<template>
  <div class="home">
    <!-- Hero 区域 -->
    <header class="hero">
      <div class="hero-bg-decoration">
        <div class="hero-blob blob-1"></div>
        <div class="hero-blob blob-2"></div>
        <div class="hero-blob blob-3"></div>
      </div>
      <div class="hero-content">
        <div class="hero-badge">🎓 教学辅助平台</div>
        <h1 class="hero-title">
          <span class="hero-title-line">算法设计与分析</span>
        </h1>
        <p class="hero-subtitle">从基础到进阶的算法学习之旅</p>
        <p class="hero-desc">
          涵盖六大核心章节：复杂度分析 · 分治法 · 动态规划 · 贪心算法 · 回溯法 · 分支限界法
        </p>
        <div class="hero-stats">
          <div class="hero-stat">
            <span class="stat-number">6</span>
            <span class="stat-label">核心章节</span>
          </div>
          <div class="hero-stat">
            <span class="stat-number">50+</span>
            <span class="stat-label">算法示例</span>
          </div>
          <div class="hero-stat">
            <span class="stat-number">C</span>
            <span class="stat-label">&amp; Python</span>
          </div>
        </div>
        <div class="hero-actions">
          <router-link to="/chapter/ch1" class="btn-primary">
            <span>开始学习</span>
            <svg width="18" height="18" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2.5" stroke-linecap="round" stroke-linejoin="round"><line x1="5" y1="12" x2="19" y2="12"/><polyline points="12 5 19 12 12 19"/></svg>
          </router-link>
          <a href="#chapters" class="btn-secondary">浏览章节</a>
        </div>
      </div>
    </header>

    <!-- 章节卡片网格 -->
    <section id="chapters" class="chapters-section">
      <div class="section-header">
        <h2 class="section-title">📚 课程章节</h2>
        <p class="section-desc">选择章节开始学习对应的算法知识</p>
      </div>
      <div class="chapters-grid">
        <router-link
          v-for="(ch, index) in chapters"
          :key="ch.id"
          :to="`/chapter/${ch.id}`"
          class="chapter-card"
          :style="{ '--delay': index * 0.08 + 's' }"
        >
          <div class="card-accent"></div>
          <div class="card-icon">{{ ch.icon }}</div>
          <h3 class="card-title">{{ ch.title.split('—')[0].trim() }}</h3>
          <p class="card-subtitle">{{ ch.subtitle }}</p>
          <p class="card-desc">{{ ch.description }}</p>
          <div class="card-topics">
            <span v-for="topic in ch.topics.slice(0, 3)" :key="topic" class="topic-tag">
              {{ topic }}
            </span>
            <span v-if="ch.topics.length > 3" class="topic-tag more">+{{ ch.topics.length - 3 }}</span>
          </div>
          <div class="card-footer">
            <span class="explore-link">
              查看详情
              <svg width="14" height="14" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2.5" stroke-linecap="round" stroke-linejoin="round"><line x1="5" y1="12" x2="19" y2="12"/><polyline points="12 5 19 12 12 19"/></svg>
            </span>
          </div>
        </router-link>
      </div>
    </section>

    <!-- 功能特性 -->
    <section class="features-section">
      <div class="section-header">
        <h2 class="section-title">✨ 平台功能</h2>
        <p class="section-desc">全方位辅助算法学习与教学</p>
      </div>
      <div class="features-grid">
        <div class="feature-card">
          <div class="feature-icon-wrapper" style="--feature-color: #3b82f6">
            <span class="feature-icon">📖</span>
          </div>
          <h3>代码阅览</h3>
          <p>所有算法代码源文件在线展示，支持语法高亮与一键复制</p>
        </div>
        <div class="feature-card">
          <div class="feature-icon-wrapper" style="--feature-color: #8b5cf6">
            <span class="feature-icon">📂</span>
          </div>
          <h3>分类导航</h3>
          <p>按章节和子主题分类组织，快速定位所需算法示例</p>
        </div>
        <div class="feature-card">
          <div class="feature-icon-wrapper" style="--feature-color: #06b6d4">
            <span class="feature-icon">🎯</span>
          </div>
          <h3>动态演示</h3>
          <p>排序算法动画演示，直观理解每一步操作过程</p>
        </div>
        <div class="feature-card">
          <div class="feature-icon-wrapper" style="--feature-color: #10b981">
            <span class="feature-icon">💻</span>
          </div>
          <h3>双语言实现</h3>
          <p>同时提供 C 和 Python 实现，满足不同教学需求</p>
        </div>
      </div>
    </section>

