(function () {
  var root = document.querySelector("[data-hero]");
  if (!root) return;

  var slides = Array.prototype.slice.call(root.querySelectorAll("[data-hero-slide]"));
  var thumbs = Array.prototype.slice.call(root.querySelectorAll("[data-hero-index]"));
  var currentEl = root.querySelector("[data-hero-current]");
  var fillEl = root.querySelector(".hero__pager-fill");
  var bgEl = root.querySelector("[data-hero-bg]");
  var total = slides.length;
  if (!total) return;

  var index = 0;
  var timer = null;
  var interval = 3000;
  var bgToken = 0;
  var touchStartX = null;
  var touchStartY = null;
  var mouseStartX = null;
  var mouseStartY = null;
  var mouseDown = false;
  var suppressClickUntil = 0;
  var posterPreloadTimer = null;
  var bgLayers = [];
  var activeBgIndex = 0;

  if (bgEl) {
    var alternateBg = bgEl.cloneNode(false);
    alternateBg.classList.remove("is-active", "lazy");
    alternateBg.removeAttribute("data-hero-bg");
    alternateBg.removeAttribute("data-src");
    alternateBg.removeAttribute("data-lazy-eager");
    alternateBg.removeAttribute("data-decrypted");
    alternateBg.removeAttribute("data-decrypt-failed");
    alternateBg.removeAttribute("fetchpriority");
    alternateBg.src = "/static/images/placeholder.png?v=2";
    bgEl.parentNode.insertBefore(alternateBg, bgEl.nextSibling);
    bgLayers = [bgEl, alternateBg];
  }

  // 初始 HTML 只展示首张；脚本就绪后改为叠层，由 CSS 完成平滑交叉过渡。
  slides.forEach(function (slide, i) {
    slide.removeAttribute("hidden");
    slide.setAttribute("aria-hidden", i === index ? "false" : "true");
  });

  function pad(n) {
    return n < 10 ? "0" + n : String(n);
  }

  function slideBgSrc(slide) {
    var media = slide.querySelector("[data-hero-media]");
    if (!media) return "";
    return media.getAttribute("data-hero-media") || media.getAttribute("data-src") || "";
  }

  function loadSlidePoster(slideIndex) {
    var slide = slides[slideIndex];
    if (!slide) return;
    var poster = slide.querySelector("[data-hero-poster]");
    if (!poster || poster.getAttribute("data-hero-loaded") === "1" || poster.getAttribute("data-hero-loading") === "1") {
      return;
    }

    var src = poster.getAttribute("data-src") || "";
    if (!src) return;
    poster.setAttribute("data-hero-loading", "1");

    function done() {
      poster.removeAttribute("data-hero-loading");
      poster.setAttribute("data-hero-loaded", "1");
    }

    if (typeof window.processImage === "function") {
      window.processImage(src, poster).then(done);
      return;
    }

    poster.addEventListener("load", done, { once: true });
    poster.addEventListener("error", done, { once: true });
    poster.src = src;
  }

  function queueNextPoster() {
    if (posterPreloadTimer) {
      window.clearTimeout(posterPreloadTimer);
    }
    if (total < 2) return;
    posterPreloadTimer = window.setTimeout(function () {
      loadSlidePoster((index + 1) % total);
    }, 600);
  }

  function syncBg(slide) {
    if (!bgLayers.length) return;
    var src = slideBgSrc(slide);
    if (!src) return;

    var currentBg = bgLayers[activeBgIndex];
    var nextBgIndex = activeBgIndex === 0 ? 1 : 0;
    var targetBg = bgLayers[nextBgIndex];

    if (currentBg.getAttribute("data-src") === src) {
      targetBg = currentBg;
      nextBgIndex = activeBgIndex;
    }

    targetBg.setAttribute("data-src", src);
    targetBg.removeAttribute("data-decrypted");
    targetBg.removeAttribute("data-decrypt-failed");

    var token = ++bgToken;
    function reveal(result) {
      if (token !== bgToken) return;
      if (result) {
        targetBg.setAttribute("data-decrypted", "1");
      }
      if (nextBgIndex === activeBgIndex) return;
      window.requestAnimationFrame(function () {
        if (token !== bgToken) return;
        targetBg.classList.add("is-active");
        currentBg.classList.remove("is-active");
        activeBgIndex = nextBgIndex;
      });
    }

    if (typeof window.processImage === "function") {
      // 必须走解密；禁止把加密原址直接赋给 src
      window.processImage(src, targetBg).then(reveal);
      return;
    }
    targetBg.src = src;
    reveal(src);
  }

  function goTo(next) {
    var nextIndex = ((next % total) + total) % total;
    if (nextIndex === index) return;
    index = nextIndex;
    loadSlidePoster(index);
    queueNextPoster();

    slides.forEach(function (slide, i) {
      var active = i === index;
      slide.classList.toggle("is-active", active);
      slide.setAttribute("aria-hidden", active ? "false" : "true");
      if (active) {
        syncBg(slide);
      }
    });

