/* ============================================================
   About Us — CSS sticky pin + rAF scroll-linked (no GSAP)
   Smoothest approach: CSS position:sticky handles the pin
   (native GPU compositing), rAF drives the cross-fade timeline.
   Stage 1 (au-1): intro(screen1) -> slogan(screen2)
   Stage 2 (au-3): Strong Resources(screen3) -> zoom+logo(screen4)
   ============================================================ */
(function () {
  var s1 = document.querySelector('#au-1');
  var s3 = document.querySelector('#au-3');
  if (!s1) return;

  var bg = s1.querySelector('.au-bg');
  var intro = s1.querySelector('.au-inner');
  var corner = s1.querySelector('.au-corner-img');
  var mask = s1.querySelector('.au-mask');
  var layer = s1.querySelector('.au-slogan-layer');
  var sl = s1.querySelector('.au-slogan');
  var cn = s1.querySelector('.au-slogan-cn');

  var head = s3 ? s3.querySelector('.au-sec-head') : null;
  var zoom = s3 ? s3.querySelector('.au-zoom-img') : null;
  var zoomMask = s3 ? s3.querySelector('.au-zoom-mask') : null;
  var reveal = s3 ? s3.querySelector('.au-reveal') : null;

  function clamp(v, a, b) { return Math.max(a, Math.min(b, v)); }
  function lerp(a, b, t) { return a + (b - a) * clamp(t, 0, 1); }

  var start1 = 0, start3 = 0;
  function measure() {
    function dt(el) { var r = el.getBoundingClientRect(); return r.top + window.scrollY; }
    start1 = dt(s1);
    if (s3) start3 = dt(s3);
  }

  function update() {
    var vh = window.innerHeight;

    /* ---- au-1 (pin 2vh): intro held -> cross-fade to slogan ---- */
    var p = clamp((window.scrollY - start1) / vh, 0, 2);  // 0 -> 2

    // bg: subtle cinematic scale throughout
    if (bg) bg.style.transform = 'scale(' + lerp(1.04, 1, p / 2).toFixed(4) + ')';

    // intro (screen 1): held 0-0.3, fades up 0.3-0.6
    var introT = clamp((p - 0.3) / 0.3, 0, 1);
    if (intro) { intro.style.opacity = String(1 - introT); intro.style.transform = 'translateY(' + (-introT * 30).toFixed(1) + 'px)'; }
    if (corner) corner.style.opacity = String(1 - introT);

    // mask: darkens 0.3-0.6
    if (mask) mask.style.opacity = String(introT);

    // slogan (screen 2): triggered CSS transition at threshold (NIO-style auto rise-up)
    if (layer) layer.classList.toggle('is-current', p >= 0.5);

    /* ---- au-3 (pin 2vh): Strong Resources -> zoom + logo ---- */
    if (s3) {
      var q = clamp((window.scrollY - start3) / vh, 0, 2);
      var t = clamp((q - 1.0) / 1.0, 0, 1);

      // head (screen 3): held first screen, fades second
      if (head) head.style.opacity = String(clamp(1 - (q - 0.6) / 0.3, 0, 1));
      // zoom: scale to fullscreen; photo opacity stays 1 — a black veil fades in over it
      if (zoom) {
        zoom.style.transform = 'translate(-50%, -50%) scale(' + lerp(1, 2.2, t).toFixed(3) + ')';
      }
      if (zoomMask) zoomMask.style.opacity = String(lerp(0, 0.8, t).toFixed(3));
      // reveal (screen 4): logo+text in second screen
      if (reveal) reveal.style.opacity = String(clamp((q - 1.1) / 0.4, 0, 1));
    }
  }

  var ticking = false;
  function onScroll() {
    if (ticking) return;
    ticking = true;
    requestAnimationFrame(function () { update(); ticking = false; });
  }

  window.addEventListener('scroll', onScroll, { passive: true });
  window.addEventListener('resize', function () { measure(); onScroll(); });
  measure();
  update();
})();

/* ============================================================
   GPS data carousel — auto-rotate + dot navigation
   ============================================================ */
(function () {
  var track = document.querySelector('.au-gps__track');
  var dotsWrap = document.querySelector('.au-gps__dots');
  if (!track || !dotsWrap) return;
  var cards = Array.prototype.slice.call(track.children);
  if (cards.length < 2) return;
  var idx = 0, timer = null;

  cards.forEach(function (_, i) {
    var b = document.createElement('button');
    b.setAttribute('aria-label', 'Slide ' + (i + 1));
    b.addEventListener('click', function () { goTo(i); restart(); });
    dotsWrap.appendChild(b);
  });
  var dots = Array.prototype.slice.call(dotsWrap.children);

  function render() {
    track.style.transform = 'translateX(' + (-idx * 100) + '%)';
    dots.forEach(function (d, i) { d.classList.toggle('active', i === idx); });
  }
  function goTo(i) { idx = ((i % cards.length) + cards.length) % cards.length; render(); }
  function next() { goTo(idx + 1); }
  function start() { timer = setInterval(next, 4000); }
  function restart() { clearInterval(timer); start(); }

  render();
  start();
  // pause auto-rotate while hovering
  track.addEventListener('mouseenter', function () { clearInterval(timer); });
  track.addEventListener('mouseleave', start);
})();