Title.php

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<?php
namespace MediaWiki\Title;
 
use AtomicSectionUpdate;
use AutoCommitUpdate;
use BacklinkCache;
use ContentHandler;
use DBAccessObjectUtils;
use DeferredUpdates;
use DeprecationHelper;
use HTMLCacheUpdateJob;
use IDBAccessObject;
use ILanguageConverter;
use InvalidArgumentException;
use Language;
use LinkCache;
use MalformedTitleException;
use MapCacheLRU;
use MediaWiki\DAO\WikiAwareEntityTrait;
use MediaWiki\HookContainer\HookRunner;
use MediaWiki\Html\Html;
use MediaWiki\Interwiki\InterwikiLookup;
use MediaWiki\Linker\LinkTarget;
use MediaWiki\MainConfigNames;
use MediaWiki\MediaWikiServices;
use MediaWiki\Page\ExistingPageRecord;
use MediaWiki\Page\PageIdentity;
use MediaWiki\Page\PageIdentityValue;
use MediaWiki\Page\PageReference;
use MediaWiki\Page\PageStoreRecord;
use MediaWiki\Page\ProperPageIdentity;
use MediaWiki\Request\PathRouter;
use MediaWiki\ResourceLoader\WikiModule;
use MediaWiki\StubObject\StubUserLang;
use MediaWikiTitleCodec;
use Message;
use MessageLocalizer;
use MWException;
use MWTimestamp;
use RuntimeException;
use Sanitizer;
use SpecialPage;
use stdClass;
use TitleFormatter;
use TitleValue;
use Wikimedia\Assert\Assert;
use Wikimedia\Assert\PreconditionException;
use Wikimedia\Rdbms\IDatabase;
use WikiPage;
 
class Title implements LinkTarget, PageIdentity, IDBAccessObject {
    use DeprecationHelper;
    use WikiAwareEntityTrait;
 
    private static $titleCache = null;
 
    private const CACHE_MAX = 1000;
 
    public const GAID_FOR_UPDATE = 512;
 
    public const NEW_CLONE = 'clone';
 
    private $mTextform = '';
 
    private $mUrlform = '';
 
    private $mDbkeyform = '';
 
    private $mNamespace = NS_MAIN;
 
    private $mInterwiki = '';
 
    private $mLocalInterwiki = false;
 
    private $mFragment = '';
 
    /***************************************************************************/
    // region   Private member variables
    public $mArticleID = -1;
 
    protected $mLatestID = false;
 
    private $mContentModel = false;
 
    private $mForcedContentModel = false;
 
    private $mEstimateRevisions;
 
    public $prefixedText = null;
 
    private const DEFAULT_NAMESPACE = NS_MAIN;
 
    protected $mLength = -1;
 
    public $mRedirect = null;
 
    private $mHasSubpages;
 
    private $mPageLanguage;
 
    private $mDbPageLanguage = false;
 
    private $mTitleValue = null;
 
    private $mIsBigDeletion = null;
 
    private $mIsValid = null;
 
    private $mInstanceCacheKey = null;
 
    // endregion -- end of private member variables
    /***************************************************************************/
 
    private function getLanguageConverter( $language ): ILanguageConverter {
        return MediaWikiServices::getInstance()->getLanguageConverterFactory()
            ->getLanguageConverter( $language );
    }
 
    private function getPageLanguageConverter(): ILanguageConverter {
        return $this->getLanguageConverter( $this->getPageLanguage() );
    }
 
    private static function getTitleFormatter() {
        return MediaWikiServices::getInstance()->getTitleFormatter();
    }
 
    private static function getInterwikiLookup() {
        return MediaWikiServices::getInstance()->getInterwikiLookup();
    }
 
    private function __construct() {
        $this->deprecatePublicProperty( 'mTextform', '1.37', __CLASS__ );
        $this->deprecatePublicProperty( 'mUrlform', '1.37', __CLASS__ );
        $this->deprecatePublicProperty( 'mDbkeyform', '1.37', __CLASS__ );
        $this->deprecatePublicProperty( 'mNamespace', '1.37', __CLASS__ );
        $this->deprecatePublicProperty( 'mInterwiki', '1.37', __CLASS__ );
 
        // Phan is being silly about callable|string, see T297352.
        // @phan-suppress-next-line PhanUndeclaredFunctionInCallable
        $this->deprecatePublicPropertyFallback( 'mFragment', '1.37', 'getFragment', 'setFragment' );
    }
 
    public static function newFromDBkey( $key ) {
        $t = new self();
 
        try {
            $t->secureAndSplit( $key );
            return $t;
        } catch ( MalformedTitleException $ex ) {
            return null;
        }
    }
 
    public static function newFromTitleValue( TitleValue $titleValue, $forceClone = '' ) {
        wfDeprecated( __METHOD__, '1.34' );
        return self::newFromLinkTarget( $titleValue, $forceClone );
    }
 
    public static function newFromLinkTarget( LinkTarget $linkTarget, $forceClone = '' ) {
        if ( $linkTarget instanceof Title ) {
            // Special case if it's already a Title object
            if ( $forceClone === self::NEW_CLONE ) {
                return clone $linkTarget;
            } else {
                return $linkTarget;
            }
        }
        return self::makeTitle(
            $linkTarget->getNamespace(),
            $linkTarget->getText(),
            $linkTarget->getFragment(),
            $linkTarget->getInterwiki()
        );
    }
 
    public static function castFromLinkTarget( ?LinkTarget $linkTarget ) {
        if ( !$linkTarget ) {
            return null;
        }
        return self::newFromLinkTarget( $linkTarget );
    }
 
    public static function newFromPageIdentity( PageIdentity $pageIdentity ): Title {
        return self::newFromPageReference( $pageIdentity );
    }
 
    public static function castFromPageIdentity( ?PageIdentity $pageIdentity ): ?Title {
        return self::castFromPageReference( $pageIdentity );
    }
 
    public static function newFromPageReference( PageReference $pageReference ): Title {
        if ( $pageReference instanceof Title ) {
            return $pageReference;
        }
 
        $pageReference->assertWiki( self::LOCAL );
        $title = self::makeTitle( $pageReference->getNamespace(), $pageReference->getDBkey() );
 
        if ( $pageReference instanceof PageIdentity ) {
            $title->mArticleID = $pageReference->getId();
        }
        return $title;
    }
 
    public static function castFromPageReference( ?PageReference $pageReference ): ?Title {
        if ( !$pageReference ) {
            return null;
        }
        return self::newFromPageReference( $pageReference );
    }
 
    public static function newFromText( $text, $defaultNamespace = NS_MAIN ) {
        // DWIM: Integers can be passed in here when page titles are used as array keys.
        if ( $text !== null && !is_string( $text ) && !is_int( $text ) ) {
            throw new InvalidArgumentException( '$text must be a string.' );
        }
        if ( $text === null || $text === '' ) {
            return null;
        }
 
        try {
            return self::newFromTextThrow( (string)$text, (int)$defaultNamespace );
        } catch ( MalformedTitleException $ex ) {
            return null;
        }
    }
 
    public static function newFromTextThrow( $text, $defaultNamespace = NS_MAIN ) {
        if ( is_object( $text ) ) {
            throw new MWException( '$text must be a string, given an object' );
        } elseif ( $text === null ) {
            // Legacy code relies on MalformedTitleException being thrown in this case
            //  TODO: fix(happens when URL with no title in it is parsed).
            throw new MalformedTitleException( 'title-invalid-empty' );
        }
 
        $titleCache = self::getTitleCache();
 
        // 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.
        if ( $defaultNamespace === NS_MAIN ) {
            $t = $titleCache->get( $text );
            if ( $t ) {
                return $t;
            }
        }
 
        // Convert things like &eacute; &#257; or &#x3017; into normalized (T16952) text
        $filteredText = Sanitizer::decodeCharReferencesAndNormalize( $text );
 
        $t = new Title();
        $dbKeyForm = strtr( $filteredText, ' ', '_' );
 
        $t->secureAndSplit( $dbKeyForm, (int)$defaultNamespace );
        if ( $defaultNamespace === NS_MAIN ) {
            $t->mInstanceCacheKey = $text;
            $titleCache->set( $text, $t );
        }
        return $t;
    }
 
    private function uncache() {
        if ( $this->mInstanceCacheKey !== null ) {
            $titleCache = self::getTitleCache();
            $titleCache->clear( $this->mInstanceCacheKey );
            $this->mInstanceCacheKey = null;
        }
    }
 
    public static function newFromURL( $url ) {
        $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 ( !str_contains( self::legalChars(), '+' ) ) {
            $url = strtr( $url, '+', ' ' );
        }
 
        $dbKeyForm = strtr( $url, ' ', '_' );
 
        try {
            $t->secureAndSplit( $dbKeyForm );
            return $t;
        } catch ( MalformedTitleException $ex ) {
            return null;
        }
    }
 
    private static function getTitleCache() {
        if ( self::$titleCache === null ) {
            self::$titleCache = new MapCacheLRU( self::CACHE_MAX );
        }
        return self::$titleCache;
    }
 
    protected static function getSelectFields() {
        wfDeprecated( __METHOD__, '1.36' );
        return MediaWikiServices::getInstance()->getPageStore()->getSelectFields();
    }
 
    public static function newFromID( $id, $flags = 0 ) {
        $flags |= ( $flags & self::GAID_FOR_UPDATE ) ? self::READ_LATEST : 0; // b/c
        $pageStore = MediaWikiServices::getInstance()->getPageStore();
        [ $index, $options ] = DBAccessObjectUtils::getDBOptions( $flags );
        $row = wfGetDB( $index )->selectRow(
            'page',
            $pageStore->getSelectFields(),
            [ 'page_id' => $id ],
            __METHOD__,
            $options
        );
        if ( $row !== false ) {
            $title = self::newFromRow( $row );
        } else {
            $title = null;
        }
 
        return $title;
    }
 
    public static function newFromIDs( $ids ) {
        wfDeprecated( __METHOD__, '1.38' );
 
        if ( !count( $ids ) ) {
            return [];
        }
        $dbr = wfGetDB( DB_REPLICA );
 
        $res = $dbr->select(
            'page',
            self::getSelectFields(),
            [ 'page_id' => $ids ],
            __METHOD__
        );
 
