Fix bug that brakes the 'jquery.tabIndex > firstTabIndex' test in IE8/IE9. Some value...

[mediawiki.git] / includes / Title.php

<?php
/**
 * See title.txt
 * @file
 */

/**
 * Represents a title within MediaWiki.
 * Optionally may contain an interwiki designation or namespace.
 * @note This class can fetch various kinds of data from the database;
 *       however, it does so inefficiently.
 *
 * @internal documentation reviewed 15 Mar 2010
 */
class Title {
        /** @name Static cache variables */
        // @{
        static private $titleCache = array();
        // @}

        /**
         * Title::newFromText maintains a cache to avoid expensive re-normalization of
         * commonly used titles. On a batch operation this can become a memory leak
         * if not bounded. After hitting this many titles reset the cache.
         */
        const CACHE_MAX = 1000;

        /**
         * Used to be GAID_FOR_UPDATE define. Used with getArticleID() and friends
         * to use the master DB
         */
        const GAID_FOR_UPDATE = 1;


        /**
         * @name Private member variables
         * Please use the accessor functions instead.
         * @private
         */
        // @{

        var $mTextform = '';              // /< Text form (spaces not underscores) of the main part
        var $mUrlform = '';               // /< URL-encoded form of the main part
        var $mDbkeyform = '';             // /< Main part with underscores
        var $mUserCaseDBKey;              // /< DB key with the initial letter in the case specified by the user
        var $mNamespace = NS_MAIN;        // /< Namespace index, i.e. one of the NS_xxxx constants
        var $mInterwiki = '';             // /< Interwiki prefix (or null string)
        var $mFragment;                   // /< Title fragment (i.e. the bit after the #)
        var $mArticleID = -1;             // /< Article ID, fetched from the link cache on demand
        var $mLatestID = false;           // /< ID of most recent revision
        var $mRestrictions = array();     // /< Array of groups allowed to edit this article
        var $mOldRestrictions = false;
        var $mCascadeRestriction;         ///< Cascade restrictions on this page to included templates and images?
        var $mCascadingRestrictions;      // Caching the results of getCascadeProtectionSources
        var $mRestrictionsExpiry = array(); ///< When do the restrictions on this page expire?
        var $mHasCascadingRestrictions;   ///< Are cascading restrictions in effect on this page?
        var $mCascadeSources;             ///< Where are the cascading restrictions coming from on this page?
        var $mRestrictionsLoaded = false; ///< Boolean for initialisation on demand
        var $mPrefixedText;               ///< Text form including namespace/interwiki, initialised on demand
        var $mTitleProtection;            ///< Cached value for getTitleProtection (create protection)
        # Don't change the following default, NS_MAIN is hardcoded in several
        # places.  See bug 696.
        var $mDefaultNamespace = NS_MAIN; // /< Namespace index when there is no namespace
                                                                          # Zero except in {{transclusion}} tags
        var $mWatched = null;             // /< Is $wgUser watching this page? null if unfilled, accessed through userIsWatching()
        var $mLength = -1;                // /< The page length, 0 for special pages
        var $mRedirect = null;            // /< Is the article at this title a redirect?
        var $mNotificationTimestamp = array(); // /< Associative array of user ID -> timestamp/false
        var $mBacklinkCache = null;       // /< Cache of links to this title
        // @}


        /**
         * Constructor
         */
        /*protected*/ function __construct() { }

        /**
         * Create a new Title from a prefixed DB key
         *
         * @param $key String the database key, which has underscores
         *      instead of spaces, possibly including namespace and
         *      interwiki prefixes
         * @return Title, or NULL on an error
         */
        public static function newFromDBkey( $key ) {
                $t = new Title();
                $t->mDbkeyform = $key;
                if ( $t->secureAndSplit() ) {
                        return $t;
                } else {
                        return null;
                }
        }

        /**
         * Create a new Title from text, such as what one would find in a link. De-
         * codes any HTML entities in the text.
         *
         * @param $text String the link text; spaces, prefixes, and an
         *   initial ':' indicating the main namespace are accepted.
         * @param $defaultNamespace Int the namespace to use if none is speci-
         *   fied by a prefix.  If you want to force a specific namespace even if
         *   $text might begin with a namespace prefix, use makeTitle() or
         *   makeTitleSafe().
         * @return Title, or null on an error.
         */
        public static function newFromText( $text, $defaultNamespace = NS_MAIN ) {
                if ( is_object( $text ) ) {
                        throw new MWException( 'Title::newFromText given an object' );
                }

                /**
                 * Wiki pages often contain multiple links to the same page.
                 * Title normalization and parsing can become expensive on
                 * pages with many links, so we can save a little time by
                 * caching them.
                 *
                 * In theory these are value objects and won't get changed...
                 */
                if ( $defaultNamespace == NS_MAIN && isset( Title::$titleCache[$text] ) ) {
                        return Title::$titleCache[$text];
                }

                # Convert things like &eacute; &#257; or &#x3017; into normalized (bug 14952) text
                $filteredText = Sanitizer::decodeCharReferencesAndNormalize( $text );

                $t = new Title();
                $t->mDbkeyform = str_replace( ' ', '_', $filteredText );
                $t->mDefaultNamespace = $defaultNamespace;

                static $cachedcount = 0 ;
                if ( $t->secureAndSplit() ) {
                        if ( $defaultNamespace == NS_MAIN ) {
                                if ( $cachedcount >= self::CACHE_MAX ) {
                                        # Avoid memory leaks on mass operations...
                                        Title::$titleCache = array();
                                        $cachedcount = 0;
                                }
                                $cachedcount++;
                                Title::$titleCache[$text] =& $t;
                        }
                        return $t;
                } else {
                        $ret = null;
                        return $ret;
                }
        }

        /**
         * THIS IS NOT THE FUNCTION YOU WANT. Use Title::newFromText().
         *
         * Example of wrong and broken code:
         * $title = Title::newFromURL( $wgRequest->getVal( 'title' ) );
         *
         * Example of right code:
         * $title = Title::newFromText( $wgRequest->getVal( 'title' ) );
         *
         * Create a new Title from URL-encoded text. Ensures that
         * the given title's length does not exceed the maximum.
         *
         * @param $url String the title, as might be taken from a URL
         * @return Title the new object, or NULL on an error
         */
        public static function newFromURL( $url ) {
                global $wgLegalTitleChars;
                $t = new Title();

                # For compatibility with old buggy URLs. "+" is usually not valid in titles,
                # but some URLs used it as a space replacement and they still come
                # from some external search tools.
                if ( strpos( $wgLegalTitleChars, '+' ) === false ) {
                        $url = str_replace( '+', ' ', $url );
                }

                $t->mDbkeyform = str_replace( ' ', '_', $url );
                if ( $t->secureAndSplit() ) {
                        return $t;
                } else {
                        return null;
                }
        }

        /**
         * Create a new Title from an article ID
         *
         * @param $id Int the page_id corresponding to the Title to create
         * @param $flags Int use Title::GAID_FOR_UPDATE to use master
         * @return Title the new object, or NULL on an error
         */
        public static function newFromID( $id, $flags = 0 ) {
                $db = ( $flags & self::GAID_FOR_UPDATE ) ? wfGetDB( DB_MASTER ) : wfGetDB( DB_SLAVE );
                $row = $db->selectRow( 'page', '*', array( 'page_id' => $id ), __METHOD__ );
                if ( $row !== false ) {
                        $title = Title::newFromRow( $row );
                } else {
                        $title = null;
                }
                return $title;
        }

        /**
         * Make an array of titles from an array of IDs
         *
         * @param $ids Array of Int Array of IDs
         * @return Array of Titles
         */
        public static function newFromIDs( $ids ) {
                if ( !count( $ids ) ) {
                        return array();
                }
                $dbr = wfGetDB( DB_SLAVE );

                $res = $dbr->select(
                        'page',
                        array(
                                'page_namespace', 'page_title', 'page_id',
                                'page_len', 'page_is_redirect', 'page_latest',
                        ),
                        array( 'page_id' => $ids ),
                        __METHOD__
                );

                $titles = array();
                foreach ( $res as $row ) {
                        $titles[] = Title::newFromRow( $row );
                }
                return $titles;
        }

        /**
         * Make a Title object from a DB row
         *
         * @param $row Object database row (needs at least page_title,page_namespace)
         * @return Title corresponding Title
         */
        public static function newFromRow( $row ) {
                $t = self::makeTitle( $row->page_namespace, $row->page_title );

                $t->mArticleID = isset( $row->page_id ) ? intval( $row->page_id ) : -1;
                $t->mLength = isset( $row->page_len ) ? intval( $row->page_len ) : -1;
                $t->mRedirect = isset( $row->page_is_redirect ) ? (bool)$row->page_is_redirect : null;
                $t->mLatestID = isset( $row->page_latest ) ? intval( $row->page_latest ) : false;

                return $t;
        }

        /**
         * Create a new Title from a namespace index and a DB key.
         * It's assumed that $ns and $title are *valid*, for instance when
         * they came directly from the database or a special page name.
         * For convenience, spaces are converted to underscores so that
         * eg user_text fields can be used directly.
         *
         * @param $ns Int the namespace of the article
         * @param $title String the unprefixed database key form
         * @param $fragment String the link fragment (after the "#")
         * @param $interwiki String the interwiki prefix
         * @return Title the new object
         */
        public static function &makeTitle( $ns, $title, $fragment = '', $interwiki = '' ) {
                $t = new Title();
                $t->mInterwiki = $interwiki;
                $t->mFragment = $fragment;
                $t->mNamespace = $ns = intval( $ns );
                $t->mDbkeyform = str_replace( ' ', '_', $title );
                $t->mArticleID = ( $ns >= 0 ) ? -1 : 0;
                $t->mUrlform = wfUrlencode( $t->mDbkeyform );
                $t->mTextform = str_replace( '_', ' ', $title );
                return $t;
        }

        /**
         * Create a new Title from a namespace index and a DB key.
         * The parameters will be checked for validity, which is a bit slower
         * than makeTitle() but safer for user-provided data.
         *
         * @param $ns Int the namespace of the article
         * @param $title String database key form
         * @param $fragment String the link fragment (after the "#")
         * @param $interwiki String interwiki prefix
         * @return Title the new object, or NULL on an error
         */
        public static function makeTitleSafe( $ns, $title, $fragment = '', $interwiki = '' ) {
                $t = new Title();
                $t->mDbkeyform = Title::makeName( $ns, $title, $fragment, $interwiki );
                if ( $t->secureAndSplit() ) {
                        return $t;
                } else {
                        return null;
                }
        }

        /**
         * Create a new Title for the Main Page
         *
         * @return Title the new object
         */
        public static function newMainPage() {
                $title = Title::newFromText( wfMsgForContent( 'mainpage' ) );
                // Don't give fatal errors if the message is broken
                if ( !$title ) {
                        $title = Title::newFromText( 'Main Page' );
                }
                return $title;
        }

        /**
         * Extract a redirect destination from a string and return the
         * Title, or null if the text doesn't contain a valid redirect
         * This will only return the very next target, useful for
         * the redirect table and other checks that don't need full recursion
         *
         * @param $text String: Text with possible redirect
         * @return Title: The corresponding Title
         */
        public static function newFromRedirect( $text ) {
                return self::newFromRedirectInternal( $text );
        }

        /**
         * Extract a redirect destination from a string and return the
         * Title, or null if the text doesn't contain a valid redirect
         * This will recurse down $wgMaxRedirects times or until a non-redirect target is hit
         * in order to provide (hopefully) the Title of the final destination instead of another redirect
         *
         * @param $text String Text with possible redirect
         * @return Title
         */
        public static function newFromRedirectRecurse( $text ) {
                $titles = self::newFromRedirectArray( $text );
                return $titles ? array_pop( $titles ) : null;
        }

        /**
         * Extract a redirect destination from a string and return an
         * array of Titles, or null if the text doesn't contain a valid redirect
         * The last element in the array is the final destination after all redirects
         * have been resolved (up to $wgMaxRedirects times)
         *
         * @param $text String Text with possible redirect
         * @return Array of Titles, with the destination last
         */
        public static function newFromRedirectArray( $text ) {
                global $wgMaxRedirects;
                $title = self::newFromRedirectInternal( $text );
                if ( is_null( $title ) ) {
                        return null;
                }
                // recursive check to follow double redirects
                $recurse = $wgMaxRedirects;
                $titles = array( $title );
                while ( --$recurse > 0 ) {
                        if ( $title->isRedirect() ) {
                                $article = new Article( $title, 0 );
                                $newtitle = $article->getRedirectTarget();
                        } else {
                                break;
                        }
                        // Redirects to some special pages are not permitted
                        if ( $newtitle instanceOf Title && $newtitle->isValidRedirectTarget() ) {
                                // the new title passes the checks, so make that our current title so that further recursion can be checked
                                $title = $newtitle;
                                $titles[] = $newtitle;
                        } else {
                                break;
                        }
                }
                return $titles;
        }

        /**
         * Really extract the redirect destination
         * Do not call this function directly, use one of the newFromRedirect* functions above
         *
         * @param $text String Text with possible redirect
         * @return Title
         */
        protected static function newFromRedirectInternal( $text ) {
                global $wgMaxRedirects;
                if ( $wgMaxRedirects < 1 ) {
                        //redirects are disabled, so quit early
                        return null;
                }
                $redir = MagicWord::get( 'redirect' );
                $text = trim( $text );
                if ( $redir->matchStartAndRemove( $text ) ) {
                        // Extract the first link and see if it's usable
                        // Ensure that it really does come directly after #REDIRECT
                        // Some older redirects included a colon, so don't freak about that!
                        $m = array();
                        if ( preg_match( '!^\s*:?\s*\[{2}(.*?)(?:\|.*?)?\]{2}!', $text, $m ) ) {
                                // Strip preceding colon used to "escape" categories, etc.
                                // and URL-decode links
                                if ( strpos( $m[1], '%' ) !== false ) {
                                        // Match behavior of inline link parsing here;
                                        $m[1] = rawurldecode( ltrim( $m[1], ':' ) );
                                }
                                $title = Title::newFromText( $m[1] );
                                // If the title is a redirect to bad special pages or is invalid, return null
                                if ( !$title instanceof Title || !$title->isValidRedirectTarget() ) {
                                        return null;
                                }
                                return $title;
                        }
                }
                return null;
        }

# ----------------------------------------------------------------------------
#       Static functions
# ----------------------------------------------------------------------------

        /**
         * Get the prefixed DB key associated with an ID
         *
         * @param $id Int the page_id of the article
         * @return Title an object representing the article, or NULL if no such article was found
         */
        public static function nameOf( $id ) {
                $dbr = wfGetDB( DB_SLAVE );

                $s = $dbr->selectRow(
                        'page',
                        array( 'page_namespace', 'page_title' ),
                        array( 'page_id' => $id ),
                        __METHOD__
                );
                if ( $s === false ) {
                        return null;
                }

                $n = self::makeName( $s->page_namespace, $s->page_title );
                return $n;
        }

        /**
         * Get a regex character class describing the legal characters in a link
         *
         * @return String the list of characters, not delimited
         */
        public static function legalChars() {
                global $wgLegalTitleChars;
                return $wgLegalTitleChars;
        }

        /**
         * Get a string representation of a title suitable for
         * including in a search index
         *
         * @param $ns Int a namespace index
         * @param $title String text-form main part
         * @return String a stripped-down title string ready for the search index
         */
        public static function indexTitle( $ns, $title ) {
                global $wgContLang;

                $lc = SearchEngine::legalSearchChars() . '&#;';
                $t = $wgContLang->normalizeForSearch( $title );
                $t = preg_replace( "/[^{$lc}]+/", ' ', $t );
                $t = $wgContLang->lc( $t );

                # Handle 's, s'
                $t = preg_replace( "/([{$lc}]+)'s( |$)/", "\\1 \\1's ", $t );
                $t = preg_replace( "/([{$lc}]+)s'( |$)/", "\\1s ", $t );

                $t = preg_replace( "/\\s+/", ' ', $t );

                if ( $ns == NS_FILE ) {
                        $t = preg_replace( "/ (png|gif|jpg|jpeg|ogg)$/", "", $t );
                }
                return trim( $t );
        }

        /**
         * Make a prefixed DB key from a DB key and a namespace index
         *
         * @param $ns Int numerical representation of the namespace
         * @param $title String the DB key form the title
         * @param $fragment String The link fragment (after the "#")
         * @param $interwiki String The interwiki prefix
         * @return String the prefixed form of the title
         */
        public static function makeName( $ns, $title, $fragment = '', $interwiki = '' ) {
                global $wgContLang;

                $namespace = $wgContLang->getNsText( $ns );
                $name = $namespace == '' ? $title : "$namespace:$title";
                if ( strval( $interwiki ) != '' ) {
                        $name = "$interwiki:$name";
                }
                if ( strval( $fragment ) != '' ) {
                        $name .= '#' . $fragment;
                }
                return $name;
        }

        /**
         * Determine whether the object refers to a page within
         * this project.
         *
         * @return Bool TRUE if this is an in-project interwiki link or a wikilink, FALSE otherwise
         */
        public function isLocal() {
                if ( $this->mInterwiki != '' ) {
                        return Interwiki::fetch( $this->mInterwiki )->isLocal();
                } else {
                        return true;
                }
        }

        /**
         * Determine whether the object refers to a page within
         * this project and is transcludable.
         *
         * @return Bool TRUE if this is transcludable
         */
        public function isTrans() {
                if ( $this->mInterwiki == '' ) {
                        return false;
                }

                return Interwiki::fetch( $this->mInterwiki )->isTranscludable();
        }

        /**
         * Returns the DB name of the distant wiki which owns the object.
         *
         * @return String the DB name
         */
        public function getTransWikiID() {
                if ( $this->mInterwiki == '' ) {
                        return false;
                }

                return Interwiki::fetch( $this->mInterwiki )->getWikiID();
        }

        /**
         * Escape a text fragment, say from a link, for a URL
         *
         * @param $fragment string containing a URL or link fragment (after the "#")
         * @return String: escaped string
         */
        static function escapeFragmentForURL( $fragment ) {
                # Note that we don't urlencode the fragment.  urlencoded Unicode
                # fragments appear not to work in IE (at least up to 7) or in at least
                # one version of Opera 9.x.  The W3C validator, for one, doesn't seem
                # to care if they aren't encoded.
                return Sanitizer::escapeId( $fragment, 'noninitial' );
        }

