util: add diff URL parser

src/modules/ante/ui/pages/CopiedTemplateRowPage.tsx

@@ -16,6 +16,7 @@ import RevisionDateGetButton from '../components/RevisionDateGetButton';
 import SmartTitleInputWidget from '../components/SmartTitleInputWidget';
 import PageLatestRevisionGetButton from '../components/PageLatestRevisionGetButton';
 import dangerModeConfirm from '../../../../util/dangerModeConfirm';
+import parseDiffUrl from '../../../../wiki/util/parseDiffUrl';
 
 export interface CopiedTemplateRowPageData {
 	/**
@@ -551,33 +552,12 @@ function initCopiedTemplateRowPage() {
 						return;
 					}
 				}
-				// From the same wiki, accept deprecation
-
-				// Attempt to get values from URL parameters (when using `/w/index.php?action=diff`)
-				let oldid = url.searchParams.get( 'oldid' );
-				let diff = url.searchParams.get( 'diff' );
-				const title = url.searchParams.get( 'title' );
-
-				// Attempt to get values from Special:Diff short-link
-				const diffSpecialPageCheck =
-					// eslint-disable-next-line security/detect-unsafe-regex
-					/\/wiki\/Special:Diff\/(prev|next|\d+)(?:\/(prev|next|\d+))?/.exec( url.pathname );
-				if ( diffSpecialPageCheck != null ) {
-					if (
-						diffSpecialPageCheck[ 1 ] != null &&
-						diffSpecialPageCheck[ 2 ] == null
-					) {
-						// Special:Diff/diff
-						diff = diffSpecialPageCheck[ 1 ];
-					} else if (
-						diffSpecialPageCheck[ 1 ] != null &&
-						diffSpecialPageCheck[ 2 ] != null
-					) {
-						// Special:Diff/oldid/diff
-						oldid = diffSpecialPageCheck[ 1 ];
-						diff = diffSpecialPageCheck[ 2 ];
-					}
-				}
+				// From the same wiki, accept deprecation immediately.
+
+				// Parse out info from this diff URL
+				const parseInfo = parseDiffUrl( url );
+				let { diff, oldid } = parseInfo;
+				const { title } = parseInfo;
 
 				// If only an oldid was provided, and no diff
 				if ( oldid && !diff ) {

src/wiki/util/index.ts

@@ -43,6 +43,7 @@ export default {
 	nsId: nsId,
 	openWindow: openWindow,
 	pagelinkToTitle: pagelinkToTitle,
+	parseDiffUrl: parseDiffUrl,
 	performHacks: performHacks,
 	purge: purge,
 	renderWikitext: renderWikitext,

src/wiki/util/parseDiffUrl.ts

@@ -0,0 +1,92 @@
+interface DiffInfo {
+	diff?: number | string;
+	oldid?: number | string;
+	title?: string;
+}
+
+/**
+ * What it says on the tin. Attempt to parse out a `title`, `diff`,
+ * or `oldid` from a URL. This is useful for converting diff URLs into actual
+ * diff information, and especially useful for {{copied}} templates.
+ *
+ * @param url The URL to parse
+ * @return Parsed info: `diff` or `oldid` revision IDs, and/or the page title.
+ */
+export default function parseDiffUrl( url: URL | string ): DiffInfo {
+	if ( typeof url === 'string' ) {
+		url = new URL( url );
+	}
+
+	// Attempt to get values from URL parameters (when using `/w/index.php?action=diff`)
+	let oldid: string | number = url.searchParams.get( 'oldid' );
+	let diff: string | number = url.searchParams.get( 'diff' );
+	let title = url.searchParams.get( 'title' );
+
+	// Attempt to get information from this URL.
+	tryConvert: {
+		if ( title && oldid && diff ) {
+			// Skip if there's nothing else we need to get.
+			break tryConvert;
+		}
+
+		// Attempt to get values from Special:Diff short-link
+		const diffSpecialPageCheck =
+			// eslint-disable-next-line security/detect-unsafe-regex
+			/\/wiki\/Special:Diff\/(prev|next|\d+)(?:\/(prev|next|\d+))?/i.exec( url.pathname );
+		if ( diffSpecialPageCheck != null ) {
+			if (
+				diffSpecialPageCheck[ 1 ] != null &&
+				diffSpecialPageCheck[ 2 ] == null
+			) {
+				// Special:Diff/diff
+				diff = diffSpecialPageCheck[ 1 ];
+			} else if (
+				diffSpecialPageCheck[ 1 ] != null &&
+				diffSpecialPageCheck[ 2 ] != null
+			) {
+				// Special:Diff/oldid/diff
+				oldid = diffSpecialPageCheck[ 1 ];
+				diff = diffSpecialPageCheck[ 2 ];
+			}
+			break tryConvert;
+		}
+
+		// Attempt to get values from Special:PermanentLink short-link
+		const permanentLinkCheck =
+			/\/wiki\/Special:Perma(nent)?link\/(\d+)/i.exec( url.pathname );
+		if ( permanentLinkCheck != null ) {
+			oldid = permanentLinkCheck[ 2 ];
+			break tryConvert;
+		}
+
+		// Attempt to get values from article path with ?oldid or ?diff
+		// eslint-disable-next-line security/detect-non-literal-regexp
+		const articlePathRegex = new RegExp( mw.util.getUrl( '(.*)' ) )
+			.exec( url.pathname );
+		if ( articlePathRegex != null ) {
+			title = articlePathRegex[ 1 ];
+			break tryConvert;
+		}
+	}
+
+	// Convert numbers to numbers
+	if ( oldid != null && !isNaN( +oldid ) ) {
+		oldid = +oldid;
+	}
+	if ( diff != null && !isNaN( +diff ) ) {
+		diff = +diff;
+	}
+
+	// Try to convert a page title
+	try {
+		title = new mw.Title( title ).getPrefixedText();
+	} catch ( e ) {
+		console.warn( 'Failed to normalize page title during diff URL conversion.' );
+	}
+
+	return {
+		diff: diff,
+		oldid: oldid,
+		title: title
+	};
+}