        $titles = [];
        foreach ( $res as $row ) {
            $titles[] = self::newFromRow( $row );
        }
        return $titles;
    }
 
    public static function newFromRow( $row ) {
        $t = self::makeTitle( $row->page_namespace, $row->page_title );
        $t->loadFromRow( $row );
        return $t;
    }
 
    public function loadFromRow( $row ) {
        if ( $row ) { // page found
            if ( isset( $row->page_id ) ) {
                $this->mArticleID = (int)$row->page_id;
            }
            if ( isset( $row->page_len ) ) {
                $this->mLength = (int)$row->page_len;
            }
            if ( isset( $row->page_is_redirect ) ) {
                $this->mRedirect = (bool)$row->page_is_redirect;
            }
            if ( isset( $row->page_latest ) ) {
                $this->mLatestID = (int)$row->page_latest;
            }
            if ( isset( $row->page_content_model ) ) {
                $this->lazyFillContentModel( $row->page_content_model );
            } else {
                $this->lazyFillContentModel( false ); // lazily-load getContentModel()
            }
            if ( isset( $row->page_lang ) ) {
                $this->mDbPageLanguage = (string)$row->page_lang;
            }
        } else { // page not found
            $this->mArticleID = 0;
            $this->mLength = 0;
            $this->mRedirect = false;
            $this->mLatestID = 0;
            $this->lazyFillContentModel( false ); // lazily-load getContentModel()
        }
    }
 
    public static function makeTitle( $ns, $title, $fragment = '', $interwiki = '' ) {
        $t = new Title();
        $t->mInterwiki = $interwiki;
        $t->mFragment = self::normalizeFragment( $fragment );
        $t->mNamespace = $ns = (int)$ns;
        $t->mDbkeyform = strtr( $title, ' ', '_' );
        $t->mArticleID = ( $ns >= 0 ) ? -1 : 0;
        $t->mUrlform = wfUrlencode( $t->mDbkeyform );
        $t->mTextform = strtr( $title, '_', ' ' );
        return $t;
    }
 
    public static function makeTitleSafe( $ns, $title, $fragment = '', $interwiki = '' ) {
        // NOTE: ideally, this would just call makeTitle() and then isValid(),
        // but presently, that means more overhead on a potential performance hotspot.
 
        if ( !MediaWikiServices::getInstance()->getNamespaceInfo()->exists( $ns ) ) {
            return null;
        }
 
        $t = new Title();
        $dbKeyForm = self::makeName( $ns, $title, $fragment, $interwiki, true );
 
        try {
            $t->secureAndSplit( $dbKeyForm );
            return $t;
        } catch ( MalformedTitleException $ex ) {
            return null;
        }
    }
 
    public static function newMainPage( MessageLocalizer $localizer = null ) {
        static $recursionGuard = false;
 
        $title = null;
 
        if ( !$recursionGuard ) {
            $msg = $localizer ? $localizer->msg( 'mainpage' ) : wfMessage( 'mainpage' );
 
            $recursionGuard = true;
            $title = self::newFromText( $msg->inContentLanguage()->text() );
            $recursionGuard = false;
        }
 
        // Every page renders at least one link to the Main Page (e.g. sidebar).
        // Don't produce fatal errors that would make the wiki inaccessible, and hard to fix the
        // invalid message.
        //
        // Fallback scenarios:
        // * Recursion guard
        //   If the message contains a bare local interwiki (T297571), then
        //   Title::newFromText via MediaWikiTitleCodec::splitTitleString can get back here.
        // * Invalid title
        //   If the 'mainpage' message contains something that is invalid,  Title::newFromText
        //   will return null.
 
        // @phan-suppress-next-line PhanTypeMismatchReturnNullable Fallback is always valid
        return $title ?? self::newFromText( 'Main Page' );
    }
 
    public static function legalChars() {
        global $wgLegalTitleChars;
        return $wgLegalTitleChars;
    }
 
    public static function convertByteClassToUnicodeClass( $byteClass ) {
        $length = strlen( $byteClass );
        // Input token queue
        $x0 = $x1 = $x2 = '';
        // Decoded queue
        $d0 = $d1 = '';
        // Decoded integer codepoints
        $ord0 = $ord1 = $ord2 = 0;
        // Re-encoded queue
        $r0 = $r1 = $r2 = '';
        // Output
        $out = '';
        // Flags
        $allowUnicode = false;
        for ( $pos = 0; $pos < $length; $pos++ ) {
            // Shift the queues down
            $x2 = $x1;
            $x1 = $x0;
            $d1 = $d0;
            $ord2 = $ord1;
            $ord1 = $ord0;
            $r2 = $r1;
            $r1 = $r0;
            // Load the current input token and decoded values
            $inChar = $byteClass[$pos];
            if ( $inChar === '\\' ) {
                if ( preg_match( '/x([0-9a-fA-F]{2})/A', $byteClass, $m, 0, $pos + 1 ) ) {
                    $x0 = $inChar . $m[0];
                    $d0 = chr( hexdec( $m[1] ) );
                    $pos += strlen( $m[0] );
                } elseif ( preg_match( '/[0-7]{3}/A', $byteClass, $m, 0, $pos + 1 ) ) {
                    $x0 = $inChar . $m[0];
                    $d0 = chr( octdec( $m[0] ) );
                    $pos += strlen( $m[0] );
                } elseif ( $pos + 1 >= $length ) {
                    $x0 = $d0 = '\\';
                } else {
                    $d0 = $byteClass[$pos + 1];
                    $x0 = $inChar . $d0;
                    $pos++;
                }
            } else {
                $x0 = $d0 = $inChar;
            }
            $ord0 = ord( $d0 );
            // Load the current re-encoded value
            if ( $ord0 < 32 || $ord0 == 0x7f ) {
                $r0 = sprintf( '\x%02x', $ord0 );
            } elseif ( $ord0 >= 0x80 ) {
                // Allow unicode if a single high-bit character appears
                $r0 = sprintf( '\x%02x', $ord0 );
                $allowUnicode = true;
                // @phan-suppress-next-line PhanParamSuspiciousOrder false positive
            } elseif ( strpos( '-\\[]^', $d0 ) !== false ) {
                $r0 = '\\' . $d0;
            } else {
                $r0 = $d0;
            }
            // Do the output
            if ( $x0 !== '' && $x1 === '-' && $x2 !== '' ) {
                // Range
                if ( $ord2 > $ord0 ) {
                    // Empty range
                } elseif ( $ord0 >= 0x80 ) {
                    // Unicode range
                    $allowUnicode = true;
                    if ( $ord2 < 0x80 ) {
                        // Keep the non-unicode section of the range
                        $out .= "$r2-\\x7F";
                    }
                } else {
                    // Normal range
                    $out .= "$r2-$r0";
                }
                // Reset state to the initial value
                // @phan-suppress-next-line PhanPluginRedundantAssignmentInLoop
                $x0 = $x1 = $d0 = $d1 = $r0 = $r1 = '';
            } elseif ( $ord2 < 0x80 ) {
                // ASCII character
                $out .= $r2;
            }
        }
        // @phan-suppress-next-line PhanSuspiciousValueComparison
        if ( $ord1 < 0x80 ) {
            $out .= $r1;
        }
        if ( $ord0 < 0x80 ) {
            $out .= $r0;
        }
        if ( $allowUnicode ) {
            $out .= '\u0080-\uFFFF';
        }
        return $out;
    }
 
    public static function makeName( $ns, $title, $fragment = '', $interwiki = '',
        $canonicalNamespace = false
    ) {
        if ( $canonicalNamespace ) {
            $namespace = MediaWikiServices::getInstance()->getNamespaceInfo()->
                getCanonicalName( $ns );
        } else {
            $namespace = MediaWikiServices::getInstance()->getContentLanguage()->getNsText( $ns );
        }
        if ( $namespace === false ) {
            // See T165149. Awkward, but better than erroneously linking to the main namespace.
            $namespace = self::makeName( NS_SPECIAL, "Badtitle/NS$ns", '', '', $canonicalNamespace );
        }
        $name = $namespace === '' ? $title : "$namespace:$title";
        if ( strval( $interwiki ) != '' ) {
            $name = "$interwiki:$name";
        }
        if ( strval( $fragment ) != '' ) {
            $name .= '#' . $fragment;
        }
        return $name;
    }
 
    public static function compare( $a, $b ) {
        return $a->getNamespace() <=> $b->getNamespace()
            ?: strcmp( $a->getDBkey(), $b->getDBkey() );
    }
 
    public function isValid() {
        if ( $this->mIsValid !== null ) {
            return $this->mIsValid;
        }
 
        try {
            // Optimization: Avoid Title::getFullText because that involves GenderCache
            // and (unbatched) database queries. For validation, canonical namespace suffices.
            $text = self::makeName( $this->mNamespace, $this->mDbkeyform, $this->mFragment, $this->mInterwiki, true );
            $titleCodec = MediaWikiServices::getInstance()->getTitleParser();
 
            '@phan-var MediaWikiTitleCodec $titleCodec';
            $parts = $titleCodec->splitTitleString( $text, $this->mNamespace );
 
            // Check that nothing changed!
            // This ensures that $text was already properly normalized.
            if ( $parts['fragment'] !== $this->mFragment
                || $parts['interwiki'] !== $this->mInterwiki
                || $parts['local_interwiki'] !== $this->mLocalInterwiki
                || $parts['namespace'] !== $this->mNamespace
                || $parts['dbkey'] !== $this->mDbkeyform
            ) {
                $this->mIsValid = false;
                return $this->mIsValid;
            }
        } catch ( MalformedTitleException $ex ) {
            $this->mIsValid = false;
            return $this->mIsValid;
        }
 