    <!-- 页脚 -->
    <footer class="footer">
      <div class="footer-wave">
        <svg viewBox="0 0 1440 60" preserveAspectRatio="none">
          <path d="M0,30 C360,60 720,0 1440,30 L1440,60 L0,60 Z" fill="var(--border-color)" opacity="0.3"/>
        </svg>
      </div>
      <div class="footer-content">
        <div class="footer-brand">
          <span class="footer-logo">📚</span>
          <span>算法分析与设计</span>
        </div>
        <p class="footer-sub">教学辅助平台 — 培养计算思维，掌握算法精髓</p>
      </div>
    </footer>
  </div>
</template>

<script setup>
import { chapters } from '../data/chapters.js'
</script>

<style scoped>
/* ============================
   首页布局
   ============================ */
.home {
  max-width: 100%;
}

/* ============================
   Section Header 通用
   ============================ */
.section-header {
  text-align: center;
  margin-bottom: 40px;
}

.section-title {
  font-size: 28px;
  font-weight: 800;
  color: var(--text-primary);
  margin-bottom: 8px;
  letter-spacing: -0.3px;
}

.section-desc {
  font-size: 15px;
  color: var(--text-tertiary);
}

/* ============================
   Hero 区域
   ============================ */
.hero {
  position: relative;
  text-align: center;
  padding: 80px 20px 60px;
  overflow: hidden;
  border-radius: 24px;
  margin-top: 8px;
  background:
    radial-gradient(ellipse 80% 60% at 50% -10%, rgba(59, 130, 246, 0.08), transparent),
    radial-gradient(ellipse 60% 50% at 20% 80%, rgba(139, 92, 246, 0.06), transparent),
    radial-gradient(ellipse 50% 40% at 80% 70%, rgba(6, 182, 212, 0.05), transparent);
}

/* 背景装饰 blob */
.hero-bg-decoration {
  position: absolute;
  inset: 0;
  pointer-events: none;
  overflow: hidden;
}

.hero-blob {
  position: absolute;
  border-radius: 50%;
  filter: blur(60px);
  opacity: 0.3;
  animation: blobFloat 8s ease-in-out infinite;
}

.blob-1 {
  width: 300px;
  height: 300px;
  background: var(--primary-color);
  top: -80px;
  right: -60px;
  animation-delay: 0s;
}

.blob-2 {
  width: 200px;
  height: 200px;
  background: #8b5cf6;
  bottom: -40px;
  left: -40px;
  animation-delay: -3s;
}

.blob-3 {
  width: 150px;
  height: 150px;
  background: #06b6d4;
  top: 50%;
  left: 50%;
  transform: translate(-50%, -50%);
  animation-delay: -6s;
}

@keyframes blobFloat {
  0%, 100% { transform: translate(0, 0) scale(1); }
  33% { transform: translate(20px, -20px) scale(1.1); }
  66% { transform: translate(-15px, 15px) scale(0.95); }
}

.hero-content {
  position: relative;
  z-index: 1;
}

.hero-badge {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  font-size: 13px;
  font-weight: 600;
  color: var(--primary-color);
  background: color-mix(in srgb, var(--primary-color) 10%, transparent);
  border: 1px solid color-mix(in srgb, var(--primary-color) 20%, transparent);
  padding: 6px 16px;
  border-radius: 20px;
  margin-bottom: 20px;
  letter-spacing: 0.3px;
}

.hero-title {
  font-size: 48px;
  font-weight: 900;
  line-height: 1.15;
  margin-bottom: 16px;
  letter-spacing: -1px;
}

.hero-title-line {
  background: linear-gradient(135deg, var(--primary-color) 0%, #8b5cf6 50%, #06b6d4 100%);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
  background-size: 200% 200%;
  animation: gradientShift 4s ease-in-out infinite;
}

@keyframes gradientShift {
  0%, 100% { background-position: 0% 50%; }
  50% { background-position: 100% 50%; }
}

