.
                        //
                        // Some pages are not valid targets
                        if ( $rt->isValidRedirectTarget() ) {
                                return $rt->getFullURL();
                        } else {
                                return false;
                        }
                }

                return $rt;
        }

        /**
         * Get a list of users who have edited this article, not including the user who made
         * the most recent revision, which you can get from $article->getUser() if you want it
         * @return UserArrayFromResult
         */
        public function getContributors() {
                // @todo FIXME: This is expensive; cache this info somewhere.

                $dbr = wfGetDB( DB_SLAVE );

                if ( $dbr->implicitGroupby() ) {
                        $realNameField = 'user_real_name';
                } else {
                        $realNameField = 'MIN(user_real_name) AS user_real_name';
                }

                $tables = array( 'revision', 'user' );

                $fields = array(
                        'user_id' => 'rev_user',
                        'user_name' => 'rev_user_text',
                        $realNameField,
                        'timestamp' => 'MAX(rev_timestamp)',
                );

                $conds = array( 'rev_page' => $this->getId() );

                // The user who made the top revision gets credited as "this page was last edited by
                // John, based on contributions by Tom, Dick and Harry", so don't include them twice.
                $user = $this->getUser();
                if ( $user ) {
                        $conds[] = "rev_user != $user";
                } else {
                        $conds[] = "rev_user_text != {$dbr->addQuotes( $this->getUserText() )}";
                }

                $conds[] = "{$dbr->bitAnd( 'rev_deleted', Revision::DELETED_USER )} = 0"; // username hidden?

                $jconds = array(
                        'user' => array( 'LEFT JOIN', 'rev_user = user_id' ),
                );

                $options = array(
                        'GROUP BY' => array( 'rev_user', 'rev_user_text' ),
                        'ORDER BY' => 'timestamp DESC',
                );

                $res = $dbr->select( $tables, $fields, $conds, __METHOD__, $options, $jconds );
                return new UserArrayFromResult( $res );
        }

        /**
         * Get the last N authors
         * @param int $num Number of revisions to get
         * @param int|string $revLatest The latest rev_id, selected from the master (optional)
         * @return array Array of authors, duplicates not removed
         */
        public function getLastNAuthors( $num, $revLatest = 0 ) {
                // First try the slave
                // If that doesn't have the latest revision, try the master
                $continue = 2;
                $db = wfGetDB( DB_SLAVE );

                do {
                        $res = $db->select( array( 'page', 'revision' ),
                                array( 'rev_id', 'rev_user_text' ),
                                array(
                                        'page_namespace' => $this->mTitle->getNamespace(),
                                        'page_title' => $this->mTitle->getDBkey(),
                                        'rev_page = page_id'
                                ), __METHOD__,
                                array(
                                        'ORDER BY' => 'rev_timestamp DESC',
                                        'LIMIT' => $num
                                )
                        );

                        if ( !$res ) {
                                return array();
                        }

                        $row = $db->fetchObject( $res );

                        if ( $continue == 2 && $revLatest && $row->rev_id != $revLatest ) {
                                $db = wfGetDB( DB_MASTER );
                                $continue--;
                        } else {
                                $continue = 0;
                        }
                } while ( $continue );

                $authors = array( $row->rev_user_text );

                foreach ( $res as $row ) {
                        $authors[] = $row->rev_user_text;
                }

                return $authors;
        }

        /**
         * Should the parser cache be used?
         *
         * @param ParserOptions $parserOptions ParserOptions to check
         * @param int $oldid
         * @return bool
         */
        public function isParserCacheUsed( ParserOptions $parserOptions, $oldid ) {
                global $wgEnableParserCache;

                return $wgEnableParserCache
                        && $parserOptions->getStubThreshold() == 0
                        && $this->exists()
                        && ( $oldid === null || $oldid === 0 || $oldid === $this->getLatest() )
                        && $this->getContentHandler()->isParserCacheSupported();
        }

        /**
         * Get a ParserOutput for the given ParserOptions and revision ID.
         * The parser cache will be used if possible.
         *
         * @since 1.19
         * @param ParserOptions $parserOptions ParserOptions to use for the parse operation
         * @param null|int $oldid Revision ID to get the text from, passing null or 0 will
         *   get the current revision (default value)
         *
         * @return ParserOutput|bool ParserOutput or false if the revision was not found
         */
        public function getParserOutput( ParserOptions $parserOptions, $oldid = null ) {

                $useParserCache = $this->isParserCacheUsed( $parserOptions, $oldid );
                wfDebug( __METHOD__ . ': using parser cache: ' . ( $useParserCache ? 'yes' : 'no' ) . "\n" );
                if ( $parserOptions->getStubThreshold() ) {
                        wfIncrStats( 'pcache_miss_stub' );
                }

                if ( $useParserCache ) {
                        $parserOutput = ParserCache::singleton()->get( $this, $parserOptions );
                        if ( $parserOutput !== false ) {
                                return $parserOutput;
                        }
                }

                if ( $oldid === null || $oldid === 0 ) {
                        $oldid = $this->getLatest();
                }

                $pool = new PoolWorkArticleView( $this, $parserOptions, $oldid, $useParserCache );
                $pool->execute();


                return $pool->getParserOutput();
        }

        /**
         * Do standard deferred updates after page view (existing or missing page)
         * @param User $user The relevant user
         * @param int $oldid The revision id being viewed. If not given or 0, latest revision is assumed.
         */
        public function doViewUpdates( User $user, $oldid = 0 ) {
                if ( wfReadOnly() ) {
                        return;
                }

                // Update newtalk / watchlist notification status
                $user->clearNotification( $this->mTitle, $oldid );
        }

        /**
         * Perform the actions of a page purging
         * @return bool
         */
        public function doPurge() {
                global $wgUseSquid;

                if ( !Hooks::run( 'ArticlePurge', array( &$this ) ) ) {
                        return false;
                }

                // Invalidate the cache
                $this->mTitle->invalidateCache();

                if ( $wgUseSquid ) {
                        // Commit the transaction before the purge is sent
                        $dbw = wfGetDB( DB_MASTER );
                        $dbw->commit( __METHOD__ );

                        // Send purge
                        $update = SquidUpdate::newSimplePurge( $this->mTitle );
                        $update->doUpdate();
                }

                if ( $this->mTitle->getNamespace() == NS_MEDIAWIKI ) {
                        // @todo move this logic to MessageCache

                        if ( $this->exists() ) {
                                // NOTE: use transclusion text for messages.
                                //       This is consistent with  MessageCache::getMsgFromNamespace()

                                $content = $this->getContent();
                                $text = $content === null ? null : $content->getWikitextForTransclusion();

                                if ( $text === null ) {
                                        $text = false;
                                }
                        } else {
                                $text = false;
                        }

                        MessageCache::singleton()->replace( $this->mTitle->getDBkey(), $text );
                }
                return true;
        }

        /**
         * Insert a new empty page record for this article.
         * This *must* be followed up by creating a revision
         * and running $this->updateRevisionOn( ... );
         * or else the record will be left in a funky state.
         * Best if all done inside a transaction.
         *
         * @param DatabaseBase $dbw
         * @return int The newly created page_id key, or false if the title already existed
         */
        public function insertOn( $dbw ) {

                $page_id = $dbw->nextSequenceValue( 'page_page_id_seq' );
                $dbw->insert( 'page', array(
                        'page_id'           => $page_id,
                        'page_namespace'    => $this->mTitle->getNamespace(),
                        'page_title'        => $this->mTitle->getDBkey(),
                        'page_restrictions' => '',
                        'page_is_redirect'  => 0, // Will set this shortly...
                        'page_is_new'       => 1,
                        'page_random'       => wfRandom(),
                        'page_touched'      => $dbw->timestamp(),
                        'page_latest'       => 0, // Fill this in shortly...
                        'page_len'          => 0, // Fill this in shortly...
                ), __METHOD__, 'IGNORE' );

                $affected = $dbw->affectedRows();

                if ( $affected ) {
                        $newid = $dbw->insertId();
                        $this->mId = $newid;
                        $this->mTitle->resetArticleID( $newid );
                }

                return $affected ? $newid : false;
        }

        /**
         * Update the page record to point to a newly saved revision.
         *
         * @param DatabaseBase $dbw
         * @param Revision $revision For ID number, and text used to set
         *   length and redirect status fields
         * @param int $lastRevision If given, will not overwrite the page field
         *   when different from the currently set value.
         *   Giving 0 indicates the new page flag should be set on.
         * @param bool $lastRevIsRedirect If given, will optimize adding and
         *   removing rows in redirect table.
         * @return bool True on success, false on failure
         */
        public function updateRevisionOn( $dbw, $revision, $lastRevision = null,
                $lastRevIsRedirect = null
        ) {
                global $wgContentHandlerUseDB;


                $content = $revision->getContent();
                $len = $content ? $content->getSize() : 0;
                $rt = $content ? $content->getUltimateRedirectTarget() : null;

                $conditions = array( 'page_id' => $this->getId() );

                if ( !is_null( $lastRevision ) ) {
                        // An extra check against threads stepping on each other
                        $conditions['page_latest'] = $lastRevision;
                }

                $now = wfTimestampNow();
                $row = array( /* SET */
                        'page_latest'      => $revision->getId(),
                        'page_touched'     => $dbw->timestamp( $now ),
                        'page_is_new'      => ( $lastRevision === 0 ) ? 1 : 0,
                        'page_is_redirect' => $rt !== null ? 1 : 0,
                        'page_len'         => $len,
                );

                if ( $wgContentHandlerUseDB ) {
                        $row['page_content_model'] = $revision->getContentModel();
                }

                $dbw->update( 'page',
                        $row,
                        $conditions,
                        __METHOD__ );

                $result = $dbw->affectedRows() > 0;
                if ( $result ) {
                        $this->updateRedirectOn( $dbw, $rt, $lastRevIsRedirect );
                        $this->setLastEdit( $revision );
                        $this->setCachedLastEditTime( $now );
                        $this->mLatest = $revision->getId();
                        $this->mIsRedirect = (bool)$rt;
                        // Update the LinkCache.
                        LinkCache::singleton()->addGoodLinkObj( $this->getId(), $this->mTitle, $len, $this->mIsRedirect,
                                                                                                        $this->mLatest, $revision->getContentModel() );
                }

                return $result;
        }

        /**
         * Add row to the redirect table if this is a redirect, remove otherwise.
         *
         * @param DatabaseBase $dbw
         * @param Title $redirectTitle Title object pointing to the redirect target,
         *   or NULL if this is not a redirect
         * @param null|bool $lastRevIsRedirect If given, will optimize adding and
         *   removing rows in redirect table.
         * @return bool True on success, false on failure
         * @private
         */
        public function updateRedirectOn( $dbw, $redirectTitle, $lastRevIsRedirect = null ) {
                // Always update redirects (target link might have changed)
                // Update/Insert if we don't know if the last revision was a redirect or not
                // Delete if changing from redirect to non-redirect
                $isRedirect = !is_null( $redirectTitle );

                if ( !$isRedirect && $lastRevIsRedirect === false ) {
                        return true;
                }

                if ( $isRedirect ) {
                        $this->insertRedirectEntry( $redirectTitle );
                } else {
                        // This is not a redirect, remove row from redirect table
                        $where = array( 'rd_from' => $this->getId() );
                        $dbw->delete( 'redirect', $where, __METHOD__ );
                }

                if ( $this->getTitle()->getNamespace() == NS_FILE ) {
                        RepoGroup::singleton()->getLocalRepo()->invalidateImageRedirect( $this->getTitle() );
                }

                return ( $dbw->affectedRows() != 0 );
        }

        /**
         * If the given revision is newer than the currently set page_latest,
         * update the page record. Otherwise, do nothing.
         *
         * @deprecated since 1.24, use updateRevisionOn instead
         *
         * @param DatabaseBase $dbw
         * @param Revision $revision
         * @return bool
         */
        public function updateIfNewerOn( $dbw, $revision ) {