        $this->mIsValid = true;
        return $this->mIsValid;
    }
 
    public function isLocal() {
        if ( $this->isExternal() ) {
            $iw = self::getInterwikiLookup()->fetch( $this->mInterwiki );
            if ( $iw ) {
                return $iw->isLocal();
            }
        }
        return true;
    }
 
    public function isExternal(): bool {
        return $this->mInterwiki !== '';
    }
 
    public function getInterwiki(): string {
        return $this->mInterwiki;
    }
 
    public function wasLocalInterwiki() {
        return $this->mLocalInterwiki;
    }
 
    public function isTrans() {
        if ( !$this->isExternal() ) {
            return false;
        }
 
        return self::getInterwikiLookup()->fetch( $this->mInterwiki )->isTranscludable();
    }
 
    public function getTransWikiID() {
        if ( !$this->isExternal() ) {
            return false;
        }
 
        return self::getInterwikiLookup()->fetch( $this->mInterwiki )->getWikiID();
    }
 
    public function getTitleValue() {
        if ( $this->mTitleValue === null ) {
            try {
                $this->mTitleValue = new TitleValue(
                    $this->mNamespace,
                    $this->mDbkeyform,
                    $this->mFragment,
                    $this->mInterwiki
                );
            } catch ( InvalidArgumentException $ex ) {
                wfDebug( __METHOD__ . ': Can\'t create a TitleValue for [[' .
                    $this->getPrefixedText() . ']]: ' . $ex->getMessage() );
            }
        }
 
        return $this->mTitleValue;
    }
 
    public function getText(): string {
        return $this->mTextform;
    }
 
    public function getPartialURL() {
        return $this->mUrlform;
    }
 
    public function getDBkey(): string {
        return $this->mDbkeyform;
    }
 
    public function getNamespace(): int {
        return $this->mNamespace;
    }
 
    private function shouldReadLatest( int $flags ) {
        return ( $flags & ( self::READ_LATEST | self::GAID_FOR_UPDATE ) ) > 0;
    }
 
    public function getContentModel( $flags = 0 ) {
        if ( $this->mForcedContentModel ) {
            if ( !$this->mContentModel ) {
                throw new RuntimeException( 'Got out of sync; an empty model is being forced' );
            }
            // Content model is locked to the currently loaded one
            return $this->mContentModel;
        }
 
        if ( $this->shouldReadLatest( $flags ) || !$this->mContentModel ) {
            $this->lazyFillContentModel( $this->getFieldFromPageStore( 'page_content_model', $flags ) );
        }
 
        if ( !$this->mContentModel ) {
            $this->lazyFillContentModel( ContentHandler::getDefaultModelFor( $this ) );
        }
 
        return $this->mContentModel;
    }
 
    public function hasContentModel( $id ) {
        return $this->getContentModel() == $id;
    }
 
    public function setContentModel( $model ) {
        if ( (string)$model === '' ) {
            throw new InvalidArgumentException( "Missing CONTENT_MODEL_* constant" );
        }
 
        $this->uncache();
        $this->mContentModel = $model;
        $this->mForcedContentModel = true;
    }
 
    private function lazyFillContentModel( $model ) {
        if ( !$this->mForcedContentModel ) {
            $this->mContentModel = ( $model === false ) ? false : (string)$model;
        }
    }
 
    public function getNsText() {
        if ( $this->isExternal() ) {
            // This probably shouldn't even happen, except for interwiki transclusion.
            // If possible, use the canonical name for the foreign namespace.
            if ( $this->mNamespace === NS_MAIN ) {
                // Optimisation
                return '';
            } else {
                $nsText = MediaWikiServices::getInstance()->getNamespaceInfo()->
                    getCanonicalName( $this->mNamespace );
                if ( $nsText !== false ) {
                    return $nsText;
                }
            }
        }
 
        try {
            $formatter = self::getTitleFormatter();
            return $formatter->getNamespaceName( $this->mNamespace, $this->mDbkeyform );
        } catch ( InvalidArgumentException $ex ) {
            wfDebug( __METHOD__ . ': ' . $ex->getMessage() );
            return false;
        }
    }
 
    public function getSubjectNsText() {
        $services = MediaWikiServices::getInstance();
        return $services->getContentLanguage()->
            getNsText( $services->getNamespaceInfo()->getSubject( $this->mNamespace ) );
    }
 
    public function getTalkNsText() {
        $services = MediaWikiServices::getInstance();
        return $services->getContentLanguage()->
            getNsText( $services->getNamespaceInfo()->getTalk( $this->mNamespace ) );
    }
 
    public function canHaveTalkPage() {
        return MediaWikiServices::getInstance()->getNamespaceInfo()->canHaveTalkPage( $this );
    }
 
    public function canExist(): bool {
        // NOTE: Don't use getArticleID(), we don't want to
        // trigger a database query here. This check is supposed to
        // act as an optimization, not add extra cost.
        if ( $this->mArticleID > 0 ) {
            // It exists, so it can exist.
            return true;
        }
 
        // NOTE: we call the relatively expensive isValid() method further down,
        // but we can bail out early if we already know the title is invalid.
        if ( $this->mIsValid === false ) {
            // It's invalid, so it can't exist.
            return false;
        }
 
        if ( $this->getNamespace() < NS_MAIN ) {
            // It's a special page, so it can't exist in the database.
            return false;
        }
 
        if ( $this->isExternal() ) {
            // If it's external, it's not local, so it can't exist.
            return false;
        }
 
        if ( $this->getText() === '' ) {
            // The title has no text, so it can't exist in the database.
            // It's probably an on-page section link, like "#something".
            return false;
        }
 
        // Double check that the title is valid.
        return $this->isValid();
    }
 
    public function isSpecialPage() {
        return $this->mNamespace === NS_SPECIAL;
    }
 
    public function isSpecial( $name ) {
        if ( $this->isSpecialPage() ) {
            [ $thisName, /* $subpage */ ] =
                MediaWikiServices::getInstance()->getSpecialPageFactory()->
                    resolveAlias( $this->mDbkeyform );
            if ( $name == $thisName ) {
                return true;
            }
        }
        return false;
    }
 
    public function fixSpecialName() {
        if ( $this->isSpecialPage() ) {
            $spFactory = MediaWikiServices::getInstance()->getSpecialPageFactory();
            [ $canonicalName, $par ] = $spFactory->resolveAlias( $this->mDbkeyform );
            if ( $canonicalName ) {
                $localName = $spFactory->getLocalNameFor( $canonicalName, $par );
                if ( $localName != $this->mDbkeyform ) {
                    return self::makeTitle( NS_SPECIAL, $localName );
                }
            }
        }
        return $this;
    }
 
    public function inNamespace( int $ns ): bool {
        return MediaWikiServices::getInstance()->getNamespaceInfo()->
            equals( $this->mNamespace, $ns );
    }
 
    public function inNamespaces( ...$namespaces ) {
        if ( count( $namespaces ) > 0 && is_array( $namespaces[0] ) ) {
            $namespaces = $namespaces[0];
        }
 
        foreach ( $namespaces as $ns ) {
            if ( $this->inNamespace( $ns ) ) {
                return true;
            }
        }
 
        return false;
    }
 
    public function hasSubjectNamespace( $ns ) {
        return MediaWikiServices::getInstance()->getNamespaceInfo()->
            subjectEquals( $this->mNamespace, $ns );
    }
 
    public function isContentPage() {
        return MediaWikiServices::getInstance()->getNamespaceInfo()->
            isContent( $this->mNamespace );
    }
 
    public function isMovable() {
        $services = MediaWikiServices::getInstance();
        if (
            !$services->getNamespaceInfo()->
                isMovable( $this->mNamespace ) || $this->isExternal()
        ) {
            // Interwiki title or immovable namespace. Hooks don't get to override here
            return false;
        }
 
        $result = true;
        ( new HookRunner( $services->getHookContainer() ) )->onTitleIsMovable( $this, $result );
        return $result;
    }
 
    public function isMainPage() {
        return $this->equals( self::newMainPage() );
    }
 
    public function isSubpage() {
        return MediaWikiServices::getInstance()
                ->getNamespaceInfo()
                ->hasSubpages( $this->mNamespace )
            && str_contains( $this->getText(), '/' );
    }
 
    public function isConversionTable() {
        // @todo ConversionTable should become a separate content model.
        // @todo And the prefix should be localized, too!
 
        return $this->mNamespace === NS_MEDIAWIKI &&
            str_starts_with( $this->getText(), 'Conversiontable/' );
    }
 
    public function isWikitextPage() {
        return $this->hasContentModel( CONTENT_MODEL_WIKITEXT );
    }
 
    public function isSiteConfigPage() {
        return (
            $this->isSiteCssConfigPage()
            || $this->isSiteJsonConfigPage()
            || $this->isSiteJsConfigPage()
        );
    }
 
    public function isUserConfigPage() {
        return (
            $this->isUserCssConfigPage()
            || $this->isUserJsonConfigPage()
            || $this->isUserJsConfigPage()
        );
    }
 
    public function getSkinFromConfigSubpage() {
        $text = $this->getText();
        $lastSlashPos = $this->findSubpageDivider( $text, -1 );
        if ( $lastSlashPos === false ) {
            return '';
        }
 
        $lastDot = strrpos( $text, '.', $lastSlashPos );
        if ( $lastDot === false ) {
            return '';
        }
 
        return substr( $text, $lastSlashPos + 1, $lastDot - $lastSlashPos - 1 );
    }
 
    public function isUserCssConfigPage() {
        return (
            $this->mNamespace === NS_USER
            && $this->isSubpage()
            && $this->hasContentModel( CONTENT_MODEL_CSS )
        );
    }
 
    public function isUserJsonConfigPage() {
        return (
            $this->mNamespace === NS_USER
            && $this->isSubpage()
            && $this->hasContentModel( CONTENT_MODEL_JSON )
        );
    }
 
    public function isUserJsConfigPage() {
        return (
            $this->mNamespace === NS_USER
            && $this->isSubpage()
            && $this->hasContentModel( CONTENT_MODEL_JAVASCRIPT )
        );
    }
 
    public function isSiteCssConfigPage() {
        return (
            $this->mNamespace === NS_MEDIAWIKI
            && (
                $this->hasContentModel( CONTENT_MODEL_CSS )
                // paranoia - a MediaWiki: namespace page with mismatching extension and content
                // model is probably by mistake and might get handled incorrectly (see e.g. T112937)
                || str_ends_with( $this->mDbkeyform, '.css' )
            )
        );
    }
 
    public function isSiteJsonConfigPage() {
        return (
            $this->mNamespace === NS_MEDIAWIKI
            && (
                $this->hasContentModel( CONTENT_MODEL_JSON )
                // paranoia - a MediaWiki: namespace page with mismatching extension and content
                // model is probably by mistake and might get handled incorrectly (see e.g. T112937)
                || str_ends_with( $this->mDbkeyform, '.json' )
            )
        );
    }
 
    public function isSiteJsConfigPage() {
        return (
            $this->mNamespace === NS_MEDIAWIKI
            && (
                $this->hasContentModel( CONTENT_MODEL_JAVASCRIPT )
                // paranoia - a MediaWiki: namespace page with mismatching extension and content
                // model is probably by mistake and might get handled incorrectly (see e.g. T112937)
                || str_ends_with( $this->mDbkeyform, '.js' )
            )
        );
    }
 
    public function isRawHtmlMessage() {
        global $wgRawHtmlMessages;
 
        if ( !$this->inNamespace( NS_MEDIAWIKI ) ) {
            return false;
        }
        $message = lcfirst( $this->getRootTitle()->getDBkey() );
        return in_array( $message, $wgRawHtmlMessages, true );
    }
 
    public function isTalkPage() {
        return MediaWikiServices::getInstance()->getNamespaceInfo()->
            isTalk( $this->mNamespace );
    }
 
    public function getTalkPage() {
        // NOTE: The equivalent code in NamespaceInfo is less lenient about producing invalid titles.
        //       Instead of failing on invalid titles, let's just log the issue for now.
        //       See the discussion on T227817.
 
