cci: fix section element detection

Prior to this, the "Start working on this
section" overlay would appear far after
the next available section, instead only
appearing after the next contribution
survey row (which does not account for H1
headings, other sections, etc.)

This changes the detection to also break
the detection as soon as it finds a
section heading that isn't a CSR heading.

src/util/last.ts

@@ -1,5 +1,3 @@
-// These don't recognize TypeScript multiple definitions.
-/* eslint-disable jsdoc/require-returns-check */
 /**
  * Returns the last item of a NodeList array.
  *
@@ -14,6 +12,13 @@ function last<T extends Node>( array: NodeListOf<T> ): T;
  * @return The last element of the array
  */
 function last<T>( array: T[] ): T;
+/**
+ * Returns the last character of a string.
+ *
+ * @param string The string to get the last character from
+ * @return The last character of the string
+ */
+function last( string: string ): string;
 /**
  * Returns the last item of an array.
  *

src/wiki/DeputyCasePage.ts

@@ -3,6 +3,8 @@ import sectionHeadingName from './util/sectionHeadingName';
 import getPageTitle from './util/getPageTitle';
 import DeputyCase from './DeputyCase';
 import sectionHeadingId from './util/sectionHeadingId';
+import isWikiHeading from './util/isWikiHeading';
+import getWikiHeadingLevel from './util/getWikiHeadingLevel';
 
 export type ContributionSurveyHeading = HTMLHeadingElement;
 
@@ -147,7 +149,7 @@ export default class DeputyCasePage extends DeputyCase {
 			el :
 			el.querySelector<HTMLElement>( '.mw-headline' );
 		// Handle DiscussionTools case (.mw-heading)
-		return ( el.classList.contains( 'mw-heading' ) || /^H\d$/.test( el.tagName ) ) &&
+		return isWikiHeading( el ) &&
 			headlineElement != null &&
 			/(Page|Article|Local file|File)s? \d+ (to|through) \d+$/.test( headlineElement.innerText );
 	}
@@ -248,11 +250,24 @@ export default class DeputyCasePage extends DeputyCase {
 	getContributionSurveySection( sectionHeading: HTMLElement ): Node[] {
 		// Normalize "sectionHeading" to use the h* element and not the .mw-heading span.
 		sectionHeading = this.normalizeSectionHeading( sectionHeading );
+		const sectionHeadingLevel = getWikiHeadingLevel( sectionHeading );
 
 		const sectionMembers: Node[] = [];
 
 		let nextSibling = sectionHeading.nextSibling;
-		while ( nextSibling != null && !this.isContributionSurveyHeading( nextSibling ) ) {
+		while (
+			// Not the end of rendered page content and
+			nextSibling != null &&
+			// Next node is not...
+			!(
+				// An element
+				nextSibling instanceof Element &&
+				// A heading (of any level)
+				isWikiHeading( nextSibling ) &&
+				// Higher than the current heading level
+				sectionHeadingLevel >= getWikiHeadingLevel( nextSibling )
+			)
+		) {
 			sectionMembers.push( nextSibling );
 			nextSibling = nextSibling.nextSibling as HTMLElement;
 		}

src/wiki/util/getWikiHeadingLevel.ts

@@ -0,0 +1,23 @@
+import last from '../../util/last';
+
+/**
+ * Get the level (1 to 6) of any parsed wikitext heading.
+ *
+ * This is its own function to account for different parse outputs (Legacy, Parsoid,
+ * DiscussionTools, etc.)
+ *
+ * @param el The element to check. This MUST be a wikitext heading.
+ * @return The level of the heading (1 to 6)
+ */
+export default function getWikiHeadingLevel( el: Element ) {
+	const h = el.classList.contains( 'mw-heading' ) ?
+		el.querySelector( 'h1, h2, h3, h4, h5, h6' ) :
+		el;
+
+	// Check if this is a valid header
+	if ( !/^H\d+$/.test( h.tagName ) ) {
+		throw new Error( 'Heading element does not contain a valid <h*> element' );
+	}
+
+	return +last( h.tagName ) as 1 | 2 | 3 | 4 | 5 | 6;
+}

src/wiki/util/isWikiHeading.ts

@@ -0,0 +1,12 @@
+/**
+ * Check if a given parameter is a wikitext heading parsed into HTML.
+ *
+ * This is its own function to account for different parse outputs (Legacy, Parsoid,
+ * DiscussionTools, etc.)
+ *
+ * @param el The element to check
+ * @return `true` if the element is a heading, `false` otherwise
+ */
+export default function isWikiHeading( el: Element ): boolean {
+	return ( el.classList.contains( 'mw-heading' ) || /^H\d$/.test( el.tagName ) );
+}