<template>
  <div class="course-detail">
    <!-- 返回按钮（可选） -->
    <div v-if="showBackButton" class="back-header">
      <el-button @click="handleBack" :icon="ArrowLeft">{{ backButtonText }}</el-button>
    </div>

    <!-- 加载中 -->
    <div v-if="loading" class="loading">
      <el-skeleton :rows="10" animated />
    </div>

    <!-- 课程详情 -->
    <div v-else-if="courseVO" class="course-content">
      <!-- 课程封面和基本信息 -->
      <div class="course-header">
        <div class="cover-section">
          <img 
            :src="courseVO.course.coverImage? FILE_DOWNLOAD_URL + courseVO.course.coverImage : defaultCover" 
            :alt="courseVO.course.name"
            class="cover-image"
          />
        </div>
        
        <div class="info-section">
          <h1 class="course-title">{{ courseVO.course.name }}</h1>
          
          <div class="course-meta">
            <div class="meta-item">
              <el-icon><User /></el-icon>
              <span>授课老师：{{ courseVO.course.teacher }}</span>
            </div>
            <div class="meta-item">
              <el-icon><Clock /></el-icon>
              <span>课程时长：{{ formatDuration(courseVO.course.duration) }}</span>
            </div>
            <div class="meta-item">
              <el-icon><View /></el-icon>
              <span>{{ courseVO.course.viewCount || 0 }} 人浏览</span>
            </div>
            <div class="meta-item">
              <el-icon><Reading /></el-icon>
              <span>{{ courseVO.course.learnCount || 0 }} 人学习</span>
            </div>
          </div>

          <div class="course-description">
            <p>{{ courseVO.course.description }}</p>
          </div>

          <!-- 操作按钮 -->
          <div class="action-buttons">
            <el-button 
              type="primary" 
              size="large" 
              @click="handleStartLearning"
              :loading="enrolling"
            >
              <el-icon><VideoPlay /></el-icon>
              {{ isEnrolled ? '继续学习' : '开始学习' }}
            </el-button>
            
            <el-button 
              size="large"
              :icon="isCollected ? StarFilled : Star"
              @click="handleCollect"
            >
              {{ isCollected ? '已收藏' : '收藏课程' }}
            </el-button>
          </div>

          <!-- 学习进度 -->
          <div v-if="learningProgress" class="learning-progress">
            <div class="progress-header">
              <span>学习进度</span>
              <span class="progress-text">{{ learningProgress.progress }}%</span>
            </div>
            <el-progress 
              :percentage="learningProgress.progress" 
              :stroke-width="10"
              :color="progressColor"
            />
          </div>
        </div>
      </div>

      <!-- 课程章节 -->
      <el-card class="chapter-card" shadow="never">
        <template #header>
          <div class="card-header">
            <span>课程章节</span>
            <span class="chapter-count">共 {{ courseVO.courseChapters.length }} 章</span>
          </div>
        </template>

        <div v-if="courseVO.courseChapters.length === 0" class="empty-tip">
          暂无章节内容
        </div>

        <el-collapse v-else v-model="activeChapters">
          <el-collapse-item
            v-for="(chapterVO, chapterIndex) in courseVO.courseChapters"
            :key="chapterIndex"
            :name="chapterIndex"
          >
            <template #title>
              <div class="chapter-title-bar">
                <span class="chapter-name">
                  <el-icon><DocumentCopy /></el-icon>
                  章节 {{ chapterIndex + 1 }}: {{ chapterVO.chapter.name }}
                </span>
                <span class="chapter-meta">
                  {{ chapterVO.nodes.length }} 个节点
                </span>
              </div>
            </template>

            <!-- 节点列表 -->
            <div v-if="chapterVO.nodes.length === 0" class="empty-tip">
              暂无学习节点
            </div>
            
            <div v-else class="node-list">
              <div
                v-for="(node, nodeIndex) in chapterVO.nodes"
                :key="nodeIndex"
                class="node-item"
                @click="handleNodeClick(chapterIndex, nodeIndex)"
              >
                <div class="node-info">
                  <el-icon class="node-icon">
                    <Document v-if="node.nodeType === 0" />
                    <Edit v-else-if="node.nodeType === 1" />
                    <Upload v-else />
                  </el-icon>
                  <span class="node-name">{{ node.name }}</span>
                  <el-tag 
                    v-if="node.isRequired === 1" 
                    type="danger" 
                    size="small"
                    effect="plain"
                  >
                    必修
                  </el-tag>
                </div>
                <div class="node-meta">
                  <span v-if="node.duration" class="node-duration">
                    <el-icon><Clock /></el-icon>
                    {{ node.duration }} 分钟
                  </span>
                  <el-icon class="arrow-icon"><ArrowRight /></el-icon>
                </div>
              </div>
            </div>
          </el-collapse-item>
        </el-collapse>
      </el-card>

      <!-- 收藏按钮（底部浮动） -->
      <div class="floating-collect">
        <el-button
          circle
          size="large"
          :icon="isCollected ? StarFilled : Star"
          @click="handleCollect"
          :type="isCollected ? 'warning' : 'default'"
        />
      </div>
    </div>

    <!-- 加载失败 -->
    <div v-else class="error-tip">
      <el-empty description="加载课程失败" />
    </div>
  </div>
</template>