                $row = $dbw->selectRow(
                        array( 'revision', 'page' ),
                        array( 'rev_id', 'rev_timestamp', 'page_is_redirect' ),
                        array(
                                'page_id' => $this->getId(),
                                'page_latest=rev_id' ),
                        __METHOD__ );

                if ( $row ) {
                        if ( wfTimestamp( TS_MW, $row->rev_timestamp ) >= $revision->getTimestamp() ) {
                                return false;
                        }
                        $prev = $row->rev_id;
                        $lastRevIsRedirect = (bool)$row->page_is_redirect;
                } else {
                        // No or missing previous revision; mark the page as new
                        $prev = 0;
                        $lastRevIsRedirect = null;
                }

                $ret = $this->updateRevisionOn( $dbw, $revision, $prev, $lastRevIsRedirect );

                return $ret;
        }

        /**
         * Get the content that needs to be saved in order to undo all revisions
         * between $undo and $undoafter. Revisions must belong to the same page,
         * must exist and must not be deleted
         * @param Revision $undo
         * @param Revision $undoafter Must be an earlier revision than $undo
         * @return mixed String on success, false on failure
         * @since 1.21
         * Before we had the Content object, this was done in getUndoText
         */
        public function getUndoContent( Revision $undo, Revision $undoafter = null ) {
                $handler = $undo->getContentHandler();
                return $handler->getUndoContent( $this->getRevision(), $undo, $undoafter );
        }

        /**
         * Get the text that needs to be saved in order to undo all revisions
         * between $undo and $undoafter. Revisions must belong to the same page,
         * must exist and must not be deleted
         * @param Revision $undo
         * @param Revision $undoafter Must be an earlier revision than $undo
         * @return string|bool String on success, false on failure
         * @deprecated since 1.21: use ContentHandler::getUndoContent() instead.
         */
        public function getUndoText( Revision $undo, Revision $undoafter = null ) {
                ContentHandler::deprecated( __METHOD__, '1.21' );

                $this->loadLastEdit();

                if ( $this->mLastRevision ) {
                        if ( is_null( $undoafter ) ) {
                                $undoafter = $undo->getPrevious();
                        }

                        $handler = $this->getContentHandler();
                        $undone = $handler->getUndoContent( $this->mLastRevision, $undo, $undoafter );

                        if ( !$undone ) {
                                return false;
                        } else {
                                return ContentHandler::getContentText( $undone );
                        }
                }

                return false;
        }

        /**
         * @param string|number|null|bool $sectionId Section identifier as a number or string
         * (e.g. 0, 1 or 'T-1'), null/false or an empty string for the whole page
         * or 'new' for a new section.
         * @param string $text New text of the section.
         * @param string $sectionTitle New section's subject, only if $section is "new".
         * @param string $edittime Revision timestamp or null to use the current revision.
         *
         * @throws MWException
         * @return string New complete article text, or null if error.
         *
         * @deprecated since 1.21, use replaceSectionAtRev() instead
         */
        public function replaceSection( $sectionId, $text, $sectionTitle = '',
                $edittime = null
        ) {
                ContentHandler::deprecated( __METHOD__, '1.21' );

                //NOTE: keep condition in sync with condition in replaceSectionContent!
                if ( strval( $sectionId ) === '' ) {
                        // Whole-page edit; let the whole text through
                        return $text;
                }

                if ( !$this->supportsSections() ) {
                        throw new MWException( "sections not supported for content model " .
                                $this->getContentHandler()->getModelID() );
                }

                // could even make section title, but that's not required.
                $sectionContent = ContentHandler::makeContent( $text, $this->getTitle() );

                $newContent = $this->replaceSectionContent( $sectionId, $sectionContent, $sectionTitle,
                        $edittime );

                return ContentHandler::getContentText( $newContent );
        }

        /**
         * Returns true if this page's content model supports sections.
         *
         * @return bool
         *
         * @todo The skin should check this and not offer section functionality if
         *   sections are not supported.
         * @todo The EditPage should check this and not offer section functionality
         *   if sections are not supported.
         */
        public function supportsSections() {
                return $this->getContentHandler()->supportsSections();
        }

        /**
         * @param string|number|null|bool $sectionId Section identifier as a number or string
         * (e.g. 0, 1 or 'T-1'), null/false or an empty string for the whole page
         * or 'new' for a new section.
         * @param Content $sectionContent New content of the section.
         * @param string $sectionTitle New section's subject, only if $section is "new".
         * @param string $edittime Revision timestamp or null to use the current revision.
         *
         * @throws MWException
         * @return Content New complete article content, or null if error.
         *
         * @since 1.21
         * @deprecated since 1.24, use replaceSectionAtRev instead
         */
        public function replaceSectionContent( $sectionId, Content $sectionContent, $sectionTitle = '',
                $edittime = null ) {

                $baseRevId = null;
                if ( $edittime && $sectionId !== 'new' ) {
                        $dbw = wfGetDB( DB_MASTER );
                        $rev = Revision::loadFromTimestamp( $dbw, $this->mTitle, $edittime );
                        if ( $rev ) {
                                $baseRevId = $rev->getId();
                        }
                }

                return $this->replaceSectionAtRev( $sectionId, $sectionContent, $sectionTitle, $baseRevId );
        }

        /**
         * @param string|number|null|bool $sectionId Section identifier as a number or string
         * (e.g. 0, 1 or 'T-1'), null/false or an empty string for the whole page
         * or 'new' for a new section.
         * @param Content $sectionContent New content of the section.
         * @param string $sectionTitle New section's subject, only if $section is "new".
         * @param int|null $baseRevId
         *
         * @throws MWException
         * @return Content New complete article content, or null if error.
         *
         * @since 1.24
         */
        public function replaceSectionAtRev( $sectionId, Content $sectionContent,
                $sectionTitle = '', $baseRevId = null
        ) {

                if ( strval( $sectionId ) === '' ) {
                        // Whole-page edit; let the whole text through
                        $newContent = $sectionContent;
                } else {
                        if ( !$this->supportsSections() ) {
                                throw new MWException( "sections not supported for content model " .
                                        $this->getContentHandler()->getModelID() );
                        }

                        // Bug 30711: always use current version when adding a new section
                        if ( is_null( $baseRevId ) || $sectionId === 'new' ) {
                                $oldContent = $this->getContent();
                        } else {
                                // TODO: try DB_SLAVE first
                                $dbw = wfGetDB( DB_MASTER );
                                $rev = Revision::loadFromId( $dbw, $baseRevId );

                                if ( !$rev ) {
                                        wfDebug( __METHOD__ . " asked for bogus section (page: " .
                                                $this->getId() . "; section: $sectionId)\n" );
                                        return null;
                                }

                                $oldContent = $rev->getContent();
                        }

                        if ( !$oldContent ) {
                                wfDebug( __METHOD__ . ": no page text\n" );
                                return null;
                        }

                        $newContent = $oldContent->replaceSection( $sectionId, $sectionContent, $sectionTitle );
                }

                return $newContent;
        }

        /**
         * Check flags and add EDIT_NEW or EDIT_UPDATE to them as needed.
         * @param int $flags
         * @return int Updated $flags
         */
        public function checkFlags( $flags ) {
                if ( !( $flags & EDIT_NEW ) && !( $flags & EDIT_UPDATE ) ) {
                        if ( $this->exists() ) {
                                $flags |= EDIT_UPDATE;
                        } else {
                                $flags |= EDIT_NEW;
                        }
                }

                return $flags;
        }

        /**
         * Change an existing article or create a new article. Updates RC and all necessary caches,
         * optionally via the deferred update array.
         *
         * @param string $text New text
         * @param string $summary Edit summary
         * @param int $flags Bitfield:
         *      EDIT_NEW
         *          Article is known or assumed to be non-existent, create a new one
         *      EDIT_UPDATE
         *          Article is known or assumed to be pre-existing, update it
         *      EDIT_MINOR
         *          Mark this edit minor, if the user is allowed to do so
         *      EDIT_SUPPRESS_RC
         *          Do not log the change in recentchanges
         *      EDIT_FORCE_BOT
         *          Mark the edit a "bot" edit regardless of user rights
         *      EDIT_DEFER_UPDATES
         *          Defer some of the updates until the end of index.php
         *      EDIT_AUTOSUMMARY
         *          Fill in blank summaries with generated text where possible
         *
         * If neither EDIT_NEW nor EDIT_UPDATE is specified, the status of the
         * article will be detected. If EDIT_UPDATE is specified and the article
         * doesn't exist, the function will return an edit-gone-missing error. If
         * EDIT_NEW is specified and the article does exist, an edit-already-exists
         * error will be returned. These two conditions are also possible with
         * auto-detection due to MediaWiki's performance-optimised locking strategy.
         *
         * @param bool|int $baseRevId The revision ID this edit was based off, if any
         * @param User $user The user doing the edit
         *
         * @throws MWException
         * @return Status Possible errors:
         *   edit-hook-aborted: The ArticleSave hook aborted the edit but didn't
         *     set the fatal flag of $status
         *   edit-gone-missing: In update mode, but the article didn't exist.
         *   edit-conflict: In update mode, the article changed unexpectedly.
         *   edit-no-change: Warning that the text was the same as before.
         *   edit-already-exists: In creation mode, but the article already exists.
         *
         * Extensions may define additional errors.
         *
         * $return->value will contain an associative array with members as follows:
         *     new: Boolean indicating if the function attempted to create a new article.
         *     revision: The revision object for the inserted revision, or null.
         *
         * Compatibility note: this function previously returned a boolean value
         * indicating success/failure
         *
         * @deprecated since 1.21: use doEditContent() instead.
         */
        public function doEdit( $text, $summary, $flags = 0, $baseRevId = false, $user = null ) {
                ContentHandler::deprecated( __METHOD__, '1.21' );

