<?php
/**
 * Parsoid/RESTBase+MediaWiki API wrapper.
 *
 * @file
 * @ingroup Extensions
 * @copyright 2011-2021 VisualEditor Team and others; see AUTHORS.txt
 * @license MIT
 */

use MediaWiki\Block\DatabaseBlock;
use MediaWiki\Content\Transform\ContentTransformer;
use MediaWiki\Linker\LinkRenderer;
use MediaWiki\Logger\LoggerFactory;
use MediaWiki\MediaWikiServices;
use MediaWiki\Revision\RevisionRecord;
use MediaWiki\SpecialPage\SpecialPageFactory;
use MediaWiki\User\UserNameUtils;
use MediaWiki\User\UserOptionsLookup;
use MediaWiki\Watchlist\WatchlistManager;
use Wikimedia\ParamValidator\ParamValidator;

class ApiVisualEditor extends ApiBase {
	use ApiBlockInfoTrait;
	use ApiParsoidTrait;

	/** @var UserNameUtils */
	private $userNameUtils;

	/** @var Parser */
	private $parser;

	/** @var LinkRenderer */
	private $linkRenderer;

	/** @var userOptionsLookup */
	private $userOptionsLookup;

	/** @var WatchlistManager */
	private $watchlistManager;

	/** @var ContentTransformer */
	private $contentTransformer;

	/** @var SpecialPageFactory */
	private $specialPageFactory;

	/** @var ReadOnlyMode */
	private $readOnlyMode;

	/**
	 * @param ApiMain $main
	 * @param string $name
	 * @param UserNameUtils $userNameUtils
	 * @param Parser $parser
	 * @param LinkRenderer $linkRenderer
	 * @param UserOptionsLookup $userOptionsLookup
	 * @param WatchlistManager $watchlistManager
	 * @param ContentTransformer $contentTransformer
	 * @param SpecialPageFactory $specialPageFactory
	 * @param ReadOnlyMode $readOnlyMode
	 */
	public function __construct(
		ApiMain $main,
		$name,
		UserNameUtils $userNameUtils,
		Parser $parser,
		LinkRenderer $linkRenderer,
		UserOptionsLookup $userOptionsLookup,
		WatchlistManager $watchlistManager,
		ContentTransformer $contentTransformer,
		SpecialPageFactory $specialPageFactory,
		ReadOnlyMode $readOnlyMode
	) {
		parent::__construct( $main, $name );
		$this->setLogger( LoggerFactory::getInstance( 'VisualEditor' ) );
		$this->userNameUtils = $userNameUtils;
		$this->parser = $parser;
		$this->linkRenderer = $linkRenderer;
		$this->userOptionsLookup = $userOptionsLookup;
		$this->watchlistManager = $watchlistManager;
		$this->contentTransformer = $contentTransformer;
		$this->specialPageFactory = $specialPageFactory;
		$this->readOnlyMode = $readOnlyMode;
	}

	/**
	 * Run wikitext through the parser's Pre-Save-Transform
	 *
	 * @param Title $title The title of the page to use as the parsing context
	 * @param string $wikitext The wikitext to transform
	 * @return string The transformed wikitext
	 */
	protected function pstWikitext( Title $title, $wikitext ) {
		$content = ContentHandler::makeContent( $wikitext, $title, CONTENT_MODEL_WIKITEXT );
		return $this->contentTransformer->preSaveTransform(
			$content,
			$title,
			$this->getUser(),
			WikiPage::factory( $title )->makeParserOptions( $this->getContext() )
		)
		->serialize( 'text/x-wiki' );
	}

	/**
	 * Provide the preload content for a page being created from another page
	 *
	 * @param string $preload The title of the page to use as the preload content
	 * @param string[] $params The preloadTransform parameters to pass in, if any
	 * @return string Wikitext content
	 */
	protected function getPreloadContent( $preload, $params ) {
		$content = '';
		$preloadTitle = Title::newFromText( $preload );

