<template>
  <aside class="sidebar" :class="{ collapsed }">
    <div class="sidebar-header">
      <h2 class="sidebar-title" @click="$router.push('/')" v-show="!collapsed">
        <span class="logo">📚</span>
        <span>算法分析教学</span>
      </h2>
      <button class="toggle-btn" @click="$emit('toggle')">
        {{ collapsed ? '☰' : '✕' }}
      </button>
    </div>
    <nav class="sidebar-nav">
      <router-link
        v-for="ch in chapters"
        :key="ch.id"
        :to="`/chapter/${ch.id}`"
        class="nav-item"
        :class="{ active: currentId === ch.id }"
      >
        <span class="nav-icon">{{ ch.icon }}</span>
        <span class="nav-text" v-show="!collapsed">
          <span class="nav-title">{{ ch.title.split('—')[0].trim() }}</span>
          <span class="nav-subtitle">{{ ch.subtitle }}</span>
        </span>
      </router-link>
    </nav>
    <div class="sidebar-footer" v-show="!collapsed">
      <p>算法分析与设计</p>
      <p class="footer-sub">教学辅助平台</p>
    </div>
  </aside>
</template>

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

defineProps({
  collapsed: Boolean,
  currentId: String
})

defineEmits(['toggle'])
</script>

<style scoped>
.sidebar {
  width: 280px;
  min-width: 280px;
  background: var(--sidebar-bg);
  border-right: 1px solid var(--border-color);
  display: flex;
  flex-direction: column;
  transition: all 0.3s ease;
  overflow: hidden;
}

.sidebar.collapsed {
  width: 60px;
  min-width: 60px;
}

.sidebar-header {
  padding: 16px;
  border-bottom: 1px solid var(--border-color);
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.sidebar.collapsed .sidebar-header {
  padding: 16px 8px;
  justify-content: center;
}

.sidebar-title {
  font-size: 16px;
  cursor: pointer;
  display: flex;
  align-items: center;
  gap: 8px;
  color: var(--text-primary);
  white-space: nowrap;
  text-align: left;
}

.logo {
  font-size: 20px;
}

.toggle-btn {
  background: none;
  border: none;
  font-size: 18px;
  cursor: pointer;
  color: var(--text-secondary);
  padding: 4px 8px;
  border-radius: 4px;
}

.toggle-btn:hover {
  background: var(--hover-bg);
}

.sidebar-nav {
  flex: 1;
  padding: 12px 8px;
  overflow-y: auto;
}

.nav-item {
  display: flex;
  align-items: center;
  gap: 10px;
  padding: 12px 12px;
  margin-bottom: 4px;
  border-radius: 8px;
  color: var(--text-secondary);
  text-decoration: none;
  transition: all 0.2s ease;
  cursor: pointer;
  text-align: left;
  justify-content: flex-start;
}

.nav-item:hover {
  background: var(--hover-bg);
  color: var(--text-primary);
}

.nav-item.active {
  background: var(--active-bg);
  color: var(--primary-color);
  font-weight: 600;
}

.nav-icon {
  font-size: 20px;
  flex-shrink: 0;
}

.nav-text {
  display: flex;
  flex-direction: column;
  overflow: hidden;
  text-align: left;
}

.nav-title {
  font-size: 14px;
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
}

.nav-subtitle {
  font-size: 11px;
  color: var(--text-tertiary);
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
}

.sidebar-footer {
  padding: 16px;
  border-top: 1px solid var(--border-color);
  text-align: left;
  font-size: 12px;
  color: var(--text-tertiary);
}

.footer-sub {
  font-size: 10px;
  margin-top: 2px;
}
</style>