                $content = ContentHandler::makeContent( $text, $this->getTitle() );

                return $this->doEditContent( $content, $summary, $flags, $baseRevId, $user );
        }

        /**
         * Change an existing article or create a new article. Updates RC and all necessary caches,
         * optionally via the deferred update array.
         *
         * @param Content $content New content
         * @param string $summary Edit summary
         * @param int $flags Bitfield:
         *      EDIT_NEW
         *          Article is known or assumed to be non-existent, create a new one
         *      EDIT_UPDATE
         *          Article is known or assumed to be pre-existing, update it
         *      EDIT_MINOR
         *          Mark this edit minor, if the user is allowed to do so
         *      EDIT_SUPPRESS_RC
         *          Do not log the change in recentchanges
         *      EDIT_FORCE_BOT
         *          Mark the edit a "bot" edit regardless of user rights
         *      EDIT_DEFER_UPDATES
         *          Defer some of the updates until the end of index.php
         *      EDIT_AUTOSUMMARY
         *          Fill in blank summaries with generated text where possible
         *
         * If neither EDIT_NEW nor EDIT_UPDATE is specified, the status of the
         * article will be detected. If EDIT_UPDATE is specified and the article
         * doesn't exist, the function will return an edit-gone-missing error. If
         * EDIT_NEW is specified and the article does exist, an edit-already-exists
         * error will be returned. These two conditions are also possible with
         * auto-detection due to MediaWiki's performance-optimised locking strategy.
         *
         * @param bool|int $baseRevId The revision ID this edit was based off, if any
         * @param User $user The user doing the edit
         * @param string $serialFormat Format for storing the content in the
         *   database.
         *
         * @throws MWException
         * @return Status Possible errors:
         *     edit-hook-aborted: The ArticleSave hook aborted the edit but didn't
         *       set the fatal flag of $status.
         *     edit-gone-missing: In update mode, but the article didn't exist.
         *     edit-conflict: In update mode, the article changed unexpectedly.
         *     edit-no-change: Warning that the text was the same as before.
         *     edit-already-exists: In creation mode, but the article already exists.
         *
         *  Extensions may define additional errors.
         *
         *  $return->value will contain an associative array with members as follows:
         *     new: Boolean indicating if the function attempted to create a new article.
         *     revision: The revision object for the inserted revision, or null.
         *
         * @since 1.21
         */
        public function doEditContent( Content $content, $summary, $flags = 0, $baseRevId = false,
                User $user = null, $serialFormat = null
        ) {
                global $wgUser, $wgUseAutomaticEditSummaries, $wgUseRCPatrol, $wgUseNPPatrol;

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


                if ( !$content->getContentHandler()->canBeUsedOn( $this->getTitle() ) ) {
                        return Status::newFatal( 'content-not-allowed-here',
                                ContentHandler::getLocalizedName( $content->getModel() ),
                                $this->getTitle()->getPrefixedText() );
                }

                $user = is_null( $user ) ? $wgUser : $user;
                $status = Status::newGood( array() );

                // Load the data from the master database if needed.
                // The caller may already loaded it from the master or even loaded it using
                // SELECT FOR UPDATE, so do not override that using clear().
                $this->loadPageData( 'fromdbmaster' );

                $flags = $this->checkFlags( $flags );

                // handle hook
                $hook_args = array( &$this, &$user, &$content, &$summary,
                                                        $flags & EDIT_MINOR, null, null, &$flags, &$status );

                if ( !Hooks::run( 'PageContentSave', $hook_args )
                        || !ContentHandler::runLegacyHooks( 'ArticleSave', $hook_args ) ) {

                        wfDebug( __METHOD__ . ": ArticleSave or ArticleSaveContent hook aborted save!\n" );

                        if ( $status->isOK() ) {
                                $status->fatal( 'edit-hook-aborted' );
                        }

                        return $status;
                }

                // Silently ignore EDIT_MINOR if not allowed
                $isminor = ( $flags & EDIT_MINOR ) && $user->isAllowed( 'minoredit' );
                $bot = $flags & EDIT_FORCE_BOT;

                $old_content = $this->getContent( Revision::RAW ); // current revision's content

                $oldsize = $old_content ? $old_content->getSize() : 0;
                $oldid = $this->getLatest();
                $oldIsRedirect = $this->isRedirect();
                $oldcountable = $this->isCountable();

                $handler = $content->getContentHandler();

                // Provide autosummaries if one is not provided and autosummaries are enabled.
                if ( $wgUseAutomaticEditSummaries && $flags & EDIT_AUTOSUMMARY && $summary == '' ) {
                        if ( !$old_content ) {
                                $old_content = null;
                        }
                        $summary = $handler->getAutosummary( $old_content, $content, $flags );
                }

                $editInfo = $this->prepareContentForEdit( $content, null, $user, $serialFormat );
                $serialized = $editInfo->pst;

                /**
                 * @var Content $content
                 */
                $content = $editInfo->pstContent;
                $newsize = $content->getSize();

                $dbw = wfGetDB( DB_MASTER );
                $now = wfTimestampNow();
                $this->mTimestamp = $now;

                if ( $flags & EDIT_UPDATE ) {
                        // Update article, but only if changed.
                        $status->value['new'] = false;

                        if ( !$oldid ) {
                                // Article gone missing
                                wfDebug( __METHOD__ . ": EDIT_UPDATE specified but article doesn't exist\n" );
                                $status->fatal( 'edit-gone-missing' );

                                return $status;
                        } elseif ( !$old_content ) {
                                // Sanity check for bug 37225
                                throw new MWException( "Could not find text for current revision {$oldid}." );
                        }

                        $revision = new Revision( array(
                                'page'       => $this->getId(),
                                'title'      => $this->getTitle(), // for determining the default content model
                                'comment'    => $summary,
                                'minor_edit' => $isminor,
                                'text'       => $serialized,
                                'len'        => $newsize,
                                'parent_id'  => $oldid,
                                'user'       => $user->getId(),
                                'user_text'  => $user->getName(),
                                'timestamp'  => $now,
                                'content_model' => $content->getModel(),
                                'content_format' => $serialFormat,
                        ) ); // XXX: pass content object?!

                        $changed = !$content->equals( $old_content );

                        if ( $changed ) {
                                $dbw->begin( __METHOD__ );
                                try {

                                        $prepStatus = $content->prepareSave( $this, $flags, $baseRevId, $user );
                                        $status->merge( $prepStatus );

                                        if ( !$status->isOK() ) {
                                                $dbw->rollback( __METHOD__ );

                                                return $status;
                                        }
                                        $revisionId = $revision->insertOn( $dbw );

                                        // Update page
                                        //
                                        // We check for conflicts by comparing $oldid with the current latest revision ID.
                                        $ok = $this->updateRevisionOn( $dbw, $revision, $oldid, $oldIsRedirect );

                                        if ( !$ok ) {
                                                // Belated edit conflict! Run away!!
                                                $status->fatal( 'edit-conflict' );

                                                $dbw->rollback( __METHOD__ );

                                                return $status;
                                        }

                                        Hooks::run( 'NewRevisionFromEditComplete', array( $this, $revision, $baseRevId, $user ) );
                                        // Update recentchanges
                                        if ( !( $flags & EDIT_SUPPRESS_RC ) ) {
                                                // Mark as patrolled if the user can do so
                                                $patrolled = $wgUseRCPatrol && !count(
                                                $this->mTitle->getUserPermissionsErrors( 'autopatrol', $user ) );
                                                // Add RC row to the DB
                                                $rc = RecentChange::notifyEdit( $now, $this->mTitle, $isminor, $user, $summary,
                                                        $oldid, $this->getTimestamp(), $bot, '', $oldsize, $newsize,
                                                        $revisionId, $patrolled
                                                );

                                                // Log auto-patrolled edits
                                                if ( $patrolled ) {
                                                        PatrolLog::record( $rc, true, $user );
                                                }
                                        }
                                        $user->incEditCount();
                                } catch ( MWException $e ) {
                                        $dbw->rollback( __METHOD__ );
                                        // Question: Would it perhaps be better if this method turned all
                                        // exceptions into $status's?
                                        throw $e;
                                }
                                $dbw->commit( __METHOD__ );
                        } else {
                                // Bug 32948: revision ID must be set to page {{REVISIONID}} and
                                // related variables correctly
                                $revision->setId( $this->getLatest() );
                        }

                        // Update links tables, site stats, etc.
                        $this->doEditUpdates(
                                $revision,
                                $user,
                                array(
                                        'changed' => $changed,
                                        'oldcountable' => $oldcountable
                                )
                        );

                        if ( !$changed ) {
                                $status->warning( 'edit-no-change' );
                                $revision = null;
                                // Update page_touched, this is usually implicit in the page update
                                // Other cache updates are done in onArticleEdit()
                                $this->mTitle->invalidateCache();
                        }
                } else {
                        // Create new article
                        $status->value['new'] = true;

                        $dbw->begin( __METHOD__ );
                        try {

                                $prepStatus = $content->prepareSave( $this, $flags, $baseRevId, $user );
                                $status->merge( $prepStatus );

                                if ( !$status->isOK() ) {
                                        $dbw->rollback( __METHOD__ );

                                        return $status;
                                }

                                $status->merge( $prepStatus );

                                // Add the page record; stake our claim on this title!
                                // This will return false if the article already exists
                                $newid = $this->insertOn( $dbw );

                                if ( $newid === false ) {
                                        $dbw->rollback( __METHOD__ );
                                        $status->fatal( 'edit-already-exists' );

                                        return $status;
                                }

                                // Save the revision text...
                                $revision = new Revision( array(
                                        'page'       => $newid,
                                        'title'      => $this->getTitle(), // for determining the default content model
                                        'comment'    => $summary,
                                        'minor_edit' => $isminor,
                                        'text'       => $serialized,
                                        'len'        => $newsize,
                                        'user'       => $user->getId(),
                                        'user_text'  => $user->getName(),
                                        'timestamp'  => $now,
                                        'content_model' => $content->getModel(),
                                        'content_format' => $serialFormat,
                                ) );
                                $revisionId = $revision->insertOn( $dbw );

                                // Bug 37225: use accessor to get the text as Revision may trim it
                                $content = $revision->getContent(); // sanity; get normalized version

                                if ( $content ) {
                                        $newsize = $content->getSize();
                                }

                                // Update the page record with revision data
                                $this->updateRevisionOn( $dbw, $revision, 0 );

                                Hooks::run( 'NewRevisionFromEditComplete', array( $this, $revision, false, $user ) );

                                // Update recentchanges
                                if ( !( $flags & EDIT_SUPPRESS_RC ) ) {
                                        // Mark as patrolled if the user can do so
                                        $patrolled = ( $wgUseRCPatrol || $wgUseNPPatrol ) && !count(
                                                $this->mTitle->getUserPermissionsErrors( 'autopatrol', $user ) );
                                        // Add RC row to the DB
                                        $rc = RecentChange::notifyNew( $now, $this->mTitle, $isminor, $user, $summary, $bot,
                                                '', $newsize, $revisionId, $patrolled );

