Enable clicking on wikilinks and external links in highlighted code

It's common practise to use [[wikilink]] syntax to mention page names
in comments of JS/CSS/Scribunto code where the links ordinarily don't
work. Using JavaScript to actually make the syntax clickable makes
navigation easier.

{{Templates links}} and external links are also supported.

Bug: T368166
Change-Id: I999937c1f6303ecc64adb6285e73a9ce10f67bd8

extension.json

@@ -38,9 +38,10 @@
 				"pygments.wrapper.less"
 			]
 		},
-		"ext.pygments.linenumbers": {
+		"ext.pygments.view": {
 			"scripts": [
-				"pygments.linenumbers.js"
+				"pygments.linenumbers.js",
+				"pygments.links.js"
 			],
 			"dependencies": [
 				"mediawiki.util"

includes/SyntaxHighlight.php

@@ -196,10 +196,7 @@ class SyntaxHighlight extends ExtensionTagHandler implements
 
 		// Register CSS
 		$parser->getOutput()->addModuleStyles( self::getModuleStyles() );
-		if ( !empty( $args['linelinks'] ) ) {
+		$parser->getOutput()->addModules( [ 'ext.pygments.view' ] );
-			$parser->getOutput()->addModules( [ 'ext.pygments.linenumbers' ] );
-		}
-
 		return $result['html'];
 	}
 
@@ -598,7 +595,7 @@ class SyntaxHighlight extends ExtensionTagHandler implements
 		$out = $status->getValue();
 
 		$parserOutput->addModuleStyles( self::getModuleStyles() );
-		$parserOutput->addModules( [ 'ext.pygments.linenumbers' ] );
+		$parserOutput->addModules( [ 'ext.pygments.view' ] );
 		$parserOutput->setText( $out );
 
 		// Inform MediaWiki that we have parsed this page and it shouldn't mess with it.

modules/pygments.links.js

@@ -0,0 +1,61 @@
+/**
+ * Adapted from https://en.wiktionary.org/wiki/MediaWiki:Gadget-CodeLinks.js
+ * Original authors: Kephir, Erutuon
+ * License: CC-BY-SA 4.0
+ */
+
+$( () => {
+	// by John Gruber, from https://daringfireball.net/2010/07/improved_regex_for_matching_urls
+	const URLRegExp = /\b((?:https?:\/\/|www\d{0,3}[.]|[a-z0-9.-]+[.][a-z]{2,4}\/)(?:[^\s()<>]+|\(([^\s()<>]+|(\([^\s()<>]+\)))*\))+(?:\(([^\s()<>]+|(\([^\s()<>]+\)))*\)|[^\s`!()[\]{};:'".,<>?«»“”‘’]))/i;
+
+	function processComment( node ) {
+		let wikilinkMatch, templateMatch, URLMatch;
+		const textNode = node.firstChild; // always a text node.
+
+		while (
+			( wikilinkMatch = /\[\[([^|{}[\]\n]+)?(?:\|.*?)?]]/.exec( textNode.data ) ) ||
+			( templateMatch = /\{\{([^|{}[\]\n#]+)(?=\||}})/i.exec( textNode.data ) ) ||
+			( URLMatch = URLRegExp.exec( textNode.data ) )
+		) {
+			const link = document.createElement( 'a' );
+			let start = ( wikilinkMatch || templateMatch || URLMatch ).index;
+			let linkText;
+			link.classList.add( 'code-link' );
+
+			if ( URLMatch ) {
+				const URL = URLMatch[ 0 ];
+				link.href = URL;
+				linkText = URL;
+			} else {
+				let fullPageName;
+				if ( wikilinkMatch ) {
+					linkText = wikilinkMatch[ 0 ];
+					fullPageName = wikilinkMatch[ 1 ];
+				} else if ( templateMatch ) {
+					const pageName = templateMatch[ 1 ];
+					linkText = pageName;
+					fullPageName = mw.config.get( 'wgFormattedNamespaces' )[ 10 ] + ':' + pageName;
+					link.title = fullPageName;
+					start += 2; // opening braces "{{"
+				}
+				link.href = mw.util.getUrl( fullPageName );
+			}
+
+			const beforeLink = textNode.data.slice( 0, Math.max( 0, start ) ),
+				afterLink = textNode.data.slice( Math.max( 0, start + linkText.length ) );
+
+			textNode.data = afterLink;
+			link.appendChild( document.createTextNode( linkText ) );
+			node.insertBefore( link, textNode );
+			node.insertBefore( document.createTextNode( beforeLink ), link );
+		}
+	}
+
+	const commentClasses = [ 'c', 'c1', 'cm' ];
+	Array.from( document.getElementsByClassName( 'mw-highlight' ) ).forEach( ( codeBlock ) => {
+		commentClasses.forEach( ( commentClass ) => {
+			Array.from( codeBlock.getElementsByClassName( commentClass ) ).forEach( processComment );
+		} );
+	} );
+
+} );