# ----------------------------------------------------------------------------
#       Other stuff
# ----------------------------------------------------------------------------

        /** Simple accessors */
        /**
         * Get the text form (spaces not underscores) of the main part
         *
         * @return String Main part of the title
         */
        public function getText() { return $this->mTextform; }

        /**
         * Get the URL-encoded form of the main part
         *
         * @return String Main part of the title, URL-encoded
         */
        public function getPartialURL() { return $this->mUrlform; }

        /**
         * Get the main part with underscores
         *
         * @return String: Main part of the title, with underscores
         */
        public function getDBkey() { return $this->mDbkeyform; }

        /**
         * Get the namespace index, i.e. one of the NS_xxxx constants.
         *
         * @return Integer: Namespace index
         */
        public function getNamespace() { return $this->mNamespace; }

        /**
         * Get the namespace text
         *
         * @return String: Namespace text
         */
        public function getNsText() {
                global $wgContLang;

                if ( $this->mInterwiki != '' ) {
                        // This probably shouldn't even happen. ohh man, oh yuck.
                        // But for interwiki transclusion it sometimes does.
                        // Shit. Shit shit shit.
                        //
                        // Use the canonical namespaces if possible to try to
                        // resolve a foreign namespace.
                        if ( MWNamespace::exists( $this->mNamespace ) ) {
                                return MWNamespace::getCanonicalName( $this->mNamespace );
                        }
                }

                if ( $wgContLang->needsGenderDistinction() &&
                                MWNamespace::hasGenderDistinction( $this->mNamespace ) ) {
                        $gender = GenderCache::singleton()->getGenderOf( $this->getText(), __METHOD__ );
                        return $wgContLang->getGenderNsText( $this->mNamespace, $gender );
                }

                return $wgContLang->getNsText( $this->mNamespace );
        }

        /**
         * Get the DB key with the initial letter case as specified by the user
         *
         * @return String DB key
         */
        function getUserCaseDBKey() {
                return $this->mUserCaseDBKey;
        }

        /**
         * Get the namespace text of the subject (rather than talk) page
         *
         * @return String Namespace text
         */
        public function getSubjectNsText() {
                global $wgContLang;
                return $wgContLang->getNsText( MWNamespace::getSubject( $this->mNamespace ) );
        }

        /**
         * Get the namespace text of the talk page
         *
         * @return String Namespace text
         */
        public function getTalkNsText() {
                global $wgContLang;
                return( $wgContLang->getNsText( MWNamespace::getTalk( $this->mNamespace ) ) );
        }

        /**
         * Could this title have a corresponding talk page?
         *
         * @return Bool TRUE or FALSE
         */
        public function canTalk() {
                return( MWNamespace::canTalk( $this->mNamespace ) );
        }

        /**
         * Get the interwiki prefix (or null string)
         *
         * @return String Interwiki prefix
         */
        public function getInterwiki() { return $this->mInterwiki; }

        /**
         * Get the Title fragment (i.e.\ the bit after the #) in text form
         *
         * @return String Title fragment
         */
        public function getFragment() { return $this->mFragment; }

        /**
         * Get the fragment in URL form, including the "#" character if there is one
         * @return String Fragment in URL form
         */
        public function getFragmentForURL() {
                if ( $this->mFragment == '' ) {
                        return '';
                } else {
                        return '#' . Title::escapeFragmentForURL( $this->mFragment );
                }
        }

        /**
         * Get the default namespace index, for when there is no namespace
         *
         * @return Int Default namespace index
         */
        public function getDefaultNamespace() { return $this->mDefaultNamespace; }

        /**
         * Get title for search index
         *
         * @return String a stripped-down title string ready for the
         *  search index
         */
        public function getIndexTitle() {
                return Title::indexTitle( $this->mNamespace, $this->mTextform );
        }

        /**
         * Get the prefixed database key form
         *
         * @return String the prefixed title, with underscores and
         *  any interwiki and namespace prefixes
         */
        public function getPrefixedDBkey() {
                $s = $this->prefix( $this->mDbkeyform );
                $s = str_replace( ' ', '_', $s );
                return $s;
        }

        /**
         * Get the prefixed title with spaces.
         * This is the form usually used for display
         *
         * @return String the prefixed title, with spaces
         */
        public function getPrefixedText() {
                // @todo FIXME: Bad usage of empty() ?
                if ( empty( $this->mPrefixedText ) ) {
                        $s = $this->prefix( $this->mTextform );
                        $s = str_replace( '_', ' ', $s );
                        $this->mPrefixedText = $s;
                }
                return $this->mPrefixedText;
        }

        /**
         * Get the prefixed title with spaces, plus any fragment
         * (part beginning with '#')
         *
         * @return String the prefixed title, with spaces and the fragment, including '#'
         */
        public function getFullText() {
                $text = $this->getPrefixedText();
                if ( $this->mFragment != '' ) {
                        $text .= '#' . $this->mFragment;
                }
                return $text;
        }

        /**
         * Get the base name, i.e. the leftmost parts before the /
         *
         * @return String Base name
         */
        public function getBaseText() {
                if ( !MWNamespace::hasSubpages( $this->mNamespace ) ) {
                        return $this->getText();
                }

                $parts = explode( '/', $this->getText() );
                # Don't discard the real title if there's no subpage involved
                if ( count( $parts ) > 1 ) {
                        unset( $parts[count( $parts ) - 1] );
                }
                return implode( '/', $parts );
        }

        /**
         * Get the lowest-level subpage name, i.e. the rightmost part after /
         *
         * @return String Subpage name
         */
        public function getSubpageText() {
                if ( !MWNamespace::hasSubpages( $this->mNamespace ) ) {
                        return( $this->mTextform );
                }
                $parts = explode( '/', $this->mTextform );
                return( $parts[count( $parts ) - 1] );
        }

        /**
         * Get a URL-encoded form of the subpage text
         *
         * @return String URL-encoded subpage name
         */
        public function getSubpageUrlForm() {
                $text = $this->getSubpageText();
                $text = wfUrlencode( str_replace( ' ', '_', $text ) );
                return( $text );
        }

        /**
         * Get a URL-encoded title (not an actual URL) including interwiki
         *
         * @return String the URL-encoded form
         */
        public function getPrefixedURL() {
                $s = $this->prefix( $this->mDbkeyform );
                $s = wfUrlencode( str_replace( ' ', '_', $s ) );
                return $s;
        }

        /**
         * Get a real URL referring to this title, with interwiki link and
         * fragment
         *
         * @param $query \twotypes{\string,\array} an optional query string, not used for interwiki
         *   links. Can be specified as an associative array as well, e.g.,
         *   array( 'action' => 'edit' ) (keys and values will be URL-escaped).
         * @param $variant String language variant of url (for sr, zh..)
         * @return String the URL
         */
        public function getFullURL( $query = '', $variant = false ) {
                global $wgServer, $wgRequest;

                if ( is_array( $query ) ) {
                        $query = wfArrayToCGI( $query );
                }

                $interwiki = Interwiki::fetch( $this->mInterwiki );
                if ( !$interwiki ) {
                        $url = $this->getLocalURL( $query, $variant );

                        // Ugly quick hack to avoid duplicate prefixes (bug 4571 etc)
                        // Correct fix would be to move the prepending elsewhere.
                        if ( $wgRequest->getVal( 'action' ) != 'render' ) {
                                $url = $wgServer . $url;
                        }
                } else {
                        $baseUrl = $interwiki->getURL();

                        $namespace = wfUrlencode( $this->getNsText() );
                        if ( $namespace != '' ) {
                                # Can this actually happen? Interwikis shouldn't be parsed.
                                # Yes! It can in interwiki transclusion. But... it probably shouldn't.
                                $namespace .= ':';
                        }
                        $url = str_replace( '$1', $namespace . $this->mUrlform, $baseUrl );
                        $url = wfAppendQuery( $url, $query );
                }

                # Finally, add the fragment.
                $url .= $this->getFragmentForURL();

                wfRunHooks( 'GetFullURL', array( &$this, &$url, $query ) );
                return $url;
        }

        /**
         * Get a URL with no fragment or server name.  If this page is generated
         * with action=render, $wgServer is prepended.
         *
         * @param $query Mixed: an optional query string; if not specified,
         *   $wgArticlePath will be used.  Can be specified as an associative array
         *   as well, e.g., array( 'action' => 'edit' ) (keys and values will be
         *   URL-escaped).
         * @param $variant String language variant of url (for sr, zh..)
         * @return String the URL
         */
        public function getLocalURL( $query = '', $variant = false ) {
                global $wgArticlePath, $wgScript, $wgServer, $wgRequest;
                global $wgVariantArticlePath, $wgContLang;

                if ( is_array( $query ) ) {
                        $query = wfArrayToCGI( $query );
                }

                if ( $this->isExternal() ) {
                        $url = $this->getFullURL();
                        if ( $query ) {
                                // This is currently only used for edit section links in the
                                // context of interwiki transclusion. In theory we should
                                // append the query to the end of any existing query string,
                                // but interwiki transclusion is already broken in that case.
                                $url .= "?$query";
                        }
                } else {
                        $dbkey = wfUrlencode( $this->getPrefixedDBkey() );
                        if ( $query == '' ) {
                                if ( $variant != false && $wgContLang->hasVariants() ) {
                                        if ( !$wgVariantArticlePath ) {
                                                $variantArticlePath =  "$wgScript?title=$1&variant=$2"; // default
                                        } else {
                                                $variantArticlePath = $wgVariantArticlePath;
                                        }
                                        $url = str_replace( '$2', urlencode( $variant ), $variantArticlePath );
                                        $url = str_replace( '$1', $dbkey, $url  );
                                } else {
                                        $url = str_replace( '$1', $dbkey, $wgArticlePath );
                                }
                        } else {
                                global $wgActionPaths;
                                $url = false;
                                $matches = array();
                                if ( !empty( $wgActionPaths ) &&
                                        preg_match( '/^(.*&|)action=([^&]*)(&(.*)|)$/', $query, $matches ) )
                                {
                                        $action = urldecode( $matches[2] );
                                        if ( isset( $wgActionPaths[$action] ) ) {
                                                $query = $matches[1];
                                                if ( isset( $matches[4] ) ) {
                                                        $query .= $matches[4];
                                                }
                                                $url = str_replace( '$1', $dbkey, $wgActionPaths[$action] );
                                                if ( $query != '' ) {
                                                        $url = wfAppendQuery( $url, $query );
                                                }
                                        }
                                }

                                if ( $url === false ) {
                                        if ( $query == '-' ) {
                                                $query = '';
                                        }
                                        $url = "{$wgScript}?title={$dbkey}&{$query}";
                                }
                        }

                        // @todo FIXME: This causes breakage in various places when we
                        // actually expected a local URL and end up with dupe prefixes.
                        if ( $wgRequest->getVal( 'action' ) == 'render' ) {
                                $url = $wgServer . $url;
                        }
                }
                wfRunHooks( 'GetLocalURL', array( &$this, &$url, $query ) );
                return $url;
        }

        /**
         * Get a URL that's the simplest URL that will be valid to link, locally,
         * to the current Title.  It includes the fragment, but does not include
         * the server unless action=render is used (or the link is external).  If
         * there's a fragment but the prefixed text is empty, we just return a link
         * to the fragment.
         *
         * The result obviously should not be URL-escaped, but does need to be
         * HTML-escaped if it's being output in HTML.
         *
         * @param $query Array of Strings An associative array of key => value pairs for the
         *   query string.  Keys and values will be escaped.
         * @param $variant String language variant of URL (for sr, zh..).  Ignored
         *   for external links.  Default is "false" (same variant as current page,
         *   for anonymous users).
         * @return String the URL
         */
        public function getLinkUrl( $query = array(), $variant = false ) {
                wfProfileIn( __METHOD__ );
                if ( $this->isExternal() ) {
                        $ret = $this->getFullURL( $query );
                } elseif ( $this->getPrefixedText() === '' && $this->getFragment() !== '' ) {
                        $ret = $this->getFragmentForURL();
                } else {
                        $ret = $this->getLocalURL( $query, $variant ) . $this->getFragmentForURL();
                }
                wfProfileOut( __METHOD__ );
                return $ret;
        }

        /**
         * Get an HTML-escaped version of the URL form, suitable for
         * using in a link, without a server name or fragment
         *
         * @param $query String an optional query string
         * @return String the URL
         */
        public function escapeLocalURL( $query = '' ) {
                return htmlspecialchars( $this->getLocalURL( $query ) );
        }

        /**
         * Get an HTML-escaped version of the URL form, suitable for
         * using in a link, including the server name and fragment
         *
         * @param $query String an optional query string
         * @return String the URL
         */
        public function escapeFullURL( $query = '' ) {
                return htmlspecialchars( $this->getFullURL( $query ) );
        }

        /**
         * Get the URL form for an internal link.
         * - Used in various Squid-related code, in case we have a different
         * internal hostname for the server from the exposed one.
         *
         * @param $query String an optional query string
         * @param $variant String language variant of url (for sr, zh..)
         * @return String the URL
         */
        public function getInternalURL( $query = '', $variant = false ) {
                global $wgInternalServer, $wgServer;
                $server = $wgInternalServer !== false ? $wgInternalServer : $wgServer;
                $url = $server . $this->getLocalURL( $query, $variant );
                wfRunHooks( 'GetInternalURL', array( &$this, &$url, $query ) );
                return $url;
        }

        /**
         * Get the edit URL for this Title
         *
         * @return String the URL, or a null string if this is an
         *  interwiki link
         */
        public function getEditURL() {
                if ( $this->mInterwiki != '' ) {
                        return '';
                }
                $s = $this->getLocalURL( 'action=edit' );

                return $s;
        }

        /**
         * Get the HTML-escaped displayable text form.
         * Used for the title field in <a> tags.
         *
         * @return String the text, including any prefixes
         */
        public function getEscapedText() {
                return htmlspecialchars( $this->getPrefixedText() );
        }

        /**
         * Is this Title interwiki?
         *
         * @return Bool
         */
        public function isExternal() {
                return ( $this->mInterwiki != '' );
        }

        /**
         * Is this page "semi-protected" - the *only* protection is autoconfirm?
         *
         * @param $action String Action to check (default: edit)
         * @return Bool
         */
        public function isSemiProtected( $action = 'edit' ) {
                if ( $this->exists() ) {
                        $restrictions = $this->getRestrictions( $action );
                        if ( count( $restrictions ) > 0 ) {
                                foreach ( $restrictions as $restriction ) {
                                        if ( strtolower( $restriction ) != 'autoconfirmed' ) {
                                                return false;
                                        }
                                }
                        } else {
                                # Not protected
                                return false;
                        }
                        return true;
                } else {
                        # If it doesn't exist, it can't be protected
                        return false;
                }
        }

        /**
         * Does the title correspond to a protected article?
         *
         * @param $action String the action the page is protected from,
         * by default checks all actions.
         * @return Bool
         */
        public function isProtected( $action = '' ) {
                global $wgRestrictionLevels;

                $restrictionTypes = $this->getRestrictionTypes();

                # Special pages have inherent protection
                if( $this->getNamespace() == NS_SPECIAL ) {
                        return true;
                }

                # Check regular protection levels
                foreach ( $restrictionTypes as $type ) {
                        if ( $action == $type || $action == '' ) {
                                $r = $this->getRestrictions( $type );
                                foreach ( $wgRestrictionLevels as $level ) {
                                        if ( in_array( $level, $r ) && $level != '' ) {
                                                return true;
                                        }
                                }
                        }
                }

                return false;
        }

        /**
         * Is this a conversion table for the LanguageConverter?
         *
         * @return Bool
         */
        public function isConversionTable() {
                if(
                        $this->getNamespace() == NS_MEDIAWIKI &&
                        strpos( $this->getText(), 'Conversiontable' ) !== false
                )
                {
                        return true;
                }

                return false;
        }

        /**
         * Is $wgUser watching this page?
         *
         * @return Bool
         */
        public function userIsWatching() {
                global $wgUser;

                if ( is_null( $this->mWatched ) ) {
                        if ( NS_SPECIAL == $this->mNamespace || !$wgUser->isLoggedIn() ) {
                                $this->mWatched = false;
                        } else {
                                $this->mWatched = $wgUser->isWatched( $this );
                        }
                }
                return $this->mWatched;
        }

        /**
         * Can $wgUser perform $action on this page?
         * This skips potentially expensive cascading permission checks
         * as well as avoids expensive error formatting
         *
         * Suitable for use for nonessential UI controls in common cases, but
         * _not_ for functional access control.
         *
         * May provide false positives, but should never provide a false negative.
         *
         * @param $action String action that permission needs to be checked for
         * @return Bool
         */
        public function quickUserCan( $action ) {
                return $this->userCan( $action, false );
        }

        /**
         * Determines if $user is unable to edit this page because it has been protected
         * by $wgNamespaceProtection.
         *
         * @param $user User object, $wgUser will be used if not passed
         * @return Bool
         */
        public function isNamespaceProtected( User $user = null ) {
                global $wgNamespaceProtection;

                if ( $user === null ) {
                        global $wgUser;
                        $user = $wgUser;
                }

                if ( isset( $wgNamespaceProtection[$this->mNamespace] ) ) {
                        foreach ( (array)$wgNamespaceProtection[$this->mNamespace] as $right ) {
                                if ( $right != '' && !$user->isAllowed( $right ) ) {
                                        return true;
                                }
                        }
                }
                return false;
        }

