---
interface Heading {
  depth: number;
  slug: string;
  text: string;
}

interface Props {
  headings: Heading[];
}

const { headings } = Astro.props;

// 过滤出 h2 和 h3 标题
const tocItems = headings.filter(h => h.depth >= 2 && h.depth <= 3);
---

<!-- 移动端悬浮按钮 -->
<button 
  id="toc-toggle" 
  class="toc-toggle xl:hidden"
  aria-label="切换目录"
  type="button"
>
  <svg class="w-5 h-5" fill="none" stroke="currentColor" viewBox="0 0 24 24">
    <path stroke-linecap="round" stroke-linejoin="round" stroke-width="2" d="M4 6h16M4 12h16M4 18h7" />
  </svg>
  <span class="ml-1 text-sm font-medium">目录</span>
</button>

<!-- 移动端遮罩层 -->
<div id="toc-overlay" class="toc-overlay xl:hidden"></div>

<!-- 目录导航 -->
<nav id="toc-nav" class="toc-nav" aria-label="文章目录">
  <div class="toc-header">
    <span class="text-sm font-semibold text-foreground">目录</span>
    <button id="toc-close" class="toc-close xl:hidden" aria-label="关闭目录" type="button">
      <svg class="w-4 h-4" fill="none" stroke="currentColor" viewBox="0 0 24 24">
        <path stroke-linecap="round" stroke-linejoin="round" stroke-width="2" d="M6 18L18 6M6 6l12 12" />
      </svg>
    </button>
  </div>
  
  <ul class="toc-list">
    {tocItems.map((heading) => (
      <li class={`toc-item toc-depth-${heading.depth}`}>
        <a 
          href={`#${heading.slug}`} 
          class="toc-link"
          data-heading-slug={heading.slug}
        >
          {heading.text}
        </a>
      </li>
    ))}
  </ul>
</nav>

<style>
  /* 移动端悬浮按钮 */
  .toc-toggle {
    position: fixed;
    bottom: 1.5rem;
    right: 1.5rem;
    z-index: 40;
    display: flex;
    align-items: center;
    padding: 0.75rem 1rem;
    background: linear-gradient(135deg, #3b82f6 0%, #2563eb 100%);
    color: white;
    border: none;
    border-radius: 9999px;
    box-shadow: 0 4px 14px rgba(59, 130, 246, 0.4);
    cursor: pointer;
    transition: all 0.2s ease;
  }

  .toc-toggle:hover {
    transform: translateY(-2px);
    box-shadow: 0 6px 20px rgba(59, 130, 246, 0.5);
  }

  .toc-toggle:active {
    transform: translateY(0);
  }

  /* 目录导航 - 移动端默认隐藏在右侧 */
  .toc-nav {
    position: fixed;
    top: 0;
    right: 0;
    width: 16rem;
    height: 100vh;
    background: var(--color-background);
    border-left: 1px solid var(--color-border);
    padding: 1.5rem;
    z-index: 50;
    box-shadow: -4px 0 20px rgba(0, 0, 0, 0.15);
    transform: translateX(100%);
    transition: transform 0.3s ease;
    overflow-y: auto;
  }

  .toc-nav.open {
    transform: translateX(0);
  }

  /* 桌面端 - 右侧 sticky 侧边栏 */
  @media (min-width: 1280px) {
    .toc-toggle {
      display: none;
    }

    .toc-nav {
      position: sticky;
      top: 6rem;
      right: auto;
      width: 12rem;
      height: auto;
      max-height: calc(100vh - 8rem);
      border: none;
      background: transparent;
      box-shadow: none;
      padding: 0;
      transform: none;
      overflow-y: auto;
    }

    .toc-close {
      display: none;
    }
  }

  /* 目录头部 */
  .toc-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 1rem;
    padding-bottom: 0.75rem;
    border-bottom: 1px solid var(--color-border);
  }

  @media (min-width: 1280px) {
    .toc-header {
      border-bottom: none;
      padding-bottom: 0;
      margin-bottom: 0.75rem;
    }
  }

  .toc-close {
    padding: 0.25rem;
    color: var(--color-muted-foreground);
    background: transparent;
    border: none;
    cursor: pointer;
    border-radius: 0.25rem;
    transition: all 0.2s;
  }

