(() => {
  'use strict';

  const html = document.documentElement;
  if (html.dataset.v7318BiotenGovernance !== 'professional-platform-r2') return;

  const heroTitleZh = '<span>让 PHA 水性功能乳液，</span>\n          <span>成为<em>可设计、可验证</em>的</span>\n          <span>产业材料。</span>';
  const heroTitleEn = '<span>Making PHA-based</span>\n          <span>waterborne functional emulsions</span>\n          <span><em>designable and verifiable</em></span>\n          <span>for industrial applications.</span>';
  const observedNavigationSurfaces = new WeakSet();
  let scheduled = false;
  let readingAnchor = null;

  const setAttribute = (element, name, value) => {
    if (element && element.getAttribute(name) !== value) element.setAttribute(name, value);
  };

  const isEnglish = () => /^en\b/i.test(html.dataset.lang || html.lang || '');

  function syncLanguageUrl(language) {
    const pageHistory = window.history;
    if (!pageHistory?.replaceState) return;
    const url = new URL(window.location.href);
    const next = /^en\b/i.test(language || '') ? 'en' : 'zh';
    if (url.searchParams.get('lang') === next) return;
    url.searchParams.set('lang', next);
    pageHistory.replaceState(pageHistory.state, '', `${url.pathname}${url.search}${url.hash}`);
  }

  function navigationSurfaces() {
    return [...document.querySelectorAll([
      '#dbc-global-navigation',
      '.dbc-desktop-mega-panel',
      '[id^="dbc-desktop-mega-"]',
    ].join(','))];
  }

  function syncNavigationInert() {
    for (const surface of navigationSurfaces()) {
      const closed = surface.hidden
        || surface.getAttribute('aria-hidden') === 'true'
        || (!surface.classList.contains('is-open') && surface.matches('.dbc-desktop-mega-panel, [id^="dbc-desktop-mega-"]'));
      surface.inert = closed;
      if (!observedNavigationSurfaces.has(surface)) {
        observedNavigationSurfaces.add(surface);
        new MutationObserver(syncNavigationInert).observe(surface, {
          attributes: true,
          attributeFilter: ['aria-hidden', 'hidden', 'class'],
        });
      }
    }
  }

  function captureReadingPosition() {
    const headerBottom = document.querySelector('.site-header')?.getBoundingClientRect().bottom || 0;
    const line = headerBottom + 24;
    const sections = [...document.querySelectorAll('main#main-content > section')];
    const intersecting = sections.filter((section) => {
      const rect = section.getBoundingClientRect();
      return rect.top <= line && rect.bottom > line;
    });
    const element = intersecting.at(-1)
      || sections.find((section) => section.getBoundingClientRect().top > line)
      || null;
    readingAnchor = element ? { element, top: element.getBoundingClientRect().top, capturedAt: performance.now() } : null;
    html.dataset.v7318ReadingAnchor = element?.id || 'none';
    html.dataset.v7318ReadingAnchorTop = readingAnchor ? readingAnchor.top.toFixed(2) : '';
  }

  function restoreReadingPosition(delay = 0) {
    const snapshot = readingAnchor;
    if (!snapshot) return;
    setTimeout(() => {
      requestAnimationFrame(() => {
        if (readingAnchor !== snapshot || !snapshot.element.isConnected) return;
        const delta = snapshot.element.getBoundingClientRect().top - snapshot.top;
        html.dataset.v7318ReadingRestore = snapshot.element.id || 'anonymous';
        html.dataset.v7318ReadingDelta = delta.toFixed(2);
        if (Math.abs(delta) > 1) {
          const root = document.documentElement;
          const previousScrollBehavior = root.style.scrollBehavior;
          root.style.scrollBehavior = 'auto';
          window.scrollBy(0, delta);
          root.style.scrollBehavior = previousScrollBehavior;
          html.dataset.v7318ReadingApplied = snapshot.element.id || 'anonymous';
        }
      });
    }, delay);
  }

  function applyGovernance() {
    scheduled = false;
    const english = isEnglish();
    const logo = document.querySelector('.site-header .logo-image-biocycle');
    const logoImage = logo?.querySelector('img');
    setAttribute(logo, 'href', 'bioten-platform.html');
    setAttribute(logo, 'data-aria-cn', '博碳生物主页');
    setAttribute(logo, 'data-aria-en', 'BIOTEN homepage');
    setAttribute(logo, 'aria-label', english ? 'BIOTEN homepage' : '博碳生物主页');
    setAttribute(logo, 'data-v7318-bioten-logo-route', 'platform-home');
    setAttribute(logoImage, 'data-alt-cn', 'BIOTEN 博碳生物');
    setAttribute(logoImage, 'data-alt-en', 'BIOTEN');
    setAttribute(logoImage, 'alt', english ? 'BIOTEN' : 'BIOTEN 博碳生物');

