(function() {
  'use strict';

  /* --- Header scroll effect --- */
  var header = document.getElementById('siteHeader');
  var backTop = document.querySelector('.back-top');
  var scrollThreshold = 40;
  function onScroll() {
    if (window.scrollY > scrollThreshold) {
      header.classList.add('scrolled');
    } else {
      header.classList.remove('scrolled');
    }
    if (backTop) {
      backTop.classList.toggle('visible', window.scrollY > 480);
    }
  }
  window.addEventListener('scroll', onScroll, { passive: true });
  onScroll();

  if (backTop) {
    backTop.addEventListener('click', function() {
      window.scrollTo({ top: 0, behavior: 'smooth' });
    });
  }

  /* --- Mobile menu --- */
  var menuBtn = document.querySelector('.menu-btn');
  var mobileMenu = document.getElementById('mobileMenu');
  if (menuBtn && mobileMenu) {
    menuBtn.addEventListener('click', function() {
      var isOpen = mobileMenu.classList.toggle('open');
      menuBtn.setAttribute('aria-expanded', String(isOpen));
      var spans = menuBtn.querySelectorAll('span');
      if (isOpen) {
        spans[0].style.transform = 'translateY(4px) rotate(45deg)';
        spans[1].style.transform = 'translateY(-4px) rotate(-45deg)';
      } else {
        spans[0].style.transform = '';
        spans[1].style.transform = '';
      }
    });
    mobileMenu.querySelectorAll('a').forEach(function(link) {
      link.addEventListener('click', function() {
        mobileMenu.classList.remove('open');
        menuBtn.setAttribute('aria-expanded', 'false');
        var spans = menuBtn.querySelectorAll('span');
        spans[0].style.transform = '';
        spans[1].style.transform = '';
      });
    });
  }

  /* --- Downloads use the same release feed as desktop updates. --- */
  var updateFeedURL = 'https://api.gitcode.com/api/v5/repos/wendao-ai/wendao-ai-updates/raw/updates/stable.json';
  var releasePageURL = 'https://gitcode.com/wendao-ai/wendao-ai-updates/releases';

  function formatSize(bytes) {
    if (!Number.isFinite(bytes) || bytes <= 0) return '';
    return Math.round(bytes / 1024 / 1024) + ' MB';
  }

  function detectedPlatform() {
    var agent = navigator.userAgent || '';
    if (/Windows/i.test(agent)) return { platform: 'windows', fallbackArch: 'amd64' };
    if (/Macintosh|Mac OS X/i.test(agent)) return { platform: 'macos', fallbackArch: 'arm64' };
    return null;
  }

  async function detectedPackageKey(packages) {
    var detected = detectedPlatform();
    if (!detected) return '';
    var arch = detected.fallbackArch;
    if (navigator.userAgentData && navigator.userAgentData.getHighEntropyValues) {
      try {
        var values = await navigator.userAgentData.getHighEntropyValues(['architecture']);
        if (/arm/i.test(values.architecture || '')) arch = 'arm64';
        if (/x86|x64|amd64/i.test(values.architecture || '')) arch = 'amd64';
      } catch (error) {
        // The platform fallback remains usable when the browser hides architecture.
      }
    }
    var key = detected.platform + '/' + arch;
    return packages[key] ? key : '';
  }

  function setDownloadFailure() {
    var selectedLink = document.getElementById('downloadSelected');
    if (selectedLink) selectedLink.setAttribute('href', releasePageURL);
    document.querySelectorAll('.js-download').forEach(function(link) { link.setAttribute('href', releasePageURL); });
    var note = document.getElementById('downloadVersion');
    if (note) note.textContent = '暂时无法获取最新版本，请前往发布页下载';
    var extensionVersion = document.querySelector('[data-extension-version]');
    if (extensionVersion) extensionVersion.textContent = '系统更新源暂时不可用，无法获取插件下载地址';
  }

  async function loadDownloads() {
    try {
      var response = await fetch(updateFeedURL, { headers: { Accept: 'application/json' } });
      if (!response.ok) throw new Error('HTTP ' + response.status);
      var feed = await response.json();
      if (feed.product !== 'wendao-ai' || !feed.version || !feed.packages) throw new Error('Invalid update feed');

