<?php

namespace MediaWiki\Extension\DiscussionTools;

use Language;
use MediaWiki\Extension\DiscussionTools\Hooks\HookUtils;
use MediaWiki\MediaWikiServices;
use MediaWiki\User\UserIdentity;
use MWExceptionHandler;
use ParserOutput;
use Throwable;
use Title;
use WebRequest;
use Wikimedia\Assert\Assert;
use Wikimedia\Parsoid\DOM\Element;
use Wikimedia\Parsoid\Utils\DOMCompat;
use Wikimedia\Parsoid\Utils\DOMUtils;
use Wikimedia\Parsoid\Wt2Html\XMLSerializer;

class CommentFormatter {
	// List of features which, when enabled, cause the comment formatter to run
	public const USE_WITH_FEATURES = [
		HookUtils::REPLYTOOL,
		HookUtils::TOPICSUBSCRIPTION,
	];

	/**
	 * Get a comment parser object for a DOM element
	 *
	 * This method exists so it can mocked in tests.
	 *
	 * @return CommentParser
	 */
	protected static function getParser(): CommentParser {
		return MediaWikiServices::getInstance()->getService( 'DiscussionTools.CommentParser' );
	}

	/**
	 * Add discussion tools to some HTML
	 *
	 * @param string &$text Parser text output (modified by reference)
	 * @param ParserOutput $pout ParserOutput object for metadata, e.g. parser limit report
	 * @param Title $title
	 */
	public static function addDiscussionTools( string &$text, ParserOutput $pout, Title $title ): void {
		$start = microtime( true );
		$requestId = null;

		try {
			$text = static::addDiscussionToolsInternal( $text, $title );
		} catch ( Throwable $e ) {
			// Catch errors, so that they don't cause the entire page to not display.
			// Log it and report the request ID to make it easier to find in the logs.
			MWExceptionHandler::logException( $e );
			$requestId = WebRequest::getRequestId();
		}

		$duration = microtime( true ) - $start;

		$stats = MediaWikiServices::getInstance()->getStatsdDataFactory();
		$stats->timing( 'discussiontools.addReplyLinks', $duration * 1000 );

		// How long this method took, in seconds
		$pout->setLimitReportData(
			'discussiontools-limitreport-timeusage',
			sprintf( '%.3f', $duration )
		);
		if ( $requestId ) {
			// Request ID where errors were logged (only if an error occurred)
			$pout->setLimitReportData(
				'discussiontools-limitreport-errorreqid',
				$requestId
			);
		}
	}

	/**
	 * Add discussion tools to some HTML
	 *
	 * @param string $html HTML
	 * @param Title $title
	 * @return string HTML with discussion tools
	 */
	protected static function addDiscussionToolsInternal( string $html, Title $title ): string {
		// The output of this method can end up in the HTTP cache (Varnish). Avoid changing it;
		// and when doing so, ensure that frontend code can handle both the old and new outputs.
		// See controller#init in JS.

		$doc = DOMUtils::parseHTML( $html );
		$container = DOMCompat::getBody( $doc );

		$threadItemSet = static::getParser()->parse( $container, $title->getTitleValue() );
		$threadItems = $threadItemSet->getThreadItems();

		// Iterate in reverse order, because adding the range markers for a thread item
		// can invalidate the ranges of subsequent thread items (T298096)
		foreach ( array_reverse( $threadItems ) as $threadItem ) {
			// TODO: Consider not attaching JSON data to the DOM.
			// Create a dummy node to attach data to.
			if ( $threadItem instanceof HeadingItem && $threadItem->isPlaceholderHeading() ) {
				$node = $doc->createElement( 'span' );
				$container->insertBefore( $node, $container->firstChild );
				$threadItem->setRange( new ImmutableRange( $node, 0, $node, 0 ) );
			}

