TalkBelow.php

<?php

use MediaWiki\Hook\SkinAfterContentHook;
use MediaWiki\MediaWikiServices;
use MediaWiki\Page\WikiPageFactory;

class TalkBelow implements SkinAfterContentHook {

	/** @var WikiPageFactory */
	private $wikiPageFactory;

	public function __construct( WikiPageFactory $wikiPageFactory ) {
		$this->wikiPageFactory = $wikiPageFactory;
	}

	/**
	 * @param OutputPage &$out
	 * @param Skin &$skin
	 */
	public static function onBeforePageDisplay( OutputPage &$out, Skin &$skin ) {
		$out->addModuleStyles( 'mediawiki.ui.button' );
		$out->addModules( 'ext.TalkBelow' );
	}

	/**
	 * @param array &$ids
	 */
	public static function onGetDoubleUnderscoreIDs( &$ids ) {
		$ids[] = 'NOTALKBELOW';
	}

	/**
	 * Pass the config to JavaScript
	 *
	 * @param array &$vars
	 * @param string $skin
	 * @param Config $config
	 */
	public static function onResourceLoaderGetConfigVars( array &$vars, $skin, Config $config ) {
		$vars['wgTalkBelowChangeTag'] = $config->get( 'TalkBelowChangeTag' );
	}

	/**
	 * Hide the Talk button
	 *
	 * @param SkinTemplate $skinTemplate
	 * @param array &$links
	 */
	public static function onSkinTemplateNavigationUniversal( SkinTemplate $skinTemplate, array &$links ) {
		$title = $skinTemplate->getTitle();
		if ( !$title->exists() ) {
			return;
		}
		$parserOutput = $skinTemplate->getWikiPage()->getParserOutput();
		if ( $parserOutput->getPageProperty( 'NOTALKBELOW' ) !== null ) {
			return;
		}
		unset( $links['namespaces']['talk'] );
	}

	/**
	 * Show the talk below section
	 *
	 * @param string &$data
	 * @param Skin $skin
	 */
	public function onSkinAfterContent( &$data, $skin ) {
		// Only show when viewing pages
		$context = $skin->getContext();
		$action = Action::getActionName( $context );
		if ( $action !== 'view' ) {
			return;
		}

		// Only show in pages that exist
		$title = $skin->getTitle();
		if ( !$title->exists() ) {
			return;
		}

		// Don't show in talk pages
		if ( $title->isTalkPage() ) {
			return;
		}

		// Don't show in pages that can't have talk pages
		if ( !$title->canHaveTalkPage() ) {
			return;
		}

		// Don't show if __NOTALKBELOW__ is present
		$parserOutput = $skin->getWikiPage()->getParserOutput();
		if ( $parserOutput->getPageProperty( 'NOTALKBELOW' ) !== null ) {
			return;
		}

		// If the talk page is a redirect, show the talk in the redirect target
		$talk = $title->getTalkPage();
		if ( $talk->isRedirect() ) {
			$redirectLookup = MediaWikiServices::getInstance()->getRedirectLookup();
			$talk = $redirectLookup->getRedirectTarget( $talk );
		}

		// Some pages, like the village pump, may have their talk page be a redirect to the subject page
		if ( $title->equals( $talk ) ) {
			return;
		}

		// Get the HTML of the talk page
		$talkHtml = '';
		if ( $talk->exists() ) {
			$talkPage = $this->wikiPageFactory->newFromLinkTarget( $talk );
			$talkOutput = $talkPage->getParserOutput();
			$talkHtml = $talkOutput->getText( [ 'allowTOC' => false ] );
		}

		// Build the HTML of the discussion section, starting with the section heading and actions
		$view = Html::rawElement( 'a', [ 'href' => $talk->getLinkURL() ], $context->msg( 'view' ) );
		$edit = Html::rawElement( 'a', [ 'href' => $talk->getEditURL() ], $context->msg( 'edit' ) );
		$bracket = Html::rawElement( 'span', [ 'class' => 'mw-editsection-bracket' ], '[' );
		$divider = Html::rawElement( 'span', [ 'class' => 'mw-editsection-divider' ], ' | ' );
		$bracket2 = Html::rawElement( 'span', [ 'class' => 'mw-editsection-bracket' ], ']' );
		$editsection = $bracket . $view . $divider . $edit . $bracket2;
		$wrapper = Html::rawElement( 'span', [ 'class' => 'mw-editsection' ], $editsection );
		$heading = Html::rawElement( 'h1', [ 'id' => 'talkbelow-heading' ], $context->msg( 'talk' ) . $wrapper );

		// Build the button to add a new topic. This will be replaced in the frontend, but is needed for non-JS users.
		$addTopicButton = HTML::element(
			'a',
			[
				'class' => [ 'mw-ui-button' ],
				'href' => $talk->getLinkURL( 'action=edit&section=new' ),
			],
			$context->msg( 'skin-action-addsection' )
		);
		$addTopicWrapper = Html::rawElement( 'div', [ 'id' => 'talkbelow-add-topic-button' ], $addTopicButton );

		// Put everything together
		$section = $heading . $talkHtml . $addTopicWrapper;
		$section = Html::rawElement( 'div', [ 'id' => 'talkbelow-section', 'class' => 'noprint' ], $section );
		$data = $section;
	}
}