        /**
         * Can $wgUser perform $action on this page?
         *
         * @param $action String action that permission needs to be checked for
         * @param $doExpensiveQueries Bool Set this to false to avoid doing unnecessary queries.
         * @return Bool
         */
        public function userCan( $action, $doExpensiveQueries = true ) {
                global $wgUser;
                return ( $this->getUserPermissionsErrorsInternal( $action, $wgUser, $doExpensiveQueries, true ) === array() );
        }

        /**
         * Can $user perform $action on this page?
         *
         * @todo FIXME: This *does not* check throttles (User::pingLimiter()).
         *
         * @param $action String action that permission needs to be checked for
         * @param $user User to check
         * @param $doExpensiveQueries Bool Set this to false to avoid doing unnecessary queries by
         *   skipping checks for cascading protections and user blocks.
         * @param $ignoreErrors Array of Strings Set this to a list of message keys whose corresponding errors may be ignored.
         * @return Array of arguments to wfMsg to explain permissions problems.
         */
        public function getUserPermissionsErrors( $action, $user, $doExpensiveQueries = true, $ignoreErrors = array() ) {
                $errors = $this->getUserPermissionsErrorsInternal( $action, $user, $doExpensiveQueries );

                // Remove the errors being ignored.
                foreach ( $errors as $index => $error ) {
                        $error_key = is_array( $error ) ? $error[0] : $error;

                        if ( in_array( $error_key, $ignoreErrors ) ) {
                                unset( $errors[$index] );
                        }
                }

                return $errors;
        }

        /**
         * Permissions checks that fail most often, and which are easiest to test.
         *
         * @param $action String the action to check
         * @param $user User user to check
         * @param $errors Array list of current errors
         * @param $doExpensiveQueries Boolean whether or not to perform expensive queries
         * @param $short Boolean short circuit on first error
         *
         * @return Array list of errors
         */
        private function checkQuickPermissions( $action, $user, $errors, $doExpensiveQueries, $short ) {
                if ( $action == 'create' ) {
                        if ( ( $this->isTalkPage() && !$user->isAllowed( 'createtalk' ) ) ||
                                 ( !$this->isTalkPage() && !$user->isAllowed( 'createpage' ) ) ) {
                                $errors[] = $user->isAnon() ? array( 'nocreatetext' ) : array( 'nocreate-loggedin' );
                        }
                } elseif ( $action == 'move' ) {
                        if ( !$user->isAllowed( 'move-rootuserpages' )
                                        && $this->mNamespace == NS_USER && !$this->isSubpage() ) {
                                // Show user page-specific message only if the user can move other pages
                                $errors[] = array( 'cant-move-user-page' );
                        }

                        // Check if user is allowed to move files if it's a file
                        if ( $this->mNamespace == NS_FILE && !$user->isAllowed( 'movefile' ) ) {
                                $errors[] = array( 'movenotallowedfile' );
                        }

                        if ( !$user->isAllowed( 'move' ) ) {
                                // User can't move anything
                                global $wgGroupPermissions;
                                $userCanMove = false;
                                if ( isset( $wgGroupPermissions['user']['move'] ) ) {
                                        $userCanMove = $wgGroupPermissions['user']['move'];
                                }
                                $autoconfirmedCanMove = false;
                                if ( isset( $wgGroupPermissions['autoconfirmed']['move'] ) ) {
                                        $autoconfirmedCanMove = $wgGroupPermissions['autoconfirmed']['move'];
                                }
                                if ( $user->isAnon() && ( $userCanMove || $autoconfirmedCanMove ) ) {
                                        // custom message if logged-in users without any special rights can move
                                        $errors[] = array( 'movenologintext' );
                                } else {
                                        $errors[] = array( 'movenotallowed' );
                                }
                        }
                } elseif ( $action == 'move-target' ) {
                        if ( !$user->isAllowed( 'move' ) ) {
                                // User can't move anything
                                $errors[] = array( 'movenotallowed' );
                        } elseif ( !$user->isAllowed( 'move-rootuserpages' )
                                        && $this->mNamespace == NS_USER && !$this->isSubpage() ) {
                                // Show user page-specific message only if the user can move other pages
                                $errors[] = array( 'cant-move-to-user-page' );
                        }
                } elseif ( !$user->isAllowed( $action ) ) {
                        // We avoid expensive display logic for quickUserCan's and such
                        $groups = false;
                        if ( !$short ) {
                                $groups = array_map( array( 'User', 'makeGroupLinkWiki' ),
                                        User::getGroupsWithPermission( $action ) );
                        }

                        if ( $groups ) {
                                global $wgLang;
                                $return = array(
                                        'badaccess-groups',
                                        $wgLang->commaList( $groups ),
                                        count( $groups )
                                );
                        } else {
                                $return = array( 'badaccess-group0' );
                        }
                        $errors[] = $return;
                }

                return $errors;
        }

        /**
         * Add the resulting error code to the errors array
         *
         * @param $errors Array list of current errors
         * @param $result Mixed result of errors
         *
         * @return Array list of errors
         */
        private function resultToError( $errors, $result ) {
                if ( is_array( $result ) && count( $result ) && !is_array( $result[0] ) ) {
                        // A single array representing an error
                        $errors[] = $result;
                } else if ( is_array( $result ) && is_array( $result[0] ) ) {
                        // A nested array representing multiple errors
                        $errors = array_merge( $errors, $result );
                } else if ( $result !== '' && is_string( $result ) ) {
                        // A string representing a message-id
                        $errors[] = array( $result );
                } else if ( $result === false ) {
                        // a generic "We don't want them to do that"
                        $errors[] = array( 'badaccess-group0' );
                }
                return $errors;
        }

        /**
         * Check various permission hooks
         *
         * @param $action String the action to check
         * @param $user User user to check
         * @param $errors Array list of current errors
         * @param $doExpensiveQueries Boolean whether or not to perform expensive queries
         * @param $short Boolean short circuit on first error
         *
         * @return Array list of errors
         */
        private function checkPermissionHooks( $action, $user, $errors, $doExpensiveQueries, $short ) {
                // Use getUserPermissionsErrors instead
                $result = '';
                if ( !wfRunHooks( 'userCan', array( &$this, &$user, $action, &$result ) ) ) {
                        return $result ? array() : array( array( 'badaccess-group0' ) );
                }
                // Check getUserPermissionsErrors hook
                if ( !wfRunHooks( 'getUserPermissionsErrors', array( &$this, &$user, $action, &$result ) ) ) {
                        $errors = $this->resultToError( $errors, $result );
                }
                // Check getUserPermissionsErrorsExpensive hook
                if ( $doExpensiveQueries && !( $short && count( $errors ) > 0 ) &&
                         !wfRunHooks( 'getUserPermissionsErrorsExpensive', array( &$this, &$user, $action, &$result ) ) ) {
                        $errors = $this->resultToError( $errors, $result );
                }

                return $errors;
        }

        /**
         * Check permissions on special pages & namespaces
         *
         * @param $action String the action to check
         * @param $user User user to check
         * @param $errors Array list of current errors
         * @param $doExpensiveQueries Boolean whether or not to perform expensive queries
         * @param $short Boolean short circuit on first error
         *
         * @return Array list of errors
         */
        private function checkSpecialsAndNSPermissions( $action, $user, $errors, $doExpensiveQueries, $short ) {
                # Only 'createaccount' and 'execute' can be performed on
                # special pages, which don't actually exist in the DB.
                $specialOKActions = array( 'createaccount', 'execute' );
                if ( NS_SPECIAL == $this->mNamespace && !in_array( $action, $specialOKActions ) ) {
                        $errors[] = array( 'ns-specialprotected' );
                }

                # Check $wgNamespaceProtection for restricted namespaces
                if ( $this->isNamespaceProtected( $user ) ) {
                        $ns = $this->mNamespace == NS_MAIN ?
                                wfMsg( 'nstab-main' ) : $this->getNsText();
                        $errors[] = $this->mNamespace == NS_MEDIAWIKI ?
                                array( 'protectedinterface' ) : array( 'namespaceprotected',  $ns );
                }

                return $errors;
        }

        /**
         * Check CSS/JS sub-page permissions
         *
         * @param $action String the action to check
         * @param $user User user to check
         * @param $errors Array list of current errors
         * @param $doExpensiveQueries Boolean whether or not to perform expensive queries
         * @param $short Boolean short circuit on first error
         *
         * @return Array list of errors
         */
        private function checkCSSandJSPermissions( $action, $user, $errors, $doExpensiveQueries, $short ) {
                # Protect css/js subpages of user pages
                # XXX: this might be better using restrictions
                # XXX: Find a way to work around the php bug that prevents using $this->userCanEditCssSubpage()
                #      and $this->userCanEditJsSubpage() from working
                # XXX: right 'editusercssjs' is deprecated, for backward compatibility only
                if ( $action != 'patrol' && !$user->isAllowed( 'editusercssjs' )
                                && !preg_match( '/^' . preg_quote( $user->getName(), '/' ) . '\//', $this->mTextform ) ) {
                        if ( $this->isCssSubpage() && !$user->isAllowed( 'editusercss' ) ) {
                                $errors[] = array( 'customcssprotected' );
                        } else if ( $this->isJsSubpage() && !$user->isAllowed( 'edituserjs' ) ) {
                                $errors[] = array( 'customjsprotected' );
                        }
                }

                return $errors;
        }

        /**
         * Check against page_restrictions table requirements on this
         * page. The user must possess all required rights for this
         * action.
         *
         * @param $action String the action to check
         * @param $user User user to check
         * @param $errors Array list of current errors
         * @param $doExpensiveQueries Boolean whether or not to perform expensive queries
         * @param $short Boolean short circuit on first error
         *
         * @return Array list of errors
         */
        private function checkPageRestrictions( $action, $user, $errors, $doExpensiveQueries, $short ) {
                foreach ( $this->getRestrictions( $action ) as $right ) {
                        // Backwards compatibility, rewrite sysop -> protect
                        if ( $right == 'sysop' ) {
                                $right = 'protect';
                        }
                        if ( $right != '' && !$user->isAllowed( $right ) ) {
                                // Users with 'editprotected' permission can edit protected pages
                                if ( $action == 'edit' && $user->isAllowed( 'editprotected' ) ) {
                                        // Users with 'editprotected' permission cannot edit protected pages
                                        // with cascading option turned on.
                                        if ( $this->mCascadeRestriction ) {
                                                $errors[] = array( 'protectedpagetext', $right );
                                        }
                                } else {
                                        $errors[] = array( 'protectedpagetext', $right );
                                }
                        }
                }

                return $errors;
        }

        /**
         * Check restrictions on cascading pages.
         *
         * @param $action String the action to check
         * @param $user User to check
         * @param $errors Array list of current errors
         * @param $doExpensiveQueries Boolean whether or not to perform expensive queries
         * @param $short Boolean short circuit on first error
         *
         * @return Array list of errors
         */
        private function checkCascadingSourcesRestrictions( $action, $user, $errors, $doExpensiveQueries, $short ) {
                if ( $doExpensiveQueries && !$this->isCssJsSubpage() ) {
                        # We /could/ use the protection level on the source page, but it's
                        # fairly ugly as we have to establish a precedence hierarchy for pages
                        # included by multiple cascade-protected pages. So just restrict
                        # it to people with 'protect' permission, as they could remove the
                        # protection anyway.
                        list( $cascadingSources, $restrictions ) = $this->getCascadeProtectionSources();
                        # Cascading protection depends on more than this page...
                        # Several cascading protected pages may include this page...
                        # Check each cascading level
                        # This is only for protection restrictions, not for all actions
                        if ( isset( $restrictions[$action] ) ) {
                                foreach ( $restrictions[$action] as $right ) {
                                        $right = ( $right == 'sysop' ) ? 'protect' : $right;
                                        if ( $right != '' && !$user->isAllowed( $right ) ) {
                                                $pages = '';
                                                foreach ( $cascadingSources as $page )
                                                        $pages .= '* [[:' . $page->getPrefixedText() . "]]\n";
                                                $errors[] = array( 'cascadeprotected', count( $cascadingSources ), $pages );
                                        }
                                }
                        }
                }

                return $errors;
        }

        /**
         * Check action permissions not already checked in checkQuickPermissions
         *
         * @param $action String the action to check
         * @param $user User to check
         * @param $errors Array list of current errors
         * @param $doExpensiveQueries Boolean whether or not to perform expensive queries
         * @param $short Boolean short circuit on first error
         *
         * @return Array list of errors
         */
        private function checkActionPermissions( $action, $user, $errors, $doExpensiveQueries, $short ) {
                if ( $action == 'protect' ) {
                        if ( $this->getUserPermissionsErrors( 'edit', $user ) != array() ) {
                                // If they can't edit, they shouldn't protect.
                                $errors[] = array( 'protect-cantedit' );
                        }
                } elseif ( $action == 'create' ) {
                        $title_protection = $this->getTitleProtection();
                        if( $title_protection ) {
                                if( $title_protection['pt_create_perm'] == 'sysop' ) {
                                        $title_protection['pt_create_perm'] = 'protect'; // B/C
                                }
                                if( $title_protection['pt_create_perm'] == '' || !$user->isAllowed( $title_protection['pt_create_perm'] ) ) {
                                        $errors[] = array( 'titleprotected', User::whoIs( $title_protection['pt_user'] ), $title_protection['pt_reason'] );
                                }
                        }
                } elseif ( $action == 'move' ) {
                        // Check for immobile pages
                        if ( !MWNamespace::isMovable( $this->mNamespace ) ) {
                                // Specific message for this case
                                $errors[] = array( 'immobile-source-namespace', $this->getNsText() );
                        } elseif ( !$this->isMovable() ) {
                                // Less specific message for rarer cases
                                $errors[] = array( 'immobile-page' );
                        }
                } elseif ( $action == 'move-target' ) {
                        if ( !MWNamespace::isMovable( $this->mNamespace ) ) {
                                $errors[] = array( 'immobile-target-namespace', $this->getNsText() );
                        } elseif ( !$this->isMovable() ) {
                                $errors[] = array( 'immobile-target-page' );
                        }
                }
                return $errors;
        }

        /**
         * Check that the user isn't blocked from editting.
         *
         * @param $action String the action to check
         * @param $user User to check
         * @param $errors Array list of current errors
         * @param $doExpensiveQueries Boolean whether or not to perform expensive queries
         * @param $short Boolean short circuit on first error
         *
         * @return Array list of errors
         */
        private function checkUserBlock( $action, $user, $errors, $doExpensiveQueries, $short ) {
                if( !$doExpensiveQueries ) {
                        return $errors;
                }

                global $wgContLang, $wgLang, $wgEmailConfirmToEdit;

                if ( $wgEmailConfirmToEdit && !$user->isEmailConfirmed() && $action != 'createaccount' ) {
                        $errors[] = array( 'confirmedittext' );
                }

                if ( in_array( $action, array( 'read', 'createaccount', 'unblock' ) ) ){
                        // Edit blocks should not affect reading.
                        // Account creation blocks handled at userlogin.
                        // Unblocking handled in SpecialUnblock
                } elseif( ( $action == 'edit' || $action == 'create' ) && !$user->isBlockedFrom( $this ) ){
                        // Don't block the user from editing their own talk page unless they've been
                        // explicitly blocked from that too.
                } elseif( $user->isBlocked() && $user->mBlock->prevents( $action ) !== false ) {
                        $block = $user->mBlock;

                        // This is from OutputPage::blockedPage
                        // Copied at r23888 by werdna

                        $id = $user->blockedBy();
                        $reason = $user->blockedFor();
                        if ( $reason == '' ) {
                                $reason = wfMsg( 'blockednoreason' );
                        }
                        $ip = wfGetIP();

                        if ( is_numeric( $id ) ) {
                                $name = User::whoIs( $id );
                        } else {
                                $name = $id;
                        }

                        $link = '[[' . $wgContLang->getNsText( NS_USER ) . ":{$name}|{$name}]]";
                        $blockid = $block->getId();
                        $blockExpiry = $user->mBlock->mExpiry;
                        $blockTimestamp = $wgLang->timeanddate( wfTimestamp( TS_MW, $user->mBlock->mTimestamp ), true );
                        if ( $blockExpiry == 'infinity' ) {
                                $blockExpiry = wfMessage( 'infiniteblock' )->text();
                        } else {
                                $blockExpiry = $wgLang->timeanddate( wfTimestamp( TS_MW, $blockExpiry ), true );
                        }

                        $intended = strval( $user->mBlock->getTarget() );

                        $errors[] = array( ( $block->mAuto ? 'autoblockedtext' : 'blockedtext' ), $link, $reason, $ip, $name,
                                $blockid, $blockExpiry, $intended, $blockTimestamp );
                }

                return $errors;
        }

        /**
         * Can $user perform $action on this page? This is an internal function,
         * which checks ONLY that previously checked by userCan (i.e. it leaves out
         * checks on wfReadOnly() and blocks)
         *
         * @param $action String action that permission needs to be checked for
         * @param $user User to check
         * @param $doExpensiveQueries Bool Set this to false to avoid doing unnecessary queries.
         * @param $short Bool Set this to true to stop after the first permission error.
         * @return Array of arrays of the arguments to wfMsg to explain permissions problems.
         */
        protected function getUserPermissionsErrorsInternal( $action, $user, $doExpensiveQueries = true, $short = false ) {
                wfProfileIn( __METHOD__ );

                $errors = array();
                $checks = array(
                        'checkQuickPermissions',
                        'checkPermissionHooks',
                        'checkSpecialsAndNSPermissions',
                        'checkCSSandJSPermissions',
                        'checkPageRestrictions',
                        'checkCascadingSourcesRestrictions',
                        'checkActionPermissions',
                        'checkUserBlock'
                );

                while( count( $checks ) > 0 &&
                           !( $short && count( $errors ) > 0 ) ) {
                        $method = array_shift( $checks );
                        $errors = $this->$method( $action, $user, $errors, $doExpensiveQueries, $short );
                }

                wfProfileOut( __METHOD__ );
                return $errors;
        }

        /**
         * Is this title subject to title protection?
         * Title protection is the one applied against creation of such title.
         *
         * @return Mixed An associative array representing any existent title
         *   protection, or false if there's none.
         */
        private function getTitleProtection() {
                // Can't protect pages in special namespaces
                if ( $this->getNamespace() < 0 ) {
                        return false;
                }

