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

/**
 * @brief Set options of the Parser
 *
 * How to add an option in core:
 *  1. Add it to one of the arrays in ParserOptions::setDefaults()
 *  2. If necessary, add an entry to ParserOptions::$inCacheKey
 *  3. Add a getter and setter in the section for that.
 *
 * How to add an option in an extension:
 *  1. Use the 'ParserOptionsRegister' hook to register it.
 *  2. Where necessary, use $popt->getOption() and $popt->setOption()
 *     to access it.
 *
 * @ingroup Parser
 */
class ParserOptions {

	/**
	 * Default values for all options that are relevant for caching.
	 * @see self::getDefaults()
	 * @var array|null
	 */
	private static $defaults = null;

	/**
	 * Lazy-loaded options
	 * @var callback[]
	 */
	private static $lazyOptions = [
		'dateformat' => [ __CLASS__, 'initDateFormat' ],
	];

	/**
	 * Specify options that are included in the cache key
	 * @var array
	 */
	private static $inCacheKey = [
		'dateformat' => true,
		'numberheadings' => true,
		'thumbsize' => true,
		'stubthreshold' => true,
		'printable' => true,
		'userlang' => true,
	];

	/**
	 * Current values for all options that are relevant for caching.
	 * @var array
	 */
	private $options;

	/**
	 * Timestamp used for {{CURRENTDAY}} etc.
	 * @var string|null
	 * @note Caching based on parse time is handled externally
	 */
	private $mTimestamp;

	/**
	 * Stored user object
	 * @var User
	 * @todo Track this for caching somehow without fragmenting the cache insanely
	 */
	private $mUser;

	/**
	 * Function to be called when an option is accessed.
	 * @var callable|null
	 * @note Used for collecting used options, does not affect caching
	 */
	private $onAccessCallback = null;

	/**
	 * If the page being parsed is a redirect, this should hold the redirect
	 * target.
	 * @var Title|null
	 * @todo Track this for caching somehow
	 */
	private $redirectTarget = null;

	/**
	 * Appended to the options hash
	 */
	private $mExtraKey = '';

	/**
	 * @name Option accessors
	 * @{
	 */

	/**
	 * Fetch an option, generically
	 * @since 1.30
	 * @param string $name Option name
	 * @return mixed
	 */
	public function getOption( $name ) {
		if ( !array_key_exists( $name, $this->options ) ) {
			throw new InvalidArgumentException( "Unknown parser option $name" );
		}

		if ( isset( self::$lazyOptions[$name] ) && $this->options[$name] === null ) {
			$this->options[$name] = call_user_func( self::$lazyOptions[$name], $this, $name );
		}
		if ( !empty( self::$inCacheKey[$name] ) ) {
			$this->optionUsed( $name );
		}
		return $this->options[$name];
	}

	/**
	 * Set an option, generically
	 * @since 1.30
	 * @param string $name Option name
	 * @param mixed $value New value. Passing null will set null, unlike many
	 *  of the existing accessors which ignore null for historical reasons.
	 * @return mixed Old value
	 */
	public function setOption( $name, $value ) {
		if ( !array_key_exists( $name, $this->options ) ) {
			throw new InvalidArgumentException( "Unknown parser option $name" );
		}
		$old = $this->options[$name];
		$this->options[$name] = $value;
		return $old;
	}

	/**
	 * Legacy implementation
	 * @since 1.30 For implementing legacy setters only. Don't use this in new code.
	 * @deprecated since 1.30
	 * @param string $name Option name
	 * @param mixed $value New value. Passing null does not set the value.
	 * @return mixed Old value
	 */
	protected function setOptionLegacy( $name, $value ) {
		if ( !array_key_exists( $name, $this->options ) ) {
			throw new InvalidArgumentException( "Unknown parser option $name" );
		}
		return wfSetVar( $this->options[$name], $value );
	}

	/**
	 * Whether to extract interlanguage links
	 *
	 * When true, interlanguage links will be returned by
	 * ParserOutput::getLanguageLinks() instead of generating link HTML.
	 *
	 * @return bool
	 */
	public function getInterwikiMagic() {
		return $this->getOption( 'interwikiMagic' );
	}

	/**
	 * Specify whether to extract interlanguage links
	 * @param bool|null $x New value (null is no change)
	 * @return bool Old value
	 */
	public function setInterwikiMagic( $x ) {
		return $this->setOptionLegacy( 'interwikiMagic', $x );
	}

	/**
	 * Allow all external images inline?
	 * @return bool
	 */
	public function getAllowExternalImages() {
		return $this->getOption( 'allowExternalImages' );
	}

	/**
	 * Allow all external images inline?
	 * @param bool|null $x New value (null is no change)
	 * @return bool Old value
	 */
	public function setAllowExternalImages( $x ) {
		return $this->setOptionLegacy( 'allowExternalImages', $x );
	}

	/**
	 * External images to allow
	 *
	 * When self::getAllowExternalImages() is false
	 *
	 * @return string|string[] URLs to allow
	 */
	public function getAllowExternalImagesFrom() {
		return $this->getOption( 'allowExternalImagesFrom' );
	}