    const languageToggle = document.querySelector('[data-language-toggle]');
    const languageLabel = english ? 'Switch to Chinese' : '切换至英文';
    setAttribute(languageToggle, 'aria-label', languageLabel);
    setAttribute(languageToggle, 'title', languageLabel);

    const kicker = document.querySelector('.btp580-hero .btp580-kicker');
    const kickerZh = 'BIOTEN 博碳生物 ｜ PHA 生物基水性功能乳液';
    const kickerEn = 'BIOTEN | PHA-based waterborne functional emulsions';
    setAttribute(kicker, 'data-nav-cn', kickerZh);
    setAttribute(kicker, 'data-nav-en', kickerEn);
    if (kicker && kicker.textContent.trim() !== (english ? kickerEn : kickerZh)) {
      kicker.textContent = english ? kickerEn : kickerZh;
    }

    const heroTitle = document.querySelector('#btp580-title');
    const governedHeroTitle = english ? heroTitleEn : heroTitleZh;
    if (heroTitle && heroTitle.innerHTML.trim() !== governedHeroTitle.trim()) {
      heroTitle.innerHTML = governedHeroTitle;
    }
    setAttribute(heroTitle, 'data-v7318-hero-copy', english ? 'directional-en' : 'accepted-zh');

    const methodImage = document.querySelector('.btp580-system__visual img');
    const imageZh = '水性乳液、材料状态与刮涂试样的研发编辑示意，不作为实验现场、样品或测试证据';
    const imageEn = 'Editorial R&D illustration of waterborne emulsions, material states and drawdown samples; not experimental, sample or test evidence';
    setAttribute(methodImage, 'data-alt-cn', imageZh);
    setAttribute(methodImage, 'data-alt-en', imageEn);
    setAttribute(methodImage, 'alt', english ? imageEn : imageZh);

    const capabilities = document.querySelector('.btp580-capabilities');
    setAttribute(capabilities, 'data-aria-cn', '博碳生物研发控制维度');
    setAttribute(capabilities, 'data-aria-en', 'BIOTEN R&D control dimensions');
    setAttribute(capabilities, 'aria-label', english ? 'BIOTEN R&D control dimensions' : '博碳生物研发控制维度');

    syncNavigationInert();
    html.dataset.v7318BiotenRuntime = 'ready';
  }

  function scheduleGovernance() {
    if (scheduled) return;
    scheduled = true;
    requestAnimationFrame(applyGovernance);
  }

  function start() {
    applyGovernance();

    const header = document.querySelector('.site-header');
    if (header) {
      new MutationObserver(() => {
        scheduleGovernance();
        syncNavigationInert();
      }).observe(header, { childList: true, subtree: true });
    }

    new MutationObserver(() => {
      scheduleGovernance();
      restoreReadingPosition(0);
      restoreReadingPosition(80);
      restoreReadingPosition(200);
      restoreReadingPosition(400);
      restoreReadingPosition(440);
      restoreReadingPosition(700);
      restoreReadingPosition(960);
    }).observe(html, { attributes: true, attributeFilter: ['lang', 'data-lang'] });

    const skipLink = document.querySelector('.skip-link');
    const main = document.querySelector('#main-content');
    skipLink?.addEventListener('click', () => {
      requestAnimationFrame(() => main?.focus({ preventScroll: true }));
    });

    document.addEventListener('pointerdown', (event) => {
      if (event.target.closest('[data-language-toggle]')) captureReadingPosition();
    }, true);

    document.addEventListener('keydown', (event) => {
      if ((event.key === 'Enter' || event.key === ' ') && event.target.closest('[data-language-toggle]')) {
        captureReadingPosition();
      }
    }, true);

    document.addEventListener('click', (event) => {
      if (event.target.closest('[data-language-toggle]')) setTimeout(scheduleGovernance, 0);
    }, true);

    document.addEventListener('dbc:languagechange', (event) => {
      syncLanguageUrl(event.detail?.language || (isEnglish() ? 'en' : 'zh'));
      scheduleGovernance();
      restoreReadingPosition(0);
      restoreReadingPosition(80);
      restoreReadingPosition(200);
      restoreReadingPosition(400);
      restoreReadingPosition(440);
      restoreReadingPosition(700);
      restoreReadingPosition(960);
    });

    const bodySurfaceObserver = new MutationObserver(syncNavigationInert);
    bodySurfaceObserver.observe(document.body, { childList: true });
    syncNavigationInert();
    window.addEventListener('pageshow', scheduleGovernance);
  }

  if (document.readyState === 'loading') document.addEventListener('DOMContentLoaded', start, { once: true });
  else start();
})();