                                        // Log auto-patrolled edits
                                        if ( $patrolled ) {
                                                PatrolLog::record( $rc, true, $user );
                                        }
                                }
                                $user->incEditCount();

                        } catch ( MWException $e ) {
                                $dbw->rollback( __METHOD__ );
                                throw $e;
                        }
                        $dbw->commit( __METHOD__ );

                        // Update links, etc.
                        $this->doEditUpdates( $revision, $user, array( 'created' => true ) );

                        $hook_args = array( &$this, &$user, $content, $summary,
                                                                $flags & EDIT_MINOR, null, null, &$flags, $revision );

                        ContentHandler::runLegacyHooks( 'ArticleInsertComplete', $hook_args );
                        Hooks::run( 'PageContentInsertComplete', $hook_args );
                }

                // Do updates right now unless deferral was requested
                if ( !( $flags & EDIT_DEFER_UPDATES ) ) {
                        DeferredUpdates::doUpdates();
                }

                // Return the new revision (or null) to the caller
                $status->value['revision'] = $revision;

                $hook_args = array( &$this, &$user, $content, $summary,
                                                        $flags & EDIT_MINOR, null, null, &$flags, $revision, &$status, $baseRevId );

                ContentHandler::runLegacyHooks( 'ArticleSaveComplete', $hook_args );
                Hooks::run( 'PageContentSaveComplete', $hook_args );

                // Promote user to any groups they meet the criteria for
                $dbw->onTransactionIdle( function () use ( $user ) {
                        $user->addAutopromoteOnceGroups( 'onEdit' );
                } );

                return $status;
        }

        /**
         * Get parser options suitable for rendering the primary article wikitext
         *
         * @see ContentHandler::makeParserOptions
         *
         * @param IContextSource|User|string $context One of the following:
         *        - IContextSource: Use the User and the Language of the provided
         *          context
         *        - User: Use the provided User object and $wgLang for the language,
         *          so use an IContextSource object if possible.
         *        - 'canonical': Canonical options (anonymous user with default
         *          preferences and content language).
         * @return ParserOptions
         */
        public function makeParserOptions( $context ) {
                $options = $this->getContentHandler()->makeParserOptions( $context );

                if ( $this->getTitle()->isConversionTable() ) {
                        // @todo ConversionTable should become a separate content model, so
                        // we don't need special cases like this one.
                        $options->disableContentConversion();
                }

                return $options;
        }

        /**
         * Prepare text which is about to be saved.
         * Returns a stdClass with source, pst and output members
         *
         * @deprecated since 1.21: use prepareContentForEdit instead.
         * @return object
         */
        public function prepareTextForEdit( $text, $revid = null, User $user = null ) {
                ContentHandler::deprecated( __METHOD__, '1.21' );
                $content = ContentHandler::makeContent( $text, $this->getTitle() );
                return $this->prepareContentForEdit( $content, $revid, $user );
        }

        /**
         * Prepare content which is about to be saved.
         * Returns a stdClass with source, pst and output members
         *
         * @param Content $content
         * @param int|null $revid
         * @param User|null $user
         * @param string|null $serialFormat
         * @param bool $useCache Check shared prepared edit cache
         *
         * @return object
         *
         * @since 1.21
         */
        public function prepareContentForEdit(
                Content $content, $revid = null, User $user = null, $serialFormat = null, $useCache = true
        ) {
                global $wgContLang, $wgUser;

                $user = is_null( $user ) ? $wgUser : $user;
                //XXX: check $user->getId() here???

                // Use a sane default for $serialFormat, see bug 57026
                if ( $serialFormat === null ) {
                        $serialFormat = $content->getContentHandler()->getDefaultFormat();
                }

                if ( $this->mPreparedEdit
                        && $this->mPreparedEdit->newContent
                        && $this->mPreparedEdit->newContent->equals( $content )
                        && $this->mPreparedEdit->revid == $revid
                        && $this->mPreparedEdit->format == $serialFormat
                        // XXX: also check $user here?
                ) {
                        // Already prepared
                        return $this->mPreparedEdit;
                }

                // The edit may have already been prepared via api.php?action=stashedit
                $cachedEdit = $useCache
                        ? ApiStashEdit::checkCache( $this->getTitle(), $content, $user )
                        : false;

                $popts = ParserOptions::newFromUserAndLang( $user, $wgContLang );
                Hooks::run( 'ArticlePrepareTextForEdit', array( $this, $popts ) );

                $edit = (object)array();
                if ( $cachedEdit ) {
                        $edit->timestamp = $cachedEdit->timestamp;
                } else {
                        $edit->timestamp = wfTimestampNow();
                }
                // @note: $cachedEdit is not used if the rev ID was referenced in the text
                $edit->revid = $revid;

                if ( $cachedEdit ) {
                        $edit->pstContent = $cachedEdit->pstContent;
                } else {
                        $edit->pstContent = $content
                                ? $content->preSaveTransform( $this->mTitle, $user, $popts )
                                : null;
                }

                $edit->format = $serialFormat;
                $edit->popts = $this->makeParserOptions( 'canonical' );
                if ( $cachedEdit ) {
                        $edit->output = $cachedEdit->output;
                } else {
                        $edit->output = $edit->pstContent
                                ? $edit->pstContent->getParserOutput( $this->mTitle, $revid, $edit->popts )
                                : null;
                }

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

                // NOTE: B/C for hooks! don't use these fields!
                $edit->newText = $edit->newContent ? ContentHandler::getContentText( $edit->newContent ) : '';
                $edit->oldText = $edit->oldContent ? ContentHandler::getContentText( $edit->oldContent ) : '';
                $edit->pst = $edit->pstContent ? $edit->pstContent->serialize( $serialFormat ) : '';

                $this->mPreparedEdit = $edit;
                return $edit;
        }

        /**
         * Do standard deferred updates after page edit.
         * Update links tables, site stats, search index and message cache.
         * Purges pages that include this page if the text was changed here.
         * Every 100th edit, prune the recent changes table.
         *
         * @param Revision $revision
         * @param User $user User object that did the revision
         * @param array $options Array of options, following indexes are used:
         * - changed: boolean, whether the revision changed the content (default true)
         * - created: boolean, whether the revision created the page (default false)
         * - moved: boolean, whether the page was moved (default false)
         * - oldcountable: boolean or null (default null):
         *   - boolean: whether the page was counted as an article before that
         *     revision, only used in changed is true and created is false
         *   - null: don't change the article count
         */
        public function doEditUpdates( Revision $revision, User $user, array $options = array() ) {
                global $wgEnableParserCache;


                $options += array(
                        'changed' => true,
                        'created' => false,
                        'moved' => false,
                        'oldcountable' => null
                );
                $content = $revision->getContent();

                // Parse the text
                // Be careful not to do pre-save transform twice: $text is usually
                // already pre-save transformed once.
                if ( !$this->mPreparedEdit || $this->mPreparedEdit->output->getFlag( 'vary-revision' ) ) {
                        wfDebug( __METHOD__ . ": No prepared edit or vary-revision is set...\n" );
                        $editInfo = $this->prepareContentForEdit( $content, $revision->getId(), $user );
                } else {
                        wfDebug( __METHOD__ . ": No vary-revision, using prepared edit...\n" );
                        $editInfo = $this->mPreparedEdit;
                }

                // Save it to the parser cache
                if ( $wgEnableParserCache ) {
                        $parserCache = ParserCache::singleton();
                        $parserCache->save(
                                $editInfo->output, $this, $editInfo->popts, $editInfo->timestamp, $editInfo->revid
                        );
                }

                // Update the links tables and other secondary data
                if ( $content ) {
                        $recursive = $options['changed']; // bug 50785
                        $updates = $content->getSecondaryDataUpdates(
                                $this->getTitle(), null, $recursive, $editInfo->output );
                        DataUpdate::runUpdates( $updates );
                }

                Hooks::run( 'ArticleEditUpdates', array( &$this, &$editInfo, $options['changed'] ) );

                if ( Hooks::run( 'ArticleEditUpdatesDeleteFromRecentchanges', array( &$this ) ) ) {
                        if ( 0 == mt_rand( 0, 99 ) ) {
                                // Flush old entries from the `recentchanges` table; we do this on
                                // random requests so as to avoid an increase in writes for no good reason
                                RecentChange::purgeExpiredChanges();
                        }
                }

                if ( !$this->exists() ) {
                        return;
                }

                $id = $this->getId();
                $title = $this->mTitle->getPrefixedDBkey();
                $shortTitle = $this->mTitle->getDBkey();

                if ( !$options['changed'] && !$options['moved'] ) {
                        $good = 0;
                } elseif ( $options['created'] ) {
                        $good = (int)$this->isCountable( $editInfo );
                } elseif ( $options['oldcountable'] !== null ) {
                        $good = (int)$this->isCountable( $editInfo ) - (int)$options['oldcountable'];
                } else {
                        $good = 0;
                }
                $edits = $options['changed'] ? 1 : 0;
                $total = $options['created'] ? 1 : 0;

                DeferredUpdates::addUpdate( new SiteStatsUpdate( 0, $edits, $good, $total ) );
                DeferredUpdates::addUpdate( new SearchUpdate( $id, $title, $content ) );

                // If this is another user's talk page, update newtalk.
                // Don't do this if $options['changed'] = false (null-edits) nor if
                // it's a minor edit and the user doesn't want notifications for those.
                if ( $options['changed']
                        && $this->mTitle->getNamespace() == NS_USER_TALK
                        && $shortTitle != $user->getTitleKey()
                        && !( $revision->isMinor() && $user->isAllowed( 'nominornewtalk' ) )
                ) {
                        $recipient = User::newFromName( $shortTitle, false );
                        if ( !$recipient ) {
                                wfDebug( __METHOD__ . ": invalid username\n" );
                        } else {
                                // Allow extensions to prevent user notification when a new message is added to their talk page
                                if ( Hooks::run( 'ArticleEditUpdateNewTalk', array( &$this, $recipient ) ) ) {
                                        if ( User::isIP( $shortTitle ) ) {
                                                // An anonymous user
                                                $recipient->setNewtalk( true, $revision );
                                        } elseif ( $recipient->isLoggedIn() ) {
                                                $recipient->setNewtalk( true, $revision );
                                        } else {
                                                wfDebug( __METHOD__ . ": don't need to notify a nonexistent user\n" );
                                        }
                                }
                        }
                }

                if ( $this->mTitle->getNamespace() == NS_MEDIAWIKI ) {
                        // XXX: could skip pseudo-messages like js/css here, based on content model.
                        $msgtext = $content ? $content->getWikitextForTransclusion() : null;
                        if ( $msgtext === false || $msgtext === null ) {
                                $msgtext = '';
                        }

