import { defineRouteMiddleware } from "@astrojs/starlight/route-data";
import type { StarlightRouteData } from "@astrojs/starlight/route-data";

// starlight always seeds the table of contents with a link back to the page
// title, so `toc` is truthy even on pages with no headings and the "on this
// page" overview renders empty. drop it in that case.
const PAGE_TITLE_ID = "_top";

type TocItem = NonNullable<StarlightRouteData["toc"]>["items"][number];

function hasSections(items: TocItem[]): boolean {
	return items.some(
		(item) => item.slug !== PAGE_TITLE_ID || hasSections(item.children),
	);
}

export const onRequest = defineRouteMiddleware((context) => {
	const route = context.locals.starlightRoute;
	if (route.toc && !hasSections(route.toc.items)) {
		route.toc = undefined;
	}
});