.hero-subtitle {
  font-size: 20px;
  color: var(--text-secondary);
  font-weight: 500;
  margin-bottom: 8px;
}

.hero-desc {
  font-size: 15px;
  color: var(--text-tertiary);
  max-width: 600px;
  margin: 0 auto 28px;
  line-height: 1.6;
}

/* Hero 数据统计 */
.hero-stats {
  display: flex;
  justify-content: center;
  gap: 40px;
  margin-bottom: 32px;
}

.hero-stat {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 2px;
}

.stat-number {
  font-size: 28px;
  font-weight: 800;
  color: var(--text-primary);
  letter-spacing: -0.5px;
}

.stat-label {
  font-size: 13px;
  color: var(--text-tertiary);
  font-weight: 500;
}

/* 按钮 */
.hero-actions {
  display: flex;
  gap: 12px;
  justify-content: center;
}

.btn-primary, .btn-secondary {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 14px 32px;
  border-radius: 12px;
  font-size: 15px;
  font-weight: 600;
  text-decoration: none;
  transition: all 0.25s cubic-bezier(0.4, 0, 0.2, 1);
  cursor: pointer;
}

.btn-primary {
  background: linear-gradient(135deg, var(--primary-color), #6366f1);
  color: white;
  box-shadow: 0 4px 16px rgba(59, 130, 246, 0.35);
}

.btn-primary:hover {
  transform: translateY(-2px);
  box-shadow: 0 8px 28px rgba(59, 130, 246, 0.45);
  text-decoration: none;
}

.btn-primary:active {
  transform: translateY(0);
}

.btn-secondary {
  background: var(--card-bg);
  color: var(--text-primary);
  border: 1.5px solid var(--border-color);
}

.btn-secondary:hover {
  background: var(--hover-bg);
  border-color: var(--primary-color);
  transform: translateY(-2px);
  text-decoration: none;
}

/* ============================
   章节卡片区域
   ============================ */
.chapters-section {
  margin: 60px 0 20px;
}

.chapters-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(340px, 1fr));
  gap: 20px;
}

.chapter-card {
  position: relative;
  background: var(--card-bg);
  border: 1px solid var(--border-color);
  border-radius: 18px;
  padding: 28px 24px 20px;
  text-decoration: none;
  color: inherit;
  transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
  display: flex;
  flex-direction: column;
  overflow: hidden;
  animation: cardFadeIn 0.6s ease-out backwards;
  animation-delay: var(--delay, 0s);
}

@keyframes cardFadeIn {
  from {
    opacity: 0;
    transform: translateY(20px);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

/* 卡片顶部彩色装饰条 */
.card-accent {
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  height: 4px;
  background: linear-gradient(90deg, var(--primary-color), #8b5cf6, #06b6d4);
  opacity: 0;
  transition: opacity 0.3s ease;
}

.chapter-card:hover .card-accent {
  opacity: 1;
}

.chapter-card:hover {
  transform: translateY(-6px);
  box-shadow: 0 12px 40px rgba(0,0,0,0.1);
  border-color: transparent;
  background: linear-gradient(135deg, var(--card-bg), color-mix(in srgb, var(--primary-color) 3%, var(--card-bg)));
}

.card-icon {
  font-size: 42px;
  margin-bottom: 14px;
  transition: transform 0.3s ease;
}

.chapter-card:hover .card-icon {
  transform: scale(1.1) rotate(-5deg);
}

.card-title {
  font-size: 18px;
  font-weight: 700;
  color: var(--text-primary);
  margin-bottom: 4px;
  letter-spacing: -0.2px;
}

.card-subtitle {
  font-size: 13px;
  color: var(--primary-color);
  margin-bottom: 10px;
  font-weight: 500;
}

.card-desc {
  font-size: 13px;
  color: var(--text-secondary);
  line-height: 1.6;
  margin-bottom: 16px;
  flex: 1;
}

.card-topics {
  display: flex;
  flex-wrap: wrap;
  gap: 6px;
  margin-bottom: 14px;
}

.topic-tag {
  font-size: 11px;
  background: var(--tag-bg);
  color: var(--text-secondary);
  padding: 4px 10px;
  border-radius: 20px;
  font-weight: 500;
  transition: all 0.2s;
}