                        MessageCache::singleton()->replace( $shortTitle, $msgtext );
                }

                if ( $options['created'] ) {
                        self::onArticleCreate( $this->mTitle );
                } elseif ( $options['changed'] ) { // bug 50785
                        self::onArticleEdit( $this->mTitle );
                }

        }

        /**
         * Edit an article without doing all that other stuff
         * The article must already exist; link tables etc
         * are not updated, caches are not flushed.
         *
         * @param string $text Text submitted
         * @param User $user The relevant user
         * @param string $comment Comment submitted
         * @param bool $minor Whereas it's a minor modification
         *
         * @deprecated since 1.21, use doEditContent() instead.
         */
        public function doQuickEdit( $text, User $user, $comment = '', $minor = 0 ) {
                ContentHandler::deprecated( __METHOD__, "1.21" );

                $content = ContentHandler::makeContent( $text, $this->getTitle() );
                $this->doQuickEditContent( $content, $user, $comment, $minor );
        }

        /**
         * Edit an article without doing all that other stuff
         * The article must already exist; link tables etc
         * are not updated, caches are not flushed.
         *
         * @param Content $content Content submitted
         * @param User $user The relevant user
         * @param string $comment Comment submitted
         * @param bool $minor Whereas it's a minor modification
         * @param string $serialFormat Format for storing the content in the database
         */
        public function doQuickEditContent( Content $content, User $user, $comment = '', $minor = false,
                $serialFormat = null
        ) {

                $serialized = $content->serialize( $serialFormat );

                $dbw = wfGetDB( DB_MASTER );
                $revision = new Revision( array(
                        'title'      => $this->getTitle(), // for determining the default content model
                        'page'       => $this->getId(),
                        'user_text'  => $user->getName(),
                        'user'       => $user->getId(),
                        'text'       => $serialized,
                        'length'     => $content->getSize(),
                        'comment'    => $comment,
                        'minor_edit' => $minor ? 1 : 0,
                ) ); // XXX: set the content object?
                $revision->insertOn( $dbw );
                $this->updateRevisionOn( $dbw, $revision );

                Hooks::run( 'NewRevisionFromEditComplete', array( $this, $revision, false, $user ) );

        }

        /**
         * Update the article's restriction field, and leave a log entry.
         * This works for protection both existing and non-existing pages.
         *
         * @param array $limit Set of restriction keys
         * @param array $expiry Per restriction type expiration
         * @param int &$cascade Set to false if cascading protection isn't allowed.
         * @param string $reason
         * @param User $user The user updating the restrictions
         * @return Status
         */
        public function doUpdateRestrictions( array $limit, array $expiry,
                &$cascade, $reason, User $user
        ) {
                global $wgCascadingRestrictionLevels, $wgContLang;

                if ( wfReadOnly() ) {
                        return Status::newFatal( 'readonlytext', wfReadOnlyReason() );
                }

                $this->loadPageData( 'fromdbmaster' );
                $restrictionTypes = $this->mTitle->getRestrictionTypes();
                $id = $this->getId();

                if ( !$cascade ) {
                        $cascade = false;
                }

                // Take this opportunity to purge out expired restrictions
                Title::purgeExpiredRestrictions();

                // @todo FIXME: Same limitations as described in ProtectionForm.php (line 37);
                // we expect a single selection, but the schema allows otherwise.
                $isProtected = false;
                $protect = false;
                $changed = false;

                $dbw = wfGetDB( DB_MASTER );

                foreach ( $restrictionTypes as $action ) {
                        if ( !isset( $expiry[$action] ) ) {
                                $expiry[$action] = $dbw->getInfinity();
                        }
                        if ( !isset( $limit[$action] ) ) {
                                $limit[$action] = '';
                        } elseif ( $limit[$action] != '' ) {
                                $protect = true;
                        }

                        // Get current restrictions on $action
                        $current = implode( '', $this->mTitle->getRestrictions( $action ) );
                        if ( $current != '' ) {
                                $isProtected = true;
                        }

                        if ( $limit[$action] != $current ) {
                                $changed = true;
                        } elseif ( $limit[$action] != '' ) {
                                // Only check expiry change if the action is actually being
                                // protected, since expiry does nothing on an not-protected
                                // action.
                                if ( $this->mTitle->getRestrictionExpiry( $action ) != $expiry[$action] ) {
                                        $changed = true;
                                }
                        }
                }

                if ( !$changed && $protect && $this->mTitle->areRestrictionsCascading() != $cascade ) {
                        $changed = true;
                }

                // If nothing has changed, do nothing
                if ( !$changed ) {
                        return Status::newGood();
                }

                if ( !$protect ) { // No protection at all means unprotection
                        $revCommentMsg = 'unprotectedarticle';
                        $logAction = 'unprotect';
                } elseif ( $isProtected ) {
                        $revCommentMsg = 'modifiedarticleprotection';
                        $logAction = 'modify';
                } else {
                        $revCommentMsg = 'protectedarticle';
                        $logAction = 'protect';
                }

                // Truncate for whole multibyte characters
                $reason = $wgContLang->truncate( $reason, 255 );

                $logRelationsValues = array();
                $logRelationsField = null;

                if ( $id ) { // Protection of existing page
                        if ( !Hooks::run( 'ArticleProtect', array( &$this, &$user, $limit, $reason ) ) ) {
                                return Status::newGood();
                        }

                        // Only certain restrictions can cascade...
                        $editrestriction = isset( $limit['edit'] )
                                ? array( $limit['edit'] )
                                : $this->mTitle->getRestrictions( 'edit' );
                        foreach ( array_keys( $editrestriction, 'sysop' ) as $key ) {
                                $editrestriction[$key] = 'editprotected'; // backwards compatibility
                        }
                        foreach ( array_keys( $editrestriction, 'autoconfirmed' ) as $key ) {
                                $editrestriction[$key] = 'editsemiprotected'; // backwards compatibility
                        }

                        $cascadingRestrictionLevels = $wgCascadingRestrictionLevels;
                        foreach ( array_keys( $cascadingRestrictionLevels, 'sysop' ) as $key ) {
                                $cascadingRestrictionLevels[$key] = 'editprotected'; // backwards compatibility
                        }
                        foreach ( array_keys( $cascadingRestrictionLevels, 'autoconfirmed' ) as $key ) {
                                $cascadingRestrictionLevels[$key] = 'editsemiprotected'; // backwards compatibility
                        }

                        // The schema allows multiple restrictions
                        if ( !array_intersect( $editrestriction, $cascadingRestrictionLevels ) ) {
                                $cascade = false;
                        }

                        // insert null revision to identify the page protection change as edit summary
                        $latest = $this->getLatest();
                        $nullRevision = $this->insertProtectNullRevision(
                                $revCommentMsg,
                                $limit,
                                $expiry,
                                $cascade,
                                $reason,
                                $user
                        );

                        if ( $nullRevision === null ) {
                                return Status::newFatal( 'no-null-revision', $this->mTitle->getPrefixedText() );
                        }

                        $logRelationsField = 'pr_id';

                        // Update restrictions table
                        foreach ( $limit as $action => $restrictions ) {
                                $dbw->delete(
                                        'page_restrictions',
                                        array(
                                                'pr_page' => $id,
                                                'pr_type' => $action
                                        ),
                                        __METHOD__
                                );
                                if ( $restrictions != '' ) {
                                        $dbw->insert(
                                                'page_restrictions',
                                                array(
                                                        'pr_id' => $dbw->nextSequenceValue( 'page_restrictions_pr_id_seq' ),
                                                        'pr_page' => $id,
                                                        'pr_type' => $action,
                                                        'pr_level' => $restrictions,
                                                        'pr_cascade' => ( $cascade && $action == 'edit' ) ? 1 : 0,
                                                        'pr_expiry' => $dbw->encodeExpiry( $expiry[$action] )
                                                ),
                                                __METHOD__
                                        );
                                        $logRelationsValues[] = $dbw->insertId();
                                }
                        }

                        // Clear out legacy restriction fields
                        $dbw->update(
                                'page',
                                array( 'page_restrictions' => '' ),
                                array( 'page_id' => $id ),
                                __METHOD__
                        );

                        Hooks::run( 'NewRevisionFromEditComplete', array( $this, $nullRevision, $latest, $user ) );
                        Hooks::run( 'ArticleProtectComplete', array( &$this, &$user, $limit, $reason ) );
                } else { // Protection of non-existing page (also known as "title protection")
                        // Cascade protection is meaningless in this case
                        $cascade = false;

                        if ( $limit['create'] != '' ) {
                                $dbw->replace( 'protected_titles',
                                        array( array( 'pt_namespace', 'pt_title' ) ),
                                        array(
                                                'pt_namespace' => $this->mTitle->getNamespace(),
                                                'pt_title' => $this->mTitle->getDBkey(),
                                                'pt_create_perm' => $limit['create'],
                                                'pt_timestamp' => $dbw->timestamp(),
                                                'pt_expiry' => $dbw->encodeExpiry( $expiry['create'] ),
                                                'pt_user' => $user->getId(),
                                                'pt_reason' => $reason,
                                        ), __METHOD__
                                );
                        } else {
                                $dbw->delete( 'protected_titles',
                                        array(
                                                'pt_namespace' => $this->mTitle->getNamespace(),
                                                'pt_title' => $this->mTitle->getDBkey()
                                        ), __METHOD__
                                );
                        }
                }

                $this->mTitle->flushRestrictions();
                InfoAction::invalidateCache( $this->mTitle );

                if ( $logAction == 'unprotect' ) {
                        $params = array();
                } else {
                        $protectDescriptionLog = $this->protectDescriptionLog( $limit, $expiry );
                        $params = array( $protectDescriptionLog, $cascade ? 'cascade' : '' );
                }

                // Update the protection log
                $log = new LogPage( 'protect' );
                $logId = $log->addEntry( $logAction, $this->mTitle, $reason, $params, $user );
                if ( $logRelationsField !== null && count( $logRelationsValues ) ) {
                        $log->addRelations( $logRelationsField, $logRelationsValues, $logId );
                }

                return Status::newGood();
        }

        /**
         * Insert a new null revision for this page.
         *
         * @param string $revCommentMsg Comment message key for the revision
         * @param array $limit Set of restriction keys
         * @param array $expiry Per restriction type expiration
         * @param int $cascade Set to false if cascading protection isn't allowed.
         * @param string $reason
         * @param User|null $user
         * @return Revision|null Null on error
         */
        public function insertProtectNullRevision( $revCommentMsg, array $limit,
                array $expiry, $cascade, $reason, $user = null
        ) {
                global $wgContLang;
                $dbw = wfGetDB( DB_MASTER );

