(function () {
  'use strict';

  if (window.__DBC_SITE_V280__) return;
  window.__DBC_SITE_V280__ = true;

  const body = document.body;
  const html = document.documentElement;
  const reducedMotion = window.matchMedia('(prefers-reduced-motion: reduce)').matches;

  function markRelease() {
    const release = body.dataset.dbcRelease || html.dataset.dbcRelease || 'v3.0.0';
    html.dataset.dbcRelease = release;
    body.dataset.dbcRelease = release;
    body.classList.add('v280-enhanced');
    const footer = document.querySelector('footer.site-footer');
    if (footer) footer.dataset.dbcRelease = release;
  }

  function markHero() {
    if (body.dataset.v280Archetype === 'home') return;
    const hero = document.querySelector('main > :is(section, article):first-child');
    if (!hero) return;
    hero.dataset.v280Hero = '';
  }

  function addMeasuredReveal() {
    if (body.dataset.v280Archetype === 'home') return;

    const candidates = Array.from(document.querySelectorAll([
      'main > section:not(:first-child) > :is(.section-head, .home-section-title, .formal-shell > .formal-section-head, .news-list-heading)',
      'main > section:not(:first-child) > :is(.v245-shell, .formal-shell) > :is(.v245-section-head, .formal-section-head)',
      'main > section:not(:first-child) > :is(.about-hero-copy, .request-intro)'
    ].join(','))).slice(0, 18);

    if (!candidates.length) return;
    candidates.forEach(function (element) { element.dataset.v280Reveal = ''; });

    if (reducedMotion || !('IntersectionObserver' in window)) {
      candidates.forEach(function (element) { element.classList.add('is-v280-visible'); });
      return;
    }

    html.classList.add('v280-motion-ready');
    const observer = new IntersectionObserver(function (entries) {
      entries.forEach(function (entry) {
        if (!entry.isIntersecting) return;
        entry.target.classList.add('is-v280-visible');
        observer.unobserve(entry.target);
      });
    }, { threshold: .12, rootMargin: '0px 0px -8% 0px' });

    candidates.forEach(function (element) {
      if (element.getBoundingClientRect().top < window.innerHeight * .94) {
        element.classList.add('is-v280-visible');
      } else {
        observer.observe(element);
      }
    });
  }

  function enhanceSectionNavigation() {
    const navs = Array.from(document.querySelectorAll('main + nav, main nav, .about-anchor-nav, .formal-page-nav'));
    const links = navs.flatMap(function (nav) {
      return Array.from(nav.querySelectorAll('a[href^="#"]'));
    });
    if (!links.length || !('IntersectionObserver' in window)) return;

    const map = new Map();
    links.forEach(function (link) {
      const id = decodeURIComponent(link.getAttribute('href').slice(1));
      const section = id ? document.getElementById(id) : null;
      if (section) map.set(section, link);
    });
    if (!map.size) return;

    const observer = new IntersectionObserver(function (entries) {
      const visible = entries
        .filter(function (entry) { return entry.isIntersecting; })
        .sort(function (a, b) { return b.intersectionRatio - a.intersectionRatio; });
      if (!visible.length) return;
      links.forEach(function (link) { link.removeAttribute('data-v280-current'); });
      const current = map.get(visible[0].target);
      if (current) current.setAttribute('data-v280-current', 'true');
    }, { rootMargin: '-22% 0px -66% 0px', threshold: [0, .1, .3] });

    map.forEach(function (_, section) { observer.observe(section); });
  }

  markRelease();
  markHero();
  addMeasuredReveal();
  enhanceSectionNavigation();
})();