    thumbs.forEach(function (thumb, i) {
      var active = i === index;
      thumb.classList.toggle("is-active", active);
      thumb.setAttribute("aria-selected", active ? "true" : "false");
    });

    if (currentEl) currentEl.textContent = pad(index + 1);
    if (fillEl) fillEl.style.width = ((index + 1) / total) * 100 + "%";
  }

  function next() {
    goTo(index + 1);
  }

  function previous() {
    goTo(index - 1);
  }

  function start() {
    stop();
    if (total < 2 || mouseDown || touchStartX !== null) return;
    timer = window.setInterval(next, interval);
  }

  function stop() {
    if (timer) {
      window.clearInterval(timer);
      timer = null;
    }
  }

  thumbs.forEach(function (thumb) {
    var thumbIndex = Number(thumb.getAttribute("data-hero-index"));

    function preloadThumbSlide() {
      if (!Number.isNaN(thumbIndex)) {
        loadSlidePoster(thumbIndex);
      }
    }

    thumb.addEventListener("mouseenter", preloadThumbSlide);
    thumb.addEventListener("focus", preloadThumbSlide);
    thumb.addEventListener("touchstart", preloadThumbSlide, { passive: true });
    thumb.addEventListener("click", function () {
      if (Number.isNaN(thumbIndex)) return;
      goTo(thumbIndex);
      start();
    });
  });

  var canHover = !window.matchMedia || window.matchMedia("(hover: hover)").matches;
  if (canHover) {
    root.addEventListener("mouseenter", stop);
    root.addEventListener("mouseleave", start);
  }

  root.addEventListener("dragstart", function (event) {
    event.preventDefault();
  });

  root.addEventListener("mousedown", function (event) {
    if (event.button !== 0) return;
    mouseStartX = event.clientX;
    mouseStartY = event.clientY;
    mouseDown = true;
    root.classList.add("is-dragging");
    stop();
  });

  window.addEventListener("mousemove", function (event) {
    if (!mouseDown || mouseStartX === null || mouseStartY === null) return;
    var deltaX = event.clientX - mouseStartX;
    var deltaY = event.clientY - mouseStartY;
    if (Math.abs(deltaX) > Math.abs(deltaY) && Math.abs(deltaX) >= 6) {
      event.preventDefault();
    }
  });

  window.addEventListener("mouseup", function (event) {
    if (!mouseDown || mouseStartX === null || mouseStartY === null) return;

    var deltaX = event.clientX - mouseStartX;
    var deltaY = event.clientY - mouseStartY;
    var isHorizontalSwipe = Math.abs(deltaX) >= 50 && Math.abs(deltaX) > Math.abs(deltaY) * 1.2;

    mouseStartX = null;
    mouseStartY = null;
    mouseDown = false;
    root.classList.remove("is-dragging");

    if (isHorizontalSwipe) {
      suppressClickUntil = Date.now() + 400;
      if (deltaX < 0) {
        next();
      } else {
        previous();
      }
    }
    start();
  });

  window.addEventListener("blur", function () {
    if (!mouseDown) return;
    mouseStartX = null;
    mouseStartY = null;
    mouseDown = false;
    root.classList.remove("is-dragging");
    start();
  });

  root.addEventListener(
    "touchstart",
    function (event) {
      if (event.touches.length !== 1) return;
      touchStartX = event.touches[0].clientX;
      touchStartY = event.touches[0].clientY;
      stop();
    },
    { passive: true }
  );

  root.addEventListener(
    "touchend",
    function (event) {
      if (touchStartX === null || touchStartY === null || !event.changedTouches.length) {
        start();
        return;
      }

      var touch = event.changedTouches[0];
      var deltaX = touch.clientX - touchStartX;
      var deltaY = touch.clientY - touchStartY;
      var isHorizontalSwipe = Math.abs(deltaX) >= 50 && Math.abs(deltaX) > Math.abs(deltaY) * 1.2;

      touchStartX = null;
      touchStartY = null;

      if (isHorizontalSwipe) {
        event.preventDefault();
        suppressClickUntil = Date.now() + 400;
        if (deltaX < 0) {
          next();
        } else {
          previous();
        }
      }
      start();
    },
    { passive: false }
  );

  root.addEventListener(
    "touchcancel",
    function () {
      touchStartX = null;
      touchStartY = null;
      start();
    },
    { passive: true }
  );

  root.addEventListener(
    "click",
    function (event) {
      if (Date.now() >= suppressClickUntil) return;
      event.preventDefault();
      event.stopPropagation();
    },
    true
  );

  document.addEventListener("visibilitychange", function () {
    if (document.hidden) {
      stop();
    } else {
      start();
    }
  });

  if (fillEl) fillEl.style.width = (1 / total) * 100 + "%";
  loadSlidePoster(index);
  queueNextPoster();
  // 首帧也走解密；与 imgDecypt 的 eager 加载可共享 decryptedURLCache
  syncBg(slides[0]);
  start();
})();