      var browserExtensions = feed.browserExtensions;
      var extensionPackages = browserExtensions && browserExtensions.packages;
      ['chrome', 'edge', 'safari', 'firefox'].forEach(function(browser) {
        var link = document.querySelector('[data-extension-browser="' + browser + '"]');
        var item = extensionPackages && extensionPackages[browser];
        if (!link || !item || !/^https:\/\//.test(item.url || '')) return;
        link.setAttribute('href', item.url);
        link.removeAttribute('aria-disabled');
        link.classList.remove('is-disabled');
        var browserNames = { chrome: 'Chrome', edge: 'Edge', safari: 'Safari', firefox: 'Firefox' };
        link.innerHTML = '下载 ' + browserNames[browser] + ' 版 <span class="arrow">&darr;</span>';
      });
      var extensionVersion = document.querySelector('[data-extension-version]');
      if (extensionVersion) {
        extensionVersion.textContent = browserExtensions && browserExtensions.version
          ? '当前插件版本 v' + browserExtensions.version + ' \u00b7 支持 Chrome / Edge / Safari / Firefox'
          : '系统更新源暂未提供浏览器插件下载';
      }

      var note = document.getElementById('downloadVersion');
      var packageKey = await detectedPackageKey(feed.packages);
      var picker = document.getElementById('downloadPackage');
      var selectedLink = document.getElementById('downloadSelected');
      if (picker && packageKey) picker.value = packageKey;

      function applySelectedPackage() {
        var key = picker ? picker.value : packageKey;
        var selected = key && feed.packages[key];
        var url = selected && /^https:\/\//.test(selected.url || '') ? selected.url : releasePageURL;
        var size = selected ? formatSize(Number(selected.size)) : '';
        if (selectedLink) selectedLink.setAttribute('href', url);
        document.querySelectorAll('.js-download').forEach(function(link) {
          link.setAttribute('href', url);
          link.removeAttribute('download');
        });
        if (note) note.textContent = '当前版本 v' + feed.version + (size ? ' \u00b7 安装包 ' + size : '') + ' \u00b7 已选择 ' + picker.options[picker.selectedIndex].text;
      }

      if (picker) picker.addEventListener('change', applySelectedPackage);
      applySelectedPackage();
    } catch (error) {
      setDownloadFailure();
    }
  }
  loadDownloads();

  /* Stable deep-link positioning for campaign previews and screenshot QA. */
  if (new URLSearchParams(window.location.search).get('view') === 'workflow') {
    var workflowSection = document.getElementById('workflow');
    if (workflowSection) {
      workflowSection.querySelectorAll('.reveal').forEach(function(item) { item.classList.add('visible'); });
      var main = document.querySelector('main');
      if (main) main.prepend(workflowSection);
    }
  }

  /* --- Product screenshot preview --- */
  var screenDialog = document.getElementById('screenDialog');
  if (screenDialog && typeof screenDialog.showModal === 'function') {
    var dialogImage = screenDialog.querySelector('img');
    var dialogCaption = screenDialog.querySelector('figcaption');
    var dialogClose = screenDialog.querySelector('.screen-dialog-close');

    document.querySelectorAll('.js-screen-open').forEach(function(button) {
      button.addEventListener('click', function() {
        var source = button.getAttribute('data-screen') || '';
        var caption = button.getAttribute('data-caption') || '文到AI真实产品界面';
        if (dialogImage) {
          dialogImage.setAttribute('src', source);
          dialogImage.setAttribute('alt', caption);
        }
        if (dialogCaption) dialogCaption.textContent = caption;
        screenDialog.showModal();
      });
    });

    if (dialogClose) dialogClose.addEventListener('click', function() { screenDialog.close(); });
    screenDialog.addEventListener('click', function(event) {
      if (event.target === screenDialog) screenDialog.close();
    });
  }

  /* --- Scroll reveal --- */
  if ('IntersectionObserver' in window && !window.matchMedia('(prefers-reduced-motion: reduce)').matches) {
    var revealItems = document.querySelectorAll('.reveal');
    var observer = new IntersectionObserver(function(entries) {
      entries.forEach(function(entry) {
        if (entry.isIntersecting) {
          entry.target.classList.add('visible');
          observer.unobserve(entry.target);
        }
      });
    }, { threshold: 0.1, rootMargin: '0px 0px -40px 0px' });
    revealItems.forEach(function(item) { observer.observe(item); });
  } else {
    document.querySelectorAll('.reveal').forEach(function(item) {
      item.classList.add('visible');
    });
  }

  /* --- Smooth scroll for anchor links --- */
  document.querySelectorAll('a[href^="#"]').forEach(function(anchor) {
    anchor.addEventListener('click', function(e) {
      var targetId = this.getAttribute('href');
      if (!targetId || targetId.charAt(0) !== '#' || targetId === '#') return;
      var target = document.querySelector(targetId);
      if (target) {
        e.preventDefault();
        var headerHeight = header ? header.offsetHeight : 0;
        var targetPos = target.getBoundingClientRect().top + window.scrollY - headerHeight - 20;
        window.scrollTo({ top: targetPos, behavior: 'smooth' });
      }
    });
  });
})();