		// Use SpecialMyLanguage redirect so that nonexistent translated pages can
		// fall back to the corresponding page in a suitable language
		if ( $preloadTitle && $preloadTitle->isSpecialPage() ) {
			[ $spName, $spParam ] = $this->specialPageFactory->resolveAlias( $preloadTitle->getText() );
			if ( $spName ) {
				$specialPage = $this->specialPageFactory->getPage( $spName );
				if ( $specialPage instanceof SpecialMyLanguage ) {
					$preloadTitle = $specialPage->getRedirect( $spParam );
				}
			}
		}

		// Check for existence to avoid getting MediaWiki:Noarticletext
		if (
			$preloadTitle instanceof Title &&
			$preloadTitle->exists() &&
			$this->getPermissionManager()->userCan( 'read', $this->getUser(), $preloadTitle )
		) {
			$preloadPage = WikiPage::factory( $preloadTitle );
			if ( $preloadPage->isRedirect() ) {
				$preloadTitle = $preloadPage->getRedirectTarget();
				$preloadPage = WikiPage::factory( $preloadTitle );
			}

			$content = $preloadPage->getContent( RevisionRecord::RAW );
			$parserOptions = ParserOptions::newFromUser( $this->getUser() );

			$content = $this->contentTransformer->preloadTransform(
				$content,
				$preloadTitle,
				$parserOptions,
				(array)$params
			)->serialize();
		}
		return $content;
	}

	/**
	 * @inheritDoc
	 * @suppress PhanPossiblyUndeclaredVariable False positives
	 */
	public function execute() {
		$user = $this->getUser();
		$params = $this->extractRequestParams();
		$permissionManager = $this->getPermissionManager();

		$title = Title::newFromText( $params['page'] );
		if ( $title && $title->isSpecial( 'CollabPad' ) ) {
			// Convert Special:CollabPad/MyPage to MyPage so we can parsefragment properly
			$title = SpecialCollabPad::getSubPage( $title );
		}
		if ( !$title ) {
			$this->dieWithError( [ 'apierror-invalidtitle', wfEscapeWikiText( $params['page'] ) ] );
		}
		if ( !$title->canExist() ) {
			$this->dieWithError( 'apierror-pagecannotexist' );
		}

		$parserParams = [];
		if ( isset( $params['oldid'] ) ) {
			$parserParams['oldid'] = $params['oldid'];
		}

		wfDebugLog( 'visualeditor', "called on '$title' with paction: '{$params['paction']}'" );
		switch ( $params['paction'] ) {
			case 'parse':
			case 'wikitext':
			case 'metadata':
				$preloaded = false;
				$restbaseHeaders = null;

				$section = $params['section'] ?? null;

				// Get information about current revision
				if ( $title->exists() ) {
					$revision = $this->getValidRevision( $title, $parserParams['oldid'] ?? null );
					$latestRevision = $this->getLatestRevision( $title );

					$restoring = !$revision->isCurrent();
					$baseTimestamp = $latestRevision->getTimestamp();
					$oldid = $revision->getId();

					// If requested, request HTML from Parsoid/RESTBase
					if ( $params['paction'] === 'parse' ) {
						$wikitext = $params['wikitext'] ?? null;
						if ( $wikitext !== null ) {
							$stash = $params['stash'];
							if ( $params['pst'] ) {
								$wikitext = $this->pstWikitext( $title, $wikitext );
							}
							if ( $section !== null ) {
								$sectionContent = new WikitextContent( $wikitext );
								$page = WikiPage::factory( $title );
								$newSectionContent = $page->replaceSectionAtRev(
									$section, $sectionContent, '', $oldid
								);
								'@phan-var WikitextContent $newSectionContent';
								$wikitext = $newSectionContent->getText();
							}
							$response = $this->transformWikitext(
								$title, $wikitext, false, $oldid, $stash
							);
						} else {
							$response = $this->requestRestbasePageHtml( $revision );
						}
						$content = $response['body'];
						$restbaseHeaders = $response['headers'];
						if ( $content === false ) {
							$this->dieWithError( 'apierror-visualeditor-docserver', 'docserver' );
						}
					} elseif ( $params['paction'] === 'wikitext' ) {
						$apiParams = [
							'action' => 'query',
							'revids' => $oldid,
							'prop' => 'revisions',
							'rvprop' => 'content|ids'
						];