        // Is this the same title?
        $talkNS = MediaWikiServices::getInstance()->getNamespaceInfo()->getTalk( $this->mNamespace );
        if ( $this->mNamespace == $talkNS ) {
            return $this;
        }
 
        $title = self::makeTitle( $talkNS, $this->mDbkeyform );
 
        $this->warnIfPageCannotExist( $title, __METHOD__ );
 
        return $title;
        // TODO: replace the above with the code below:
        // return self::castFromLinkTarget(
        // MediaWikiServices::getInstance()->getNamespaceInfo()->getTalkPage( $this ) );
    }
 
    public function getTalkPageIfDefined() {
        if ( !$this->canHaveTalkPage() ) {
            return null;
        }
 
        return $this->getTalkPage();
    }
 
    public function getSubjectPage() {
        // Is this the same title?
        $subjectNS = MediaWikiServices::getInstance()->getNamespaceInfo()
            ->getSubject( $this->mNamespace );
        if ( $this->mNamespace == $subjectNS ) {
            return $this;
        }
        // NOTE: The equivalent code in NamespaceInfo is less lenient about producing invalid titles.
        //       Instead of failing on invalid titles, let's just log the issue for now.
        //       See the discussion on T227817.
        $title = self::makeTitle( $subjectNS, $this->mDbkeyform );
 
        $this->warnIfPageCannotExist( $title, __METHOD__ );
 
        return $title;
        // TODO: replace the above with the code below:
        // return self::castFromLinkTarget(
        // MediaWikiServices::getInstance()->getNamespaceInfo()->getSubjectPage( $this ) );
    }
 
    private function warnIfPageCannotExist( Title $title, $method ) {
        if ( $this->getText() == '' ) {
            wfLogWarning(
                $method . ': called on empty title ' . $this->getFullText() . ', returning '
                . $title->getFullText()
            );
 
            return true;
        }
 
        if ( $this->getInterwiki() !== '' ) {
            wfLogWarning(
                $method . ': called on interwiki title ' . $this->getFullText() . ', returning '
                . $title->getFullText()
            );
 
            return true;
        }
 
        return false;
    }
 
    public function getOtherPage() {
        // NOTE: Depend on the methods in this class instead of their equivalent in NamespaceInfo,
        //       until their semantics has become exactly the same.
        //       See the discussion on T227817.
        if ( $this->isSpecialPage() ) {
            throw new MWException( 'Special pages cannot have other pages' );
        }
        if ( $this->isTalkPage() ) {
            return $this->getSubjectPage();
        } else {
            if ( !$this->canHaveTalkPage() ) {
                throw new MWException( "{$this->getPrefixedText()} does not have an other page" );
            }
            return $this->getTalkPage();
        }
        // TODO: replace the above with the code below:
        // return self::castFromLinkTarget(
        // MediaWikiServices::getInstance()->getNamespaceInfo()->getAssociatedPage( $this ) );
    }
 
    public function getFragment(): string {
        return $this->mFragment;
    }
 
    public function hasFragment(): bool {
        return $this->mFragment !== '';
    }
 
    public function getFragmentForURL() {
        if ( !$this->hasFragment() ) {
            return '';
        } elseif ( $this->isExternal() ) {
            // Note: If the interwiki is unknown, it's treated as a namespace on the local wiki,
            // so we treat it like a local interwiki.
            $interwiki = self::getInterwikiLookup()->fetch( $this->mInterwiki );
            if ( $interwiki && !$interwiki->isLocal() ) {
                return '#' . Sanitizer::escapeIdForExternalInterwiki( $this->mFragment );
            }
        }
 
        return '#' . Sanitizer::escapeIdForLink( $this->mFragment );
    }
 
    public function setFragment( $fragment ) {
        $this->uncache();
        $this->mFragment = self::normalizeFragment( $fragment );
    }
 
    public function createFragmentTarget( string $fragment ): self {
        return self::makeTitle(
            $this->mNamespace,
            $this->getText(),
            $fragment,
            $this->mInterwiki
        );
    }
 
    private static function normalizeFragment( $fragment ) {
        if ( str_starts_with( $fragment, '#' ) ) {
            $fragment = substr( $fragment, 1 );
        }
        return strtr( $fragment, '_', ' ' );
    }
 
    private function prefix( $name ) {
        $p = '';
        if ( $this->isExternal() ) {
            $p = $this->mInterwiki . ':';
        }
 
        if ( $this->mNamespace != 0 ) {
            $nsText = $this->getNsText();
 
            if ( $nsText === false ) {
                // See T165149. Awkward, but better than erroneously linking to the main namespace.
                $nsText = MediaWikiServices::getInstance()->getContentLanguage()->
                    getNsText( NS_SPECIAL ) . ":Badtitle/NS{$this->mNamespace}";
            }
 
            $p .= $nsText . ':';
        }
        return $p . $name;
    }
 
    public function getPrefixedDBkey() {
        $s = $this->prefix( $this->mDbkeyform );
        $s = strtr( $s, ' ', '_' );
        return $s;
    }
 
    public function getPrefixedText() {
        if ( $this->prefixedText === null ) {
            $s = $this->prefix( $this->mTextform );
            $s = strtr( $s, '_', ' ' );
            $this->prefixedText = $s;
        }
        return $this->prefixedText;
    }
 
    public function __toString(): string {
        return $this->getPrefixedText();
    }
 
    public function getFullText() {
        $text = $this->getPrefixedText();
        if ( $this->hasFragment() ) {
            $text .= '#' . $this->mFragment;
        }
        return $text;
    }
 
    private function findSubpageDivider( $text, $dir ) {
        if ( $dir > 0 ) {
            // Skip leading slashes, but keep the last one when there is nothing but slashes
            $bottom = strspn( $text, '/', 0, -1 );
            $idx = strpos( $text, '/', $bottom );
        } else {
            // Any slash from the end can be a divider, as subpage names can be empty
            $idx = strrpos( $text, '/' );
        }
 
        // The first character can never be a divider, as that would result in an empty base
        return $idx === 0 ? false : $idx;
    }
 
    private function hasSubpagesEnabled() {
        return MediaWikiServices::getInstance()->getNamespaceInfo()->
            hasSubpages( $this->mNamespace );
    }
 
    public function getRootText() {
        $text = $this->getText();
        if ( !$this->hasSubpagesEnabled() ) {
            return $text;
        }
 
        $firstSlashPos = $this->findSubpageDivider( $text, +1 );
        // Don't discard the real title if there's no subpage involved
        if ( $firstSlashPos === false ) {
            return $text;
        }
 
        return substr( $text, 0, $firstSlashPos );
    }
 
    public function getRootTitle() {
        $title = self::makeTitleSafe( $this->mNamespace, $this->getRootText() );
        Assert::postcondition(
            $title !== null,
            'makeTitleSafe() should always return a Title for the text returned by getRootText().'
        );
        return $title;
    }
 
    public function getBaseText() {
        $text = $this->getText();
        if ( !$this->hasSubpagesEnabled() ) {
            return $text;
        }
 
        $lastSlashPos = $this->findSubpageDivider( $text, -1 );
        // Don't discard the real title if there's no subpage involved
        if ( $lastSlashPos === false ) {
            return $text;
        }
 
        return substr( $text, 0, $lastSlashPos );
    }
 
    public function getBaseTitle() {
        $title = self::makeTitleSafe( $this->mNamespace, $this->getBaseText() );
        Assert::postcondition(
            $title !== null,
            'makeTitleSafe() should always return a Title for the text returned by getBaseText().'
        );
        return $title;
    }
 
    public function getSubpageText() {
        $text = $this->getText();
        if ( !$this->hasSubpagesEnabled() ) {
            return $text;
        }
 
        $lastSlashPos = $this->findSubpageDivider( $text, -1 );
        if ( $lastSlashPos === false ) {
            // T256922 - Return the title text if no subpages
            return $text;
        }
        return substr( $text, $lastSlashPos + 1 );
    }
 
    public function getSubpage( $text ) {
        return self::makeTitleSafe(
            $this->mNamespace,
            $this->getText() . '/' . $text,
            '',
            $this->mInterwiki
        );
    }
 
    public function getSubpageUrlForm() {
        $text = $this->getSubpageText();
        $text = wfUrlencode( strtr( $text, ' ', '_' ) );
        return $text;
    }
 
    public function getPrefixedURL() {
        $s = $this->prefix( $this->mDbkeyform );
        $s = wfUrlencode( strtr( $s, ' ', '_' ) );
        return $s;
    }
 
    private static function fixUrlQueryArgs( $query, $query2 = false ) {
        if ( $query2 !== false ) {
            wfDeprecatedMsg( "Title::get{Canonical,Full,Link,Local,Internal}URL " .
                "method called with a second parameter is deprecated since MediaWiki 1.19. " .
                "Add your parameter to an array passed as the first parameter.", "1.19" );
        }
        if ( is_array( $query ) ) {
            $query = wfArrayToCgi( $query );
        }
        if ( $query2 ) {
            if ( is_string( $query2 ) ) {
                // $query2 is a string, we will consider this to be
                // a deprecated $variant argument and add it to the query
                $query2 = wfArrayToCgi( [ 'variant' => $query2 ] );
            } else {
                $query2 = wfArrayToCgi( $query2 );
            }
            // If we have $query content add a & to it first
            if ( $query ) {
                $query .= '&';
            }
            // Now append the queries together
            $query .= $query2;
        }
        return $query;
    }
 
    public function getFullURL( $query = '', $query2 = false, $proto = PROTO_RELATIVE ) {
        $query = self::fixUrlQueryArgs( $query, $query2 );
 
        # Hand off all the decisions on urls to getLocalURL
        $url = $this->getLocalURL( $query );
 
        # Expand the url to make it a full url. Note that getLocalURL has the
        # potential to output full urls for a variety of reasons, so we use
        # wfExpandUrl instead of simply prepending $wgServer
        $url = wfExpandUrl( $url, $proto );
 