	/**
	 * External images to allow
	 *
	 * When self::getAllowExternalImages() is false
	 *
	 * @param string|string[]|null $x New value (null is no change)
	 * @return string|string[] Old value
	 */
	public function setAllowExternalImagesFrom( $x ) {
		return $this->setOptionLegacy( 'allowExternalImagesFrom', $x );
	}

	/**
	 * Use the on-wiki external image whitelist?
	 * @return bool
	 */
	public function getEnableImageWhitelist() {
		return $this->getOption( 'enableImageWhitelist' );
	}

	/**
	 * Use the on-wiki external image whitelist?
	 * @param bool|null $x New value (null is no change)
	 * @return bool Old value
	 */
	public function setEnableImageWhitelist( $x ) {
		return $this->setOptionLegacy( 'enableImageWhitelist', $x );
	}

	/**
	 * Automatically number headings?
	 * @return bool
	 */
	public function getNumberHeadings() {
		return $this->getOption( 'numberheadings' );
	}

	/**
	 * Automatically number headings?
	 * @param bool|null $x New value (null is no change)
	 * @return bool Old value
	 */
	public function setNumberHeadings( $x ) {
		return $this->setOptionLegacy( 'numberheadings', $x );
	}

	/**
	 * Allow inclusion of special pages?
	 * @return bool
	 */
	public function getAllowSpecialInclusion() {
		return $this->getOption( 'allowSpecialInclusion' );
	}

	/**
	 * Allow inclusion of special pages?
	 * @param bool|null $x New value (null is no change)
	 * @return bool Old value
	 */
	public function setAllowSpecialInclusion( $x ) {
		return $this->setOptionLegacy( 'allowSpecialInclusion', $x );
	}

	/**
	 * Use tidy to cleanup output HTML?
	 * @return bool
	 */
	public function getTidy() {
		return $this->getOption( 'tidy' );
	}

	/**
	 * Use tidy to cleanup output HTML?
	 * @param bool|null $x New value (null is no change)
	 * @return bool Old value
	 */
	public function setTidy( $x ) {
		return $this->setOptionLegacy( 'tidy', $x );
	}

	/**
	 * Parsing an interface message?
	 * @return bool
	 */
	public function getInterfaceMessage() {
		return $this->getOption( 'interfaceMessage' );
	}

	/**
	 * Parsing an interface message?
	 * @param bool|null $x New value (null is no change)
	 * @return bool Old value
	 */
	public function setInterfaceMessage( $x ) {
		return $this->setOptionLegacy( 'interfaceMessage', $x );
	}

	/**
	 * Target language for the parse
	 * @return Language|null
	 */
	public function getTargetLanguage() {
		return $this->getOption( 'targetLanguage' );
	}

	/**
	 * Target language for the parse
	 * @param Language|null $x New value
	 * @return Language|null Old value
	 */
	public function setTargetLanguage( $x ) {
		return $this->setOption( 'targetLanguage', $x );
	}

	/**
	 * Maximum size of template expansions, in bytes
	 * @return int
	 */
	public function getMaxIncludeSize() {
		return $this->getOption( 'maxIncludeSize' );
	}

	/**
	 * Maximum size of template expansions, in bytes
	 * @param int|null $x New value (null is no change)
	 * @return int Old value
	 */
	public function setMaxIncludeSize( $x ) {
		return $this->setOptionLegacy( 'maxIncludeSize', $x );
	}

	/**
	 * Maximum number of nodes touched by PPFrame::expand()
	 * @return int
	 */
	public function getMaxPPNodeCount() {
		return $this->getOption( 'maxPPNodeCount' );
	}

	/**
	 * Maximum number of nodes touched by PPFrame::expand()
	 * @param int|null $x New value (null is no change)
	 * @return int Old value
	 */
	public function setMaxPPNodeCount( $x ) {
		return $this->setOptionLegacy( 'maxPPNodeCount', $x );
	}

	/**
	 * Maximum number of nodes generated by Preprocessor::preprocessToObj()
	 * @return int
	 */
	public function getMaxGeneratedPPNodeCount() {
		return $this->getOption( 'maxGeneratedPPNodeCount' );
	}

	/**
	 * Maximum number of nodes generated by Preprocessor::preprocessToObj()
	 * @param int|null $x New value (null is no change)
	 * @return int
	 */
	public function setMaxGeneratedPPNodeCount( $x ) {
		return $this->setOptionLegacy( 'maxGeneratedPPNodeCount', $x );
	}

	/**
	 * Maximum recursion depth in PPFrame::expand()
	 * @return int
	 */
	public function getMaxPPExpandDepth() {
		return $this->getOption( 'maxPPExpandDepth' );
	}

	/**
	 * Maximum recursion depth for templates within templates
	 * @return int
	 */
	public function getMaxTemplateDepth() {
		return $this->getOption( 'maxTemplateDepth' );
	}

	/**
	 * Maximum recursion depth for templates within templates
	 * @param int|null $x New value (null is no change)
	 * @return int Old value
	 */
	public function setMaxTemplateDepth( $x ) {
		return $this->setOptionLegacy( 'maxTemplateDepth', $x );
	}