						$apiParams['rvsection'] = $section;

						$context = new DerivativeContext( $this->getContext() );
						$context->setRequest(
							new DerivativeRequest(
								$context->getRequest(),
								$apiParams,
								/* was posted? */ true
							)
						);
						$api = new ApiMain(
							$context,
							/* enable write? */ true
						);
						$api->execute();
						$result = $api->getResult()->getResultData();
						$pid = $title->getArticleID();
						$content = false;
						if ( isset( $result['query']['pages'][$pid]['revisions'] ) ) {
							foreach ( $result['query']['pages'][$pid]['revisions'] as $revArr ) {
								// Check 'revisions' is an array (T193718)
								if ( is_array( $revArr ) && $revArr['revid'] === $oldid ) {
									$content = $revArr['content'];
								}
							}
						}
						if ( $content === false ) {
							$this->dieWithError( 'apierror-visualeditor-docserver', 'docserver' );
						}
					}
				}

				if ( !$title->exists() || $section === 'new' ) {
					if ( isset( $params['wikitext'] ) ) {
						$content = $params['wikitext'];
						if ( $params['pst'] ) {
							$content = $this->pstWikitext( $title, $content );
						}
					} else {
						$content = '';
						if ( $title->getNamespace() == NS_MEDIAWIKI && $section !== 'new' ) {
							// If this is a system message, get the default text.
							$msg = $title->getDefaultMessageText();
							if ( $msg !== false ) {
								$content = $title->getDefaultMessageText();
							}
						}

						$contentBeforeHook = $content;
						if ( $section !== 'new' ) {
							Hooks::run( 'EditFormPreloadText', [ &$content, &$title ] );
						}
						// Make sure we don't mark default system message content as a preload
						if ( $content !== '' && $contentBeforeHook !== $content ) {
							$preloaded = true;
						} elseif ( $content === '' && !empty( $params['preload'] ) ) {
							$content = $this->getPreloadContent(
								$params['preload'], $params['preloadparams']
							);
							$preloaded = true;
						}
					}

					if ( $content !== '' && $params['paction'] !== 'wikitext' ) {
						$response = $this->transformWikitext( $title, $content, false, null, true );
						$content = $response['body'];
						$restbaseHeaders = $response['headers'];
					}
					$baseTimestamp = wfTimestampNow();
					$oldid = 0;
					$restoring = false;
				}

				$notices = [];

				// From EditPage#showCustomIntro
				if ( $params['editintro'] ) {
					$eiTitle = Title::newFromText( $params['editintro'] );
					if (
						$eiTitle instanceof Title &&
						$eiTitle->exists() &&
						$permissionManager->userCan( 'read', $user, $eiTitle )
					) {
						$notices['editintro'] = $this->parser->parse(
							'<div class="mw-editintro">{{:' . $eiTitle->getFullText() . '}}</div>',
							$title,
							new ParserOptions( $user )
						)->getText();
					}
				}

				// Add all page notices
				$notices = array_merge( $notices, $title->getEditNotices() );

				// Anonymous user notice
				if ( !$user->isRegistered() ) {
					$notices['anoneditwarning'] = $this->msg(
						'anoneditwarning',
						// Log-in link
						'{{fullurl:Special:UserLogin|returnto={{FULLPAGENAMEE}}}}',
						// Sign-up link
						'{{fullurl:Special:UserLogin/signup|returnto={{FULLPAGENAMEE}}}}'
					)->page( $title )->parseAsBlock();
				}