                // Prepare a null revision to be added to the history
                $editComment = $wgContLang->ucfirst(
                        wfMessage(
                                $revCommentMsg,
                                $this->mTitle->getPrefixedText()
                        )->inContentLanguage()->text()
                );
                if ( $reason ) {
                        $editComment .= wfMessage( 'colon-separator' )->inContentLanguage()->text() . $reason;
                }
                $protectDescription = $this->protectDescription( $limit, $expiry );
                if ( $protectDescription ) {
                        $editComment .= wfMessage( 'word-separator' )->inContentLanguage()->text();
                        $editComment .= wfMessage( 'parentheses' )->params( $protectDescription )
                                ->inContentLanguage()->text();
                }
                if ( $cascade ) {
                        $editComment .= wfMessage( 'word-separator' )->inContentLanguage()->text();
                        $editComment .= wfMessage( 'brackets' )->params(
                                wfMessage( 'protect-summary-cascade' )->inContentLanguage()->text()
                        )->inContentLanguage()->text();
                }

                $nullRev = Revision::newNullRevision( $dbw, $this->getId(), $editComment, true, $user );
                if ( $nullRev ) {
                        $nullRev->insertOn( $dbw );

                        // Update page record and touch page
                        $oldLatest = $nullRev->getParentId();
                        $this->updateRevisionOn( $dbw, $nullRev, $oldLatest );
                }

                return $nullRev;
        }

        /**
         * @param string $expiry 14-char timestamp or "infinity", or false if the input was invalid
         * @return string
         */
        protected function formatExpiry( $expiry ) {
                global $wgContLang;
                $dbr = wfGetDB( DB_SLAVE );

                $encodedExpiry = $dbr->encodeExpiry( $expiry );
                if ( $encodedExpiry != 'infinity' ) {
                        return wfMessage(
                                'protect-expiring',
                                $wgContLang->timeanddate( $expiry, false, false ),
                                $wgContLang->date( $expiry, false, false ),
                                $wgContLang->time( $expiry, false, false )
                        )->inContentLanguage()->text();
                } else {
                        return wfMessage( 'protect-expiry-indefinite' )
                                ->inContentLanguage()->text();
                }
        }

        /**
         * Builds the description to serve as comment for the edit.
         *
         * @param array $limit Set of restriction keys
         * @param array $expiry Per restriction type expiration
         * @return string
         */
        public function protectDescription( array $limit, array $expiry ) {
                $protectDescription = '';

                foreach ( array_filter( $limit ) as $action => $restrictions ) {
                        # $action is one of $wgRestrictionTypes = array( 'create', 'edit', 'move', 'upload' ).
                        # All possible message keys are listed here for easier grepping:
                        # * restriction-create
                        # * restriction-edit
                        # * restriction-move
                        # * restriction-upload
                        $actionText = wfMessage( 'restriction-' . $action )->inContentLanguage()->text();
                        # $restrictions is one of $wgRestrictionLevels = array( '', 'autoconfirmed', 'sysop' ),
                        # with '' filtered out. All possible message keys are listed below:
                        # * protect-level-autoconfirmed
                        # * protect-level-sysop
                        $restrictionsText = wfMessage( 'protect-level-' . $restrictions )->inContentLanguage()->text();

                        $expiryText = $this->formatExpiry( $expiry[$action] );

                        if ( $protectDescription !== '' ) {
                                $protectDescription .= wfMessage( 'word-separator' )->inContentLanguage()->text();
                        }
                        $protectDescription .= wfMessage( 'protect-summary-desc' )
                                ->params( $actionText, $restrictionsText, $expiryText )
                                ->inContentLanguage()->text();
                }

                return $protectDescription;
        }

        /**
         * Builds the description to serve as comment for the log entry.
         *
         * Some bots may parse IRC lines, which are generated from log entries which contain plain
         * protect description text. Keep them in old format to avoid breaking compatibility.
         * TODO: Fix protection log to store structured description and format it on-the-fly.
         *
         * @param array $limit Set of restriction keys
         * @param array $expiry Per restriction type expiration
         * @return string
         */
        public function protectDescriptionLog( array $limit, array $expiry ) {
                global $wgContLang;

                $protectDescriptionLog = '';

                foreach ( array_filter( $limit ) as $action => $restrictions ) {
                        $expiryText = $this->formatExpiry( $expiry[$action] );
                        $protectDescriptionLog .= $wgContLang->getDirMark() . "[$action=$restrictions] ($expiryText)";
                }

                return trim( $protectDescriptionLog );
        }

        /**
         * Take an array of page restrictions and flatten it to a string
         * suitable for insertion into the page_restrictions field.
         *
         * @param string[] $limit
         *
         * @throws MWException
         * @return string
         */
        protected static function flattenRestrictions( $limit ) {
                if ( !is_array( $limit ) ) {
                        throw new MWException( 'WikiPage::flattenRestrictions given non-array restriction set' );
                }

                $bits = array();
                ksort( $limit );

                foreach ( array_filter( $limit ) as $action => $restrictions ) {
                        $bits[] = "$action=$restrictions";
                }

                return implode( ':', $bits );
        }

        /**
         * Same as doDeleteArticleReal(), but returns a simple boolean. This is kept around for
         * backwards compatibility, if you care about error reporting you should use
         * doDeleteArticleReal() instead.
         *
         * Deletes the article with database consistency, writes logs, purges caches
         *
         * @param string $reason Delete reason for deletion log
         * @param bool $suppress Suppress all revisions and log the deletion in
         *        the suppression log instead of the deletion log
         * @param int $id Article ID
         * @param bool $commit Defaults to true, triggers transaction end
         * @param array &$error Array of errors to append to
         * @param User $user The deleting user
         * @return bool True if successful
         */
        public function doDeleteArticle(
                $reason, $suppress = false, $id = 0, $commit = true, &$error = '', User $user = null
        ) {
                $status = $this->doDeleteArticleReal( $reason, $suppress, $id, $commit, $error, $user );
                return $status->isGood();
        }

        /**
         * Back-end article deletion
         * Deletes the article with database consistency, writes logs, purges caches
         *
         * @since 1.19
         *
         * @param string $reason Delete reason for deletion log
         * @param bool $suppress Suppress all revisions and log the deletion in
         *   the suppression log instead of the deletion log
         * @param int $id Article ID
         * @param bool $commit Defaults to true, triggers transaction end
         * @param array &$error Array of errors to append to
         * @param User $user The deleting user
         * @return Status Status object; if successful, $status->value is the log_id of the
         *   deletion log entry. If the page couldn't be deleted because it wasn't
         *   found, $status is a non-fatal 'cannotdelete' error
         */
        public function doDeleteArticleReal(
                $reason, $suppress = false, $id = 0, $commit = true, &$error = '', User $user = null
        ) {
                global $wgUser, $wgContentHandlerUseDB;

                wfDebug( __METHOD__ . "\n" );

                $status = Status::newGood();

                if ( $this->mTitle->getDBkey() === '' ) {
                        $status->error( 'cannotdelete', wfEscapeWikiText( $this->getTitle()->getPrefixedText() ) );
                        return $status;
                }

                $user = is_null( $user ) ? $wgUser : $user;
                if ( !Hooks::run( 'ArticleDelete', array( &$this, &$user, &$reason, &$error, &$status ) ) ) {
                        if ( $status->isOK() ) {
                                // Hook aborted but didn't set a fatal status
                                $status->fatal( 'delete-hook-aborted' );
                        }
                        return $status;
                }

                $dbw = wfGetDB( DB_MASTER );
                $dbw->begin( __METHOD__ );

                if ( $id == 0 ) {
                        $this->loadPageData( 'forupdate' );
                        $id = $this->getID();
                        if ( $id == 0 ) {
                                $dbw->rollback( __METHOD__ );
                                $status->error( 'cannotdelete', wfEscapeWikiText( $this->getTitle()->getPrefixedText() ) );
                                return $status;
                        }
                }

                // we need to remember the old content so we can use it to generate all deletion updates.
                $content = $this->getContent( Revision::RAW );

                // Bitfields to further suppress the content
                if ( $suppress ) {
                        $bitfield = 0;
                        // This should be 15...
                        $bitfield |= Revision::DELETED_TEXT;
                        $bitfield |= Revision::DELETED_COMMENT;
                        $bitfield |= Revision::DELETED_USER;
                        $bitfield |= Revision::DELETED_RESTRICTED;
                } else {
                        $bitfield = 'rev_deleted';
                }

                // For now, shunt the revision data into the archive table.
                // Text is *not* removed from the text table; bulk storage
                // is left intact to avoid breaking block-compression or
                // immutable storage schemes.
                //
                // For backwards compatibility, note that some older archive
                // table entries will have ar_text and ar_flags fields still.
                //
                // In the future, we may keep revisions and mark them with
                // the rev_deleted field, which is reserved for this purpose.

                $row = array(
                        'ar_namespace'  => 'page_namespace',
                        'ar_title'      => 'page_title',
                        'ar_comment'    => 'rev_comment',
                        'ar_user'       => 'rev_user',
                        'ar_user_text'  => 'rev_user_text',
                        'ar_timestamp'  => 'rev_timestamp',
                        'ar_minor_edit' => 'rev_minor_edit',
                        'ar_rev_id'     => 'rev_id',
                        'ar_parent_id'  => 'rev_parent_id',
                        'ar_text_id'    => 'rev_text_id',
                        'ar_text'       => '\'\'', // Be explicit to appease
                        'ar_flags'      => '\'\'', // MySQL's "strict mode"...
                        'ar_len'        => 'rev_len',
                        'ar_page_id'    => 'page_id',
                        'ar_deleted'    => $bitfield,
                        'ar_sha1'       => 'rev_sha1',
                );

                if ( $wgContentHandlerUseDB ) {
                        $row['ar_content_model'] = 'rev_content_model';
                        $row['ar_content_format'] = 'rev_content_format';
                }

                $dbw->insertSelect( 'archive', array( 'page', 'revision' ),
                        $row,
                        array(
                                'page_id' => $id,
                                'page_id = rev_page'
                        ), __METHOD__
                );

                // Now that it's safely backed up, delete it
                $dbw->delete( 'page', array( 'page_id' => $id ), __METHOD__ );
                $ok = ( $dbw->affectedRows() > 0 ); // $id could be laggy

                if ( !$ok ) {
                        $dbw->rollback( __METHOD__ );
                        $status->error( 'cannotdelete', wfEscapeWikiText( $this->getTitle()->getPrefixedText() ) );
                        return $status;
                }

                if ( !$dbw->cascadingDeletes() ) {
                        $dbw->delete( 'revision', array( 'rev_page' => $id ), __METHOD__ );
                }

                // Clone the title, so we have the information we need when we log
                $logTitle = clone $this->mTitle;

                // Log the deletion, if the page was suppressed, log it at Oversight instead
                $logtype = $suppress ? 'suppress' : 'delete';

                $logEntry = new ManualLogEntry( $logtype, 'delete' );
                $logEntry->setPerformer( $user );
                $logEntry->setTarget( $logTitle );
                $logEntry->setComment( $reason );
                $logid = $logEntry->insert();