			// Add start and end markers to range
			$id = $threadItem->getId();
			$range = $threadItem->getRange();
			$startMarker = $doc->createElement( 'span' );
			$startMarker->setAttribute( 'data-mw-comment-start', '' );
			$startMarker->setAttribute( 'id', $id );
			$endMarker = $doc->createElement( 'span' );
			$endMarker->setAttribute( 'data-mw-comment-end', $id );

			// Extend the range if the start or end is inside an element which can't have element children.
			// (There may be other problematic elements... but this seems like a good start.)
			while ( CommentUtils::cantHaveElementChildren( $range->startContainer ) ) {
				$range = $range->setStart(
					$range->startContainer->parentNode,
					CommentUtils::childIndexOf( $range->startContainer )
				);
			}
			while ( CommentUtils::cantHaveElementChildren( $range->endContainer ) ) {
				$range = $range->setEnd(
					$range->endContainer->parentNode,
					CommentUtils::childIndexOf( $range->endContainer ) + 1
				);
			}

			$range->setStart( $range->endContainer, $range->endOffset )->insertNode( $endMarker );
			$range->insertNode( $startMarker );

			$itemData = $threadItem->jsonSerialize();
			$itemJSON = json_encode( $itemData );

			if ( $threadItem instanceof HeadingItem ) {
				// <span class="mw-headline" …>, or <hN …> in Parsoid HTML
				$headline = $threadItem->getRange()->endContainer;
				Assert::precondition( $headline instanceof Element, 'HeadingItem refers to an element node' );
				$headline->setAttribute( 'data-mw-comment', $itemJSON );
				if ( $threadItem->isSubscribable() ) {
					$headingNode = CommentUtils::closestElement( $headline, [ 'h2' ] );

					if ( $headingNode ) {
						DOMCompat::getClassList( $headingNode )->add( 'ext-discussiontools-init-section' );

						// Replaced in ::postprocessTopicSubscription() as the icon depends on user state
						$subscribe = $doc->createComment( '__DTSUBSCRIBE__' . $threadItem->getName() );

						$headingNode->appendChild( $subscribe );
					}
				}
			} elseif ( $threadItem instanceof CommentItem ) {
				$replyLinkButtons = $doc->createElement( 'span' );
				$replyLinkButtons->setAttribute( 'class', 'ext-discussiontools-init-replylink-buttons' );

				// Reply
				$replyLink = $doc->createElement( 'a' );
				$replyLink->setAttribute( 'class', 'ext-discussiontools-init-replylink-reply' );
				$replyLink->setAttribute( 'role', 'button' );
				$replyLink->setAttribute( 'tabindex', '0' );
				$replyLink->setAttribute( 'data-mw-comment', $itemJSON );
				// Set empty 'href' to avoid a:not([href]) selector in MobileFrontend
				$replyLink->setAttribute( 'href', '' );
				// Replaced in ::postprocessReplyTool() as the label depends on user language
				$replyText = $doc->createComment( '__DTREPLY__' );
				$replyLink->appendChild( $replyText );

				$bracket = $doc->createElement( 'span' );
				$bracket->setAttribute( 'class', 'ext-discussiontools-init-replylink-bracket' );
				$bracketOpen = $bracket->cloneNode( false );
				$bracketClose = $bracket->cloneNode( false );
				// Replaced in ::postprocessReplyTool() to avoid displaying empty brackets in various
				// contexts where parser output is used (API T292345, search T294168, action=render)
				$bracketOpen->appendChild( $doc->createComment( '__DTREPLYBRACKETOPEN__' ) );
				$bracketClose->appendChild( $doc->createComment( '__DTREPLYBRACKETCLOSE__' ) );

				$replyLinkButtons->appendChild( $bracketOpen );
				$replyLinkButtons->appendChild( $replyLink );
				$replyLinkButtons->appendChild( $bracketClose );

				CommentModifier::addReplyLink( $threadItem, $replyLinkButtons );
			}
		}

		// Like DOMCompat::getInnerHTML(), but disable 'smartQuote' for compatibility with
		// ParserOutput::EDITSECTION_REGEX matching 'mw:editsection' tags (T274709)
		return XMLSerializer::serialize( $container, [ 'innerXML' => true, 'smartQuote' => false ] )['html'];
	}