				// Old revision notice
				if ( $restoring ) {
					$notices['editingold'] = $this->msg( 'editingold' )->page( $title )->parseAsBlock();
				}

				if ( $this->readOnlyMode->isReadOnly() ) {
					$notices['readonlywarning'] = $this->msg( 'readonlywarning', $this->readOnlyMode->getReason() );
				}

				// Edit notices about the page being protected (only used when we're allowed to edit it;
				// otherwise, a generic permission error is displayed via #getUserPermissionsErrors)
				$protectionNotices = [];

				// New page notices
				if ( !$title->exists() ) {
					$newArticleKey = $user->isRegistered() ? 'newarticletext' : 'newarticletextanon';
					$notices[$newArticleKey] = $this->msg(
						$newArticleKey,
						wfExpandUrl( Skin::makeInternalOrExternalUrl(
							$this->msg( 'helppage' )->inContentLanguage()->text()
						) )
					)->page( $title )->parseAsBlock();

					// Page protected from creation
					if ( $title->getRestrictions( 'create' ) ) {
						$protectionNotices['titleprotectedwarning'] =
							$this->msg( 'titleprotectedwarning' )->page( $title )->parseAsBlock() .
							$this->getLastLogEntry( $title, 'protect' );
					}

					// From EditPage#showIntro, checking if the page has previously been deleted:
					$dbr = wfGetDB( DB_REPLICA );
					LogEventsList::showLogExtract( $out, [ 'delete', 'move' ], $title,
						'',
						[
							'lim' => 10,
							'conds' => [ 'log_action != ' . $dbr->addQuotes( 'revision' ) ],
							'showIfEmpty' => false,
							'msgKey' => [ 'recreate-moveddeleted-warn' ]
						]
					);
					if ( $out ) {
						$notices['recreate-moveddeleted-warn'] = $out;
					}
				}

				// Look at protection status to set up notices + surface class(es)
				$protectedClasses = [];
				if (
					$permissionManager->getNamespaceRestrictionLevels( $title->getNamespace() ) !== [ '' ]
				) {
					// Page protected from editing
					if ( $title->isProtected( 'edit' ) ) {
						// Is the title semi-protected?
						if ( $title->isSemiProtected() ) {
							$protectedClasses[] = 'mw-textarea-sprotected';

							$noticeMsg = 'semiprotectedpagewarning';
						} else {
							$protectedClasses[] = 'mw-textarea-protected';

							// Then it must be protected based on static groups (regular)
							$noticeMsg = 'protectedpagewarning';
						}
						$protectionNotices[$noticeMsg] = $this->msg( $noticeMsg )->page( $title )->parseAsBlock() .
							$this->getLastLogEntry( $title, 'protect' );
					}

					// Deal with cascading edit protection
					list( $sources, $restrictions ) = $title->getCascadeProtectionSources();
					if ( isset( $restrictions['edit'] ) ) {
						$protectedClasses[] = ' mw-textarea-cprotected';

						$notice = $this->msg( 'cascadeprotectedwarning', count( $sources ) )
							->page( $title )->parseAsBlock() . '<ul>';
						// Unfortunately there's no nice way to get only the pages which cause
						// editing to be restricted
						foreach ( $sources as $source ) {
							$notice .= "<li>" .
								$this->linkRenderer->makeLink( $source ) .
								"</li>";
						}
						$notice .= '</ul>';
						$protectionNotices['cascadeprotectedwarning'] = $notice;
					}
				}

