<?php
/**
 * 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
 */

namespace MediaWiki\Preferences;

use MediaWiki\Config\ServiceOptions;
use MediaWiki\Html\Html;
use MediaWiki\MainConfigNames;
use MediaWiki\Parser\ParserFactory;
use MediaWiki\Parser\ParserOptions;
use MediaWiki\Parser\ParserOutputFlags;
use MediaWiki\Parser\Parsoid\LintErrorChecker;
use MediaWiki\SpecialPage\SpecialPage;
use MediaWiki\SpecialPage\SpecialPageFactory;
use MediaWiki\Title\TitleFactory;
use MediaWiki\User\UserIdentity;
use MessageLocalizer;
use OOUI\ButtonWidget;

/**
 * @since 1.35
 */
class SignatureValidator {

	/** @var array Made public for use in services */
	public const CONSTRUCTOR_OPTIONS = [
		MainConfigNames::SignatureAllowedLintErrors,
		MainConfigNames::VirtualRestConfig,
	];

	/** @var UserIdentity */
	private $user;
	/** @var MessageLocalizer|null */
	private $localizer;
	/** @var ParserOptions */
	private $popts;
	/** @var ParserFactory */
	private $parserFactory;
	private LintErrorChecker $lintErrorChecker;
	/** @var ServiceOptions */
	private $serviceOptions;
	/** @var SpecialPageFactory */
	private $specialPageFactory;
	/** @var TitleFactory */
	private $titleFactory;

	/**
	 * @param ServiceOptions $options
	 * @param UserIdentity $user
	 * @param ?MessageLocalizer $localizer
	 * @param ParserOptions $popts
	 * @param ParserFactory $parserFactory
	 * @param LintErrorChecker $lintErrorChecker
	 * @param SpecialPageFactory $specialPageFactory
	 * @param TitleFactory $titleFactory
	 */
	public function __construct(
		ServiceOptions $options,
		UserIdentity $user,
		?MessageLocalizer $localizer,
		ParserOptions $popts,
		ParserFactory $parserFactory,
		LintErrorChecker $lintErrorChecker,
		SpecialPageFactory $specialPageFactory,
		TitleFactory $titleFactory
	) {
		$this->user = $user;
		$this->localizer = $localizer;
		$this->popts = $popts;
		$this->parserFactory = $parserFactory;
		$this->lintErrorChecker = $lintErrorChecker;
		// Configuration
		$this->serviceOptions = $options;
		$this->serviceOptions->assertRequiredOptions( self::CONSTRUCTOR_OPTIONS );
		// TODO SpecialPage::getTitleFor should also be available via SpecialPageFactory
		$this->specialPageFactory = $specialPageFactory;
		$this->titleFactory = $titleFactory;
	}

	/**
	 * @param string $signature Signature before PST
	 * @return string[]|bool If localizer is defined: List of errors, as HTML (empty array for no errors)
	 *   If localizer is not defined: True if there are errors, false if there are no errors
	 */
	public function validateSignature( string $signature ) {
		$pstSignature = $this->applyPreSaveTransform( $signature );
		if ( $pstSignature === false ) {
			// Return early because the rest of the validation uses wikitext parsing, which requires
			// the pre-save transform to be applied first, and we just found out that the result of the
			// pre-save transform would require *another* pre-save transform, which is crazy
			if ( $this->localizer ) {
				return [ $this->localizer->msg( 'badsigsubst' )->parse() ];
			}
			return true;
		}

		$pstWasApplied = false;
		if ( $pstSignature !== $signature ) {
			$pstWasApplied = true;
			$signature = $pstSignature;
		}

		$errors = $this->localizer ? [] : false;

		$lintErrors = $this->checkLintErrors( $signature );
		if ( $lintErrors ) {
			$messages = '';

			foreach ( $lintErrors as $error ) {
				if ( !$this->localizer ) {
					$errors = true;
					break;
				}

				$details = $this->getLintErrorDetails( $error );
				$location = $this->getLintErrorLocation( $error );
				// THESE MESSAGE IDS SHOULD BE KEPT IN SYNC WITH
				// those declared in Extension:Linter -- in particular
				// there should be a linterror-<cat> declared here for every
				// linter-pager-<cat>-details declared in Linter's qqq.json.
				// T360809: this redundancy should be eventually eliminated