        # Finally, add the fragment.
        $url .= $this->getFragmentForURL();
        ( new HookRunner( MediaWikiServices::getInstance()->getHookContainer() ) )->onGetFullURL( $this, $url, $query );
        return $url;
    }
 
    public function getFullUrlForRedirect( $query = '', $proto = PROTO_CURRENT ) {
        $target = $this;
        if ( $this->isExternal() ) {
            $target = SpecialPage::getTitleFor(
                'GoToInterwiki',
                $this->getPrefixedDBkey()
            );
        }
        return $target->getFullURL( $query, false, $proto );
    }
 
    public function getLocalURL( $query = '', $query2 = false ) {
        global $wgArticlePath, $wgScript, $wgMainPageIsDomainRoot;
 
        $query = self::fixUrlQueryArgs( $query, $query2 );
 
        $services = MediaWikiServices::getInstance();
        $hookRunner = new HookRunner( $services->getHookContainer() );
        $interwiki = self::getInterwikiLookup()->fetch( $this->mInterwiki );
        if ( $interwiki ) {
            $namespace = $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 = $interwiki->getURL( $namespace . $this->mDbkeyform );
            $url = wfAppendQuery( $url, $query );
        } else {
            $dbkey = wfUrlencode( $this->getPrefixedDBkey() );
            if ( $query == '' ) {
                if ( $wgMainPageIsDomainRoot && $this->isMainPage() ) {
                    $url = '/';
                } else {
                    $url = str_replace( '$1', $dbkey, $wgArticlePath );
                }
                $hookRunner->onGetLocalURL__Article( $this, $url );
            } else {
                global $wgVariantArticlePath, $wgActionPaths;
                $url = false;
                $matches = [];
 
                $articlePaths = PathRouter::getActionPaths( $wgActionPaths, $wgArticlePath );
 
                if ( $articlePaths
                    && preg_match( '/^(.*&|)action=([^&]*)(&(.*)|)$/', $query, $matches )
                ) {
                    $action = urldecode( $matches[2] );
                    if ( isset( $articlePaths[$action] ) ) {
                        $query = $matches[1];
                        if ( isset( $matches[4] ) ) {
                            $query .= $matches[4];
                        }
                        $url = str_replace( '$1', $dbkey, $articlePaths[$action] );
                        if ( $query != '' ) {
                            $url = wfAppendQuery( $url, $query );
                        }
                    }
                }
 
                if ( $url === false
                    && $wgVariantArticlePath
                    && preg_match( '/^variant=([^&]*)$/', $query, $matches )
                    && $this->getPageLanguage()->equals( $services->getContentLanguage() )
                    && $this->getPageLanguageConverter()->hasVariants()
                ) {
                    $variant = urldecode( $matches[1] );
                    if ( $this->getPageLanguageConverter()->hasVariant( $variant ) ) {
                        // Only do the variant replacement if the given variant is a valid
                        // variant for the page's language.
                        $url = str_replace( '$2', urlencode( $variant ), $wgVariantArticlePath );
                        $url = str_replace( '$1', $dbkey, $url );
                    }
                }
 
                if ( $url === false ) {
                    if ( $query == '-' ) {
                        $query = '';
                    }
                    $url = "{$wgScript}?title={$dbkey}&{$query}";
                }
            }
            $hookRunner->onGetLocalURL__Internal( $this, $url, $query );
        }
 
        $hookRunner->onGetLocalURL( $this, $url, $query );
        return $url;
    }
 
    public function getLinkURL( $query = '', $query2 = false, $proto = false ) {
        if ( $this->isExternal() || $proto !== false ) {
            $ret = $this->getFullURL( $query, $query2, $proto );
        } elseif ( $this->getPrefixedText() === '' && $this->hasFragment() ) {
            $ret = $this->getFragmentForURL();
        } else {
            $ret = $this->getLocalURL( $query, $query2 ) . $this->getFragmentForURL();
        }
        return $ret;
    }
 
    public function getInternalURL( $query = '', $query2 = false ) {
        global $wgInternalServer, $wgServer;
        $query = self::fixUrlQueryArgs( $query, $query2 );
        $server = $wgInternalServer !== false ? $wgInternalServer : $wgServer;
        $url = wfExpandUrl( $server . $this->getLocalURL( $query ), PROTO_HTTP );
        ( new HookRunner( MediaWikiServices::getInstance()->getHookContainer() ) )
            ->onGetInternalURL( $this, $url, $query );
        return $url;
    }
 
    public function getCanonicalURL( $query = '', $query2 = false ) {
        $query = self::fixUrlQueryArgs( $query, $query2 );
        $url = wfExpandUrl( $this->getLocalURL( $query ) . $this->getFragmentForURL(), PROTO_CANONICAL );
        ( new HookRunner( MediaWikiServices::getInstance()->getHookContainer() ) )
            ->onGetCanonicalURL( $this, $url, $query );
        return $url;
    }
 
    public function getEditURL() {
        if ( $this->isExternal() ) {
            return '';
        }
        $s = $this->getLocalURL( 'action=edit' );
 
        return $s;
    }
 
    public function getTitleProtection() {
        return MediaWikiServices::getInstance()->getRestrictionStore()->getCreateProtection( $this )
            ?: false;
    }
 
    public function deleteTitleProtection() {
        MediaWikiServices::getInstance()->getRestrictionStore()->deleteCreateProtection( $this );
    }
 
    public function loadRestrictions( $flags = 0 ) {
        MediaWikiServices::getInstance()->getRestrictionStore()->loadRestrictions( $this, $flags );
    }
 
    public function flushRestrictions() {
        MediaWikiServices::getInstance()->getRestrictionStore()->flushRestrictions( $this );
    }
 
    public static function purgeExpiredRestrictions() {
        if ( MediaWikiServices::getInstance()->getReadOnlyMode()->isReadOnly() ) {
            return;
        }
 
        DeferredUpdates::addUpdate( new AtomicSectionUpdate(
            wfGetDB( DB_PRIMARY ),
            __METHOD__,
            static function ( IDatabase $dbw, $fname ) {
                $config = MediaWikiServices::getInstance()->getMainConfig();
                $ids = $dbw->selectFieldValues(
                    'page_restrictions',
                    'pr_id',
                    [ 'pr_expiry < ' . $dbw->addQuotes( $dbw->timestamp() ) ],
                    $fname,
                    [ 'LIMIT' => $config->get( MainConfigNames::UpdateRowsPerQuery ) ] // T135470
                );
                if ( $ids ) {
                    $dbw->delete( 'page_restrictions', [ 'pr_id' => $ids ], $fname );
                }
            }
        ) );
 
        DeferredUpdates::addUpdate( new AtomicSectionUpdate(
            wfGetDB( DB_PRIMARY ),
            __METHOD__,
            static function ( IDatabase $dbw, $fname ) {
                $dbw->delete(
                    'protected_titles',
                    [ 'pt_expiry < ' . $dbw->addQuotes( $dbw->timestamp() ) ],
                    $fname
                );
            }
        ) );
    }
 
    public function hasSubpages() {
        if (
            !MediaWikiServices::getInstance()->getNamespaceInfo()->
                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 ( $this->mHasSubpages === null ) {
            $subpages = $this->getSubpages( 1 );
            $this->mHasSubpages = $subpages instanceof TitleArray && $subpages->count();
        }
 
        return $this->mHasSubpages;
    }
 
    public function getSubpages( $limit = -1 ) {
        if (
            !MediaWikiServices::getInstance()->getNamespaceInfo()->
                hasSubpages( $this->mNamespace )
        ) {
            return [];
        }
 
        $options = [];
        if ( $limit > -1 ) {
            $options['LIMIT'] = $limit;
        }
 
        $pageStore = MediaWikiServices::getInstance()->getPageStore();
        $query = $pageStore->newSelectQueryBuilder()
            ->fields( $pageStore->getSelectFields() )
            ->whereTitlePrefix( $this->getNamespace(), $this->getDBkey() . '/' )
            ->options( $options )
            ->caller( __METHOD__ );
 
        return TitleArray::newFromResult( $query->fetchResultSet() );
    }
 
    public function isDeleted() {
        return $this->getDeletedEditsCount();
    }
 
    public function getDeletedEditsCount() {
        if ( $this->mNamespace < 0 ) {
            $n = 0;
        } else {
            $dbr = wfGetDB( DB_REPLICA );
 
            $n = $dbr->selectField( 'archive', 'COUNT(*)',
                [ 'ar_namespace' => $this->mNamespace, 'ar_title' => $this->mDbkeyform ],
                __METHOD__
            );
            if ( $this->mNamespace === NS_FILE ) {
                $n += $dbr->selectField( 'filearchive', 'COUNT(*)',
                    [ 'fa_name' => $this->mDbkeyform ],
                    __METHOD__
                );
            }
        }
        return (int)$n;
    }
 
    public function isDeletedQuick() {
        return $this->hasDeletedEdits();
    }
 
    public function hasDeletedEdits() {
        if ( $this->mNamespace < 0 ) {
            return false;
        }
        $dbr = wfGetDB( DB_REPLICA );
        $deleted = (bool)$dbr->selectField( 'archive', '1',
            [ 'ar_namespace' => $this->mNamespace, 'ar_title' => $this->mDbkeyform ],
            __METHOD__
        );
        if ( !$deleted && $this->mNamespace === NS_FILE ) {
            $deleted = (bool)$dbr->selectField( 'filearchive', '1',
                [ 'fa_name' => $this->mDbkeyform ],
                __METHOD__
            );
        }
        return $deleted;
    }
 
    public function getArticleID( $flags = 0 ) {
        if ( $this->mArticleID === -1 && !$this->canExist() ) {
            $this->mArticleID = 0;
 
            return $this->mArticleID;
        }
 
        if ( $this->mArticleID === -1 || $this->shouldReadLatest( $flags ) ) {
            $this->mArticleID = (int)$this->getFieldFromPageStore( 'page_id', $flags );
        }
 
        return $this->mArticleID;
    }
 
    public function isRedirect( $flags = 0 ) {
        if ( $this->shouldReadLatest( $flags ) || $this->mRedirect === null ) {
            $this->mRedirect = (bool)$this->getFieldFromPageStore( 'page_is_redirect', $flags );
        }
 
        return $this->mRedirect;
    }
 
    public function getLength( $flags = 0 ) {
        if ( $this->shouldReadLatest( $flags ) || $this->mLength < 0 ) {
            $this->mLength = (int)$this->getFieldFromPageStore( 'page_len', $flags );
        }
 
        if ( $this->mLength < 0 ) {
            $this->mLength = 0;
        }
 
        return $this->mLength;
    }
 
    public function getLatestRevID( $flags = 0 ) {
        if ( $this->shouldReadLatest( $flags ) || $this->mLatestID === false ) {
            $this->mLatestID = (int)$this->getFieldFromPageStore( 'page_latest', $flags );
        }
 
        if ( !$this->mLatestID ) {
            $this->mLatestID = 0;
        }
 
        return $this->mLatestID;
    }
 
    public function resetArticleID( $id ) {
        if ( $id === false ) {
            $this->mArticleID = -1;
        } else {
            $this->mArticleID = (int)$id;
        }
        $this->mRedirect = null;
        $this->mLength = -1;
        $this->mLatestID = false;
        $this->mContentModel = false;
        $this->mForcedContentModel = false;
        $this->mEstimateRevisions = null;
        $this->mPageLanguage = null;
        $this->mDbPageLanguage = false;
        $this->mIsBigDeletion = null;
 