				// Simplified EditPage::getEditPermissionErrors()
				$permErrors = $permissionManager->getPermissionErrors( 'edit', $user, $title, 'full' );

				if ( $permErrors ) {
					// Show generic permission errors, including page protection, user blocks, etc.
					$notice = $this->getOutput()->formatPermissionsErrorMessage( $permErrors, 'edit' );
					// That method returns wikitext (eww), hack to get it parsed:
					$notice = ( new RawMessage( '$1', [ $notice ] ) )->parseAsBlock();
					// Invent a message key 'permissions-error' to store in $notices
					$notices['permissions-error'] = $notice;
				} elseif ( $protectionNotices ) {
					// If we can edit, and the page is protected, then show the details about the protection
					$notices = array_merge( $notices, $protectionNotices );
				}

				// Will be false e.g. if user is blocked or page is protected
				$canEdit = !$permErrors;

				// Show notice when editing user / user talk page of a user that doesn't exist
				// or who is blocked
				// HACK of course this code is partly duplicated from EditPage.php :(
				if ( $title->getNamespace() == NS_USER || $title->getNamespace() == NS_USER_TALK ) {
					$parts = explode( '/', $title->getText(), 2 );
					$targetUsername = $parts[0];
					$targetUser = User::newFromName(
						$targetUsername,
						/* allow IP users*/ false
					);
					$block = $targetUser ? $targetUser->getBlock() : null;

					$targetUserExists = ( $targetUser && $targetUser->isRegistered() );
					if ( $targetUserExists && $targetUser->isHidden() &&
						!$permissionManager->userHasRight( $user, 'hideuser' )
					) {
						// If the user exists, but is hidden, and the viewer cannot see hidden
						// users, pretend like they don't exist at all. See T120883/T270453
						$targetUserExists = false;
					}
					if ( !$targetUserExists && !$this->userNameUtils->isIP( $targetUsername ) ) {
						// User does not exist
						$notices['userpage-userdoesnotexist'] = Html::warningBox(
							$this->msg( 'userpage-userdoesnotexist', wfEscapeWikiText( $targetUsername ) )
								->parse(),
							'mw-userpage-userdoesnotexist'
						);
					} elseif (
						$block !== null &&
						$block->getType() != DatabaseBlock::TYPE_AUTO &&
						( $block->isSitewide() || $permissionManager->isBlockedFrom( $targetUser, $title ) )
					) {
						// Show log extract if the user is sitewide blocked or is partially
						// blocked and not allowed to edit their user page or user talk page
						$notices['blocked-notice-logextract'] = $this->msg(
							'blocked-notice-logextract',
							// Support GENDER in notice
							$targetUser->getName()
						)->parseAsBlock() . $this->getLastLogEntry( $targetUser->getUserPage(), 'block' );
					}
				}

				$block = null;
				$blockinfo = null;
				// Blocked user notice
				if ( $user->isBlockedGlobally() ) {
					$block = $user->getGlobalBlock();
				} elseif ( $permissionManager->isBlockedFrom( $user, $title, true ) ) {
					$block = $user->getBlock();
				}
				if ( $block ) {
					// Already added to $notices via #getPermissionErrors above.
					// Add block info for MobileFrontend:
					$blockinfo = $this->getBlockDetails( $block );
				}