                // Can't protect pages that exist.
                if ( $this->exists() ) {
                        return false;
                }

                if ( !isset( $this->mTitleProtection ) ) {
                        $dbr = wfGetDB( DB_SLAVE );
                        $res = $dbr->select( 'protected_titles', '*',
                                array( 'pt_namespace' => $this->getNamespace(), 'pt_title' => $this->getDBkey() ),
                                __METHOD__ );

                        // fetchRow returns false if there are no rows.
                        $this->mTitleProtection = $dbr->fetchRow( $res );
                }
                return $this->mTitleProtection;
        }

        /**
         * Update the title protection status
         *
         * @param $create_perm String Permission required for creation
         * @param $reason String Reason for protection
         * @param $expiry String Expiry timestamp
         * @return boolean true
         */
        public function updateTitleProtection( $create_perm, $reason, $expiry ) {
                global $wgUser, $wgContLang;

                if ( $create_perm == implode( ',', $this->getRestrictions( 'create' ) )
                        && $expiry == $this->mRestrictionsExpiry['create'] ) {
                        // No change
                        return true;
                }

                list ( $namespace, $title ) = array( $this->getNamespace(), $this->getDBkey() );

                $dbw = wfGetDB( DB_MASTER );

                $encodedExpiry = $dbw->encodeExpiry( $expiry );

                $expiry_description = '';
                if ( $encodedExpiry != $dbw->getInfinity() ) {
                        $expiry_description = ' (' . wfMsgForContent( 'protect-expiring', $wgContLang->timeanddate( $expiry ),
                                $wgContLang->date( $expiry ) , $wgContLang->time( $expiry ) ) . ')';
                } else {
                        $expiry_description .= ' (' . wfMsgForContent( 'protect-expiry-indefinite' ) . ')';
                }

                # Update protection table
                if ( $create_perm != '' ) {
                        $this->mTitleProtection = array(
                                        'pt_namespace' => $namespace,
                                        'pt_title' => $title,
                                        'pt_create_perm' => $create_perm,
                                        'pt_timestamp' => $dbw->encodeExpiry( wfTimestampNow() ),
                                        'pt_expiry' => $encodedExpiry,
                                        'pt_user' => $wgUser->getId(),
                                        'pt_reason' => $reason,
                                );
                        $dbw->replace( 'protected_titles', array( array( 'pt_namespace', 'pt_title' ) ),
                                $this->mTitleProtection, __METHOD__     );
                } else {
                        $dbw->delete( 'protected_titles', array( 'pt_namespace' => $namespace,
                                'pt_title' => $title ), __METHOD__ );
                        $this->mTitleProtection = false;
                }

                # Update the protection log
                if ( $dbw->affectedRows() ) {
                        $log = new LogPage( 'protect' );

                        if ( $create_perm ) {
                                $params = array( "[create=$create_perm] $expiry_description", '' );
                                $log->addEntry( ( isset( $this->mRestrictions['create'] ) && $this->mRestrictions['create'] ) ? 'modify' : 'protect', $this, trim( $reason ), $params );
                        } else {
                                $log->addEntry( 'unprotect', $this, $reason );
                        }
                }

                return true;
        }

        /**
         * Remove any title protection due to page existing
         */
        public function deleteTitleProtection() {
                $dbw = wfGetDB( DB_MASTER );

                $dbw->delete(
                        'protected_titles',
                        array( 'pt_namespace' => $this->getNamespace(), 'pt_title' => $this->getDBkey() ),
                        __METHOD__
                );
                $this->mTitleProtection = false;
        }

        /**
         * Would anybody with sufficient privileges be able to move this page?
         * Some pages just aren't movable.
         *
         * @return Bool TRUE or FALSE
         */
        public function isMovable() {
                return MWNamespace::isMovable( $this->getNamespace() ) && $this->getInterwiki() == '';
        }

        /**
         * Can $wgUser read this page?
         *
         * @return Bool
         * @todo fold these checks into userCan()
         */
        public function userCanRead() {
                global $wgUser, $wgGroupPermissions;

                static $useShortcut = null;

                # Initialize the $useShortcut boolean, to determine if we can skip quite a bit of code below
                if ( is_null( $useShortcut ) ) {
                        global $wgRevokePermissions;
                        $useShortcut = true;
                        if ( empty( $wgGroupPermissions['*']['read'] ) ) {
                                # Not a public wiki, so no shortcut
                                $useShortcut = false;
                        } elseif ( !empty( $wgRevokePermissions ) ) {
                                /**
                                 * Iterate through each group with permissions being revoked (key not included since we don't care
                                 * what the group name is), then check if the read permission is being revoked. If it is, then
                                 * we don't use the shortcut below since the user might not be able to read, even though anon
                                 * reading is allowed.
                                 */
                                foreach ( $wgRevokePermissions as $perms ) {
                                        if ( !empty( $perms['read'] ) ) {
                                                # We might be removing the read right from the user, so no shortcut
                                                $useShortcut = false;
                                                break;
                                        }
                                }
                        }
                }

                $result = null;
                wfRunHooks( 'userCan', array( &$this, &$wgUser, 'read', &$result ) );
                if ( $result !== null ) {
                        return $result;
                }

                # Shortcut for public wikis, allows skipping quite a bit of code
                if ( $useShortcut ) {
                        return true;
                }

                if ( $wgUser->isAllowed( 'read' ) ) {
                        return true;
                } else {
                        global $wgWhitelistRead;

                        # Always grant access to the login page.
                        # Even anons need to be able to log in.
                        if ( $this->isSpecial( 'Userlogin' ) || $this->isSpecial( 'ChangePassword' ) ) {
                                return true;
                        }

                        # Bail out if there isn't whitelist
                        if ( !is_array( $wgWhitelistRead ) ) {
                                return false;
                        }

                        # Check for explicit whitelisting
                        $name = $this->getPrefixedText();
                        $dbName = $this->getPrefixedDBKey();
                        // Check with and without underscores
                        if ( in_array( $name, $wgWhitelistRead, true ) || in_array( $dbName, $wgWhitelistRead, true ) )
                                return true;

                        # Old settings might have the title prefixed with
                        # a colon for main-namespace pages
                        if ( $this->getNamespace() == NS_MAIN ) {
                                if ( in_array( ':' . $name, $wgWhitelistRead ) ) {
                                        return true;
                                }
                        }

                        # If it's a special page, ditch the subpage bit and check again
                        if ( $this->getNamespace() == NS_SPECIAL ) {
                                $name = $this->getDBkey();
                                list( $name, /* $subpage */ ) = SpecialPageFactory::resolveAlias( $name );
                                if ( $name === false ) {
                                        # Invalid special page, but we show standard login required message
                                        return false;
                                }

                                $pure = SpecialPage::getTitleFor( $name )->getPrefixedText();
                                if ( in_array( $pure, $wgWhitelistRead, true ) ) {
                                        return true;
                                }
                        }

                }
                return false;
        }

        /**
         * Is this the mainpage?
         * @note Title::newFromText seams to be sufficiently optimized by the title
         * cache that we don't need to over-optimize by doing direct comparisons and
         * acidentally creating new bugs where $title->equals( Title::newFromText() )
         * ends up reporting something differently than $title->isMainPage();
         *
         * @return Bool
         */
        public function isMainPage() {
                return $this->equals( Title::newMainPage() );
        }

        /**
         * Is this a talk page of some sort?
         *
         * @return Bool
         */
        public function isTalkPage() {
                return MWNamespace::isTalk( $this->getNamespace() );
        }

        /**
         * Is this a subpage?
         *
         * @return Bool
         */
        public function isSubpage() {
                return MWNamespace::hasSubpages( $this->mNamespace )
                        ? strpos( $this->getText(), '/' ) !== false
                        : false;
        }

        /**
         * Does this have subpages?  (Warning, usually requires an extra DB query.)
         *
         * @return Bool
         */
        public function hasSubpages() {
                if ( !MWNamespace::hasSubpages( $this->mNamespace ) ) {
                        # Duh
                        return false;
                }

                # We dynamically add a member variable for the purpose of this method
                # alone to cache the result.  There's no point in having it hanging
                # around uninitialized in every Title object; therefore we only add it
                # if needed and don't declare it statically.
                if ( isset( $this->mHasSubpages ) ) {
                        return $this->mHasSubpages;
                }

                $subpages = $this->getSubpages( 1 );
                if ( $subpages instanceof TitleArray ) {
                        return $this->mHasSubpages = (bool)$subpages->count();
                }
                return $this->mHasSubpages = false;
        }

        /**
         * Get all subpages of this page.
         *
         * @param $limit Int maximum number of subpages to fetch; -1 for no limit
         * @return mixed TitleArray, or empty array if this page's namespace
         *  doesn't allow subpages
         */
        public function getSubpages( $limit = -1 ) {
                if ( !MWNamespace::hasSubpages( $this->getNamespace() ) ) {
                        return array();
                }

                $dbr = wfGetDB( DB_SLAVE );
                $conds['page_namespace'] = $this->getNamespace();
                $conds[] = 'page_title ' . $dbr->buildLike( $this->getDBkey() . '/', $dbr->anyString() );
                $options = array();
                if ( $limit > -1 ) {
                        $options['LIMIT'] = $limit;
                }
                return $this->mSubpages = TitleArray::newFromResult(
                        $dbr->select( 'page',
                                array( 'page_id', 'page_namespace', 'page_title', 'page_is_redirect' ),
                                $conds,
                                __METHOD__,
                                $options
                        )
                );
        }

        /**
         * Could this page contain custom CSS or JavaScript, based
         * on the title?
         *
         * @return Bool
         */
        public function isCssOrJsPage() {
                return $this->mNamespace == NS_MEDIAWIKI
                        && preg_match( '!\.(?:css|js)$!u', $this->mTextform ) > 0;
        }

        /**
         * Is this a .css or .js subpage of a user page?
         * @return Bool
         */
        public function isCssJsSubpage() {
                return ( NS_USER == $this->mNamespace and preg_match( "/\\/.*\\.(?:css|js)$/", $this->mTextform ) );
        }

        /**
         * Is this a *valid* .css or .js subpage of a user page?
         *
         * @return Bool
         * @deprecated since 1.17
         */
        public function isValidCssJsSubpage() {
                return $this->isCssJsSubpage();
        }

        /**
         * Trim down a .css or .js subpage title to get the corresponding skin name
         *
         * @return string containing skin name from .css or .js subpage title
         */
        public function getSkinFromCssJsSubpage() {
                $subpage = explode( '/', $this->mTextform );
                $subpage = $subpage[ count( $subpage ) - 1 ];
                return( str_replace( array( '.css', '.js' ), array( '', '' ), $subpage ) );
        }

        /**
         * Is this a .css subpage of a user page?
         *
         * @return Bool
         */
        public function isCssSubpage() {
                return ( NS_USER == $this->mNamespace && preg_match( "/\\/.*\\.css$/", $this->mTextform ) );
        }

        /**
         * Is this a .js subpage of a user page?
         *
         * @return Bool
         */
        public function isJsSubpage() {
                return ( NS_USER == $this->mNamespace && preg_match( "/\\/.*\\.js$/", $this->mTextform ) );
        }

        /**
         * Protect css subpages of user pages: can $wgUser edit
         * this page?
         *
         * @return Bool
         * @todo XXX: this might be better using restrictions
         */
        public function userCanEditCssSubpage() {
                global $wgUser;
                return ( ( $wgUser->isAllowedAll( 'editusercssjs', 'editusercss' ) )
                        || preg_match( '/^' . preg_quote( $wgUser->getName(), '/' ) . '\//', $this->mTextform ) );
        }

        /**
         * Protect js subpages of user pages: can $wgUser edit
         * this page?
         *
         * @return Bool
         * @todo XXX: this might be better using restrictions
         */
        public function userCanEditJsSubpage() {
                global $wgUser;
                return ( ( $wgUser->isAllowedAll( 'editusercssjs', 'edituserjs' ) )
                           || preg_match( '/^' . preg_quote( $wgUser->getName(), '/' ) . '\//', $this->mTextform ) );
        }

        /**
         * Cascading protection: Return true if cascading restrictions apply to this page, false if not.
         *
         * @return Bool If the page is subject to cascading restrictions.
         */
        public function isCascadeProtected() {
                list( $sources, /* $restrictions */ ) = $this->getCascadeProtectionSources( false );
                return ( $sources > 0 );
        }

        /**
         * Cascading protection: Get the source of any cascading restrictions on this page.
         *
         * @param $getPages Bool Whether or not to retrieve the actual pages
         *        that the restrictions have come from.
         * @return Mixed Array of Title objects of the pages from which cascading restrictions
         *     have come, false for none, or true if such restrictions exist, but $getPages
         *     was not set.  The restriction array is an array of each type, each of which
         *     contains a array of unique groups.
         */
        public function getCascadeProtectionSources( $getPages = true ) {
                global $wgContLang;
                $pagerestrictions = array();

                if ( isset( $this->mCascadeSources ) && $getPages ) {
                        return array( $this->mCascadeSources, $this->mCascadingRestrictions );
                } else if ( isset( $this->mHasCascadingRestrictions ) && !$getPages ) {
                        return array( $this->mHasCascadingRestrictions, $pagerestrictions );
                }

                wfProfileIn( __METHOD__ );

                $dbr = wfGetDB( DB_SLAVE );

                if ( $this->getNamespace() == NS_FILE ) {
                        $tables = array( 'imagelinks', 'page_restrictions' );
                        $where_clauses = array(
                                'il_to' => $this->getDBkey(),
                                'il_from=pr_page',
                                'pr_cascade' => 1
                        );
                } else {
                        $tables = array( 'templatelinks', 'page_restrictions' );
                        $where_clauses = array(
                                'tl_namespace' => $this->getNamespace(),
                                'tl_title' => $this->getDBkey(),
                                'tl_from=pr_page',
                                'pr_cascade' => 1
                        );
                }

                if ( $getPages ) {
                        $cols = array( 'pr_page', 'page_namespace', 'page_title',
                                                   'pr_expiry', 'pr_type', 'pr_level' );
                        $where_clauses[] = 'page_id=pr_page';
                        $tables[] = 'page';
                } else {
                        $cols = array( 'pr_expiry' );
                }

                $res = $dbr->select( $tables, $cols, $where_clauses, __METHOD__ );

                $sources = $getPages ? array() : false;
                $now = wfTimestampNow();
                $purgeExpired = false;

                foreach ( $res as $row ) {
                        $expiry = $wgContLang->formatExpiry( $row->pr_expiry, TS_MW );
                        if ( $expiry > $now ) {
                                if ( $getPages ) {
                                        $page_id = $row->pr_page;
                                        $page_ns = $row->page_namespace;
                                        $page_title = $row->page_title;
                                        $sources[$page_id] = Title::makeTitle( $page_ns, $page_title );
                                        # Add groups needed for each restriction type if its not already there
                                        # Make sure this restriction type still exists

                                        if ( !isset( $pagerestrictions[$row->pr_type] ) ) {
                                                $pagerestrictions[$row->pr_type] = array();
                                        }

                                        if ( isset( $pagerestrictions[$row->pr_type] ) &&
                                                 !in_array( $row->pr_level, $pagerestrictions[$row->pr_type] ) ) {
                                                $pagerestrictions[$row->pr_type][] = $row->pr_level;
                                        }
                                } else {
                                        $sources = true;
                                }
                        } else {
                                // Trigger lazy purge of expired restrictions from the db
                                $purgeExpired = true;
                        }
                }
                if ( $purgeExpired ) {
                        Title::purgeExpiredRestrictions();
                }

                if ( $getPages ) {
                        $this->mCascadeSources = $sources;
                        $this->mCascadingRestrictions = $pagerestrictions;
                } else {
                        $this->mHasCascadingRestrictions = $sources;
                }

                wfProfileOut( __METHOD__ );
                return array( $sources, $pagerestrictions );
        }

        /**
         * Returns cascading restrictions for the current article
         *
         * @return Boolean
         */
        function areRestrictionsCascading() {
                if ( !$this->mRestrictionsLoaded ) {
                        $this->loadRestrictions();
                }

                return $this->mCascadeRestriction;
        }

        /**
         * Loads a string into mRestrictions array
         *
         * @param $res Resource restrictions as an SQL result.
         * @param $oldFashionedRestrictions String comma-separated list of page
         *        restrictions from page table (pre 1.10)
         */
        private function loadRestrictionsFromResultWrapper( $res, $oldFashionedRestrictions = null ) {
                $rows = array();

                foreach ( $res as $row ) {
                        $rows[] = $row;
                }

                $this->loadRestrictionsFromRows( $rows, $oldFashionedRestrictions );
        }

        /**
         * Compiles list of active page restrictions from both page table (pre 1.10)
         * and page_restrictions table for this existing page.
         * Public for usage by LiquidThreads.
         *
         * @param $rows array of db result objects
         * @param $oldFashionedRestrictions string comma-separated list of page
         *        restrictions from page table (pre 1.10)
         */
        public function loadRestrictionsFromRows( $rows, $oldFashionedRestrictions = null ) {
                global $wgContLang;
                $dbr = wfGetDB( DB_SLAVE );

                $restrictionTypes = $this->getRestrictionTypes();

                foreach ( $restrictionTypes as $type ) {
                        $this->mRestrictions[$type] = array();
                        $this->mRestrictionsExpiry[$type] = $wgContLang->formatExpiry( '', TS_MW );
                }

                $this->mCascadeRestriction = false;