				// Messages used here:
				// * linterror-bogus-image-options
				// * linterror-deletable-table-tag
				// * linterror-fostered
				// * linterror-html5-misnesting
				// * linterror-inline-media-caption
				// * linterror-large-tables
				// * linterror-misc-tidy-replacement-issues
				// * linterror-misnested-tag
				// * linterror-missing-end-tag
				// * linterror-missing-end-tag-in-heading
				// * linterror-missing-image-alt-text
				// * linterror-multi-colon-escape
				// * linterror-multiline-html-table-in-list
				// * linterror-multiple-unclosed-formatting-tags
				// * linterror-night-mode-unaware-background-color
				// * linterror-obsolete-tag
				// * linterror-pwrap-bug-workaround
				// * linterror-self-closed-tag
				// * linterror-stripped-tag
				// * linterror-tidy-font-bug
				// * linterror-tidy-whitespace-bug
				// * linterror-unclosed-quotes-in-heading
				// * linterror-wikilink-in-extlink
				$label = $this->localizer->msg( "linterror-{$error['type']}" )->parse();
				$docsLink = new ButtonWidget( [
					'href' =>
						"https://www.mediawiki.org/wiki/Special:MyLanguage/Help:Lint_errors/{$error['type']}",
					'target' => '_blank',
					'label' => $this->localizer->msg( 'prefs-signature-error-details' )->text(),
				] );

				// If pre-save transform was applied (i.e., the signature has 'subst:' syntax),
				// error locations will be incorrect, because Parsoid can't expand templates.
				// Don't display them.
				$encLocation = $pstWasApplied ? null : json_encode( $location );

				$messages .= Html::rawElement(
					'li',
					[ 'data-mw-lint-error-location' => $encLocation ],
					$label . $this->localizer->msg( 'colon-separator' )->escaped() .
						$details . ' ' . $docsLink
				);
			}

			if ( $messages && $this->localizer ) {
				$errors[] = $this->localizer->msg( 'badsightml' )->parse() .
					Html::rawElement( 'ol', [], $messages );
			}
		}

		if ( !$this->checkUserLinks( $signature ) ) {
			if ( $this->localizer ) {
				$userText = wfEscapeWikiText( $this->user->getName() );
				$linkWikitext = $this->localizer->msg( 'signature', $userText, $userText )->inContentLanguage()->text();
				$errors[] = $this->localizer->msg( 'badsiglinks', wfEscapeWikiText( $linkWikitext ) )->parse();
			} else {
				$errors = true;
			}
		}

		if ( !$this->checkLineBreaks( $signature ) ) {
			if ( $this->localizer ) {
				$errors[] = $this->localizer->msg( 'badsiglinebreak' )->parse();
			} else {
				$errors = true;
			}
		}

		return $errors;
	}

	/**
	 * @param string $signature Signature before PST
	 * @return string|false Signature with PST applied, or false if applying PST yields wikitext that
	 *     would change if PST was applied again
	 */
	protected function applyPreSaveTransform( string $signature ) {
		// This may be called by the Parser when it's displaying a signature, so we need a new instance
		$parser = $this->parserFactory->getInstance();

		$pstSignature = $parser->preSaveTransform(
			$signature,
			SpecialPage::getTitleFor( 'Preferences' ),
			$this->user,
			$this->popts
		);

		// The signature wikitext contains another '~~~~' or similar (T230652)
		if ( $parser->getOutput()->getOutputFlag( ParserOutputFlags::USER_SIGNATURE ) ) {
			return false;
		}

		// The signature wikitext contains '{{subst:...}}' markup that produces another subst (T230652)
		$pstPstSignature = $parser->preSaveTransform(
			$pstSignature,
			SpecialPage::getTitleFor( 'Preferences' ),
			$this->user,
			$this->popts
		);
		if ( $pstPstSignature !== $pstSignature ) {
			return false;
		}

		return $pstSignature;
	}

	/**
	 * @param string $signature Signature after PST
	 * @return array Array of error objects returned by Parsoid's lint API (empty array for no errors)
	 */
	protected function checkLintErrors( string $signature ): array {
		// Real check for mismatched HTML tags in the *output*.
		// This has to use Parsoid because PHP Parser doesn't produce this information,
		// it just fixes up the result quietly.