	/**
	 * Replace placeholders for topic subscription buttons with the real thing.
	 *
	 * @param string $text
	 * @param Language $lang
	 * @param SubscriptionStore $subscriptionStore
	 * @param UserIdentity $user
	 * @return string
	 */
	public static function postprocessTopicSubscription(
		string $text, Language $lang, SubscriptionStore $subscriptionStore, UserIdentity $user
	): string {
		$doc = DOMCompat::newDocument( true );

		$matches = [];
		preg_match_all( '/<!--__DTSUBSCRIBE__(.*?)-->/', $text, $matches );
		$itemNames = $matches[1];

		$items = $subscriptionStore->getSubscriptionItemsForUser(
			$user,
			$itemNames
		);
		$itemsByName = [];
		foreach ( $items as $item ) {
			$itemsByName[ $item->getItemName() ] = $item;
		}

		$text = preg_replace_callback(
			'/<!--__DTSUBSCRIBE__(.*?)-->/',
			static function ( $matches ) use ( $doc, $itemsByName, $lang ) {
				$itemName = $matches[1];
				$isSubscribed = isset( $itemsByName[ $itemName ] ) && !$itemsByName[ $itemName ]->isMuted();
				$subscribedState = isset( $itemsByName[ $itemName ] ) ? $itemsByName[ $itemName ]->getState() : null;

				$subscribe = $doc->createElement( 'span' );
				$subscribe->setAttribute(
					'class',
					'ext-discussiontools-init-section-subscribe mw-editsection-like'
				);

				$subscribeLink = $doc->createElement( 'a' );
				// Set empty 'href' to avoid a:not([href]) selector in MobileFrontend
				$subscribeLink->setAttribute( 'href', '' );
				$subscribeLink->setAttribute( 'class', 'ext-discussiontools-init-section-subscribe-link' );
				$subscribeLink->setAttribute( 'role', 'button' );
				$subscribeLink->setAttribute( 'tabindex', '0' );
				$subscribeLink->setAttribute( 'title', wfMessage(
					$isSubscribed ?
						'discussiontools-topicsubscription-button-unsubscribe-tooltip' :
						'discussiontools-topicsubscription-button-subscribe-tooltip'
				)->inLanguage( $lang )->text() );
				$subscribeLink->nodeValue = wfMessage(
					$isSubscribed ?
						'discussiontools-topicsubscription-button-unsubscribe' :
						'discussiontools-topicsubscription-button-subscribe'
				)->inLanguage( $lang )->text();

				if ( $subscribedState !== null ) {
					$subscribeLink->setAttribute( 'data-mw-subscribed', (string)$subscribedState );
				}

				$bracket = $doc->createElement( 'span' );
				$bracket->setAttribute( 'class', 'ext-discussiontools-init-section-subscribe-bracket' );
				$bracketOpen = $bracket->cloneNode( false );
				$bracketOpen->nodeValue = '[';
				$bracketClose = $bracket->cloneNode( false );
				$bracketClose->nodeValue = ']';

				$subscribe->appendChild( $bracketOpen );
				$subscribe->appendChild( $subscribeLink );
				$subscribe->appendChild( $bracketClose );

				return DOMCompat::getOuterHTML( $subscribe );
			},
			$text
		);
		return $text;
	}

	/**
	 * Replace placeholders for reply links with the real thing.
	 *
	 * @param string $text
	 * @param Language $lang
	 * @return string
	 */
	public static function postprocessReplyTool(
		string $text, Language $lang
	) {
		$replyText = wfMessage( 'discussiontools-replylink' )->inLanguage( $lang )->escaped();

		$text = strtr( $text, [
			 '<!--__DTREPLY__-->' => $replyText,
			 '<!--__DTREPLYBRACKETOPEN__-->' => '[',
			 '<!--__DTREPLYBRACKETCLOSE__-->' => ']',
		] );

		return $text;
	}

}