                # Backwards-compatibility: also load the restrictions from the page record (old format).

                if ( $oldFashionedRestrictions === null ) {
                        $oldFashionedRestrictions = $dbr->selectField( 'page', 'page_restrictions',
                                array( 'page_id' => $this->getArticleId() ), __METHOD__ );
                }

                if ( $oldFashionedRestrictions != '' ) {

                        foreach ( explode( ':', trim( $oldFashionedRestrictions ) ) as $restrict ) {
                                $temp = explode( '=', trim( $restrict ) );
                                if ( count( $temp ) == 1 ) {
                                        // old old format should be treated as edit/move restriction
                                        $this->mRestrictions['edit'] = explode( ',', trim( $temp[0] ) );
                                        $this->mRestrictions['move'] = explode( ',', trim( $temp[0] ) );
                                } else {
                                        $this->mRestrictions[$temp[0]] = explode( ',', trim( $temp[1] ) );
                                }
                        }

                        $this->mOldRestrictions = true;

                }

                if ( count( $rows ) ) {
                        # Current system - load second to make them override.
                        $now = wfTimestampNow();
                        $purgeExpired = false;

                        # Cycle through all the restrictions.
                        foreach ( $rows as $row ) {

                                // Don't take care of restrictions types that aren't allowed
                                if ( !in_array( $row->pr_type, $restrictionTypes ) )
                                        continue;

                                // This code should be refactored, now that it's being used more generally,
                                // But I don't really see any harm in leaving it in Block for now -werdna
                                $expiry = $wgContLang->formatExpiry( $row->pr_expiry, TS_MW );

                                // Only apply the restrictions if they haven't expired!
                                if ( !$expiry || $expiry > $now ) {
                                        $this->mRestrictionsExpiry[$row->pr_type] = $expiry;
                                        $this->mRestrictions[$row->pr_type] = explode( ',', trim( $row->pr_level ) );

                                        $this->mCascadeRestriction |= $row->pr_cascade;
                                } else {
                                        // Trigger a lazy purge of expired restrictions
                                        $purgeExpired = true;
                                }
                        }

                        if ( $purgeExpired ) {
                                Title::purgeExpiredRestrictions();
                        }
                }

                $this->mRestrictionsLoaded = true;
        }

        /**
         * Load restrictions from the page_restrictions table
         *
         * @param $oldFashionedRestrictions String comma-separated list of page
         *        restrictions from page table (pre 1.10)
         */
        public function loadRestrictions( $oldFashionedRestrictions = null ) {
                global $wgContLang;
                if ( !$this->mRestrictionsLoaded ) {
                        if ( $this->exists() ) {
                                $dbr = wfGetDB( DB_SLAVE );

                                $res = $dbr->select(
                                        'page_restrictions',
                                        '*',
                                        array( 'pr_page' => $this->getArticleId() ),
                                        __METHOD__
                                );

                                $this->loadRestrictionsFromResultWrapper( $res, $oldFashionedRestrictions );
                        } else {
                                $title_protection = $this->getTitleProtection();

                                if ( $title_protection ) {
                                        $now = wfTimestampNow();
                                        $expiry = $wgContLang->formatExpiry( $title_protection['pt_expiry'], TS_MW );

                                        if ( !$expiry || $expiry > $now ) {
                                                // Apply the restrictions
                                                $this->mRestrictionsExpiry['create'] = $expiry;
                                                $this->mRestrictions['create'] = explode( ',', trim( $title_protection['pt_create_perm'] ) );
                                        } else { // Get rid of the old restrictions
                                                Title::purgeExpiredRestrictions();
                                                $this->mTitleProtection = false;
                                        }
                                } else {
                                        $this->mRestrictionsExpiry['create'] = $wgContLang->formatExpiry( '', TS_MW );
                                }
                                $this->mRestrictionsLoaded = true;
                        }
                }
        }

        /**
         * Purge expired restrictions from the page_restrictions table
         */
        static function purgeExpiredRestrictions() {
                $dbw = wfGetDB( DB_MASTER );
                $dbw->delete(
                        'page_restrictions',
                        array( 'pr_expiry < ' . $dbw->addQuotes( $dbw->timestamp() ) ),
                        __METHOD__
                );

                $dbw->delete(
                        'protected_titles',
                        array( 'pt_expiry < ' . $dbw->addQuotes( $dbw->timestamp() ) ),
                        __METHOD__
                );
        }

        /**
         * Accessor/initialisation for mRestrictions
         *
         * @param $action String action that permission needs to be checked for
         * @return Array of Strings the array of groups allowed to edit this article
         */
        public function getRestrictions( $action ) {
                if ( !$this->mRestrictionsLoaded ) {
                        $this->loadRestrictions();
                }
                return isset( $this->mRestrictions[$action] )
                                ? $this->mRestrictions[$action]
                                : array();
        }

        /**
         * Get the expiry time for the restriction against a given action
         *
         * @return String|Bool 14-char timestamp, or 'infinity' if the page is protected forever
         *      or not protected at all, or false if the action is not recognised.
         */
        public function getRestrictionExpiry( $action ) {
                if ( !$this->mRestrictionsLoaded ) {
                        $this->loadRestrictions();
                }
                return isset( $this->mRestrictionsExpiry[$action] ) ? $this->mRestrictionsExpiry[$action] : false;
        }

        /**
         * Is there a version of this page in the deletion archive?
         *
         * @return Int the number of archived revisions
         */
        public function isDeleted() {
                if ( $this->getNamespace() < 0 ) {
                        $n = 0;
                } else {
                        $dbr = wfGetDB( DB_SLAVE );
                        $n = $dbr->selectField( 'archive', 'COUNT(*)',
                                array( 'ar_namespace' => $this->getNamespace(), 'ar_title' => $this->getDBkey() ),
                                __METHOD__
                        );
                        if ( $this->getNamespace() == NS_FILE ) {
                                $n += $dbr->selectField( 'filearchive', 'COUNT(*)',
                                        array( 'fa_name' => $this->getDBkey() ),
                                        __METHOD__
                                );
                        }
                }
                return (int)$n;
        }

        /**
         * Is there a version of this page in the deletion archive?
         *
         * @return Boolean
         */
        public function isDeletedQuick() {
                if ( $this->getNamespace() < 0 ) {
                        return false;
                }
                $dbr = wfGetDB( DB_SLAVE );
                $deleted = (bool)$dbr->selectField( 'archive', '1',
                        array( 'ar_namespace' => $this->getNamespace(), 'ar_title' => $this->getDBkey() ),
                        __METHOD__
                );
                if ( !$deleted && $this->getNamespace() == NS_FILE ) {
                        $deleted = (bool)$dbr->selectField( 'filearchive', '1',
                                array( 'fa_name' => $this->getDBkey() ),
                                __METHOD__
                        );
                }
                return $deleted;
        }

        /**
         * Get the article ID for this Title from the link cache,
         * adding it if necessary
         *
         * @param $flags Int a bit field; may be Title::GAID_FOR_UPDATE to select
         *  for update
         * @return Int the ID
         */
        public function getArticleID( $flags = 0 ) {
                if ( $this->getNamespace() < 0 ) {
                        return $this->mArticleID = 0;
                }
                $linkCache = LinkCache::singleton();
                if ( $flags & self::GAID_FOR_UPDATE ) {
                        $oldUpdate = $linkCache->forUpdate( true );
                        $linkCache->clearLink( $this );
                        $this->mArticleID = $linkCache->addLinkObj( $this );
                        $linkCache->forUpdate( $oldUpdate );
                } else {
                        if ( -1 == $this->mArticleID ) {
                                $this->mArticleID = $linkCache->addLinkObj( $this );
                        }
                }
                return $this->mArticleID;
        }

        /**
         * Is this an article that is a redirect page?
         * Uses link cache, adding it if necessary
         *
         * @param $flags Int a bit field; may be Title::GAID_FOR_UPDATE to select for update
         * @return Bool
         */
        public function isRedirect( $flags = 0 ) {
                if ( !is_null( $this->mRedirect ) ) {
                        return $this->mRedirect;
                }
                # Calling getArticleID() loads the field from cache as needed
                if ( !$this->getArticleID( $flags ) ) {
                        return $this->mRedirect = false;
                }
                $linkCache = LinkCache::singleton();
                $this->mRedirect = (bool)$linkCache->getGoodLinkFieldObj( $this, 'redirect' );

                return $this->mRedirect;
        }

        /**
         * What is the length of this page?
         * Uses link cache, adding it if necessary
         *
         * @param $flags Int a bit field; may be Title::GAID_FOR_UPDATE to select for update
         * @return Int
         */
        public function getLength( $flags = 0 ) {
                if ( $this->mLength != -1 ) {
                        return $this->mLength;
                }
                # Calling getArticleID() loads the field from cache as needed
                if ( !$this->getArticleID( $flags ) ) {
                        return $this->mLength = 0;
                }
                $linkCache = LinkCache::singleton();
                $this->mLength = intval( $linkCache->getGoodLinkFieldObj( $this, 'length' ) );

                return $this->mLength;
        }

        /**
         * What is the page_latest field for this page?
         *
         * @param $flags Int a bit field; may be Title::GAID_FOR_UPDATE to select for update
         * @return Int or 0 if the page doesn't exist
         */
        public function getLatestRevID( $flags = 0 ) {
                if ( $this->mLatestID !== false ) {
                        return intval( $this->mLatestID );
                }
                # Calling getArticleID() loads the field from cache as needed
                if ( !$this->getArticleID( $flags ) ) {
                        return $this->mLatestID = 0;
                }
                $linkCache = LinkCache::singleton();
                $this->mLatestID = intval( $linkCache->getGoodLinkFieldObj( $this, 'revision' ) );

                return $this->mLatestID;
        }

        /**
         * This clears some fields in this object, and clears any associated
         * keys in the "bad links" section of the link cache.
         *
         * - This is called from Article::doEdit() and Article::insertOn() to allow
         * loading of the new page_id. It's also called from
         * Article::doDeleteArticle()
         *
         * @param $newid Int the new Article ID
         */
        public function resetArticleID( $newid ) {
                $linkCache = LinkCache::singleton();
                $linkCache->clearBadLink( $this->getPrefixedDBkey() );

                if ( $newid === false ) {
                        $this->mArticleID = -1;
                } else {
                        $this->mArticleID = intval( $newid );
                }
                $this->mRestrictionsLoaded = false;
                $this->mRestrictions = array();
                $this->mRedirect = null;
                $this->mLength = -1;
                $this->mLatestID = false;
        }

        /**
         * Updates page_touched for this page; called from LinksUpdate.php
         *
         * @return Bool true if the update succeded
         */
        public function invalidateCache() {
                if ( wfReadOnly() ) {
                        return;
                }
                $dbw = wfGetDB( DB_MASTER );
                $success = $dbw->update(
                        'page',
                        array( 'page_touched' => $dbw->timestamp() ),
                        $this->pageCond(),
                        __METHOD__
                );
                HTMLFileCache::clearFileCache( $this );
                return $success;
        }

        /**
         * Prefix some arbitrary text with the namespace or interwiki prefix
         * of this object
         *
         * @param $name String the text
         * @return String the prefixed text
         * @private
         */
        private function prefix( $name ) {
                $p = '';
                if ( $this->mInterwiki != '' ) {
                        $p = $this->mInterwiki . ':';
                }

                if ( 0 != $this->mNamespace ) {
                        $p .= $this->getNsText() . ':';
                }
                return $p . $name;
        }

        /**
         * Returns a simple regex that will match on characters and sequences invalid in titles.
         * Note that this doesn't pick up many things that could be wrong with titles, but that
         * replacing this regex with something valid will make many titles valid.
         *
         * @return String regex string
         */
        static function getTitleInvalidRegex() {
                static $rxTc = false;
                if ( !$rxTc ) {
                        # Matching titles will be held as illegal.
                        $rxTc = '/' .
                                # Any character not allowed is forbidden...
                                '[^' . Title::legalChars() . ']' .
                                # URL percent encoding sequences interfere with the ability
                                # to round-trip titles -- you can't link to them consistently.
                                '|%[0-9A-Fa-f]{2}' .
                                # XML/HTML character references produce similar issues.
                                '|&[A-Za-z0-9\x80-\xff]+;' .
                                '|&#[0-9]+;' .
                                '|&#x[0-9A-Fa-f]+;' .
                                '/S';
                }

                return $rxTc;
        }

        /**
         * Capitalize a text string for a title if it belongs to a namespace that capitalizes
         *
         * @param $text String containing title to capitalize
         * @param $ns int namespace index, defaults to NS_MAIN
         * @return String containing capitalized title
         */
        public static function capitalize( $text, $ns = NS_MAIN ) {
                global $wgContLang;

                if ( MWNamespace::isCapitalized( $ns ) ) {
                        return $wgContLang->ucfirst( $text );
                } else {
                        return $text;
                }
        }

        /**
         * Secure and split - main initialisation function for this object
         *
         * Assumes that mDbkeyform has been set, and is urldecoded
         * and uses underscores, but not otherwise munged.  This function
         * removes illegal characters, splits off the interwiki and
         * namespace prefixes, sets the other forms, and canonicalizes
         * everything.
         *
         * @return Bool true on success
         */
        private function secureAndSplit() {
                global $wgContLang, $wgLocalInterwiki;

                # Initialisation
                $this->mInterwiki = $this->mFragment = '';
                $this->mNamespace = $this->mDefaultNamespace; # Usually NS_MAIN

                $dbkey = $this->mDbkeyform;

                # Strip Unicode bidi override characters.
                # Sometimes they slip into cut-n-pasted page titles, where the
                # override chars get included in list displays.
                $dbkey = preg_replace( '/\xE2\x80[\x8E\x8F\xAA-\xAE]/S', '', $dbkey );

                # Clean up whitespace
                # Note: use of the /u option on preg_replace here will cause
                # input with invalid UTF-8 sequences to be nullified out in PHP 5.2.x,
                # conveniently disabling them.
                $dbkey = preg_replace( '/[ _\xA0\x{1680}\x{180E}\x{2000}-\x{200A}\x{2028}\x{2029}\x{202F}\x{205F}\x{3000}]+/u', '_', $dbkey );
                $dbkey = trim( $dbkey, '_' );

                if ( $dbkey == '' ) {
                        return false;
                }

                if ( false !== strpos( $dbkey, UTF8_REPLACEMENT ) ) {
                        # Contained illegal UTF-8 sequences or forbidden Unicode chars.
                        return false;
                }

                $this->mDbkeyform = $dbkey;

                # Initial colon indicates main namespace rather than specified default
                # but should not create invalid {ns,title} pairs such as {0,Project:Foo}
                if ( ':' == $dbkey { 0 } ) {
                        $this->mNamespace = NS_MAIN;
                        $dbkey = substr( $dbkey, 1 ); # remove the colon but continue processing
                        $dbkey = trim( $dbkey, '_' ); # remove any subsequent whitespace
                }

                # Namespace or interwiki prefix
                $firstPass = true;
                $prefixRegexp = "/^(.+?)_*:_*(.*)$/S";
                do {
                        $m = array();
                        if ( preg_match( $prefixRegexp, $dbkey, $m ) ) {
                                $p = $m[1];
                                if ( ( $ns = $wgContLang->getNsIndex( $p ) ) !== false ) {
                                        # Ordinary namespace
                                        $dbkey = $m[2];
                                        $this->mNamespace = $ns;
                                        # For Talk:X pages, check if X has a "namespace" prefix
                                        if ( $ns == NS_TALK && preg_match( $prefixRegexp, $dbkey, $x ) ) {
                                                if ( $wgContLang->getNsIndex( $x[1] ) ) {
                                                        # Disallow Talk:File:x type titles...
                                                        return false;
                                                } else if ( Interwiki::isValidInterwiki( $x[1] ) ) {
                                                        # Disallow Talk:Interwiki:x type titles...
                                                        return false;
                                                }
                                        }
                                } elseif ( Interwiki::isValidInterwiki( $p ) ) {
                                        if ( !$firstPass ) {
                                                # Can't make a local interwiki link to an interwiki link.
                                                # That's just crazy!
                                                return false;
                                        }

                                        # Interwiki link
                                        $dbkey = $m[2];
                                        $this->mInterwiki = $wgContLang->lc( $p );

                                        # Redundant interwiki prefix to the local wiki
                                        if ( $wgLocalInterwiki !== false
                                                && 0 == strcasecmp( $this->mInterwiki, $wgLocalInterwiki ) )
                                        {
                                                if ( $dbkey == '' ) {
                                                        # Can't have an empty self-link
                                                        return false;
                                                }
                                                $this->mInterwiki = '';
                                                $firstPass = false;
                                                # Do another namespace split...
                                                continue;
                                        }

                                        # If there's an initial colon after the interwiki, that also
                                        # resets the default namespace
                                        if ( $dbkey !== '' && $dbkey[0] == ':' ) {
                                                $this->mNamespace = NS_MAIN;
                                                $dbkey = substr( $dbkey, 1 );
                                        }
                                }
                                # If there's no recognized interwiki or namespace,
                                # then let the colon expression be part of the title.
                        }
                        break;
                } while ( true );

                # We already know that some pages won't be in the database!
                if ( $this->mInterwiki != '' || NS_SPECIAL == $this->mNamespace ) {
                        $this->mArticleID = 0;
                }
                $fragment = strstr( $dbkey, '#' );
                if ( false !== $fragment ) {
                        $this->setFragment( $fragment );
                        $dbkey = substr( $dbkey, 0, strlen( $dbkey ) - strlen( $fragment ) );
                        # remove whitespace again: prevents "Foo_bar_#"
                        # becoming "Foo_bar_"
                        $dbkey = preg_replace( '/_*$/', '', $dbkey );
                }

                # Reject illegal characters.
                $rxTc = self::getTitleInvalidRegex();
                if ( preg_match( $rxTc, $dbkey ) ) {
                        return false;
                }