	/**
	 * Maximum number of calls per parse to expensive parser functions
	 * @since 1.20
	 * @return int
	 */
	public function getExpensiveParserFunctionLimit() {
		return $this->getOption( 'expensiveParserFunctionLimit' );
	}

	/**
	 * Maximum number of calls per parse to expensive parser functions
	 * @since 1.20
	 * @param int|null $x New value (null is no change)
	 * @return int Old value
	 */
	public function setExpensiveParserFunctionLimit( $x ) {
		return $this->setOptionLegacy( 'expensiveParserFunctionLimit', $x );
	}

	/**
	 * Remove HTML comments
	 * @warning Only applies to preprocess operations
	 * @return bool
	 */
	public function getRemoveComments() {
		return $this->getOption( 'removeComments' );
	}

	/**
	 * Remove HTML comments
	 * @warning Only applies to preprocess operations
	 * @param bool|null $x New value (null is no change)
	 * @return bool Old value
	 */
	public function setRemoveComments( $x ) {
		return $this->setOptionLegacy( 'removeComments', $x );
	}

	/**
	 * Enable limit report in an HTML comment on output
	 * @return bool
	 */
	public function getEnableLimitReport() {
		return $this->getOption( 'enableLimitReport' );
	}

	/**
	 * Enable limit report in an HTML comment on output
	 * @param bool|null $x New value (null is no change)
	 * @return bool Old value
	 */
	public function enableLimitReport( $x = true ) {
		return $this->setOptionLegacy( 'enableLimitReport', $x );
	}

	/**
	 * Clean up signature texts?
	 * @see Parser::cleanSig
	 * @return bool
	 */
	public function getCleanSignatures() {
		return $this->getOption( 'cleanSignatures' );
	}

	/**
	 * Clean up signature texts?
	 * @see Parser::cleanSig
	 * @param bool|null $x New value (null is no change)
	 * @return bool Old value
	 */
	public function setCleanSignatures( $x ) {
		return $this->setOptionLegacy( 'cleanSignatures', $x );
	}

	/**
	 * Target attribute for external links
	 * @return string
	 */
	public function getExternalLinkTarget() {
		return $this->getOption( 'externalLinkTarget' );
	}

	/**
	 * Target attribute for external links
	 * @param string|null $x New value (null is no change)
	 * @return string Old value
	 */
	public function setExternalLinkTarget( $x ) {
		return $this->setOptionLegacy( 'externalLinkTarget', $x );
	}

	/**
	 * Whether content conversion should be disabled
	 * @return bool
	 */
	public function getDisableContentConversion() {
		return $this->getOption( 'disableContentConversion' );
	}

	/**
	 * Whether content conversion should be disabled
	 * @param bool|null $x New value (null is no change)
	 * @return bool Old value
	 */
	public function disableContentConversion( $x = true ) {
		return $this->setOptionLegacy( 'disableContentConversion', $x );
	}

	/**
	 * Whether title conversion should be disabled
	 * @return bool
	 */
	public function getDisableTitleConversion() {
		return $this->getOption( 'disableTitleConversion' );
	}

	/**
	 * Whether title conversion should be disabled
	 * @param bool|null $x New value (null is no change)
	 * @return bool Old value
	 */
	public function disableTitleConversion( $x = true ) {
		return $this->setOptionLegacy( 'disableTitleConversion', $x );
	}

	/**
	 * Thumb size preferred by the user.
	 * @return int
	 */
	public function getThumbSize() {
		return $this->getOption( 'thumbsize' );
	}

	/**
	 * Thumb size preferred by the user.
	 * @param int|null $x New value (null is no change)
	 * @return int Old value
	 */
	public function setThumbSize( $x ) {
		return $this->setOptionLegacy( 'thumbsize', $x );
	}

	/**
	 * Thumb size preferred by the user.
	 * @return int
	 */
	public function getStubThreshold() {
		return $this->getOption( 'stubthreshold' );
	}

	/**
	 * Thumb size preferred by the user.
	 * @param int|null $x New value (null is no change)
	 * @return int Old value
	 */
	public function setStubThreshold( $x ) {
		return $this->setOptionLegacy( 'stubthreshold', $x );
	}

	/**
	 * Parsing the page for a "preview" operation?
	 * @return bool
	 */
	public function getIsPreview() {
		return $this->getOption( 'isPreview' );
	}

	/**
	 * Parsing the page for a "preview" operation?
	 * @param bool|null $x New value (null is no change)
	 * @return bool Old value
	 */
	public function setIsPreview( $x ) {
		return $this->setOptionLegacy( 'isPreview', $x );
	}

	/**
	 * Parsing the page for a "preview" operation on a single section?
	 * @return bool
	 */
	public function getIsSectionPreview() {
		return $this->getOption( 'isSectionPreview' );
	}

	/**
	 * Parsing the page for a "preview" operation on a single section?
	 * @param bool|null $x New value (null is no change)
	 * @return bool Old value
	 */
	public function setIsSectionPreview( $x ) {
		return $this->setOptionLegacy( 'isSectionPreview', $x );
	}