  .toc-close:hover {
    color: var(--color-foreground);
    background: var(--color-muted);
  }

  /* 目录列表 */
  .toc-list {
    list-style: none;
    padding: 0;
    margin: 0;
  }

  .toc-item {
    margin: 0;
  }

  .toc-link {
    display: block;
    padding: 0.5rem 0.75rem;
    font-size: 0.8125rem;
    line-height: 1.4;
    color: var(--color-muted-foreground);
    text-decoration: none;
    border-radius: 0.375rem;
    border-left: 2px solid transparent;
    transition: all 0.15s ease;
  }

  .toc-link:hover {
    color: var(--color-foreground);
    background: var(--color-muted);
  }

  .toc-link.active {
    color: var(--color-primary-500);
    border-left-color: var(--color-primary-500);
    background: rgba(59, 130, 246, 0.1);
    font-weight: 500;
  }

  /* 缩进层级 */
  .toc-depth-3 {
    padding-left: 0.5rem;
  }

  .toc-depth-3 .toc-link {
    font-size: 0.75rem;
    padding-left: 1rem;
  }

  /* 遮罩层 */
  .toc-overlay {
    position: fixed;
    inset: 0;
    background: rgba(0, 0, 0, 0.5);
    z-index: 45;
    opacity: 0;
    pointer-events: none;
    transition: opacity 0.3s ease;
  }

  .toc-overlay.open {
    opacity: 1;
    pointer-events: auto;
  }

  @media (min-width: 1280px) {
    .toc-overlay {
      display: none;
    }
  }

  /* 滚动条样式 */
  .toc-nav::-webkit-scrollbar {
    width: 4px;
  }

  .toc-nav::-webkit-scrollbar-track {
    background: transparent;
  }

  .toc-nav::-webkit-scrollbar-thumb {
    background: var(--color-border);
    border-radius: 2px;
  }

  .toc-nav::-webkit-scrollbar-thumb:hover {
    background: var(--color-muted-foreground);
  }
</style>

<script>
  // DOM 元素
  const tocToggle = document.getElementById('toc-toggle');
  const tocNav = document.getElementById('toc-nav');
  const tocClose = document.getElementById('toc-close');
  const tocOverlay = document.getElementById('toc-overlay');
  const tocLinks = document.querySelectorAll('.toc-link');

  // 切换目录显示
  function openToc() {
    tocNav?.classList.add('open');
    tocOverlay?.classList.add('open');
    document.body.style.overflow = 'hidden';
  }

  function closeToc() {
    tocNav?.classList.remove('open');
    tocOverlay?.classList.remove('open');
    document.body.style.overflow = '';
  }

  // 绑定事件
  tocToggle?.addEventListener('click', (e) => {
    e.preventDefault();
    e.stopPropagation();
    if (tocNav?.classList.contains('open')) {
      closeToc();
    } else {
      openToc();
    }
  });
  
  tocClose?.addEventListener('click', (e) => {
    e.preventDefault();
    e.stopPropagation();
    closeToc();
  });
  
  tocOverlay?.addEventListener('click', closeToc);

  // 点击链接后关闭目录（移动端）
  tocLinks.forEach(link => {
    link.addEventListener('click', () => {
      if (window.innerWidth < 1280) {
        closeToc();
      }
    });
  });

  // 监听窗口大小变化
  window.addEventListener('resize', () => {
    if (window.innerWidth >= 1280) {
      closeToc();
    }
  });

  // ESC 键关闭
  document.addEventListener('keydown', (e) => {
    if (e.key === 'Escape') {
      closeToc();
    }
  });

  // 滚动高亮当前标题
  const headings = document.querySelectorAll('article h2[id], article h3[id]');
  
  const observerOptions = {
    rootMargin: '-80px 0px -70% 0px',
    threshold: 0
  };

  const observer = new IntersectionObserver((entries) => {
    entries.forEach(entry => {
      if (entry.isIntersecting) {
        const id = entry.target.id;
        tocLinks.forEach(link => {
          link.classList.remove('active');
          if (link instanceof HTMLAnchorElement) {
            const slug = link.getAttribute('data-heading-slug');
            if (slug === id) {
              link.classList.add('active');
            }
          }
        });
      }
    });
  }, observerOptions);

  headings.forEach(heading => {
    observer.observe(heading);
  });
</script>