                # Pages with "/./" or "/../" appearing in the URLs will often be un-
                # reachable due to the way web browsers deal with 'relative' URLs.
                # Also, they conflict with subpage syntax.  Forbid them explicitly.
                if ( strpos( $dbkey, '.' ) !== false &&
                         ( $dbkey === '.' || $dbkey === '..' ||
                           strpos( $dbkey, './' ) === 0  ||
                           strpos( $dbkey, '../' ) === 0 ||
                           strpos( $dbkey, '/./' ) !== false ||
                           strpos( $dbkey, '/../' ) !== false  ||
                           substr( $dbkey, -2 ) == '/.' ||
                           substr( $dbkey, -3 ) == '/..' ) )
                {
                        return false;
                }

                # Magic tilde sequences? Nu-uh!
                if ( strpos( $dbkey, '~~~' ) !== false ) {
                        return false;
                }

                # Limit the size of titles to 255 bytes. This is typically the size of the
                # underlying database field. We make an exception for special pages, which
                # don't need to be stored in the database, and may edge over 255 bytes due
                # to subpage syntax for long titles, e.g. [[Special:Block/Long name]]
                if ( ( $this->mNamespace != NS_SPECIAL && strlen( $dbkey ) > 255 ) ||
                  strlen( $dbkey ) > 512 )
                {
                        return false;
                }

                # Normally, all wiki links are forced to have an initial capital letter so [[foo]]
                # and [[Foo]] point to the same place.  Don't force it for interwikis, since the
                # other site might be case-sensitive.
                $this->mUserCaseDBKey = $dbkey;
                if ( $this->mInterwiki == '' ) {
                        $dbkey = self::capitalize( $dbkey, $this->mNamespace );
                }

                # Can't make a link to a namespace alone... "empty" local links can only be
                # self-links with a fragment identifier.
                if ( $dbkey == '' && $this->mInterwiki == '' && $this->mNamespace != NS_MAIN ) {
                        return false;
                }

                // Allow IPv6 usernames to start with '::' by canonicalizing IPv6 titles.
                // IP names are not allowed for accounts, and can only be referring to
                // edits from the IP. Given '::' abbreviations and caps/lowercaps,
                // there are numerous ways to present the same IP. Having sp:contribs scan
                // them all is silly and having some show the edits and others not is
                // inconsistent. Same for talk/userpages. Keep them normalized instead.
                $dbkey = ( $this->mNamespace == NS_USER || $this->mNamespace == NS_USER_TALK )
                        ? IP::sanitizeIP( $dbkey )
                        : $dbkey;

                // Any remaining initial :s are illegal.
                if ( $dbkey !== '' && ':' == $dbkey { 0 } ) {
                        return false;
                }

                # Fill fields
                $this->mDbkeyform = $dbkey;
                $this->mUrlform = wfUrlencode( $dbkey );

                $this->mTextform = str_replace( '_', ' ', $dbkey );

                return true;
        }

        /**
         * Set the fragment for this title. Removes the first character from the
         * specified fragment before setting, so it assumes you're passing it with
         * an initial "#".
         *
         * Deprecated for public use, use Title::makeTitle() with fragment parameter.
         * Still in active use privately.
         *
         * @param $fragment String text
         */
        public function setFragment( $fragment ) {
                $this->mFragment = str_replace( '_', ' ', substr( $fragment, 1 ) );
        }

        /**
         * Get a Title object associated with the talk page of this article
         *
         * @return Title the object for the talk page
         */
        public function getTalkPage() {
                return Title::makeTitle( MWNamespace::getTalk( $this->getNamespace() ), $this->getDBkey() );
        }

        /**
         * Get a title object associated with the subject page of this
         * talk page
         *
         * @return Title the object for the subject page
         */
        public function getSubjectPage() {
                // Is this the same title?
                $subjectNS = MWNamespace::getSubject( $this->getNamespace() );
                if ( $this->getNamespace() == $subjectNS ) {
                        return $this;
                }
                return Title::makeTitle( $subjectNS, $this->getDBkey() );
        }

        /**
         * Get an array of Title objects linking to this Title
         * Also stores the IDs in the link cache.
         *
         * WARNING: do not use this function on arbitrary user-supplied titles!
         * On heavily-used templates it will max out the memory.
         *
         * @param $options Array: may be FOR UPDATE
         * @param $table String: table name
         * @param $prefix String: fields prefix
         * @return Array of Title objects linking here
         */
        public function getLinksTo( $options = array(), $table = 'pagelinks', $prefix = 'pl' ) {
                $linkCache = LinkCache::singleton();

                if ( count( $options ) > 0 ) {
                        $db = wfGetDB( DB_MASTER );
                } else {
                        $db = wfGetDB( DB_SLAVE );
                }

                $res = $db->select(
                        array( 'page', $table ),
                        array( 'page_namespace', 'page_title', 'page_id', 'page_len', 'page_is_redirect', 'page_latest' ),
                        array(
                                "{$prefix}_from=page_id",
                                "{$prefix}_namespace" => $this->getNamespace(),
                                "{$prefix}_title"     => $this->getDBkey() ),
                        __METHOD__,
                        $options
                );

                $retVal = array();
                if ( $db->numRows( $res ) ) {
                        foreach ( $res as $row ) {
                                $titleObj = Title::makeTitle( $row->page_namespace, $row->page_title );
                                if ( $titleObj ) {
                                        $linkCache->addGoodLinkObj( $row->page_id, $titleObj, $row->page_len, $row->page_is_redirect, $row->page_latest );
                                        $retVal[] = $titleObj;
                                }
                        }
                }
                return $retVal;
        }

        /**
         * Get an array of Title objects using this Title as a template
         * Also stores the IDs in the link cache.
         *
         * WARNING: do not use this function on arbitrary user-supplied titles!
         * On heavily-used templates it will max out the memory.
         *
         * @param $options Array: may be FOR UPDATE
         * @return Array of Title the Title objects linking here
         */
        public function getTemplateLinksTo( $options = array() ) {
                return $this->getLinksTo( $options, 'templatelinks', 'tl' );
        }

        /**
         * Get an array of Title objects referring to non-existent articles linked from this page
         *
         * @todo check if needed (used only in SpecialBrokenRedirects.php, and should use redirect table in this case)
         * @return Array of Title the Title objects
         */
        public function getBrokenLinksFrom() {
                if ( $this->getArticleId() == 0 ) {
                        # All links from article ID 0 are false positives
                        return array();
                }

                $dbr = wfGetDB( DB_SLAVE );
                $res = $dbr->select(
                        array( 'page', 'pagelinks' ),
                        array( 'pl_namespace', 'pl_title' ),
                        array(
                                'pl_from' => $this->getArticleId(),
                                'page_namespace IS NULL'
                        ),
                        __METHOD__, array(),
                        array(
                                'page' => array(
                                        'LEFT JOIN',
                                        array( 'pl_namespace=page_namespace', 'pl_title=page_title' )
                                )
                        )
                );

                $retVal = array();
                foreach ( $res as $row ) {
                        $retVal[] = Title::makeTitle( $row->pl_namespace, $row->pl_title );
                }
                return $retVal;
        }


        /**
         * Get a list of URLs to purge from the Squid cache when this
         * page changes
         *
         * @return Array of String the URLs
         */
        public function getSquidURLs() {
                global $wgContLang;

                $urls = array(
                        $this->getInternalURL(),
                        $this->getInternalURL( 'action=history' )
                );

                // purge variant urls as well
                if ( $wgContLang->hasVariants() ) {
                        $variants = $wgContLang->getVariants();
                        foreach ( $variants as $vCode ) {
                                $urls[] = $this->getInternalURL( '', $vCode );
                        }
                }

                return $urls;
        }

        /**
         * Purge all applicable Squid URLs
         */
        public function purgeSquid() {
                global $wgUseSquid;
                if ( $wgUseSquid ) {
                        $urls = $this->getSquidURLs();
                        $u = new SquidUpdate( $urls );
                        $u->doUpdate();
                }
        }

        /**
         * Move this page without authentication
         *
         * @param $nt Title the new page Title
         * @return Mixed true on success, getUserPermissionsErrors()-like array on failure
         */
        public function moveNoAuth( &$nt ) {
                return $this->moveTo( $nt, false );
        }

        /**
         * Check whether a given move operation would be valid.
         * Returns true if ok, or a getUserPermissionsErrors()-like array otherwise
         *
         * @param $nt Title the new title
         * @param $auth Bool indicates whether $wgUser's permissions
         *  should be checked
         * @param $reason String is the log summary of the move, used for spam checking
         * @return Mixed True on success, getUserPermissionsErrors()-like array on failure
         */
        public function isValidMoveOperation( &$nt, $auth = true, $reason = '' ) {
                global $wgUser;

                $errors = array();
                if ( !$nt ) {
                        // Normally we'd add this to $errors, but we'll get
                        // lots of syntax errors if $nt is not an object
                        return array( array( 'badtitletext' ) );
                }
                if ( $this->equals( $nt ) ) {
                        $errors[] = array( 'selfmove' );
                }
                if ( !$this->isMovable() ) {
                        $errors[] = array( 'immobile-source-namespace', $this->getNsText() );
                }
                if ( $nt->getInterwiki() != '' ) {
                        $errors[] = array( 'immobile-target-namespace-iw' );
                }
                if ( !$nt->isMovable() ) {
                        $errors[] = array( 'immobile-target-namespace', $nt->getNsText() );
                }

                $oldid = $this->getArticleID();
                $newid = $nt->getArticleID();

                if ( strlen( $nt->getDBkey() ) < 1 ) {
                        $errors[] = array( 'articleexists' );
                }
                if ( ( $this->getDBkey() == '' ) ||
                         ( !$oldid ) ||
                         ( $nt->getDBkey() == '' ) ) {
                        $errors[] = array( 'badarticleerror' );
                }

                // Image-specific checks
                if ( $this->getNamespace() == NS_FILE ) {
                        $errors = array_merge( $errors, $this->validateFileMoveOperation( $nt ) );
                }

                if ( $nt->getNamespace() == NS_FILE && $this->getNamespace() != NS_FILE ) {
                        $errors[] = array( 'nonfile-cannot-move-to-file' );
                }

                if ( $auth ) {
                        $errors = wfMergeErrorArrays( $errors,
                                $this->getUserPermissionsErrors( 'move', $wgUser ),
                                $this->getUserPermissionsErrors( 'edit', $wgUser ),
                                $nt->getUserPermissionsErrors( 'move-target', $wgUser ),
                                $nt->getUserPermissionsErrors( 'edit', $wgUser ) );
                }

                $match = EditPage::matchSummarySpamRegex( $reason );
                if ( $match !== false ) {
                        // This is kind of lame, won't display nice
                        $errors[] = array( 'spamprotectiontext' );
                }

                $err = null;
                if ( !wfRunHooks( 'AbortMove', array( $this, $nt, $wgUser, &$err, $reason ) ) ) {
                        $errors[] = array( 'hookaborted', $err );
                }

                # The move is allowed only if (1) the target doesn't exist, or
                # (2) the target is a redirect to the source, and has no history
                # (so we can undo bad moves right after they're done).

                if ( 0 != $newid ) { # Target exists; check for validity
                        if ( !$this->isValidMoveTarget( $nt ) ) {
                                $errors[] = array( 'articleexists' );
                        }
                } else {
                        $tp = $nt->getTitleProtection();
                        $right = ( $tp['pt_create_perm'] == 'sysop' ) ? 'protect' : $tp['pt_create_perm'];
                        if ( $tp and !$wgUser->isAllowed( $right ) ) {
                                $errors[] = array( 'cantmove-titleprotected' );
                        }
                }
                if ( empty( $errors ) ) {
                        return true;
                }
                return $errors;
        }

        /**
         * Check if the requested move target is a valid file move target
         * @param Title $nt Target title
         * @return array List of errors
         */
        protected function validateFileMoveOperation( $nt ) {
                global $wgUser;

                $errors = array();

                if ( $nt->getNamespace() != NS_FILE ) {
                        $errors[] = array( 'imagenocrossnamespace' );
                }

                $file = wfLocalFile( $this );
                if ( $file->exists() ) {
                        if ( $nt->getText() != wfStripIllegalFilenameChars( $nt->getText() ) ) {
                                $errors[] = array( 'imageinvalidfilename' );
                        }
                        if ( !File::checkExtensionCompatibility( $file, $nt->getDBkey() ) ) {
                                $errors[] = array( 'imagetypemismatch' );
                        }
                }

                $destFile = wfLocalFile( $nt );
                if ( !$wgUser->isAllowed( 'reupload-shared' ) && !$destFile->exists() && wfFindFile( $nt ) ) {
                        $errors[] = array( 'file-exists-sharedrepo' );
                }

                return $errors;
        }

        /**
         * Move a title to a new location
         *
         * @param $nt Title the new title
         * @param $auth Bool indicates whether $wgUser's permissions
         *  should be checked
         * @param $reason String the reason for the move
         * @param $createRedirect Bool Whether to create a redirect from the old title to the new title.
         *  Ignored if the user doesn't have the suppressredirect right.
         * @return Mixed true on success, getUserPermissionsErrors()-like array on failure
         */
        public function moveTo( &$nt, $auth = true, $reason = '', $createRedirect = true ) {
                $err = $this->isValidMoveOperation( $nt, $auth, $reason );
                if ( is_array( $err ) ) {
                        return $err;
                }

                // If it is a file, move it first. It is done before all other moving stuff is
                // done because it's hard to revert
                $dbw = wfGetDB( DB_MASTER );
                if ( $this->getNamespace() == NS_FILE ) {
                        $file = wfLocalFile( $this );
                        if ( $file->exists() ) {
                                $status = $file->move( $nt );
                                if ( !$status->isOk() ) {
                                        return $status->getErrorsArray();
                                }
                        }
                }

                $dbw->begin(); # If $file was a LocalFile, its transaction would have closed our own.
                $pageid = $this->getArticleID( self::GAID_FOR_UPDATE );
                $protected = $this->isProtected();
                $pageCountChange = ( $createRedirect ? 1 : 0 ) - ( $nt->exists() ? 1 : 0 );

                // Do the actual move
                $err = $this->moveToInternal( $nt, $reason, $createRedirect );
                if ( is_array( $err ) ) {
                        # @todo FIXME: What about the File we have already moved?
                        $dbw->rollback();
                        return $err;
                }

                $redirid = $this->getArticleID();

                // Refresh the sortkey for this row.  Be careful to avoid resetting
                // cl_timestamp, which may disturb time-based lists on some sites.
                $prefixes = $dbw->select(
                        'categorylinks',
                        array( 'cl_sortkey_prefix', 'cl_to' ),
                        array( 'cl_from' => $pageid ),
                        __METHOD__
                );
                foreach ( $prefixes as $prefixRow ) {
                        $prefix = $prefixRow->cl_sortkey_prefix;
                        $catTo = $prefixRow->cl_to;
                        $dbw->update( 'categorylinks',
                                array(
                                        'cl_sortkey' => Collation::singleton()->getSortKey(
                                                $nt->getCategorySortkey( $prefix ) ),
                                        'cl_timestamp=cl_timestamp' ),
                                array(
                                        'cl_from' => $pageid,
                                        'cl_to' => $catTo ),
                                __METHOD__
                        );
                }

                if ( $protected ) {
                        # Protect the redirect title as the title used to be...
                        $dbw->insertSelect( 'page_restrictions', 'page_restrictions',
                                array(
                                        'pr_page'    => $redirid,
                                        'pr_type'    => 'pr_type',
                                        'pr_level'   => 'pr_level',
                                        'pr_cascade' => 'pr_cascade',
                                        'pr_user'    => 'pr_user',
                                        'pr_expiry'  => 'pr_expiry'
                                ),
                                array( 'pr_page' => $pageid ),
                                __METHOD__,
                                array( 'IGNORE' )
                        );
                        # Update the protection log
                        $log = new LogPage( 'protect' );
                        $comment = wfMsgForContent( 'prot_1movedto2', $this->getPrefixedText(), $nt->getPrefixedText() );
                        if ( $reason ) {
                                $comment .= wfMsgForContent( 'colon-separator' ) . $reason;
                        }
                        // @todo FIXME: $params?
                        $log->addEntry( 'move_prot', $nt, $comment, array( $this->getPrefixedText() ) );
                }

                # Update watchlists
                $oldnamespace = $this->getNamespace() & ~1;
                $newnamespace = $nt->getNamespace() & ~1;
                $oldtitle = $this->getDBkey();
                $newtitle = $nt->getDBkey();

                if ( $oldnamespace != $newnamespace || $oldtitle != $newtitle ) {
                        WatchedItem::duplicateEntries( $this, $nt );
                }

                # Update search engine
                $u = new SearchUpdate( $pageid, $nt->getPrefixedDBkey() );
                $u->doUpdate();
                $u = new SearchUpdate( $redirid, $this->getPrefixedDBkey(), '' );
                $u->doUpdate();

                $dbw->commit();
                
                # Update site_stats
                if ( $this->isContentPage() && !$nt->isContentPage() ) {
                        # No longer a content page
                        # Not viewed, edited, removing
                        $u = new SiteStatsUpdate( 0, 1, -1, $pageCountChange );
                } elseif ( !$this->isContentPage() && $nt->isContentPage() ) {
                        # Now a content page
                        # Not viewed, edited, adding
                        $u = new SiteStatsUpdate( 0, 1, + 1, $pageCountChange );
                } elseif ( $pageCountChange ) {
                        # Redirect added
                        $u = new SiteStatsUpdate( 0, 0, 0, 1 );
                } else {
                        # Nothing special
                        $u = false;
                }
                if ( $u ) {
                        $u->doUpdate();
                }
                # Update message cache for interface messages
                if ( $this->getNamespace() == NS_MEDIAWIKI ) {
                        # @bug 17860: old article can be deleted, if this the case,
                        # delete it from message cache
                        if ( $this->getArticleID() === 0 ) {
                                MessageCache::singleton()->replace( $this->getDBkey(), false );
                        } else {
                                $oldarticle = new Article( $this );
                                MessageCache::singleton()->replace( $this->getDBkey(), $oldarticle->getContent() );
                        }
                }
                if ( $nt->getNamespace() == NS_MEDIAWIKI ) {
                        $newarticle = new Article( $nt );
                        MessageCache::singleton()->replace( $nt->getDBkey(), $newarticle->getContent() );
                }

                global $wgUser;
                wfRunHooks( 'TitleMoveComplete', array( &$this, &$nt, &$wgUser, $pageid, $redirid ) );
                return true;
        }