	/**
	 * Parsing the printable version of the page?
	 * @return bool
	 */
	public function getIsPrintable() {
		return $this->getOption( 'printable' );
	}

	/**
	 * Parsing the printable version of the page?
	 * @param bool|null $x New value (null is no change)
	 * @return bool Old value
	 */
	public function setIsPrintable( $x ) {
		return $this->setOptionLegacy( 'printable', $x );
	}

	/**
	 * Transform wiki markup when saving the page?
	 * @return bool
	 */
	public function getPreSaveTransform() {
		return $this->getOption( 'preSaveTransform' );
	}

	/**
	 * Transform wiki markup when saving the page?
	 * @param bool|null $x New value (null is no change)
	 * @return bool Old value
	 */
	public function setPreSaveTransform( $x ) {
		return $this->setOptionLegacy( 'preSaveTransform', $x );
	}

	/**
	 * Date format index
	 * @return string
	 */
	public function getDateFormat() {
		return $this->getOption( 'dateformat' );
	}

	/**
	 * Lazy initializer for dateFormat
	 */
	private static function initDateFormat( $popt ) {
		return $popt->mUser->getDatePreference();
	}

	/**
	 * Date format index
	 * @param string|null $x New value (null is no change)
	 * @return string Old value
	 */
	public function setDateFormat( $x ) {
		return $this->setOptionLegacy( 'dateformat', $x );
	}

	/**
	 * Get the user language used by the parser for this page and split the parser cache.
	 *
	 * @warning: Calling this causes the parser cache to be fragmented by user language!
	 * To avoid cache fragmentation, output should not depend on the user language.
	 * Use Parser::getFunctionLang() or Parser::getTargetLanguage() instead!
	 *
	 * @note This function will trigger a cache fragmentation by recording the
	 * 'userlang' option, see optionUsed(). This is done to avoid cache pollution
	 * when the page is rendered based on the language of the user.
	 *
	 * @note When saving, this will return the default language instead of the user's.
	 * {{int: }} uses this which used to produce inconsistent link tables (T16404).
	 *
	 * @return Language
	 * @since 1.19
	 */
	public function getUserLangObj() {
		return $this->getOption( 'userlang' );
	}

	/**
	 * Same as getUserLangObj() but returns a string instead.
	 *
	 * @warning: Calling this causes the parser cache to be fragmented by user language!
	 * To avoid cache fragmentation, output should not depend on the user language.
	 * Use Parser::getFunctionLang() or Parser::getTargetLanguage() instead!
	 *
	 * @see getUserLangObj()
	 *
	 * @return string Language code
	 * @since 1.17
	 */
	public function getUserLang() {
		return $this->getUserLangObj()->getCode();
	}

	/**
	 * Set the user language used by the parser for this page and split the parser cache.
	 * @param string|Language $x New value
	 * @return Language Old value
	 */
	public function setUserLang( $x ) {
		if ( is_string( $x ) ) {
			$x = Language::factory( $x );
		}

		return $this->setOptionLegacy( 'userlang', $x );
	}

	/**
	 * Are magic ISBN links enabled?
	 * @since 1.28
	 * @return bool
	 */
	public function getMagicISBNLinks() {
		return $this->getOption( 'magicISBNLinks' );
	}

	/**
	 * Are magic PMID links enabled?
	 * @since 1.28
	 * @return bool
	 */
	public function getMagicPMIDLinks() {
		return $this->getOption( 'magicPMIDLinks' );
	}
	/**
	 * Are magic RFC links enabled?
	 * @since 1.28
	 * @return bool
	 */
	public function getMagicRFCLinks() {
		return $this->getOption( 'magicRFCLinks' );
	}

	/**
	 * If the wiki is configured to allow raw html ($wgRawHtml = true)
	 * is it allowed in the specific case of parsing this page.
	 *
	 * This is meant to disable unsafe parser tags in cases where
	 * a malicious user may control the input to the parser.
	 *
	 * @note This is expected to be true for normal pages even if the
	 *  wiki has $wgRawHtml disabled in general. The setting only
	 *  signifies that raw html would be unsafe in the current context
	 *  provided that raw html is allowed at all.
	 * @since 1.29
	 * @return bool
	 */
	public function getAllowUnsafeRawHtml() {
		return $this->getOption( 'allowUnsafeRawHtml' );
	}

	/**
	 * If the wiki is configured to allow raw html ($wgRawHtml = true)
	 * is it allowed in the specific case of parsing this page.
	 * @see self::getAllowUnsafeRawHtml()
	 * @since 1.29
	 * @param bool|null $x Value to set or null to get current value
	 * @return bool Current value for allowUnsafeRawHtml
	 */
	public function setAllowUnsafeRawHtml( $x ) {
		return $this->setOptionLegacy( 'allowUnsafeRawHtml', $x );
	}

	/**
	 * Class to use to wrap output from Parser::parse()
	 * @since 1.30
	 * @return string|bool
	 */
	public function getWrapOutputClass() {
		return $this->getOption( 'wrapclass' );
	}