				// HACK: Build a fake EditPage so we can get checkboxes from it
				// Deliberately omitting ,0 so oldid comes from request
				$article = new Article( $title );
				$editPage = new EditPage( $article );
				$req = $this->getRequest();
				$req->setVal( 'format', $editPage->contentFormat );
				// By reference for some reason (T54466)
				$editPage->importFormData( $req );
				$states = [
					'minor' => $this->userOptionsLookup->getOption( $user, 'minordefault' ) && $title->exists(),
					'watch' => $this->userOptionsLookup->getOption( $user, 'watchdefault' ) ||
						( $this->userOptionsLookup->getOption( $user, 'watchcreations' ) && !$title->exists() ) ||
						$this->watchlistManager->isWatched( $user, $title ),
				];
				$checkboxesDef = $editPage->getCheckboxesDefinition( $states );
				$checkboxesMessagesList = [];
				foreach ( $checkboxesDef as &$options ) {
					if ( isset( $options['tooltip'] ) ) {
						$checkboxesMessagesList[] = "accesskey-{$options['tooltip']}";
						$checkboxesMessagesList[] = "tooltip-{$options['tooltip']}";
					}
					if ( isset( $options['title-message'] ) ) {
						$checkboxesMessagesList[] = $options['title-message'];
						if ( !is_string( $options['title-message'] ) ) {
							// Extract only the key. Any parameters are included in the fake message definition
							// passed via $checkboxesMessages. (This changes $checkboxesDef by reference.)
							$options['title-message'] = $this->msg( $options['title-message'] )->getKey();
						}
					}
					$checkboxesMessagesList[] = $options['label-message'];
					if ( !is_string( $options['label-message'] ) ) {
						// Extract only the key. Any parameters are included in the fake message definition
						// passed via $checkboxesMessages. (This changes $checkboxesDef by reference.)
						$options['label-message'] = $this->msg( $options['label-message'] )->getKey();
					}
				}
				$checkboxesMessages = [];
				foreach ( $checkboxesMessagesList as $messageSpecifier ) {
					// $messageSpecifier may be a string or a Message object
					$message = $this->msg( $messageSpecifier );
					$checkboxesMessages[ $message->getKey() ] = $message->plain();
				}

				foreach ( $checkboxesDef as &$value ) {
					// Don't convert the boolean to empty string with formatversion=1
					$value[ApiResult::META_BC_BOOLS] = [ 'default' ];
				}

				// Remove empty notices (T265798)
				$notices = array_filter( $notices );

				$copyrightWarning = EditPage::getCopyrightWarning(
					$title,
					'parse',
					$this
				);

				$result = [
					'result' => 'success',
					'notices' => $notices,
					'copyrightWarning' => $copyrightWarning,
					'checkboxesDef' => $checkboxesDef,
					'checkboxesMessages' => $checkboxesMessages,
					'protectedClasses' => implode( ' ', $protectedClasses ),
					'basetimestamp' => $baseTimestamp,
					'starttimestamp' => wfTimestampNow(),
					'oldid' => $oldid,
					'blockinfo' => $blockinfo,
					'canEdit' => $canEdit,
				];
				if ( isset( $restbaseHeaders['etag'] ) ) {
					$result['etag'] = $restbaseHeaders['etag'];
				}
				if ( isset( $params['badetag'] ) ) {
					$badetag = $params['badetag'];
					$goodetag = $result['etag'] ?? '';
					$this->getLogger()->info(
						__METHOD__ . ": Client reported bad ETag: {badetag}, expected: {goodetag}",
						[
							'badetag' => $badetag,
							'goodetag' => $goodetag,
						]
					);
				}

				if ( isset( $content ) ) {
					$result['content'] = $content;
					if ( $preloaded ) {
						// If the preload param was actually used, pass it
						// back so the caller knows. (It's not obvious to the
						// caller, because in some situations it'll depend on
						// whether the page has been created. They can work it
						// out from some of the other returns, but this is
						// simpler.)
						$result['preloaded'] = $params['preload'] ?? '1';
					}
				}
				break;

			case 'templatesused':
				// HACK: Build a fake EditPage so we can get checkboxes from it
				// Deliberately omitting ,0 so oldid comes from request
				$article = new Article( $title );
				$editPage = new EditPage( $article );
				$result = $editPage->makeTemplatesOnThisPageList( $editPage->getTemplates() );
				break;

			case 'parsedoc':
			case 'parsefragment':
				$wikitext = $params['wikitext'];
				if ( $wikitext === null ) {
					$this->dieWithError( [ 'apierror-missingparam', 'wikitext' ] );
				}
				$bodyOnly = ( $params['paction'] === 'parsefragment' );
				if ( $params['pst'] ) {
					$wikitext = $this->pstWikitext( $title, $wikitext );
				}
				$content = $this->transformWikitext(
					$title, $wikitext, $bodyOnly
				)['body'];
				if ( $content === false ) {
					$this->dieWithError( 'apierror-visualeditor-docserver', 'docserver' );
				} else {
					$result = [
						'result' => 'success',
						'content' => $content
					];
				}
				break;
		}