        /**
         * Move page to a title which is either a redirect to the
         * source page or nonexistent
         *
         * @param $nt Title the page to move to, which should be a redirect or nonexistent
         * @param $reason String The reason for the move
         * @param $createRedirect Bool Whether to leave a redirect at the old title.  Ignored
         *   if the user doesn't have the suppressredirect right
         */
        private function moveToInternal( &$nt, $reason = '', $createRedirect = true ) {
                global $wgUser, $wgContLang;

                $moveOverRedirect = $nt->exists();

                $commentMsg = ( $moveOverRedirect ? '1movedto2_redir' : '1movedto2' );
                $comment = wfMsgForContent( $commentMsg, $this->getPrefixedText(), $nt->getPrefixedText() );

                if ( $reason ) {
                        $comment .= wfMsgForContent( 'colon-separator' ) . $reason;
                }
                # Truncate for whole multibyte characters.
                $comment = $wgContLang->truncate( $comment, 255 );

                $oldid = $this->getArticleID();
                $latest = $this->getLatestRevID();

                $oldns = $this->getNamespace();
                $olddbk = $this->getDBkey();

                $dbw = wfGetDB( DB_MASTER );

                if ( $moveOverRedirect ) {
                        $rcts = $dbw->timestamp( $nt->getEarliestRevTime() );

                        $newid = $nt->getArticleID();
                        $newns = $nt->getNamespace();
                        $newdbk = $nt->getDBkey();

                        # Delete the old redirect. We don't save it to history since
                        # by definition if we've got here it's rather uninteresting.
                        # We have to remove it so that the next step doesn't trigger
                        # a conflict on the unique namespace+title index...
                        $dbw->delete( 'page', array( 'page_id' => $newid ), __METHOD__ );
                        if ( !$dbw->cascadingDeletes() ) {
                                $dbw->delete( 'revision', array( 'rev_page' => $newid ), __METHOD__ );
                                global $wgUseTrackbacks;
                                if ( $wgUseTrackbacks ) {
                                        $dbw->delete( 'trackbacks', array( 'tb_page' => $newid ), __METHOD__ );
                                }
                                $dbw->delete( 'pagelinks', array( 'pl_from' => $newid ), __METHOD__ );
                                $dbw->delete( 'imagelinks', array( 'il_from' => $newid ), __METHOD__ );
                                $dbw->delete( 'categorylinks', array( 'cl_from' => $newid ), __METHOD__ );
                                $dbw->delete( 'templatelinks', array( 'tl_from' => $newid ), __METHOD__ );
                                $dbw->delete( 'externallinks', array( 'el_from' => $newid ), __METHOD__ );
                                $dbw->delete( 'langlinks', array( 'll_from' => $newid ), __METHOD__ );
                                $dbw->delete( 'redirect', array( 'rd_from' => $newid ), __METHOD__ );
                        }
                        // If the target page was recently created, it may have an entry in recentchanges still
                        $dbw->delete( 'recentchanges',
                                array( 'rc_timestamp' => $rcts, 'rc_namespace' => $newns, 'rc_title' => $newdbk, 'rc_new' => 1 ),
                                __METHOD__
                        );
                }

                # Save a null revision in the page's history notifying of the move
                $nullRevision = Revision::newNullRevision( $dbw, $oldid, $comment, true );
                if ( !is_object( $nullRevision ) ) {
                        throw new MWException( 'No valid null revision produced in ' . __METHOD__ );
                }
                $nullRevId = $nullRevision->insertOn( $dbw );

                # Change the name of the target page:
                $dbw->update( 'page',
                        /* SET */ array(
                                'page_touched'   => $dbw->timestamp(),
                                'page_namespace' => $nt->getNamespace(),
                                'page_title'     => $nt->getDBkey(),
                                'page_latest'    => $nullRevId,
                        ),
                        /* WHERE */ array( 'page_id' => $oldid ),
                        __METHOD__
                );
                $nt->resetArticleID( $oldid );

                $article = new Article( $nt );
                wfRunHooks( 'NewRevisionFromEditComplete', array( $article, $nullRevision, $latest, $wgUser ) );

                # Recreate the redirect, this time in the other direction.
                if ( $createRedirect || !$wgUser->isAllowed( 'suppressredirect' ) ) {
                        $mwRedir = MagicWord::get( 'redirect' );
                        $redirectText = $mwRedir->getSynonym( 0 ) . ' [[' . $nt->getPrefixedText() . "]]\n";
                        $redirectArticle = new Article( $this );
                        $newid = $redirectArticle->insertOn( $dbw );
                        $redirectRevision = new Revision( array(
                                'page'    => $newid,
                                'comment' => $comment,
                                'text'    => $redirectText ) );
                        $redirectRevision->insertOn( $dbw );
                        $redirectArticle->updateRevisionOn( $dbw, $redirectRevision, 0 );

                        wfRunHooks( 'NewRevisionFromEditComplete', array( $redirectArticle, $redirectRevision, false, $wgUser ) );

                        # Now, we record the link from the redirect to the new title.
                        # It should have no other outgoing links...
                        $dbw->delete( 'pagelinks', array( 'pl_from' => $newid ), __METHOD__ );
                        $dbw->insert( 'pagelinks',
                                array(
                                        'pl_from'      => $newid,
                                        'pl_namespace' => $nt->getNamespace(),
                                        'pl_title'     => $nt->getDBkey() ),
                                __METHOD__ );
                        $redirectSuppressed = false;
                } else {
                        // Get rid of old new page entries in Special:NewPages and RC.
                        // Needs to be before $this->resetArticleID( 0 ).
                        $dbw->delete( 'recentchanges', array(
                                        'rc_timestamp' => $dbw->timestamp( $this->getEarliestRevTime() ),
                                        'rc_namespace' => $oldns,
                                        'rc_title' => $olddbk,
                                        'rc_new' => 1
                                ),
                                __METHOD__
                        );

                        $this->resetArticleID( 0 );
                        $redirectSuppressed = true;
                }

                # Log the move
                $log = new LogPage( 'move' );
                $logType = ( $moveOverRedirect ? 'move_redir' : 'move' );
                $log->addEntry( $logType, $this, $reason, array( 1 => $nt->getPrefixedText(), 2 => $redirectSuppressed ) );

                # Purge caches for old and new titles
                if ( $moveOverRedirect ) {
                        # A simple purge is enough when moving over a redirect
                        $nt->purgeSquid();
                } else {
                        # Purge caches as per article creation, including any pages that link to this title
                        Article::onArticleCreate( $nt );
                }
                $this->purgeSquid();
        }

        /**
         * Move this page's subpages to be subpages of $nt
         *
         * @param $nt Title Move target
         * @param $auth bool Whether $wgUser's permissions should be checked
         * @param $reason string The reason for the move
         * @param $createRedirect bool Whether to create redirects from the old subpages to
         *     the new ones Ignored if the user doesn't have the 'suppressredirect' right
         * @return mixed array with old page titles as keys, and strings (new page titles) or
         *     arrays (errors) as values, or an error array with numeric indices if no pages
         *     were moved
         */
        public function moveSubpages( $nt, $auth = true, $reason = '', $createRedirect = true ) {
                global $wgMaximumMovedPages;
                // Check permissions
                if ( !$this->userCan( 'move-subpages' ) ) {
                        return array( 'cant-move-subpages' );
                }
                // Do the source and target namespaces support subpages?
                if ( !MWNamespace::hasSubpages( $this->getNamespace() ) ) {
                        return array( 'namespace-nosubpages',
                                MWNamespace::getCanonicalName( $this->getNamespace() ) );
                }
                if ( !MWNamespace::hasSubpages( $nt->getNamespace() ) ) {
                        return array( 'namespace-nosubpages',
                                MWNamespace::getCanonicalName( $nt->getNamespace() ) );
                }

                $subpages = $this->getSubpages( $wgMaximumMovedPages + 1 );
                $retval = array();
                $count = 0;
                foreach ( $subpages as $oldSubpage ) {
                        $count++;
                        if ( $count > $wgMaximumMovedPages ) {
                                $retval[$oldSubpage->getPrefixedTitle()] =
                                                array( 'movepage-max-pages',
                                                        $wgMaximumMovedPages );
                                break;
                        }

                        // We don't know whether this function was called before
                        // or after moving the root page, so check both
                        // $this and $nt
                        if ( $oldSubpage->getArticleId() == $this->getArticleId() ||
                                        $oldSubpage->getArticleID() == $nt->getArticleId() )
                        {
                                // When moving a page to a subpage of itself,
                                // don't move it twice
                                continue;
                        }
                        $newPageName = preg_replace(
                                        '#^' . preg_quote( $this->getDBkey(), '#' ) . '#',
                                        StringUtils::escapeRegexReplacement( $nt->getDBkey() ), # bug 21234
                                        $oldSubpage->getDBkey() );
                        if ( $oldSubpage->isTalkPage() ) {
                                $newNs = $nt->getTalkPage()->getNamespace();
                        } else {
                                $newNs = $nt->getSubjectPage()->getNamespace();
                        }
                        # Bug 14385: we need makeTitleSafe because the new page names may
                        # be longer than 255 characters.
                        $newSubpage = Title::makeTitleSafe( $newNs, $newPageName );

                        $success = $oldSubpage->moveTo( $newSubpage, $auth, $reason, $createRedirect );
                        if ( $success === true ) {
                                $retval[$oldSubpage->getPrefixedText()] = $newSubpage->getPrefixedText();
                        } else {
                                $retval[$oldSubpage->getPrefixedText()] = $success;
                        }
                }
                return $retval;
        }

        /**
         * Checks if this page is just a one-rev redirect.
         * Adds lock, so don't use just for light purposes.
         *
         * @return Bool
         */
        public function isSingleRevRedirect() {
                $dbw = wfGetDB( DB_MASTER );
                # Is it a redirect?
                $row = $dbw->selectRow( 'page',
                        array( 'page_is_redirect', 'page_latest', 'page_id' ),
                        $this->pageCond(),
                        __METHOD__,
                        array( 'FOR UPDATE' )
                );
                # Cache some fields we may want
                $this->mArticleID = $row ? intval( $row->page_id ) : 0;
                $this->mRedirect = $row ? (bool)$row->page_is_redirect : false;
                $this->mLatestID = $row ? intval( $row->page_latest ) : false;
                if ( !$this->mRedirect ) {
                        return false;
                }
                # Does the article have a history?
                $row = $dbw->selectField( array( 'page', 'revision' ),
                        'rev_id',
                        array( 'page_namespace' => $this->getNamespace(),
                                'page_title' => $this->getDBkey(),
                                'page_id=rev_page',
                                'page_latest != rev_id'
                        ),
                        __METHOD__,
                        array( 'FOR UPDATE' )
                );
                # Return true if there was no history
                return ( $row === false );
        }

        /**
         * Checks if $this can be moved to a given Title
         * - Selects for update, so don't call it unless you mean business
         *
         * @param $nt Title the new title to check
         * @return Bool
         */
        public function isValidMoveTarget( $nt ) {
                # Is it an existing file?
                if ( $nt->getNamespace() == NS_FILE ) {
                        $file = wfLocalFile( $nt );
                        if ( $file->exists() ) {
                                wfDebug( __METHOD__ . ": file exists\n" );
                                return false;
                        }
                }
                # Is it a redirect with no history?
                if ( !$nt->isSingleRevRedirect() ) {
                        wfDebug( __METHOD__ . ": not a one-rev redirect\n" );
                        return false;
                }
                # Get the article text
                $rev = Revision::newFromTitle( $nt );
                $text = $rev->getText();
                # Does the redirect point to the source?
                # Or is it a broken self-redirect, usually caused by namespace collisions?
                $m = array();
                if ( preg_match( "/\\[\\[\\s*([^\\]\\|]*)]]/", $text, $m ) ) {
                        $redirTitle = Title::newFromText( $m[1] );
                        if ( !is_object( $redirTitle ) ||
                                ( $redirTitle->getPrefixedDBkey() != $this->getPrefixedDBkey() &&
                                $redirTitle->getPrefixedDBkey() != $nt->getPrefixedDBkey() ) ) {
                                wfDebug( __METHOD__ . ": redirect points to other page\n" );
                                return false;
                        }
                } else {
                        # Fail safe
                        wfDebug( __METHOD__ . ": failsafe\n" );
                        return false;
                }
                return true;
        }

        /**
         * Can this title be added to a user's watchlist?
         *
         * @return Bool TRUE or FALSE
         */
        public function isWatchable() {
                return !$this->isExternal() && MWNamespace::isWatchable( $this->getNamespace() );
        }

        /**
         * Get categories to which this Title belongs and return an array of
         * categories' names.
         *
         * @return Array of parents in the form:
         *        $parent => $currentarticle
         */
        public function getParentCategories() {
                global $wgContLang;

                $data = array();

                $titleKey = $this->getArticleId();

                if ( $titleKey === 0 ) {
                        return $data;
                }

                $dbr = wfGetDB( DB_SLAVE );

                $res = $dbr->select( 'categorylinks', '*',
                        array(
                                'cl_from' => $titleKey,
                        ),
                        __METHOD__,
                        array()
                );

                if ( $dbr->numRows( $res ) > 0 ) {
                        foreach ( $res as $row ) {
                                // $data[] = Title::newFromText($wgContLang->getNSText ( NS_CATEGORY ).':'.$row->cl_to);
                                $data[$wgContLang->getNSText( NS_CATEGORY ) . ':' . $row->cl_to] = $this->getFullText();
                        }
                }
                return $data;
        }

        /**
         * Get a tree of parent categories
         *
         * @param $children Array with the children in the keys, to check for circular refs
         * @return Array Tree of parent categories
         */
        public function getParentCategoryTree( $children = array() ) {
                $stack = array();
                $parents = $this->getParentCategories();

                if ( $parents ) {
                        foreach ( $parents as $parent => $current ) {
                                if ( array_key_exists( $parent, $children ) ) {
                                        # Circular reference
                                        $stack[$parent] = array();
                                } else {
                                        $nt = Title::newFromText( $parent );
                                        if ( $nt ) {
                                                $stack[$parent] = $nt->getParentCategoryTree( $children + array( $parent => 1 ) );
                                        }
                                }
                        }
                }

                return $stack;
        }

        /**
         * Get an associative array for selecting this title from
         * the "page" table
         *
         * @return Array suitable for the $where parameter of DB::select()
         */
        public function pageCond() {
                if ( $this->mArticleID > 0 ) {
                        // PK avoids secondary lookups in InnoDB, shouldn't hurt other DBs
                        return array( 'page_id' => $this->mArticleID );
                } else {
                        return array( 'page_namespace' => $this->mNamespace, 'page_title' => $this->mDbkeyform );
                }
        }

        /**
         * Get the revision ID of the previous revision
         *
         * @param $revId Int Revision ID. Get the revision that was before this one.
         * @param $flags Int Title::GAID_FOR_UPDATE
         * @return Int|Bool Old revision ID, or FALSE if none exists
         */
        public function getPreviousRevisionID( $revId, $flags = 0 ) {
                $db = ( $flags & self::GAID_FOR_UPDATE ) ? wfGetDB( DB_MASTER ) : wfGetDB( DB_SLAVE );
                return $db->selectField( 'revision', 'rev_id',
                        array(
                                'rev_page' => $this->getArticleId( $flags ),
                                'rev_id < ' . intval( $revId )
                        ),
                        __METHOD__,
                        array( 'ORDER BY' => 'rev_id DESC' )
                );
        }

        /**
         * Get the revision ID of the next revision
         *
         * @param $revId Int Revision ID. Get the revision that was after this one.
         * @param $flags Int Title::GAID_FOR_UPDATE
         * @return Int|Bool Next revision ID, or FALSE if none exists
         */
        public function getNextRevisionID( $revId, $flags = 0 ) {
                $db = ( $flags & self::GAID_FOR_UPDATE ) ? wfGetDB( DB_MASTER ) : wfGetDB( DB_SLAVE );
                return $db->selectField( 'revision', 'rev_id',
                        array(
                                'rev_page' => $this->getArticleId( $flags ),
                                'rev_id > ' . intval( $revId )
                        ),
                        __METHOD__,
                        array( 'ORDER BY' => 'rev_id' )
                );
        }

        /**
         * Get the first revision of the page
         *
         * @param $flags Int Title::GAID_FOR_UPDATE
         * @return Revision|Null if page doesn't exist
         */
        public function getFirstRevision( $flags = 0 ) {
                $pageId = $this->getArticleId( $flags );
                if ( $pageId ) {
                        $db = ( $flags & self::GAID_FOR_UPDATE ) ? wfGetDB( DB_MASTER ) : wfGetDB( DB_SLAVE );
                        $row = $db->selectRow( 'revision', '*',
                                array( 'rev_page' => $pageId ),
                                __METHOD__,
                                array( 'ORDER BY' => 'rev_timestamp ASC', 'LIMIT' => 1 )
                        );
                        if ( $row ) {
                                return new Revision( $row );
                        }
                }
                return null;
        }

        /**
         * Get the oldest revision timestamp of this page
         *
         * @param $flags Int Title::GAID_FOR_UPDATE
         * @return String: MW timestamp
         */
        public function getEarliestRevTime( $flags = 0 ) {
                $rev = $this->getFirstRevision( $flags );       
                return $rev ? $rev->getTimestamp() : null;
        }

        /**
         * Check if this is a new page
         *
         * @return bool
         */
        public function isNewPage() {
                $dbr = wfGetDB( DB_SLAVE );
                return (bool)$dbr->selectField( 'page', 'page_is_new', $this->pageCond(), __METHOD__ );
        }