.chapter-card:hover .topic-tag {
  background: color-mix(in srgb, var(--primary-color) 8%, var(--tag-bg));
}

.topic-tag.more {
  background: var(--active-bg);
  color: var(--primary-color);
  font-weight: 600;
}

.card-footer {
  border-top: 1px solid var(--border-color);
  padding-top: 14px;
  margin-top: auto;
}

.explore-link {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  font-size: 13px;
  color: var(--primary-color);
  font-weight: 600;
  transition: gap 0.2s ease;
}

.chapter-card:hover .explore-link {
  gap: 10px;
}

/* ============================
   功能特性区域
   ============================ */
.features-section {
  margin: 80px 0;
}

.features-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(250px, 1fr));
  gap: 20px;
}

.feature-card {
  background: var(--card-bg);
  border: 1px solid var(--border-color);
  border-radius: 16px;
  padding: 32px 24px;
  text-align: center;
  transition: all 0.3s ease;
}

.feature-card:hover {
  transform: translateY(-4px);
  box-shadow: 0 8px 30px rgba(0,0,0,0.08);
  border-color: var(--feature-color, var(--border-color));
}

.feature-icon-wrapper {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 56px;
  height: 56px;
  border-radius: 16px;
  background: color-mix(in srgb, var(--feature-color, var(--primary-color)) 10%, transparent);
  margin-bottom: 16px;
  transition: all 0.3s ease;
}

.feature-card:hover .feature-icon-wrapper {
  background: color-mix(in srgb, var(--feature-color, var(--primary-color)) 18%, transparent);
  transform: scale(1.05);
}

.feature-icon {
  font-size: 26px;
}

.feature-card h3 {
  font-size: 16px;
  font-weight: 700;
  margin-bottom: 10px;
  color: var(--text-primary);
}

.feature-card p {
  font-size: 13px;
  color: var(--text-secondary);
  line-height: 1.6;
}

/* ============================
   页脚
   ============================ */
.footer {
  position: relative;
  margin-top: 60px;
  padding-top: 40px;
  text-align: center;
}

.footer-wave {
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  height: 60px;
  overflow: hidden;
}

.footer-wave svg {
  width: 100%;
  height: 100%;
}

.footer-content {
  padding: 32px 0 48px;
  border-top: 1px solid var(--border-color);
}

.footer-brand {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  font-size: 16px;
  font-weight: 700;
  color: var(--text-primary);
  margin-bottom: 8px;
}

.footer-logo {
  font-size: 22px;
}

.footer-sub {
  font-size: 13px;
  color: var(--text-tertiary);
}

/* ============================
   深色模式适配
   ============================ */
@media (prefers-color-scheme: dark) {
  .hero {
    background:
      radial-gradient(ellipse 80% 60% at 50% -10%, rgba(59, 130, 246, 0.06), transparent),
      radial-gradient(ellipse 60% 50% at 20% 80%, rgba(139, 92, 246, 0.04), transparent),
      radial-gradient(ellipse 50% 40% at 80% 70%, rgba(6, 182, 212, 0.04), transparent);
  }

  .chapter-card:hover {
    box-shadow: 0 12px 40px rgba(0,0,0,0.3);
  }

  .btn-primary {
    box-shadow: 0 4px 16px rgba(59, 130, 246, 0.25);
  }

  .btn-primary:hover {
    box-shadow: 0 8px 28px rgba(59, 130, 246, 0.35);
  }
}

/* ============================
   响应式
   ============================ */
@media (max-width: 768px) {
  .hero {
    padding: 48px 16px 40px;
    border-radius: 16px;
  }

  .hero-title {
    font-size: 32px;
  }

  .hero-subtitle {
    font-size: 16px;
  }

  .hero-stats {
    gap: 24px;
  }

  .stat-number {
    font-size: 22px;
  }

  .hero-actions {
    flex-direction: column;
    align-items: center;
  }

  .chapters-grid {
    grid-template-columns: 1fr;
  }

  .features-grid {
    grid-template-columns: 1fr 1fr;
  }
}

@media (max-width: 480px) {
  .features-grid {
    grid-template-columns: 1fr;
  }
}
</style>