                $dbw->onTransactionPreCommitOrIdle( function () use ( $dbw, $logEntry, $logid ) {
                        // Bug 56776: avoid deadlocks (especially from FileDeleteForm)
                        $logEntry->publish( $logid );
                } );

                if ( $commit ) {
                        $dbw->commit( __METHOD__ );
                }

                $this->doDeleteUpdates( $id, $content );

                Hooks::run( 'ArticleDeleteComplete', array( &$this, &$user, $reason, $id, $content, $logEntry ) );
                $status->value = $logid;
                return $status;
        }

        /**
         * Do some database updates after deletion
         *
         * @param int $id The page_id value of the page being deleted
         * @param Content $content Optional page content to be used when determining
         *   the required updates. This may be needed because $this->getContent()
         *   may already return null when the page proper was deleted.
         */
        public function doDeleteUpdates( $id, Content $content = null ) {
                // update site status
                DeferredUpdates::addUpdate( new SiteStatsUpdate( 0, 1, - (int)$this->isCountable(), -1 ) );

                // remove secondary indexes, etc
                $updates = $this->getDeletionUpdates( $content );
                DataUpdate::runUpdates( $updates );

                // Reparse any pages transcluding this page
                LinksUpdate::queueRecursiveJobsForTable( $this->mTitle, 'templatelinks' );

                // Reparse any pages including this image
                if ( $this->mTitle->getNamespace() == NS_FILE ) {
                        LinksUpdate::queueRecursiveJobsForTable( $this->mTitle, 'imagelinks' );
                }

                // Clear caches
                WikiPage::onArticleDelete( $this->mTitle );

                // Reset this object and the Title object
                $this->loadFromRow( false, self::READ_LATEST );

                // Search engine
                DeferredUpdates::addUpdate( new SearchUpdate( $id, $this->mTitle ) );
        }

        /**
         * Roll back the most recent consecutive set of edits to a page
         * from the same user; fails if there are no eligible edits to
         * roll back to, e.g. user is the sole contributor. This function
         * performs permissions checks on $user, then calls commitRollback()
         * to do the dirty work
         *
         * @todo Separate the business/permission stuff out from backend code
         *
         * @param string $fromP Name of the user whose edits to rollback.
         * @param string $summary Custom summary. Set to default summary if empty.
         * @param string $token Rollback token.
         * @param bool $bot If true, mark all reverted edits as bot.
         *
         * @param array $resultDetails Array contains result-specific array of additional values
         *    'alreadyrolled' : 'current' (rev)
         *    success        : 'summary' (str), 'current' (rev), 'target' (rev)
         *
         * @param User $user The user performing the rollback
         * @return array Array of errors, each error formatted as
         *   array(messagekey, param1, param2, ...).
         * On success, the array is empty.  This array can also be passed to
         * OutputPage::showPermissionsErrorPage().
         */
        public function doRollback(
                $fromP, $summary, $token, $bot, &$resultDetails, User $user
        ) {
                $resultDetails = null;

                // Check permissions
                $editErrors = $this->mTitle->getUserPermissionsErrors( 'edit', $user );
                $rollbackErrors = $this->mTitle->getUserPermissionsErrors( 'rollback', $user );
                $errors = array_merge( $editErrors, wfArrayDiff2( $rollbackErrors, $editErrors ) );

                if ( !$user->matchEditToken( $token, array( $this->mTitle->getPrefixedText(), $fromP ) ) ) {
                        $errors[] = array( 'sessionfailure' );
                }

                if ( $user->pingLimiter( 'rollback' ) || $user->pingLimiter() ) {
                        $errors[] = array( 'actionthrottledtext' );
                }

                // If there were errors, bail out now
                if ( !empty( $errors ) ) {
                        return $errors;
                }

                return $this->commitRollback( $fromP, $summary, $bot, $resultDetails, $user );
        }

        /**
         * Backend implementation of doRollback(), please refer there for parameter
         * and return value documentation
         *
         * NOTE: This function does NOT check ANY permissions, it just commits the
         * rollback to the DB. Therefore, you should only call this function direct-
         * ly if you want to use custom permissions checks. If you don't, use
         * doRollback() instead.
         * @param string $fromP Name of the user whose edits to rollback.
         * @param string $summary Custom summary. Set to default summary if empty.
         * @param bool $bot If true, mark all reverted edits as bot.
         *
         * @param array $resultDetails Contains result-specific array of additional values
         * @param User $guser The user performing the rollback
         * @return array
         */
        public function commitRollback( $fromP, $summary, $bot, &$resultDetails, User $guser ) {
                global $wgUseRCPatrol, $wgContLang;

                $dbw = wfGetDB( DB_MASTER );

                if ( wfReadOnly() ) {
                        return array( array( 'readonlytext' ) );
                }

                // Get the last editor
                $current = $this->getRevision();
                if ( is_null( $current ) ) {
                        // Something wrong... no page?
                        return array( array( 'notanarticle' ) );
                }

                $from = str_replace( '_', ' ', $fromP );
                // User name given should match up with the top revision.
                // If the user was deleted then $from should be empty.
                if ( $from != $current->getUserText() ) {
                        $resultDetails = array( 'current' => $current );
                        return array( array( 'alreadyrolled',
                                htmlspecialchars( $this->mTitle->getPrefixedText() ),
                                htmlspecialchars( $fromP ),
                                htmlspecialchars( $current->getUserText() )
                        ) );
                }

                // Get the last edit not by this guy...
                // Note: these may not be public values
                $user = intval( $current->getRawUser() );
                $user_text = $dbw->addQuotes( $current->getRawUserText() );
                $s = $dbw->selectRow( 'revision',
                        array( 'rev_id', 'rev_timestamp', 'rev_deleted' ),
                        array( 'rev_page' => $current->getPage(),
                                "rev_user != {$user} OR rev_user_text != {$user_text}"
                        ), __METHOD__,
                        array( 'USE INDEX' => 'page_timestamp',
                                'ORDER BY' => 'rev_timestamp DESC' )
                        );
                if ( $s === false ) {
                        // No one else ever edited this page
                        return array( array( 'cantrollback' ) );
                } elseif ( $s->rev_deleted & Revision::DELETED_TEXT
                        || $s->rev_deleted & Revision::DELETED_USER
                ) {
                        // Only admins can see this text
                        return array( array( 'notvisiblerev' ) );
                }

                // Set patrolling and bot flag on the edits, which gets rollbacked.
                // This is done before the rollback edit to have patrolling also on failure (bug 62157).
                $set = array();
                if ( $bot && $guser->isAllowed( 'markbotedits' ) ) {
                        // Mark all reverted edits as bot
                        $set['rc_bot'] = 1;
                }

                if ( $wgUseRCPatrol ) {
                        // Mark all reverted edits as patrolled
                        $set['rc_patrolled'] = 1;
                }

                if ( count( $set ) ) {
                        $dbw->update( 'recentchanges', $set,
                                array( /* WHERE */
                                        'rc_cur_id' => $current->getPage(),
                                        'rc_user_text' => $current->getUserText(),
                                        'rc_timestamp > ' . $dbw->addQuotes( $s->rev_timestamp ),
                                ), __METHOD__
                        );
                }

                // Generate the edit summary if necessary
                $target = Revision::newFromId( $s->rev_id );
                if ( empty( $summary ) ) {
                        if ( $from == '' ) { // no public user name
                                $summary = wfMessage( 'revertpage-nouser' );
                        } else {
                                $summary = wfMessage( 'revertpage' );
                        }
                }

                // Allow the custom summary to use the same args as the default message
                $args = array(
                        $target->getUserText(), $from, $s->rev_id,
                        $wgContLang->timeanddate( wfTimestamp( TS_MW, $s->rev_timestamp ) ),
                        $current->getId(), $wgContLang->timeanddate( $current->getTimestamp() )
                );
                if ( $summary instanceof Message ) {
                        $summary = $summary->params( $args )->inContentLanguage()->text();
                } else {
                        $summary = wfMsgReplaceArgs( $summary, $args );
                }

                // Trim spaces on user supplied text
                $summary = trim( $summary );

                // Truncate for whole multibyte characters.
                $summary = $wgContLang->truncate( $summary, 255 );

                // Save
                $flags = EDIT_UPDATE;

                if ( $guser->isAllowed( 'minoredit' ) ) {
                        $flags |= EDIT_MINOR;
                }

                if ( $bot && ( $guser->isAllowedAny( 'markbotedits', 'bot' ) ) ) {
                        $flags |= EDIT_FORCE_BOT;
                }

                // Actually store the edit
                $status = $this->doEditContent(
                        $target->getContent(),
                        $summary,
                        $flags,
                        $target->getId(),
                        $guser
                );

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

                // raise error, when the edit is an edit without a new version
                if ( empty( $status->value['revision'] ) ) {
                        $resultDetails = array( 'current' => $current );
                        return array( array( 'alreadyrolled',
                                        htmlspecialchars( $this->mTitle->getPrefixedText() ),
                                        htmlspecialchars( $fromP ),
                                        htmlspecialchars( $current->getUserText() )
                        ) );
                }

                $revId = $status->value['revision']->getId();

                Hooks::run( 'ArticleRollbackComplete', array( $this, $guser, $target, $current ) );

                $resultDetails = array(
                        'summary' => $summary,
                        'current' => $current,
                        'target' => $target,
                        'newid' => $revId
                );

                return array();
        }

        /**
         * The onArticle*() functions are supposed to be a kind of hooks
         * which should be called whenever any of the specified actions
         * are done.
         *
         * This is a good place to put code to clear caches, for instance.
         *
         * This is called on page move and undelete, as well as edit
         *
         * @param Title $title
         */
        public static function onArticleCreate( Title $title ) {
                // Update existence markers on article/talk tabs...
                $other = $title->getOtherPage();

                $other->invalidateCache();
                $other->purgeSquid();

                $title->touchLinks();
                $title->purgeSquid();
                $title->deleteTitleProtection();
        }

        /**
         * Clears caches when article is deleted
         *
         * @param Title $title
         */
        public static function onArticleDelete( Title $title ) {
                // Update existence markers on article/talk tabs...
                $other = $title->getOtherPage();

                $other->invalidateCache();
                $other->purgeSquid();

                $title->touchLinks();
                $title->purgeSquid();

                // File cache
                HTMLFileCache::clearFileCache( $title );
                InfoAction::invalidateCache( $title );

                // Messages
                if ( $title->getNamespace() == NS_MEDIAWIKI ) {
                        MessageCache::singleton()->replace( $title->getDBkey(), false );
                }

                // Images
                if ( $title->getNamespace() == NS_FILE ) {
                        $update = new HTMLCacheUpdate( $title, 'imagelinks' );
                        $update->doUpdate();
                }

                // User talk pages
                if ( $title->getNamespace() == NS_USER_TALK ) {
                        $user = User::newFromName( $title->getText(), false );
                        if ( $user ) {
                                $user->setNewtalk( false );
                        }
                }

                // Image redirects
                RepoGroup::singleton()->getLocalRepo()->invalidateImageRedirect( $title );
        }