	/**
	 * CSS class to use to wrap output from Parser::parse()
	 * @since 1.30
	 * @param string $className Class name to use for wrapping.
	 *   Passing false to indicate "no wrapping" was deprecated in MediaWiki 1.31.
	 * @return string|bool Current value
	 */
	public function setWrapOutputClass( $className ) {
		if ( $className === true ) { // DWIM, they probably want the default class name
			$className = 'mw-parser-output';
		}
		if ( $className === false ) {
			wfDeprecated( __METHOD__ . '( false )', '1.31' );
		}
		return $this->setOption( 'wrapclass', $className );
	}

	/**
	 * Callback for current revision fetching; first argument to call_user_func().
	 * @since 1.24
	 * @return callable
	 */
	public function getCurrentRevisionCallback() {
		return $this->getOption( 'currentRevisionCallback' );
	}

	/**
	 * Callback for current revision fetching; first argument to call_user_func().
	 * @since 1.24
	 * @param callable|null $x New value (null is no change)
	 * @return callable Old value
	 */
	public function setCurrentRevisionCallback( $x ) {
		return $this->setOptionLegacy( 'currentRevisionCallback', $x );
	}

	/**
	 * Callback for template fetching; first argument to call_user_func().
	 * @return callable
	 */
	public function getTemplateCallback() {
		return $this->getOption( 'templateCallback' );
	}

	/**
	 * Callback for template fetching; first argument to call_user_func().
	 * @param callable|null $x New value (null is no change)
	 * @return callable Old value
	 */
	public function setTemplateCallback( $x ) {
		return $this->setOptionLegacy( 'templateCallback', $x );
	}

	/**
	 * Callback to generate a guess for {{REVISIONID}}
	 * @since 1.28
	 * @return callable|null
	 */
	public function getSpeculativeRevIdCallback() {
		return $this->getOption( 'speculativeRevIdCallback' );
	}

	/**
	 * Callback to generate a guess for {{REVISIONID}}
	 * @since 1.28
	 * @param callable|null $x New value (null is no change)
	 * @return callable|null Old value
	 */
	public function setSpeculativeRevIdCallback( $x ) {
		return $this->setOptionLegacy( 'speculativeRevIdCallback', $x );
	}

	/**@}*/

	/**
	 * Timestamp used for {{CURRENTDAY}} etc.
	 * @return string
	 */
	public function getTimestamp() {
		if ( !isset( $this->mTimestamp ) ) {
			$this->mTimestamp = wfTimestampNow();
		}
		return $this->mTimestamp;
	}

	/**
	 * Timestamp used for {{CURRENTDAY}} etc.
	 * @param string|null $x New value (null is no change)
	 * @return string Old value
	 */
	public function setTimestamp( $x ) {
		return wfSetVar( $this->mTimestamp, $x );
	}

	/**
	 * Create "edit section" links?
	 * @deprecated since 1.31, use ParserOutput::getText() options instead.
	 * @return bool
	 */
	public function getEditSection() {
		wfDeprecated( __METHOD__, '1.31' );
		return true;
	}

	/**
	 * Create "edit section" links?
	 * @deprecated since 1.31, use ParserOutput::getText() options instead.
	 * @param bool|null $x New value (null is no change)
	 * @return bool Old value
	 */
	public function setEditSection( $x ) {
		wfDeprecated( __METHOD__, '1.31' );
		return true;
	}

	/**
	 * Set the redirect target.
	 *
	 * Note that setting or changing this does not *make* the page a redirect
	 * or change its target, it merely records the information for reference
	 * during the parse.
	 *
	 * @since 1.24
	 * @param Title|null $title
	 */
	function setRedirectTarget( $title ) {
		$this->redirectTarget = $title;
	}

	/**
	 * Get the previously-set redirect target.
	 *
	 * @since 1.24
	 * @return Title|null
	 */
	function getRedirectTarget() {
		return $this->redirectTarget;
	}

	/**
	 * Extra key that should be present in the parser cache key.
	 * @warning Consider registering your additional options with the
	 *  ParserOptionsRegister hook instead of using this method.
	 * @param string $key
	 */
	public function addExtraKey( $key ) {
		$this->mExtraKey .= '!' . $key;
	}

	/**
	 * Current user
	 * @return User
	 */
	public function getUser() {
		return $this->mUser;
	}

	/**
	 * @warning For interaction with the parser cache, use
	 *  WikiPage::makeParserOptions(), ContentHandler::makeParserOptions(), or
	 *  ParserOptions::newCanonical() instead.
	 * @param User $user
	 * @param Language $lang
	 */
	public function __construct( $user = null, $lang = null ) {
		if ( $user === null ) {
			global $wgUser;
			if ( $wgUser === null ) {
				$user = new User;
			} else {
				$user = $wgUser;
			}
		}
		if ( $lang === null ) {
			global $wgLang;
			if ( !StubObject::isRealObject( $wgLang ) ) {
				$wgLang->_unstub();
			}
			$lang = $wgLang;
		}
		$this->initialiseFromUser( $user, $lang );
	}