        MediaWikiServices::getInstance()->getLinkCache()->clearLink( $this );
        MediaWikiServices::getInstance()->getRestrictionStore()->flushRestrictions( $this );
    }
 
    public static function clearCaches() {
        $linkCache = MediaWikiServices::getInstance()->getLinkCache();
        $linkCache->clear();
 
        $titleCache = self::getTitleCache();
        $titleCache->clear();
    }
 
    public static function capitalize( $text, $ns = NS_MAIN ) {
        $services = MediaWikiServices::getInstance();
        if ( $services->getNamespaceInfo()->isCapitalized( $ns ) ) {
            return $services->getContentLanguage()->ucfirst( $text );
        } else {
            return $text;
        }
    }
 
    private function secureAndSplit( $text, $defaultNamespace = null ) {
        if ( $defaultNamespace === null ) {
            $defaultNamespace = self::DEFAULT_NAMESPACE;
        }
 
        // @note: splitTitleString() is a temporary hack to allow MediaWikiTitleCodec to share
        //        the parsing code with Title, while avoiding massive refactoring.
        // @todo: get rid of secureAndSplit, refactor parsing code.
        // @note: getTitleParser() returns a TitleParser implementation which does not have a
        //        splitTitleString method, but the only implementation (MediaWikiTitleCodec) does
        $titleCodec = MediaWikiServices::getInstance()->getTitleParser();
        '@phan-var MediaWikiTitleCodec $titleCodec';
        // MalformedTitleException can be thrown here
        $parts = $titleCodec->splitTitleString( $text, $defaultNamespace );
 
        # Fill fields
        $this->setFragment( '#' . $parts['fragment'] );
        $this->mInterwiki = $parts['interwiki'];
        $this->mLocalInterwiki = $parts['local_interwiki'];
        $this->mNamespace = $parts['namespace'];
 
        $this->mDbkeyform = $parts['dbkey'];
        $this->mUrlform = wfUrlencode( $this->mDbkeyform );
        $this->mTextform = strtr( $this->mDbkeyform, '_', ' ' );
 
        // splitTitleString() guarantees that this title is valid.
        $this->mIsValid = true;
 
        # We already know that some pages won't be in the database!
        if ( $this->isExternal() || $this->isSpecialPage() || $this->mTextform === '' ) {
            $this->mArticleID = 0;
        }
    }
 
    public function getLinksTo( $options = [], $table = 'pagelinks', $prefix = 'pl' ) {
        if ( count( $options ) > 0 ) {
            $db = wfGetDB( DB_PRIMARY );
        } else {
            $db = wfGetDB( DB_REPLICA );
        }
 
        $linksMigration = MediaWikiServices::getInstance()->getLinksMigration();
        if ( isset( $linksMigration::$mapping[$table] ) ) {
            $titleConds = $linksMigration->getLinksConditions( $table, $this );
        } else {
            $titleConds = [
                "{$prefix}_namespace" => $this->mNamespace,
                "{$prefix}_title" => $this->mDbkeyform
            ];
        }
 
        $res = $db->newSelectQueryBuilder()
            ->select( LinkCache::getSelectFields() )
            ->from( $table )
            ->join( 'page', null, "{$prefix}_from=page_id" )
            ->where( $titleConds )
            ->options( $options )
            ->caller( __METHOD__ )
            ->fetchResultSet();
 
        $retVal = [];
        if ( $res->numRows() ) {
            $linkCache = MediaWikiServices::getInstance()->getLinkCache();
            foreach ( $res as $row ) {
                $titleObj = self::makeTitle( $row->page_namespace, $row->page_title );
                if ( $titleObj ) {
                    $linkCache->addGoodLinkObjFromRow( $titleObj, $row );
                    $retVal[] = $titleObj;
                }
            }
        }
        return $retVal;
    }
 
    public function getTemplateLinksTo( $options = [] ) {
        return $this->getLinksTo( $options, 'templatelinks', 'tl' );
    }
 
    public function getLinksFrom( $options = [], $table = 'pagelinks', $prefix = 'pl' ) {
        $id = $this->getArticleID();
 
        # If the page doesn't exist; there can't be any link from this page
        if ( !$id ) {
            return [];
        }
 
        $db = wfGetDB( DB_REPLICA );
        $linksMigration = MediaWikiServices::getInstance()->getLinksMigration();
 
        if ( isset( $linksMigration::$mapping[$table] ) ) {
            [ $blNamespace, $blTitle ] = $linksMigration->getTitleFields( $table );
            $linktargetQueryInfo = $linksMigration->getQueryInfo( $table );
            $fields = $linktargetQueryInfo['fields'];
            $tables = $linktargetQueryInfo['tables'];
            $joins = $linktargetQueryInfo['joins'];
        } else {
            $blNamespace = "{$prefix}_namespace";
            $blTitle = "{$prefix}_title";
            $fields = [ $blNamespace, $blTitle ];
            $tables = [ $table ];
            $joins = [];
        }
 
        $pageQuery = WikiPage::getQueryInfo();
        $res = $db->select(
            array_merge( $tables, [ 'nestpage' => $pageQuery['tables'] ] ),
            array_merge(
                $fields,
                $pageQuery['fields']
            ),
            [ "{$prefix}_from" => $id ],
            __METHOD__,
            $options,
            [ 'nestpage' => [
                'LEFT JOIN',
                [ "page_namespace=$blNamespace", "page_title=$blTitle" ]
            ] ] + $pageQuery['joins'] + $joins
        );
 
        $retVal = [];
        $linkCache = MediaWikiServices::getInstance()->getLinkCache();
        foreach ( $res as $row ) {
            if ( $row->page_id ) {
                $titleObj = self::newFromRow( $row );
            } else {
                $titleObj = self::makeTitle( $row->$blNamespace, $row->$blTitle );
                $linkCache->addBadLinkObj( $titleObj );
            }
            $retVal[] = $titleObj;
        }
 
        return $retVal;
    }
 
    public function getTemplateLinksFrom( $options = [] ) {
        return $this->getLinksFrom( $options, 'templatelinks', 'tl' );
    }
 
    public function getBrokenLinksFrom() {
        if ( $this->getArticleID() == 0 ) {
            # All links from article ID 0 are false positives
            return [];
        }
 
        $dbr = wfGetDB( DB_REPLICA );
        $res = $dbr->select(
            [ 'page', 'pagelinks' ],
            [ 'pl_namespace', 'pl_title' ],
            [
                'pl_from' => $this->getArticleID(),
                'page_namespace IS NULL'
            ],
            __METHOD__, [],
            [
                'page' => [
                    'LEFT JOIN',
                    [ 'pl_namespace=page_namespace', 'pl_title=page_title' ]
                ]
            ]
        );
 
        $retVal = [];
        foreach ( $res as $row ) {
            $retVal[] = self::makeTitle( $row->pl_namespace, $row->pl_title );
        }
        return $retVal;
    }
 
    public function getCdnUrls() {
        $htmlCache = MediaWikiServices::getInstance()->getHtmlCacheUpdater();
        return $htmlCache->getUrls( $this );
    }
 
    public function purgeSquid() {
        $htmlCache = MediaWikiServices::getInstance()->getHtmlCacheUpdater();
        $htmlCache->purgeTitleUrls( $this, $htmlCache::PURGE_INTENT_TXROUND_REFLECTED );
    }
 
    public function isSingleRevRedirect() {
        $dbw = wfGetDB( DB_PRIMARY );
        $dbw->startAtomic( __METHOD__ );
        $pageStore = MediaWikiServices::getInstance()->getPageStore();
 
        $row = $dbw->selectRow(
            'page',
            $pageStore->getSelectFields(),
            $this->pageCond(),
            __METHOD__,
            [ 'FOR UPDATE' ]
        );
        // Update the cached fields
        $this->loadFromRow( $row );
 
        if ( $this->mRedirect && $this->mLatestID ) {
            $isSingleRevRedirect = !$dbw->selectField(
                'revision',
                '1',
                [ 'rev_page' => $this->mArticleID, 'rev_id != ' . (int)$this->mLatestID ],
                __METHOD__,
                [ 'FOR UPDATE' ]
            );
        } else {
            $isSingleRevRedirect = false;
        }
 
        $dbw->endAtomic( __METHOD__ );
 
        return $isSingleRevRedirect;
    }
 
    public function getParentCategories() {
        $data = [];
 
        $titleKey = $this->getArticleID();
 
        if ( $titleKey === 0 ) {
            return $data;
        }
 
        $dbr = wfGetDB( DB_REPLICA );
 
        $res = $dbr->select(
            'categorylinks',
            'cl_to',
            [ 'cl_from' => $titleKey ],
            __METHOD__
        );
 
        if ( $res->numRows() > 0 ) {
            $contLang = MediaWikiServices::getInstance()->getContentLanguage();
            foreach ( $res as $row ) {
                // $data[] = Title::newFromText( $contLang->getNsText ( NS_CATEGORY ).':'.$row->cl_to);
                $data[$contLang->getNsText( NS_CATEGORY ) . ':' . $row->cl_to] =
                    $this->getFullText();
            }
        }
        return $data;
    }
 
    public function getParentCategoryTree( $children = [] ) {
        $stack = [];
        $parents = $this->getParentCategories();
 
        if ( $parents ) {
            foreach ( $parents as $parent => $current ) {
                if ( array_key_exists( $parent, $children ) ) {
                    # Circular reference
                    $stack[$parent] = [];
                } else {
                    $nt = self::newFromText( $parent );
                    if ( $nt ) {
                        $stack[$parent] = $nt->getParentCategoryTree( $children + [ $parent => 1 ] );
                    }
                }
            }
        }
 
        return $stack;
    }
 
    public function pageCond() {
        if ( $this->mArticleID > 0 ) {
            // PK avoids secondary lookups in InnoDB, shouldn't hurt other DBs
            return [ 'page_id' => $this->mArticleID ];
        } else {
            return [ 'page_namespace' => $this->mNamespace, 'page_title' => $this->mDbkeyform ];
        }
    }
 
    public function isNewPage( $flags = self::READ_NORMAL ) {
        // NOTE: we rely on PHP casting "0" to false here.
        return (bool)$this->getFieldFromPageStore( 'page_is_new', $flags );
    }
 
    public function isBigDeletion() {
        global $wgDeleteRevisionsLimit;
 
        if ( !$wgDeleteRevisionsLimit ) {
            return false;
        }
 
        if ( $this->mIsBigDeletion === null ) {
            $dbr = wfGetDB( DB_REPLICA );
 