        /**
         * Purge caches on page update etc
         *
         * @param Title $title
         */
        public static function onArticleEdit( Title $title ) {
                // Invalidate caches of articles which include this page
                DeferredUpdates::addHTMLCacheUpdate( $title, 'templatelinks' );

                // Invalidate the caches of all pages which redirect here
                DeferredUpdates::addHTMLCacheUpdate( $title, 'redirect' );

                // Purge squid for this page only
                $title->purgeSquid();

                // Clear file cache for this page only
                HTMLFileCache::clearFileCache( $title );
                InfoAction::invalidateCache( $title );
        }

        /**#@-*/

        /**
         * Returns a list of categories this page is a member of.
         * Results will include hidden categories
         *
         * @return TitleArray
         */
        public function getCategories() {
                $id = $this->getId();
                if ( $id == 0 ) {
                        return TitleArray::newFromResult( new FakeResultWrapper( array() ) );
                }

                $dbr = wfGetDB( DB_SLAVE );
                $res = $dbr->select( 'categorylinks',
                        array( 'cl_to AS page_title, ' . NS_CATEGORY . ' AS page_namespace' ),
                        // Have to do that since DatabaseBase::fieldNamesWithAlias treats numeric indexes
                        // as not being aliases, and NS_CATEGORY is numeric
                        array( 'cl_from' => $id ),
                        __METHOD__ );

                return TitleArray::newFromResult( $res );
        }

        /**
         * Returns a list of hidden categories this page is a member of.
         * Uses the page_props and categorylinks tables.
         *
         * @return array Array of Title objects
         */
        public function getHiddenCategories() {
                $result = array();
                $id = $this->getId();

                if ( $id == 0 ) {
                        return array();
                }

                $dbr = wfGetDB( DB_SLAVE );
                $res = $dbr->select( array( 'categorylinks', 'page_props', 'page' ),
                        array( 'cl_to' ),
                        array( 'cl_from' => $id, 'pp_page=page_id', 'pp_propname' => 'hiddencat',
                                'page_namespace' => NS_CATEGORY, 'page_title=cl_to' ),
                        __METHOD__ );

                if ( $res !== false ) {
                        foreach ( $res as $row ) {
                                $result[] = Title::makeTitle( NS_CATEGORY, $row->cl_to );
                        }
                }

                return $result;
        }

        /**
         * Return an applicable autosummary if one exists for the given edit.
         * @param string|null $oldtext The previous text of the page.
         * @param string|null $newtext The submitted text of the page.
         * @param int $flags Bitmask: a bitmask of flags submitted for the edit.
         * @return string An appropriate autosummary, or an empty string.
         *
         * @deprecated since 1.21, use ContentHandler::getAutosummary() instead
         */
        public static function getAutosummary( $oldtext, $newtext, $flags ) {
                // NOTE: stub for backwards-compatibility. assumes the given text is
                // wikitext. will break horribly if it isn't.

                ContentHandler::deprecated( __METHOD__, '1.21' );

                $handler = ContentHandler::getForModelID( CONTENT_MODEL_WIKITEXT );
                $oldContent = is_null( $oldtext ) ? null : $handler->unserializeContent( $oldtext );
                $newContent = is_null( $newtext ) ? null : $handler->unserializeContent( $newtext );

                return $handler->getAutosummary( $oldContent, $newContent, $flags );
        }

        /**
         * Auto-generates a deletion reason
         *
         * @param bool &$hasHistory Whether the page has a history
         * @return string|bool String containing deletion reason or empty string, or boolean false
         *    if no revision occurred
         */
        public function getAutoDeleteReason( &$hasHistory ) {
                return $this->getContentHandler()->getAutoDeleteReason( $this->getTitle(), $hasHistory );
        }

        /**
         * Update all the appropriate counts in the category table, given that
         * we've added the categories $added and deleted the categories $deleted.
         *
         * @param array $added The names of categories that were added
         * @param array $deleted The names of categories that were deleted
         */
        public function updateCategoryCounts( array $added, array $deleted ) {
                $that = $this;
                $method = __METHOD__;
                $dbw = wfGetDB( DB_MASTER );

                // Do this at the end of the commit to reduce lock wait timeouts
                $dbw->onTransactionPreCommitOrIdle(
                        function () use ( $dbw, $that, $method, $added, $deleted ) {
                                $ns = $that->getTitle()->getNamespace();

                                $addFields = array( 'cat_pages = cat_pages + 1' );
                                $removeFields = array( 'cat_pages = cat_pages - 1' );
                                if ( $ns == NS_CATEGORY ) {
                                        $addFields[] = 'cat_subcats = cat_subcats + 1';
                                        $removeFields[] = 'cat_subcats = cat_subcats - 1';
                                } elseif ( $ns == NS_FILE ) {
                                        $addFields[] = 'cat_files = cat_files + 1';
                                        $removeFields[] = 'cat_files = cat_files - 1';
                                }

                                if ( count( $added ) ) {
                                        $insertRows = array();
                                        foreach ( $added as $cat ) {
                                                $insertRows[] = array(
                                                        'cat_title'   => $cat,
                                                        'cat_pages'   => 1,
                                                        'cat_subcats' => ( $ns == NS_CATEGORY ) ? 1 : 0,
                                                        'cat_files'   => ( $ns == NS_FILE ) ? 1 : 0,
                                                );
                                        }
                                        $dbw->upsert(
                                                'category',
                                                $insertRows,
                                                array( 'cat_title' ),
                                                $addFields,
                                                $method
                                        );
                                }

                                if ( count( $deleted ) ) {
                                        $dbw->update(
                                                'category',
                                                $removeFields,
                                                array( 'cat_title' => $deleted ),
                                                $method
                                        );
                                }

                                foreach ( $added as $catName ) {
                                        $cat = Category::newFromName( $catName );
                                        Hooks::run( 'CategoryAfterPageAdded', array( $cat, $that ) );
                                }

                                foreach ( $deleted as $catName ) {
                                        $cat = Category::newFromName( $catName );
                                        Hooks::run( 'CategoryAfterPageRemoved', array( $cat, $that ) );
                                }
                        }
                );
        }

        /**
         * Updates cascading protections
         *
         * @param ParserOutput $parserOutput ParserOutput object for the current version
         */
        public function doCascadeProtectionUpdates( ParserOutput $parserOutput ) {
                if ( wfReadOnly() || !$this->mTitle->areRestrictionsCascading() ) {
                        return;
                }

                // templatelinks or imagelinks tables may have become out of sync,
                // especially if using variable-based transclusions.
                // For paranoia, check if things have changed and if
                // so apply updates to the database. This will ensure
                // that cascaded protections apply as soon as the changes
                // are visible.

                // Get templates from templatelinks and images from imagelinks
                $id = $this->getId();

                $dbLinks = array();

                $dbr = wfGetDB( DB_SLAVE );
                $res = $dbr->select( array( 'templatelinks' ),
                        array( 'tl_namespace', 'tl_title' ),
                        array( 'tl_from' => $id ),
                        __METHOD__
                );

                foreach ( $res as $row ) {
                        $dbLinks["{$row->tl_namespace}:{$row->tl_title}"] = true;
                }

                $dbr = wfGetDB( DB_SLAVE );
                $res = $dbr->select( array( 'imagelinks' ),
                        array( 'il_to' ),
                        array( 'il_from' => $id ),
                        __METHOD__
                );

                foreach ( $res as $row ) {
                        $dbLinks[NS_FILE . ":{$row->il_to}"] = true;
                }

                // Get templates and images from parser output.
                $poLinks = array();
                foreach ( $parserOutput->getTemplates() as $ns => $templates ) {
                        foreach ( $templates as $dbk => $id ) {
                                $poLinks["$ns:$dbk"] = true;
                        }
                }
                foreach ( $parserOutput->getImages() as $dbk => $id ) {
                        $poLinks[NS_FILE . ":$dbk"] = true;
                }

                // Get the diff
                $links_diff = array_diff_key( $poLinks, $dbLinks );

                if ( count( $links_diff ) > 0 ) {
                        // Whee, link updates time.
                        // Note: we are only interested in links here. We don't need to get
                        // other DataUpdate items from the parser output.
                        $u = new LinksUpdate( $this->mTitle, $parserOutput, false );
                        $u->doUpdate();
                }
        }

        /**
         * Return a list of templates used by this article.
         * Uses the templatelinks table
         *
         * @deprecated since 1.19; use Title::getTemplateLinksFrom()
         * @return array Array of Title objects
         */
        public function getUsedTemplates() {
                return $this->mTitle->getTemplateLinksFrom();
        }

        /**
         * This function is called right before saving the wikitext,
         * so we can do things like signatures and links-in-context.
         *
         * @deprecated since 1.19; use Parser::preSaveTransform() instead
         * @param string $text Article contents
         * @param User $user User doing the edit
         * @param ParserOptions $popts Parser options, default options for
         *   the user loaded if null given
         * @return string Article contents with altered wikitext markup (signatures
         *      converted, {{subst:}}, templates, etc.)
         */
        public function preSaveTransform( $text, User $user = null, ParserOptions $popts = null ) {
                global $wgParser, $wgUser;

                wfDeprecated( __METHOD__, '1.19' );

                $user = is_null( $user ) ? $wgUser : $user;

                if ( $popts === null ) {
                        $popts = ParserOptions::newFromUser( $user );
                }

                return $wgParser->preSaveTransform( $text, $this->mTitle, $user, $popts );
        }

        /**
         * Update the article's restriction field, and leave a log entry.
         *
         * @deprecated since 1.19
         * @param array $limit Set of restriction keys
         * @param string $reason
         * @param int &$cascade Set to false if cascading protection isn't allowed.
         * @param array $expiry Per restriction type expiration
         * @param User $user The user updating the restrictions
         * @return bool True on success
         */
        public function updateRestrictions(
                $limit = array(), $reason = '', &$cascade = 0, $expiry = array(), User $user = null
        ) {
                global $wgUser;

                $user = is_null( $user ) ? $wgUser : $user;

                return $this->doUpdateRestrictions( $limit, $expiry, $cascade, $reason, $user )->isOK();
        }

        /**
         * Returns a list of updates to be performed when this page is deleted. The
         * updates should remove any information about this page from secondary data
         * stores such as links tables.
         *
         * @param Content|null $content Optional Content object for determining the
         *   necessary updates.
         * @return array An array of DataUpdates objects
         */
        public function getDeletionUpdates( Content $content = null ) {
                if ( !$content ) {
                        // load content object, which may be used to determine the necessary updates
                        // XXX: the content may not be needed to determine the updates, then this would be overhead.
                        $content = $this->getContent( Revision::RAW );
                }

                if ( !$content ) {
                        $updates = array();
                } else {
                        $updates = $content->getDeletionUpdates( $this );
                }

                Hooks::run( 'WikiPageDeletionUpdates', array( $this, $content, &$updates ) );
                return $updates;
        }
}