	/**
	 * Get a ParserOptions object for an anonymous user
	 * @warning For interaction with the parser cache, use
	 *  WikiPage::makeParserOptions(), ContentHandler::makeParserOptions(), or
	 *  ParserOptions::newCanonical() instead.
	 * @since 1.27
	 * @return ParserOptions
	 */
	public static function newFromAnon() {
		global $wgContLang;
		return new ParserOptions( new User, $wgContLang );
	}

	/**
	 * Get a ParserOptions object from a given user.
	 * Language will be taken from $wgLang.
	 *
	 * @warning For interaction with the parser cache, use
	 *  WikiPage::makeParserOptions(), ContentHandler::makeParserOptions(), or
	 *  ParserOptions::newCanonical() instead.
	 * @param User $user
	 * @return ParserOptions
	 */
	public static function newFromUser( $user ) {
		return new ParserOptions( $user );
	}

	/**
	 * Get a ParserOptions object from a given user and language
	 *
	 * @warning For interaction with the parser cache, use
	 *  WikiPage::makeParserOptions(), ContentHandler::makeParserOptions(), or
	 *  ParserOptions::newCanonical() instead.
	 * @param User $user
	 * @param Language $lang
	 * @return ParserOptions
	 */
	public static function newFromUserAndLang( User $user, Language $lang ) {
		return new ParserOptions( $user, $lang );
	}

	/**
	 * Get a ParserOptions object from a IContextSource object
	 *
	 * @warning For interaction with the parser cache, use
	 *  WikiPage::makeParserOptions(), ContentHandler::makeParserOptions(), or
	 *  ParserOptions::newCanonical() instead.
	 * @param IContextSource $context
	 * @return ParserOptions
	 */
	public static function newFromContext( IContextSource $context ) {
		return new ParserOptions( $context->getUser(), $context->getLanguage() );
	}

	/**
	 * Creates a "canonical" ParserOptions object
	 *
	 * For historical reasons, certain options have default values that are
	 * different from the canonical values used for caching.
	 *
	 * @since 1.30
	 * @param User|null $user
	 * @param Language|StubObject|null $lang
	 * @return ParserOptions
	 */
	public static function newCanonical( User $user = null, $lang = null ) {
		$ret = new ParserOptions( $user, $lang );
		foreach ( self::getCanonicalOverrides() as $k => $v ) {
			$ret->setOption( $k, $v );
		}
		return $ret;
	}

	/**
	 * Get default option values
	 * @warning If you change the default for an existing option (unless it's
	 *  being overridden by self::getCanonicalOverrides()), all existing parser
	 *  cache entries will be invalid. To avoid bugs, you'll need to handle
	 *  that somehow (e.g. with the RejectParserCacheValue hook) because
	 *  MediaWiki won't do it for you.
	 * @return array
	 */
	private static function getDefaults() {
		global $wgInterwikiMagic, $wgAllowExternalImages,
			$wgAllowExternalImagesFrom, $wgEnableImageWhitelist, $wgAllowSpecialInclusion,
			$wgMaxArticleSize, $wgMaxPPNodeCount, $wgMaxTemplateDepth, $wgMaxPPExpandDepth,
			$wgCleanSignatures, $wgExternalLinkTarget, $wgExpensiveParserFunctionLimit,
			$wgMaxGeneratedPPNodeCount, $wgDisableLangConversion, $wgDisableTitleConversion,
			$wgEnableMagicLinks, $wgContLang;

		if ( self::$defaults === null ) {
			// *UPDATE* ParserOptions::matches() if any of this changes as needed
			self::$defaults = [
				'dateformat' => null,
				'tidy' => false,
				'interfaceMessage' => false,
				'targetLanguage' => null,
				'removeComments' => true,
				'enableLimitReport' => false,
				'preSaveTransform' => true,
				'isPreview' => false,
				'isSectionPreview' => false,
				'printable' => false,
				'allowUnsafeRawHtml' => true,
				'wrapclass' => 'mw-parser-output',
				'currentRevisionCallback' => [ Parser::class, 'statelessFetchRevision' ],
				'templateCallback' => [ Parser::class, 'statelessFetchTemplate' ],
				'speculativeRevIdCallback' => null,
			];

			Hooks::run( 'ParserOptionsRegister', [
				&self::$defaults,
				&self::$inCacheKey,
				&self::$lazyOptions,
			] );