        /**
         * Get the number of revisions between the given revision.
         * Used for diffs and other things that really need it.
         *
         * @param $old int|Revision Old revision or rev ID (first before range)
         * @param $new int|Revision New revision or rev ID (first after range)
         * @return Int Number of revisions between these revisions.
         */
        public function countRevisionsBetween( $old, $new ) {
                if ( !( $old instanceof Revision ) ) {
                        $old = Revision::newFromTitle( $this, (int)$old );
                }
                if ( !( $new instanceof Revision ) ) {
                        $new = Revision::newFromTitle( $this, (int)$new );
                }
                if ( !$old || !$new ) {
                        return 0; // nothing to compare
                }
                $dbr = wfGetDB( DB_SLAVE );
                return (int)$dbr->selectField( 'revision', 'count(*)',
                        array(
                                'rev_page' => $this->getArticleId(),
                                'rev_timestamp > ' . $dbr->addQuotes( $dbr->timestamp( $old->getTimestamp() ) ),
                                'rev_timestamp < ' . $dbr->addQuotes( $dbr->timestamp( $new->getTimestamp() ) )
                        ),
                        __METHOD__
                );
        }

        /**
         * Get the number of authors between the given revision IDs.
         * Used for diffs and other things that really need it.
         *
         * @param $old int|Revision Old revision or rev ID (first before range)
         * @param $new int|Revision New revision or rev ID (first after range)
         * @param $limit Int Maximum number of authors
         * @return Int Number of revision authors between these revisions.
         */
        public function countAuthorsBetween( $old, $new, $limit ) {
                if ( !( $old instanceof Revision ) ) {
                        $old = Revision::newFromTitle( $this, (int)$old );
                }
                if ( !( $new instanceof Revision ) ) {
                        $new = Revision::newFromTitle( $this, (int)$new );
                }
                if ( !$old || !$new ) {
                        return 0; // nothing to compare
                }
                $dbr = wfGetDB( DB_SLAVE );
                $res = $dbr->select( 'revision', 'DISTINCT rev_user_text',
                        array(
                                'rev_page' => $this->getArticleID(),
                                'rev_timestamp > ' . $dbr->addQuotes( $dbr->timestamp( $old->getTimestamp() ) ),
                                'rev_timestamp < ' . $dbr->addQuotes( $dbr->timestamp( $new->getTimestamp() ) )
                        ), __METHOD__,
                        array( 'LIMIT' => $limit + 1 ) // add one so caller knows it was truncated
                );
                return (int)$dbr->numRows( $res );
        }

        /**
         * Compare with another title.
         *
         * @param $title Title
         * @return Bool
         */
        public function equals( Title $title ) {
                // Note: === is necessary for proper matching of number-like titles.
                return $this->getInterwiki() === $title->getInterwiki()
                        && $this->getNamespace() == $title->getNamespace()
                        && $this->getDBkey() === $title->getDBkey();
        }

        /**
         * Callback for usort() to do title sorts by (namespace, title)
         *
         * @param $a Title
         * @param $b Title
         *
         * @return Integer: result of string comparison, or namespace comparison
         */
        public static function compare( $a, $b ) {
                if ( $a->getNamespace() == $b->getNamespace() ) {
                        return strcmp( $a->getText(), $b->getText() );
                } else {
                        return $a->getNamespace() - $b->getNamespace();
                }
        }

        /**
         * Return a string representation of this title
         *
         * @return String representation of this title
         */
        public function __toString() {
                return $this->getPrefixedText();
        }

        /**
         * Check if page exists.  For historical reasons, this function simply
         * checks for the existence of the title in the page table, and will
         * thus return false for interwiki links, special pages and the like.
         * If you want to know if a title can be meaningfully viewed, you should
         * probably call the isKnown() method instead.
         *
         * @return Bool
         */
        public function exists() {
                return $this->getArticleId() != 0;
        }

        /**
         * Should links to this title be shown as potentially viewable (i.e. as
         * "bluelinks"), even if there's no record by this title in the page
         * table?
         *
         * This function is semi-deprecated for public use, as well as somewhat
         * misleadingly named.  You probably just want to call isKnown(), which
         * calls this function internally.
         *
         * (ISSUE: Most of these checks are cheap, but the file existence check
         * can potentially be quite expensive.  Including it here fixes a lot of
         * existing code, but we might want to add an optional parameter to skip
         * it and any other expensive checks.)
         *
         * @return Bool
         */
        public function isAlwaysKnown() {
                if ( $this->mInterwiki != '' ) {
                        return true;  // any interwiki link might be viewable, for all we know
                }
                switch( $this->mNamespace ) {
                        case NS_MEDIA:
                        case NS_FILE:
                                // file exists, possibly in a foreign repo
                                return (bool)wfFindFile( $this );
                        case NS_SPECIAL:
                                // valid special page
                                return SpecialPageFactory::exists( $this->getDBkey() );
                        case NS_MAIN:
                                // selflink, possibly with fragment
                                return $this->mDbkeyform == '';
                        case NS_MEDIAWIKI:
                                // known system message
                                return $this->getDefaultMessageText() !== false;
                        default:
                                return false;
                }
        }

        /**
         * Does this title refer to a page that can (or might) be meaningfully
         * viewed?  In particular, this function may be used to determine if
         * links to the title should be rendered as "bluelinks" (as opposed to
         * "redlinks" to non-existent pages).
         *
         * @return Bool
         */
        public function isKnown() {
                return $this->isAlwaysKnown() || $this->exists();
        }

        /**
         * Does this page have source text?
         *
         * @return Boolean
         */
        public function hasSourceText() {
                if ( $this->exists() ) {
                        return true;
                }

                if ( $this->mNamespace == NS_MEDIAWIKI ) {
                        // If the page doesn't exist but is a known system message, default
                        // message content will be displayed, same for language subpages
                        return $this->getDefaultMessageText() !== false;
                }

                return false;
        }

        /**
         * Get the default message text or false if the message doesn't exist
         *
         * @return String or false
         */
        public function getDefaultMessageText() {
                global $wgContLang;

                if ( $this->getNamespace() != NS_MEDIAWIKI ) { // Just in case
                        return false;
                }

                list( $name, $lang ) = MessageCache::singleton()->figureMessage( $wgContLang->lcfirst( $this->getText() ) );
                $message = wfMessage( $name )->inLanguage( $lang )->useDatabase( false );

                if ( $message->exists() ) {
                        return $message->plain();
                } else {
                        return false;
                }
        }

        /**
         * Is this in a namespace that allows actual pages?
         *
         * @return Bool
         * @internal note -- uses hardcoded namespace index instead of constants
         */
        public function canExist() {
                return $this->mNamespace >= 0 && $this->mNamespace != NS_MEDIA;
        }

        /**
         * Update page_touched timestamps and send squid purge messages for
         * pages linking to this title. May be sent to the job queue depending
         * on the number of links. Typically called on create and delete.
         */
        public function touchLinks() {
                $u = new HTMLCacheUpdate( $this, 'pagelinks' );
                $u->doUpdate();

                if ( $this->getNamespace() == NS_CATEGORY ) {
                        $u = new HTMLCacheUpdate( $this, 'categorylinks' );
                        $u->doUpdate();
                }
        }

        /**
         * Get the last touched timestamp
         *
         * @param $db DatabaseBase: optional db
         * @return String last-touched timestamp
         */
        public function getTouched( $db = null ) {
                $db = isset( $db ) ? $db : wfGetDB( DB_SLAVE );
                $touched = $db->selectField( 'page', 'page_touched', $this->pageCond(), __METHOD__ );
                return $touched;
        }

        /**
         * Get the timestamp when this page was updated since the user last saw it.
         *
         * @param $user User
         * @return String|Null
         */
        public function getNotificationTimestamp( $user = null ) {
                global $wgUser, $wgShowUpdatedMarker;
                // Assume current user if none given
                if ( !$user ) {
                        $user = $wgUser;
                }
                // Check cache first
                $uid = $user->getId();
                // avoid isset here, as it'll return false for null entries
                if ( array_key_exists( $uid, $this->mNotificationTimestamp ) ) {
                        return $this->mNotificationTimestamp[$uid];
                }
                if ( !$uid || !$wgShowUpdatedMarker ) {
                        return $this->mNotificationTimestamp[$uid] = false;
                }
                // Don't cache too much!
                if ( count( $this->mNotificationTimestamp ) >= self::CACHE_MAX ) {
                        $this->mNotificationTimestamp = array();
                }
                $dbr = wfGetDB( DB_SLAVE );
                $this->mNotificationTimestamp[$uid] = $dbr->selectField( 'watchlist',
                        'wl_notificationtimestamp',
                        array( 'wl_namespace' => $this->getNamespace(),
                                'wl_title' => $this->getDBkey(),
                                'wl_user' => $user->getId()
                        ),
                        __METHOD__
                );
                return $this->mNotificationTimestamp[$uid];
        }

        /**
         * Get the trackback URL for this page
         *
         * @return String Trackback URL
         */
        public function trackbackURL() {
                global $wgScriptPath, $wgServer, $wgScriptExtension;

                return "$wgServer$wgScriptPath/trackback$wgScriptExtension?article="
                        . htmlspecialchars( urlencode( $this->getPrefixedDBkey() ) );
        }

        /**
         * Get the trackback RDF for this page
         *
         * @return String Trackback RDF
         */
        public function trackbackRDF() {
                $url = htmlspecialchars( $this->getFullURL() );
                $title = htmlspecialchars( $this->getText() );
                $tburl = $this->trackbackURL();

                // Autodiscovery RDF is placed in comments so HTML validator
                // won't barf. This is a rather icky workaround, but seems
                // frequently used by this kind of RDF thingy.
                //
                // Spec: http://www.sixapart.com/pronet/docs/trackback_spec
                return "<!--
<rdf:RDF xmlns:rdf=\"http://www.w3.org/1999/02/22-rdf-syntax-ns#\"
                 xmlns:dc=\"http://purl.org/dc/elements/1.1/\"
                 xmlns:trackback=\"http://madskills.com/public/xml/rss/module/trackback/\">
<rdf:Description
   rdf:about=\"$url\"
   dc:identifier=\"$url\"
   dc:title=\"$title\"
   trackback:ping=\"$tburl\" />
</rdf:RDF>
-->";
        }

        /**
         * Generate strings used for xml 'id' names in monobook tabs
         *
         * @param $prepend string defaults to 'nstab-'
         * @return String XML 'id' name
         */
        public function getNamespaceKey( $prepend = 'nstab-' ) {
                global $wgContLang;
                // Gets the subject namespace if this title
                $namespace = MWNamespace::getSubject( $this->getNamespace() );
                // Checks if cononical namespace name exists for namespace
                if ( MWNamespace::exists( $this->getNamespace() ) ) {
                        // Uses canonical namespace name
                        $namespaceKey = MWNamespace::getCanonicalName( $namespace );
                } else {
                        // Uses text of namespace
                        $namespaceKey = $this->getSubjectNsText();
                }
                // Makes namespace key lowercase
                $namespaceKey = $wgContLang->lc( $namespaceKey );
                // Uses main
                if ( $namespaceKey == '' ) {
                        $namespaceKey = 'main';
                }
                // Changes file to image for backwards compatibility
                if ( $namespaceKey == 'file' ) {
                        $namespaceKey = 'image';
                }
                return $prepend . $namespaceKey;
        }

        /**
         * Returns true if this is a special page.
         *
         * @return boolean
         */
        public function isSpecialPage() {
                return $this->getNamespace() == NS_SPECIAL;
        }

        /**
         * Returns true if this title resolves to the named special page
         *
         * @param $name String The special page name
         * @return boolean
         */
        public function isSpecial( $name ) {
                if ( $this->getNamespace() == NS_SPECIAL ) {
                        list( $thisName, /* $subpage */ ) = SpecialPageFactory::resolveAlias( $this->getDBkey() );
                        if ( $name == $thisName ) {
                                return true;
                        }
                }
                return false;
        }

        /**
         * If the Title refers to a special page alias which is not the local default, resolve
         * the alias, and localise the name as necessary.  Otherwise, return $this
         *
         * @return Title
         */
        public function fixSpecialName() {
                if ( $this->getNamespace() == NS_SPECIAL ) {
                        list( $canonicalName, /*...*/ ) = SpecialPageFactory::resolveAlias( $this->mDbkeyform );
                        if ( $canonicalName ) {
                                $localName = SpecialPageFactory::getLocalNameFor( $canonicalName );
                                if ( $localName != $this->mDbkeyform ) {
                                        return Title::makeTitle( NS_SPECIAL, $localName );
                                }
                        }
                }
                return $this;
        }

        /**
         * Is this Title in a namespace which contains content?
         * In other words, is this a content page, for the purposes of calculating
         * statistics, etc?
         *
         * @return Boolean
         */
        public function isContentPage() {
                return MWNamespace::isContent( $this->getNamespace() );
        }

        /**
         * Get all extant redirects to this Title
         *
         * @param $ns Int|Null Single namespace to consider; NULL to consider all namespaces
         * @return Array of Title redirects to this title
         */
        public function getRedirectsHere( $ns = null ) {
                $redirs = array();

                $dbr = wfGetDB( DB_SLAVE );
                $where = array(
                        'rd_namespace' => $this->getNamespace(),
                        'rd_title' => $this->getDBkey(),
                        'rd_from = page_id'
                );
                if ( !is_null( $ns ) ) {
                        $where['page_namespace'] = $ns;
                }

                $res = $dbr->select(
                        array( 'redirect', 'page' ),
                        array( 'page_namespace', 'page_title' ),
                        $where,
                        __METHOD__
                );

                foreach ( $res as $row ) {
                        $redirs[] = self::newFromRow( $row );
                }
                return $redirs;
        }

        /**
         * Check if this Title is a valid redirect target
         *
         * @return Bool
         */
        public function isValidRedirectTarget() {
                global $wgInvalidRedirectTargets;

                // invalid redirect targets are stored in a global array, but explicity disallow Userlogout here
                if ( $this->isSpecial( 'Userlogout' ) ) {
                        return false;
                }

                foreach ( $wgInvalidRedirectTargets as $target ) {
                        if ( $this->isSpecial( $target ) ) {
                                return false;
                        }
                }

                return true;
        }

        /**
         * Get a backlink cache object
         *
         * @return object BacklinkCache
         */
        function getBacklinkCache() {
                if ( is_null( $this->mBacklinkCache ) ) {
                        $this->mBacklinkCache = new BacklinkCache( $this );
                }
                return $this->mBacklinkCache;
        }

        /**
         * Whether the magic words __INDEX__ and __NOINDEX__ function for  this page.
         *
         * @return Boolean
         */
        public function canUseNoindex() {
                global $wgContentNamespaces, $wgExemptFromUserRobotsControl;

                $bannedNamespaces = is_null( $wgExemptFromUserRobotsControl )
                        ? $wgContentNamespaces
                        : $wgExemptFromUserRobotsControl;

                return !in_array( $this->mNamespace, $bannedNamespaces );

        }

        /**
         * Returns restriction types for the current Title
         *
         * @return array applicable restriction types
         */
        public function getRestrictionTypes() {
                if ( $this->getNamespace() == NS_SPECIAL ) {
                        return array();
                }

                $types = self::getFilteredRestrictionTypes( $this->exists() );

                if ( $this->getNamespace() != NS_FILE ) {
                        # Remove the upload restriction for non-file titles
                        $types = array_diff( $types, array( 'upload' ) );
                }

                wfRunHooks( 'TitleGetRestrictionTypes', array( $this, &$types ) );

                wfDebug( __METHOD__ . ': applicable restriction types for ' .
                        $this->getPrefixedText() . ' are ' . implode( ',', $types ) . "\n" );

                return $types;
        }
        /**
         * Get a filtered list of all restriction types supported by this wiki.
         * @param bool $exists True to get all restriction types that apply to
         * titles that do exist, False for all restriction types that apply to
         * titles that do not exist
         * @return array
         */
        public static function getFilteredRestrictionTypes( $exists = true ) {
                global $wgRestrictionTypes;
                $types = $wgRestrictionTypes;
                if ( $exists ) {
                        # Remove the create restriction for existing titles
                        $types = array_diff( $types, array( 'create' ) );
                } else {
                        # Only the create and upload restrictions apply to non-existing titles
                        $types = array_intersect( $types, array( 'create', 'upload' ) );
                }
                return $types;
        }

        /**
         * Returns the raw sort key to be used for categories, with the specified
         * prefix.  This will be fed to Collation::getSortKey() to get a
         * binary sortkey that can be used for actual sorting.
         *
         * @param $prefix string The prefix to be used, specified using
         *   {{defaultsort:}} or like [[Category:Foo|prefix]].  Empty for no
         *   prefix.
         * @return string
         */
        public function getCategorySortkey( $prefix = '' ) {
                $unprefixed = $this->getText();
                if ( $prefix !== '' ) {
                        # Separate with a line feed, so the unprefixed part is only used as
                        # a tiebreaker when two pages have the exact same prefix.
                        # In UCA, tab is the only character that can sort above LF
                        # so we strip both of them from the original prefix.
                        $prefix = strtr( $prefix, "\n\t", '  ' );
                        return "$prefix\n$unprefixed";
                }
                return $unprefixed;
        }
}

/**
 * A BadTitle is generated in MediaWiki::parseTitle() if the title is invalid; the
 * software uses this to display an error page.  Internally it's basically a Title
 * for an empty special page
 */
class BadTitle extends Title {
        public function __construct(){
                $this->mTextform = '';
                $this->mUrlform = '';
                $this->mDbkeyform = '';
                $this->mNamespace = NS_SPECIAL; // Stops talk page link, etc, being shown
        }

        public function exists(){
                return false;
        }

        public function getPrefixedText(){
                return '';
        }

        public function getText(){
                return '';
        }

        public function getPrefixedURL(){
                return '';
        }

        public function getPrefixedDBKey(){
                return '';
        }
}