		$this->getResult()->addValue( null, $this->getModuleName(), $result );
	}

	/**
	 * Check if the configured allowed namespaces include the specified namespace
	 *
	 * @param Config $config
	 * @param int $namespaceId Namespace ID
	 * @return bool
	 */
	public static function isAllowedNamespace( Config $config, $namespaceId ) {
		return in_array( $namespaceId, self::getAvailableNamespaceIds( $config ) );
	}

	/**
	 * Get a list of allowed namespace IDs
	 *
	 * @param Config $config
	 * @return int[]
	 */
	public static function getAvailableNamespaceIds( Config $config ) {
		$namespaceInfo = MediaWikiServices::getInstance()->getNamespaceInfo();
		$configuredNamespaces = array_replace(
			ExtensionRegistry::getInstance()->getAttribute( 'VisualEditorAvailableNamespaces' ),
			$config->get( 'VisualEditorAvailableNamespaces' )
		);
		$normalized = [];
		foreach ( $configuredNamespaces as $id => $enabled ) {
			// Convert canonical namespace names to IDs
			$id = $namespaceInfo->getCanonicalIndex( strtolower( $id ) ) ?? $id;
			$normalized[$id] = $enabled && $namespaceInfo->exists( $id );
		}
		ksort( $normalized );
		return array_keys( array_filter( $normalized ) );
	}

	/**
	 * Check if the configured allowed content models include the specified content model
	 *
	 * @param Config $config
	 * @param string $contentModel Content model ID
	 * @return bool
	 */
	public static function isAllowedContentType( Config $config, $contentModel ) {
		$availableContentModels = array_merge(
			ExtensionRegistry::getInstance()->getAttribute( 'VisualEditorAvailableContentModels' ),
			$config->get( 'VisualEditorAvailableContentModels' )
		);
		return (bool)( $availableContentModels[$contentModel] ?? false );
	}

	/**
	 * Gets the relevant HTML for the latest log entry on a given title, including a full log link.
	 *
	 * @param Title $title
	 * @param array|string $types
	 * @return string
	 */
	private function getLastLogEntry( Title $title, $types = '' ) {
		$outString = '';
		LogEventsList::showLogExtract( $outString, $types, $title, '',
			[ 'lim' => 1 ] );
		return $outString;
	}

	/**
	 * @inheritDoc
	 */
	public function getAllowedParams() {
		return [
			'page' => [
				ParamValidator::PARAM_REQUIRED => true,
			],
			'badetag' => null,
			'format' => [
				ParamValidator::PARAM_DEFAULT => 'jsonfm',
				ParamValidator::PARAM_TYPE => [ 'json', 'jsonfm' ],
			],
			'paction' => [
				ParamValidator::PARAM_REQUIRED => true,
				ParamValidator::PARAM_TYPE => [
					'parse',
					'metadata',
					'templatesused',
					'wikitext',
					'parsefragment',
					'parsedoc',
				],
			],
			'wikitext' => [
				ParamValidator::PARAM_TYPE => 'text',
				ParamValidator::PARAM_DEFAULT => null,
			],
			'section' => null,
			'stash' => null,
			'oldid' => null,
			'editintro' => null,
			'pst' => false,
			'preload' => null,
			'preloadparams' => [
				ParamValidator::PARAM_ISMULTI => true,
			],
		];
	}

	/**
	 * @inheritDoc
	 */
	public function needsToken() {
		return false;
	}

	/**
	 * @inheritDoc
	 */
	public function isInternal() {
		return true;
	}

	/**
	 * @inheritDoc
	 */
	public function isWriteMode() {
		return false;
	}
}