			ksort( self::$inCacheKey );
		}

		// Unit tests depend on being able to modify the globals at will
		return self::$defaults + [
			'interwikiMagic' => $wgInterwikiMagic,
			'allowExternalImages' => $wgAllowExternalImages,
			'allowExternalImagesFrom' => $wgAllowExternalImagesFrom,
			'enableImageWhitelist' => $wgEnableImageWhitelist,
			'allowSpecialInclusion' => $wgAllowSpecialInclusion,
			'maxIncludeSize' => $wgMaxArticleSize * 1024,
			'maxPPNodeCount' => $wgMaxPPNodeCount,
			'maxGeneratedPPNodeCount' => $wgMaxGeneratedPPNodeCount,
			'maxPPExpandDepth' => $wgMaxPPExpandDepth,
			'maxTemplateDepth' => $wgMaxTemplateDepth,
			'expensiveParserFunctionLimit' => $wgExpensiveParserFunctionLimit,
			'externalLinkTarget' => $wgExternalLinkTarget,
			'cleanSignatures' => $wgCleanSignatures,
			'disableContentConversion' => $wgDisableLangConversion,
			'disableTitleConversion' => $wgDisableLangConversion || $wgDisableTitleConversion,
			'magicISBNLinks' => $wgEnableMagicLinks['ISBN'],
			'magicPMIDLinks' => $wgEnableMagicLinks['PMID'],
			'magicRFCLinks' => $wgEnableMagicLinks['RFC'],
			'numberheadings' => User::getDefaultOption( 'numberheadings' ),
			'thumbsize' => User::getDefaultOption( 'thumbsize' ),
			'stubthreshold' => 0,
			'userlang' => $wgContLang,
		];
	}

	/**
	 * Get "canonical" non-default option values
	 * @see self::newCanonical
	 * @warning If you change the override for an existing option, all existing
	 *  parser cache entries will be invalid. To avoid bugs, you'll need to
	 *  handle that somehow (e.g. with the RejectParserCacheValue hook) because
	 *  MediaWiki won't do it for you.
	 * @return array
	 */
	private static function getCanonicalOverrides() {
		global $wgEnableParserLimitReporting;

		return [
			'tidy' => true,
			'enableLimitReport' => $wgEnableParserLimitReporting,
		];
	}

	/**
	 * Get user options
	 *
	 * @param User $user
	 * @param Language $lang
	 */
	private function initialiseFromUser( $user, $lang ) {
		$this->options = self::getDefaults();

		$this->mUser = $user;
		$this->options['numberheadings'] = $user->getOption( 'numberheadings' );
		$this->options['thumbsize'] = $user->getOption( 'thumbsize' );
		$this->options['stubthreshold'] = $user->getStubThreshold();
		$this->options['userlang'] = $lang;
	}

	/**
	 * Check if these options match that of another options set
	 *
	 * This ignores report limit settings that only affect HTML comments
	 *
	 * @param ParserOptions $other
	 * @return bool
	 * @since 1.25
	 */
	public function matches( ParserOptions $other ) {
		// Populate lazy options
		foreach ( self::$lazyOptions as $name => $callback ) {
			if ( $this->options[$name] === null ) {
				$this->options[$name] = call_user_func( $callback, $this, $name );
			}
			if ( $other->options[$name] === null ) {
				$other->options[$name] = call_user_func( $callback, $other, $name );
			}
		}

		// Compare most options
		$options = array_keys( $this->options );
		$options = array_diff( $options, [
			'enableLimitReport', // only affects HTML comments
		] );
		foreach ( $options as $option ) {
			$o1 = $this->optionToString( $this->options[$option] );
			$o2 = $this->optionToString( $other->options[$option] );
			if ( $o1 !== $o2 ) {
				return false;
			}
		}

		// Compare most other fields
		$fields = array_keys( get_class_vars( __CLASS__ ) );
		$fields = array_diff( $fields, [
			'defaults', // static
			'lazyOptions', // static
			'inCacheKey', // static
			'options', // Already checked above
			'onAccessCallback', // only used for ParserOutput option tracking
		] );
		foreach ( $fields as $field ) {
			if ( !is_object( $this->$field ) && $this->$field !== $other->$field ) {
				return false;
			}
		}

		return true;
	}

	/**
	 * Registers a callback for tracking which ParserOptions which are used.
	 * This is a private API with the parser.
	 * @param callable $callback
	 */
	public function registerWatcher( $callback ) {
		$this->onAccessCallback = $callback;
	}

	/**
	 * Called when an option is accessed.
	 * Calls the watcher that was set using registerWatcher().
	 * Typically, the watcher callback is ParserOutput::registerOption().
	 * The information registered that way will be used by ParserCache::save().
	 *
	 * @param string $optionName Name of the option
	 */
	public function optionUsed( $optionName ) {
		if ( $this->onAccessCallback ) {
			call_user_func( $this->onAccessCallback, $optionName );
		}
	}

	/**
	 * Returns the full array of options that would have been used by
	 * in 1.16.
	 * Used to get the old parser cache entries when available.
	 * @deprecated since 1.30. You probably want self::allCacheVaryingOptions() instead.
	 * @return array
	 */
	public static function legacyOptions() {
		wfDeprecated( __METHOD__, '1.30' );
		return [
			'stubthreshold',
			'numberheadings',
			'userlang',
			'thumbsize',
			'editsection',
			'printable'
		];
	}

	/**
	 * Return all option keys that vary the options hash
	 * @since 1.30
	 * @return string[]
	 */
	public static function allCacheVaryingOptions() {
		// Trigger a call to the 'ParserOptionsRegister' hook if it hasn't
		// already been called.
		if ( self::$defaults === null ) {
			self::getDefaults();
		}
		return array_keys( array_filter( self::$inCacheKey ) );
	}