            $revCount = $dbr->selectRowCount(
                'revision',
                '1',
                [ 'rev_page' => $this->getArticleID() ],
                __METHOD__,
                [ 'LIMIT' => $wgDeleteRevisionsLimit + 1 ]
            );
 
            $this->mIsBigDeletion = $revCount > $wgDeleteRevisionsLimit;
        }
 
        return $this->mIsBigDeletion;
    }
 
    public function estimateRevisionCount() {
        if ( !$this->exists() ) {
            return 0;
        }
 
        if ( $this->mEstimateRevisions === null ) {
            $dbr = wfGetDB( DB_REPLICA );
            $this->mEstimateRevisions = $dbr->estimateRowCount( 'revision', '*',
                [ 'rev_page' => $this->getArticleID() ], __METHOD__ );
        }
 
        return $this->mEstimateRevisions;
    }
 
    public function equals( object $other ) {
        if ( $other instanceof Title ) {
            // NOTE: In contrast to isSameLinkAs(), this ignores the fragment part!
            // NOTE: In contrast to isSamePageAs(), this ignores the page ID!
            // NOTE: === is necessary for proper matching of number-like titles
            return $this->getInterwiki() === $other->getInterwiki()
                && $this->getNamespace() === $other->getNamespace()
                && $this->getDBkey() === $other->getDBkey();
        } else {
            return false;
        }
    }
 
    public function isSameLinkAs( LinkTarget $other ): bool {
        // NOTE: keep in sync with TitleValue::isSameLinkAs()!
        // NOTE: === is needed for number-like titles
        return ( $other->getInterwiki() === $this->getInterwiki() )
            && ( $other->getDBkey() === $this->getDBkey() )
            && ( $other->getNamespace() === $this->getNamespace() )
            && ( $other->getFragment() === $this->getFragment() );
    }
 
    public function isSamePageAs( PageReference $other ): bool {
        // NOTE: keep in sync with PageIdentityValue::isSamePageAs()!
 
        if ( $other->getWikiId() !== $this->getWikiId() ) {
            return false;
        }
 
        if ( $other->getNamespace() !== $this->getNamespace()
            || $other->getDBkey() !== $this->getDBkey() ) {
            return false;
        }
 
        return true;
    }
 
    public function isSubpageOf( Title $title ) {
        return $this->mInterwiki === $title->mInterwiki
            && $this->mNamespace == $title->mNamespace
            && str_starts_with( $this->mDbkeyform, $title->mDbkeyform . '/' );
    }
 
    public function exists( $flags = 0 ): bool {
        $exists = $this->getArticleID( $flags ) != 0;
        ( new HookRunner( MediaWikiServices::getInstance()->getHookContainer() ) )->onTitleExists( $this, $exists );
        return $exists;
    }
 
    public function isAlwaysKnown() {
        $isKnown = null;
 
        $services = MediaWikiServices::getInstance();
        ( new HookRunner( $services->getHookContainer() ) )->onTitleIsAlwaysKnown( $this, $isKnown );
 
        if ( $isKnown !== null ) {
            return $isKnown;
        }
 
        if ( $this->isExternal() ) {
            return true; // any interwiki link might be viewable, for all we know
        }
 
        switch ( $this->mNamespace ) {
            case NS_MEDIA:
            case NS_FILE:
                // file exists, possibly in a foreign repo
                return (bool)$services->getRepoGroup()->findFile( $this );
            case NS_SPECIAL:
                // valid special page
                return $services->getSpecialPageFactory()->exists( $this->mDbkeyform );
            case NS_MAIN:
                // selflink, possibly with fragment
                return $this->mDbkeyform == '';
            case NS_MEDIAWIKI:
                // known system message
                return $this->hasSourceText() !== false;
            default:
                return false;
        }
    }
 
    public function isKnown() {
        return $this->isAlwaysKnown() || $this->exists();
    }
 
    public function hasSourceText() {
        if ( $this->exists() ) {
            return true;
        }
 
        if ( $this->mNamespace === NS_MEDIAWIKI ) {
            $services = MediaWikiServices::getInstance();
            // If the page doesn't exist but is a known system message, default
            // message content will be displayed, same for language subpages-
            // Use always content language to avoid loading hundreds of languages
            // to get the link color.
            $contLang = $services->getContentLanguage();
            [ $name, ] = $services->getMessageCache()->figureMessage(
                $contLang->lcfirst( $this->getText() )
            );
            $message = wfMessage( $name )->inLanguage( $contLang )->useDatabase( false );
            return $message->exists();
        }
 
        return false;
    }
 
    public function getDefaultMessageText() {
        $message = $this->getDefaultSystemMessage();
 
        return $message ? $message->plain() : false;
    }
 
    public function getDefaultSystemMessage(): ?Message {
        if ( $this->mNamespace !== NS_MEDIAWIKI ) { // Just in case
            return null;
        }
 
        [ $name, $lang ] = MediaWikiServices::getInstance()->getMessageCache()->figureMessage(
            MediaWikiServices::getInstance()->getContentLanguage()->lcfirst( $this->getText() )
        );
 
        $message = wfMessage( $name )->inLanguage( $lang )->useDatabase( false );
 
        if ( $message->exists() ) {
            return $message;
        } else {
            return null;
        }
    }
 
    public function invalidateCache( $purgeTime = null ) {
        if ( MediaWikiServices::getInstance()->getReadOnlyMode()->isReadOnly() ) {
            return false;
        }
        if ( $this->mArticleID === 0 ) {
            // avoid gap locking if we know it's not there
            return true;
        }
 
        $conds = $this->pageCond();
        DeferredUpdates::addUpdate(
            new AutoCommitUpdate(
                wfGetDB( DB_PRIMARY ),
                __METHOD__,
                function ( IDatabase $dbw, $fname ) use ( $conds, $purgeTime ) {
                    $dbTimestamp = $dbw->timestamp( $purgeTime ?: time() );
                    $dbw->newUpdateQueryBuilder()
                        ->update( 'page' )
                        ->set( [ 'page_touched' => $dbTimestamp ] )
                        ->where( $conds )
                        ->andWhere( $dbw->buildComparison( '<', [ 'page_touched' => $dbTimestamp ] ) )
                        ->caller( $fname )->execute();
 
                    MediaWikiServices::getInstance()->getLinkCache()->invalidateTitle( $this );
 
                    WikiModule::invalidateModuleCache(
                        $this, null, null, $dbw->getDomainID() );
                }
            ),
            DeferredUpdates::PRESEND
        );
 
        return true;
    }
 
    public function touchLinks() {
        $jobs = [];
        $jobs[] = HTMLCacheUpdateJob::newForBacklinks(
            $this,
            'pagelinks',
            [ 'causeAction' => 'page-touch' ]
        );
        if ( $this->mNamespace === NS_CATEGORY ) {
            $jobs[] = HTMLCacheUpdateJob::newForBacklinks(
                $this,
                'categorylinks',
                [ 'causeAction' => 'category-touch' ]
            );
        }
 
        MediaWikiServices::getInstance()->getJobQueueGroup()->lazyPush( $jobs );
    }
 
    public function getTouched( $flags = self::READ_NORMAL ) {
        if ( is_object( $flags ) ) {
            wfDeprecatedMsg(
                __METHOD__ . ' was called with a ' . get_class( $flags )
                . ' instance instead of an integer!',
                '1.38'
            );
            $flags = self::READ_LATEST;
        }
 
        $touched = $this->getFieldFromPageStore( 'page_touched', $flags );
        return $touched ? MWTimestamp::convert( TS_MW, $touched ) : false;
    }
 
    public function getNamespaceKey( $prepend = 'nstab-' ) {
        // Gets the subject namespace of this title
        $nsInfo = MediaWikiServices::getInstance()->getNamespaceInfo();
        $subjectNS = $nsInfo->getSubject( $this->mNamespace );
        // Prefer canonical namespace name for HTML IDs
        $namespaceKey = $nsInfo->getCanonicalName( $subjectNS );
        if ( $namespaceKey === false ) {
            // Fallback to localised text
            $namespaceKey = $this->getSubjectNsText();
        }
        // Makes namespace key lowercase
        $namespaceKey = MediaWikiServices::getInstance()->getContentLanguage()->lc( $namespaceKey );
        // Uses main
        if ( $namespaceKey == '' ) {
            $namespaceKey = 'main';
        }
        // Changes file to image for backwards compatibility
        if ( $namespaceKey == 'file' ) {
            $namespaceKey = 'image';
        }
        return $prepend . $namespaceKey;
    }
 
    public function getRedirectsHere( $ns = null ) {
        $redirs = [];
 
        $dbr = wfGetDB( DB_REPLICA );
        $where = [
            'rd_namespace' => $this->mNamespace,
            'rd_title' => $this->mDbkeyform,
            'rd_from = page_id'
        ];
        if ( $this->isExternal() ) {
            $where['rd_interwiki'] = $this->mInterwiki;
        } else {
            $where[] = 'rd_interwiki = ' . $dbr->addQuotes( '' ) . ' OR rd_interwiki IS NULL';
        }
        if ( $ns !== null ) {
            $where['page_namespace'] = $ns;
        }
 