		$disabled = array_merge(
			[
				// Always appears with 'missing-end-tag', we can ignore it to
				// simplify the error message
				'multiple-unclosed-formatting-tags',
			],
			$this->serviceOptions->get(
				MainConfigNames::SignatureAllowedLintErrors
			)
		);
		return $this->lintErrorChecker->checkSome( $signature, $disabled );
	}

	/**
	 * @param string $signature Signature after PST
	 * @return bool Whether signature contains required links
	 */
	protected function checkUserLinks( string $signature ): bool {
		// This may be called by the Parser when it's displaying a signature, so we need a new instance
		$parser = $this->parserFactory->getInstance();

		// Check for required links. This one's easier to do with the PHP Parser.
		$pout = $parser->parse(
			$signature,
			SpecialPage::getTitleFor( 'Preferences' ),
			$this->popts
		);

		// Checking user or talk links is easy
		$links = $pout->getLinks();
		$username = $this->user->getName();
		if (
			isset( $links[ NS_USER ][ strtr( $username, ' ', '_' ) ] ) ||
			isset( $links[ NS_USER_TALK ][ strtr( $username, ' ', '_' ) ] )
		) {
			return true;
		}

		// Checking the contributions link is harder, because the special page name and the username in
		// the "subpage parameter" are not normalized for us.
		$splinks = $pout->getLinksSpecial();
		foreach ( $splinks as $dbkey => $unused ) {
			[ $name, $subpage ] = $this->specialPageFactory->resolveAlias( $dbkey );
			if ( $name === 'Contributions' && $subpage ) {
				$userTitle = $this->titleFactory->makeTitleSafe( NS_USER, $subpage );
				if ( $userTitle && $userTitle->getText() === $username ) {
					return true;
				}
			}
		}

		return false;
	}

	/**
	 * @param string $signature Signature after PST
	 * @return bool Whether signature contains no line breaks
	 */
	protected function checkLineBreaks( string $signature ): bool {
		return !preg_match( "/[\r\n]/", $signature );
	}

	// Adapted from the Linter extension
	private function getLintErrorLocation( array $lintError ): array {
		return array_slice( $lintError['dsr'], 0, 2 );
	}

	// Adapted from the Linter extension
	private function getLintErrorDetails( array $lintError ): string {
		[ 'type' => $type, 'params' => $params ] = $lintError;

		if ( $type === 'bogus-image-options' && isset( $params['items'] ) ) {
			$list = array_map( static function ( $in ) {
				return Html::element( 'code', [], $in );
			}, $params['items'] );
			return implode(
				$this->localizer->msg( 'comma-separator' )->escaped(),
				$list
			);
		} elseif ( $type === 'pwrap-bug-workaround' &&
			isset( $params['root'] ) &&
			isset( $params['child'] ) ) {
			return Html::element( 'code', [],
				$params['root'] . " > " . $params['child'] );
		} elseif ( $type === 'tidy-whitespace-bug' &&
			isset( $params['node'] ) &&
			isset( $params['sibling'] ) ) {
			return Html::element( 'code', [],
				$params['node'] . " + " . $params['sibling'] );
		} elseif ( $type === 'multi-colon-escape' &&
			isset( $params['href'] ) ) {
			return Html::element( 'code', [], $params['href'] );
		} elseif ( $type === 'multiline-html-table-in-list' ) {
			/* ancestor and name will be set */
			return Html::element( 'code', [],
				$params['ancestorName'] . " > " . $params['name'] );
		} elseif ( $type === 'misc-tidy-replacement-issues' ) {
			/* There will be a 'subtype' param to disambiguate */
			return Html::element( 'code', [], $params['subtype'] );
		} elseif ( $type === 'missing-end-tag' ) {
			return Html::element( 'code', [], '</' . $params['name'] . '>' );
		} elseif ( isset( $params['name'] ) ) {
			return Html::element( 'code', [], $params['name'] );
		}

		return '';
	}

}