/**
 * docs.ts — scroll-spy sidebar for all Muse developer docs pages.
 *
 * Observes .devdocs-section[id] elements and marks the matching
 * .devdocs-nav-link--sub link active as sections scroll into view.
 *
 * Registered for every docs-* page key in app.ts.
 */

function initScrollSpy(): void {
  const links = document.querySelectorAll<Element>('.devdocs-nav-link--sub');
  if (!links.length) return;
  const observer = new IntersectionObserver(
    (entries) => {
      entries.forEach((e) => {
        if (e.isIntersecting) {
          links.forEach((l) => l.classList.remove('devdocs-nav-link--active'));
          const target = document.querySelector(
            `.devdocs-nav-link--sub[href="#${e.target.id}"]`
          );
          if (target) target.classList.add('devdocs-nav-link--active');
        }
      });
    },
    { rootMargin: '-20% 0px -70% 0px' }
  );
  document.querySelectorAll('.devdocs-section[id]').forEach((s) => observer.observe(s));
}

export function initDocs(): void {
  initScrollSpy();
}