	/**
	 * Convert an option to a string value
	 * @param mixed $value
	 * @return string
	 */
	private function optionToString( $value ) {
		if ( $value === true ) {
			return '1';
		} elseif ( $value === false ) {
			return '0';
		} elseif ( $value === null ) {
			return '';
		} elseif ( $value instanceof Language ) {
			return $value->getCode();
		} elseif ( is_array( $value ) ) {
			return '[' . implode( ',', array_map( [ $this, 'optionToString' ], $value ) ) . ']';
		} else {
			return (string)$value;
		}
	}

	/**
	 * Generate a hash string with the values set on these ParserOptions
	 * for the keys given in the array.
	 * This will be used as part of the hash key for the parser cache,
	 * so users sharing the options with vary for the same page share
	 * the same cached data safely.
	 *
	 * @since 1.17
	 * @param array $forOptions
	 * @param Title $title Used to get the content language of the page (since r97636)
	 * @return string Page rendering hash
	 */
	public function optionsHash( $forOptions, $title = null ) {
		global $wgRenderHashAppend;

		$options = $this->options;
		$defaults = self::getCanonicalOverrides() + self::getDefaults();
		$inCacheKey = self::$inCacheKey;

		// We only include used options with non-canonical values in the key
		// so adding a new option doesn't invalidate the entire parser cache.
		// The drawback to this is that changing the default value of an option
		// requires manual invalidation of existing cache entries, as mentioned
		// in the docs on the relevant methods and hooks.
		$values = [];
		foreach ( $inCacheKey as $option => $include ) {
			if ( $include && in_array( $option, $forOptions, true ) ) {
				$v = $this->optionToString( $options[$option] );
				$d = $this->optionToString( $defaults[$option] );
				if ( $v !== $d ) {
					$values[] = "$option=$v";
				}
			}
		}

		$confstr = $values ? implode( '!', $values ) : 'canonical';

		// add in language specific options, if any
		// @todo FIXME: This is just a way of retrieving the url/user preferred variant
		if ( !is_null( $title ) ) {
			$confstr .= $title->getPageLanguage()->getExtraHashOptions();
		} else {
			global $wgContLang;
			$confstr .= $wgContLang->getExtraHashOptions();
		}

		$confstr .= $wgRenderHashAppend;

		if ( $this->mExtraKey != '' ) {
			$confstr .= $this->mExtraKey;
		}

		// Give a chance for extensions to modify the hash, if they have
		// extra options or other effects on the parser cache.
		Hooks::run( 'PageRenderingHash', [ &$confstr, $this->getUser(), &$forOptions ] );

		// Make it a valid memcached key fragment
		$confstr = str_replace( ' ', '_', $confstr );

		return $confstr;
	}

	/**
	 * Test whether these options are safe to cache
	 * @since 1.30
	 * @return bool
	 */
	public function isSafeToCache() {
		$defaults = self::getCanonicalOverrides() + self::getDefaults();
		foreach ( $this->options as $option => $value ) {
			if ( empty( self::$inCacheKey[$option] ) ) {
				$v = $this->optionToString( $value );
				$d = $this->optionToString( $defaults[$option] );
				if ( $v !== $d ) {
					return false;
				}
			}
		}
		return true;
	}

	/**
	 * Sets a hook to force that a page exists, and sets a current revision callback to return
	 * a revision with custom content when the current revision of the page is requested.
	 *
	 * @since 1.25
	 * @param Title $title
	 * @param Content $content
	 * @param User $user The user that the fake revision is attributed to
	 * @return ScopedCallback to unset the hook
	 */
	public function setupFakeRevision( $title, $content, $user ) {
		$oldCallback = $this->setCurrentRevisionCallback(
			function (
				$titleToCheck, $parser = false ) use ( $title, $content, $user, &$oldCallback
			) {
				if ( $titleToCheck->equals( $title ) ) {
					return new Revision( [
						'page' => $title->getArticleID(),
						'user_text' => $user->getName(),
						'user' => $user->getId(),
						'parent_id' => $title->getLatestRevID(),
						'title' => $title,
						'content' => $content
					] );
				} else {
					return call_user_func( $oldCallback, $titleToCheck, $parser );
				}
			}
		);

		global $wgHooks;
		$wgHooks['TitleExists'][] =
			function ( $titleToCheck, &$exists ) use ( $title ) {
				if ( $titleToCheck->equals( $title ) ) {
					$exists = true;
				}
			};
		end( $wgHooks['TitleExists'] );
		$key = key( $wgHooks['TitleExists'] );
		LinkCache::singleton()->clearBadLink( $title->getPrefixedDBkey() );
		return new ScopedCallback( function () use ( $title, $key ) {
			global $wgHooks;
			unset( $wgHooks['TitleExists'][$key] );
			LinkCache::singleton()->clearLink( $title );
		} );
	}
}

/**
 * For really cool vim folding this needs to be at the end:
 * vim: foldmarker=@{,@} foldmethod=marker
 */