        $res = $dbr->select(
            [ 'redirect', 'page' ],
            [ 'page_namespace', 'page_title' ],
            $where,
            __METHOD__
        );
 
        foreach ( $res as $row ) {
            $redirs[] = self::newFromRow( $row );
        }
        return $redirs;
    }
 
    public function isValidRedirectTarget() {
        global $wgInvalidRedirectTargets;
 
        if ( $this->isSpecialPage() ) {
            // invalid redirect targets are stored in a global array, but explicitly disallow Userlogout here
            if ( $this->isSpecial( 'Userlogout' ) ) {
                return false;
            }
 
            foreach ( $wgInvalidRedirectTargets as $target ) {
                if ( $this->isSpecial( $target ) ) {
                    return false;
                }
            }
 
            return true;
        } elseif ( $this->getDBkey() === '' ) {
            // relative section links are not valid redirect targets (T278367)
            return false;
        }
 
        return $this->isValid();
    }
 
    public function getBacklinkCache(): BacklinkCache {
        wfDeprecated( __METHOD__, '1.37' );
        return MediaWikiServices::getInstance()->getBacklinkCacheFactory()
            ->getBacklinkCache( $this );
    }
 
    public function canUseNoindex() {
        global $wgExemptFromUserRobotsControl;
 
        $bannedNamespaces = $wgExemptFromUserRobotsControl ??
            MediaWikiServices::getInstance()->getNamespaceInfo()->getContentNamespaces();
 
        return !in_array( $this->mNamespace, $bannedNamespaces );
    }
 
    public function getCategorySortkey( $prefix = '' ) {
        $unprefixed = $this->getText();
 
        // Anything that uses this hook should only depend
        // on the Title object passed in, and should probably
        // tell the users to run updateCollations.php --force
        // in order to re-sort existing category relations.
        ( new HookRunner( MediaWikiServices::getInstance()->getHookContainer() ) )
            ->onGetDefaultSortkey( $this, $unprefixed );
        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;
    }
 
    private function getDbPageLanguageCode( int $flags = 0 ): ?string {
        global $wgPageLanguageUseDB;
 
        // check, if the page language could be saved in the database, and if so and
        // the value is not requested already, lookup the page language using PageStore
        if ( $wgPageLanguageUseDB && $this->mDbPageLanguage === false ) {
            $this->mDbPageLanguage = $this->getFieldFromPageStore( 'page_lang', $flags ) ?: null;
        }
 
        return $this->mDbPageLanguage ?: null;
    }
 
    private function getDbPageLanguage(): ?Language {
        $languageCode = $this->getDbPageLanguageCode();
        if ( $languageCode === null ) {
            return null;
        }
        $services = MediaWikiServices::getInstance();
        if ( !$services->getLanguageNameUtils()->isKnownLanguageTag( $languageCode ) ) {
            return $services->getContentLanguage();
        }
        return $services->getLanguageFactory()->getLanguage( $languageCode );
    }
 
    public function getPageLanguage() {
        global $wgLang, $wgLanguageCode;
        if ( $this->isSpecialPage() ) {
            // special pages are in the user language
            return $wgLang;
        }
 
        // Checking if DB language is set
        $dbPageLanguage = $this->getDbPageLanguage();
        if ( $dbPageLanguage ) {
            return $dbPageLanguage;
        }
 
        $services = MediaWikiServices::getInstance();
        if ( !$this->mPageLanguage || $this->mPageLanguage[1] !== $wgLanguageCode ) {
            // Note that this may depend on user settings, so the cache should
            // be only per-request.
            // NOTE: ContentHandler::getPageLanguage() may need to load the
            // content to determine the page language!
            // Checking $wgLanguageCode hasn't changed for the benefit of unit
            // tests.
            $contentHandler = $services->getContentHandlerFactory()
                ->getContentHandler( $this->getContentModel() );
            $langObj = $contentHandler->getPageLanguage( $this );
            $this->mPageLanguage = [ $langObj->getCode(), $wgLanguageCode ];
        } else {
            $langObj = $services->getLanguageFactory()
                ->getLanguage( $this->mPageLanguage[0] );
        }
 
        return $langObj;
    }
 
    public function getPageViewLanguage() {
        global $wgLang;
 
        $services = MediaWikiServices::getInstance();
 
        if ( $this->isSpecialPage() ) {
            // If the user chooses a variant, the content is actually
            // in a language whose code is the variant code.
            $variant = $this->getLanguageConverter( $wgLang )->getPreferredVariant();
            if ( $wgLang->getCode() !== $variant ) {
                return $services->getLanguageFactory()
                    ->getLanguage( $variant );
            }
 
            return $wgLang;
        }
 
        // Checking if DB language is set
        $pageLang = $this->getDbPageLanguage();
        if ( $pageLang ) {
            $variant = $this->getLanguageConverter( $pageLang )->getPreferredVariant();
            if ( $pageLang->getCode() !== $variant ) {
                return $services->getLanguageFactory()
                    ->getLanguage( $variant );
            }
 
            return $pageLang;
        }
 
        // @note Can't be cached persistently, depends on user settings.
        // @note ContentHandler::getPageViewLanguage() may need to load the
        //   content to determine the page language!
        $contentHandler = $services->getContentHandlerFactory()
            ->getContentHandler( $this->getContentModel() );
        $pageLang = $contentHandler->getPageViewLanguage( $this );
        return $pageLang;
    }
 
    public function getEditNotices( $oldid = 0 ) {
        $notices = [];
 
        // Optional notice for the entire namespace
        $editnotice_ns = 'editnotice-' . $this->mNamespace;
        $msg = wfMessage( $editnotice_ns )->page( $this );
        if ( $msg->exists() ) {
            $html = $msg->parseAsBlock();
            // Edit notices may have complex logic, but output nothing (T91715)
            if ( trim( $html ) !== '' ) {
                $notices[$editnotice_ns] = Html::rawElement(
                    'div',
                    [ 'class' => [
                        'mw-editnotice',
                        'mw-editnotice-namespace',
                        Sanitizer::escapeClass( "mw-$editnotice_ns" )
                    ] ],
                    $html
                );
            }
        }
 
        if (
            MediaWikiServices::getInstance()->getNamespaceInfo()->
                hasSubpages( $this->mNamespace )
        ) {
            // Optional notice for page itself and any parent page
            $editnotice_base = $editnotice_ns;
            foreach ( explode( '/', $this->mDbkeyform ) as $part ) {
                $editnotice_base .= '-' . $part;
                $msg = wfMessage( $editnotice_base )->page( $this );
                if ( $msg->exists() ) {
                    $html = $msg->parseAsBlock();
                    if ( trim( $html ) !== '' ) {
                        $notices[$editnotice_base] = Html::rawElement(
                            'div',
                            [ 'class' => [
                                'mw-editnotice',
                                'mw-editnotice-base',
                                Sanitizer::escapeClass( "mw-$editnotice_base" )
                            ] ],
                            $html
                        );
                    }
                }
            }
        } else {
            // Even if there are no subpages in namespace, we still don't want "/" in MediaWiki message keys
            $editnoticeText = $editnotice_ns . '-' . strtr( $this->mDbkeyform, '/', '-' );
            $msg = wfMessage( $editnoticeText )->page( $this );
            if ( $msg->exists() ) {
                $html = $msg->parseAsBlock();
                if ( trim( $html ) !== '' ) {
                    $notices[$editnoticeText] = Html::rawElement(
                        'div',
                        [ 'class' => [
                            'mw-editnotice',
                            'mw-editnotice-page',
                            Sanitizer::escapeClass( "mw-$editnoticeText" )
                        ] ],
                        $html
                    );
                }
            }
        }
 
        ( new HookRunner( MediaWikiServices::getInstance()->getHookContainer() ) )
            ->onTitleGetEditNotices( $this, $oldid, $notices );
        return $notices;
    }
 
    private function getFieldFromPageStore( $field, $flags ) {
        $flags |= ( $flags & self::GAID_FOR_UPDATE ) ? self::READ_LATEST : 0; // b/c
 
        $pageStore = MediaWikiServices::getInstance()->getPageStore();
 
        if ( !in_array( $field, $pageStore->getSelectFields(), true ) ) {
            throw new InvalidArgumentException( "Unknown field: $field" );
        }
 
        if ( $flags === self::READ_NORMAL && $this->mArticleID === 0 ) {
            // page does not exist
            return false;
        }
 
        if ( !$this->canExist() ) {
            return false;
        }
 
        $page = $pageStore->getPageByReference( $this, $flags );
 
        if ( $page instanceof PageStoreRecord ) {
            return $page->getField( $field );
        } else {
            // The page record failed to load, remember the page as non-existing.
            // Note that this can happen even if a page ID was known before under some
            // rare circumstances, if this method is called with the READ_LATEST bit set
            // and the page has been deleted since the ID had initially been determined.
            $this->mArticleID = 0;
            return false;
        }
    }
 
    public function __sleep() {
        return [
            'mNamespace',
            'mDbkeyform',
            'mFragment',
            'mInterwiki',
            'mLocalInterwiki',
        ];
    }
 
    public function __wakeup() {
        $this->mArticleID = ( $this->mNamespace >= 0 ) ? -1 : 0;
        $this->mUrlform = wfUrlencode( $this->mDbkeyform );
        $this->mTextform = strtr( $this->mDbkeyform, '_', ' ' );
    }
 
    public function __clone() {
        $this->mInstanceCacheKey = null;
    }
 
    public function getWikiId() {
        return self::LOCAL;
    }
 
    public function getId( $wikiId = self::LOCAL ): int {
        $this->assertWiki( $wikiId );
        $this->assertProperPage();
        return $this->getArticleID();
    }
 
    private function assertProperPage() {
        Assert::precondition(
            $this->canExist(),
            'This Title instance does not represent a proper page, but merely a link target.'
        );
    }
 
    public function toPageIdentity(): ProperPageIdentity {
        // TODO: replace individual member fields with a PageIdentityValue that is always present
 
        $this->assertProperPage();
 
        return new PageIdentityValue(
            $this->getId(),
            $this->getNamespace(),
            $this->getDBkey(),
            $this->getWikiId()
        );
    }
 
    public function toPageRecord( $flags = 0 ): ExistingPageRecord {
        // TODO: Cache this? Construct is more efficiently?
 
        $this->assertProperPage();
 
        Assert::precondition(
            $this->exists(),
            'This Title instance does not represent an existing page: ' . $this
        );
 
        return new PageStoreRecord(
            (object)[
                'page_id' => $this->getArticleID( $flags ),
                'page_namespace' => $this->getNamespace(),
                'page_title' => $this->getDBkey(),
                'page_wiki_id' => $this->getWikiId(),
                'page_latest' => $this->getLatestRevID( $flags ),
                'page_is_new' => $this->isNewPage( $flags ),
                'page_is_redirect' => $this->isRedirect( $flags ),
                'page_touched' => $this->getTouched( $flags ),
                'page_lang' => $this->getDbPageLanguageCode( $flags ),
            ],
            PageIdentity::LOCAL
        );
    }
 
}
 
class_alias( Title::class, 'Title' );