<script setup lang="ts">
import { ref, computed, watch } from 'vue';
import { useRouter } from 'vue-router';
import { ElMessage } from 'element-plus';
import {
  ArrowLeft,
  User,
  Clock,
  View,
  Reading,
  VideoPlay,
  Star,
  StarFilled,
  DocumentCopy,
  Document,
  Edit,
  Upload,
  ArrowRight
} from '@element-plus/icons-vue';
import { courseApi } from '@/apis/study';
import { learningRecordApi } from '@/apis/study';
import { userCollectionApi } from '@/apis/usercenter';
import { useStore } from 'vuex';
import type { CourseVO, LearningRecord } from '@/types';
import { CollectionType } from '@/types';
import { FILE_DOWNLOAD_URL } from '@/config';

defineOptions({
  name: 'CourseDetail'
});

interface Props {
  courseId: string;
  showBackButton?: boolean;
  backButtonText?: string;
}

const props = withDefaults(defineProps<Props>(), {
  showBackButton: false,
  backButtonText: '返回'
});

const emit = defineEmits<{
  'back': [];
  'start-learning': [courseId: string, chapterIndex: number, nodeIndex: number];
}>();

const router = useRouter();
const store = useStore();

// 从 store 获取用户信息
const userInfo = computed(() => store.getters['auth/user']);

const loading = ref(false);
const enrolling = ref(false);
const courseVO = ref<CourseVO | null>(null);
const isCollected = ref(false);
const isEnrolled = ref(false);
const learningProgress = ref<LearningRecord | null>(null);
const activeChapters = ref<number[]>([0]); // 默认展开第一章
const defaultCover = new URL('@/assets/imgs/article-default.png', import.meta.url).href;

// 进度条颜色
const progressColor = computed(() => {
  const progress = learningProgress.value?.progress || 0;
  if (progress >= 80) return '#67c23a';
  if (progress >= 50) return '#409eff';
  return '#e6a23c';
});

watch(() => props.courseId, (newId) => {
  if (newId) {
    loadCourseDetail();
    checkCollectionStatus();
    loadLearningProgress();
  }
}, { immediate: true });

// 加载课程详情
async function loadCourseDetail() {
  loading.value = true;
  try {
    // 增加浏览次数
    courseApi.incrementViewCount(props.courseId);
    
    const res = await courseApi.getCourseById(props.courseId);
    if (res.success && res.data) {
      courseVO.value = res.data;
      
      // 确保数据结构完整
      if (!courseVO.value.courseChapters) {
        courseVO.value.courseChapters = [];
      }
      if (!courseVO.value.courseTags) {
        courseVO.value.courseTags = [];
      }
      courseVO.value.courseChapters.forEach((chapter) => {
        if (!chapter.nodes) {
          chapter.nodes = [];
        }
      });
    } else {
      ElMessage.error('加载课程失败');
    }
  } catch (error) {
    console.error('加载课程失败:', error);
    ElMessage.error('加载课程失败');
  } finally {
    loading.value = false;
  }
}

// 检查收藏状态
async function checkCollectionStatus() {
  if (!userInfo.value?.id) return;
  
  try {
    const res = await userCollectionApi.isCollected(
      userInfo.value.id,
      CollectionType.COURSE,
      props.courseId
    );
    if (res.success) {
      isCollected.value = res.data || false;
    }
  } catch (error) {
    console.error('检查收藏状态失败:', error);
  }
}

// 加载学习进度
async function loadLearningProgress() {
  if (!userInfo.value?.id) return;
  
  try {
    const res = await learningRecordApi.getRecordList({
      userID: userInfo.value.id,
      resourceType: 2, // 课程类型
      resourceID: props.courseId
    });
    
    if (res.success && res.dataList && res.dataList.length > 0) {
      learningProgress.value = res.dataList[0];
      isEnrolled.value = true;
    }
  } catch (error) {
    console.error('加载学习进度失败:', error);
  }
}

// 处理收藏
async function handleCollect() {
  if (!userInfo.value?.id) {
    ElMessage.warning('请先登录');
    router.push('/login');
    return;
  }
  
  try {
    if (isCollected.value) {
      // 取消收藏
      const res = await userCollectionApi.removeCollection(
        userInfo.value.id,
        CollectionType.COURSE,
        props.courseId
      );
      if (res.success) {
        isCollected.value = false;
        ElMessage.success('已取消收藏');
      }
    } else {
      // 添加收藏
      const res = await userCollectionApi.addCollection({
        userID: userInfo.value.id,
        collectionType: CollectionType.COURSE,
        collectionID: props.courseId
      });
      if (res.success) {
        isCollected.value = true;
        ElMessage.success('收藏成功');
      }
    }
  } catch (error) {
    console.error('收藏操作失败:', error);
    ElMessage.error('操作失败');
  }
}

// 开始学习
async function handleStartLearning() {
  if (!userInfo.value?.id) {
    ElMessage.warning('请先登录');
    router.push('/login');
    return;
  }
  
  if (!courseVO.value || courseVO.value.courseChapters.length === 0) {
    ElMessage.warning('课程暂无内容');
    return;
  }
  
  enrolling.value = true;
  try {
    // 如果未报名，创建学习记录
    if (!isEnrolled.value) {
      await courseApi.incrementLearnCount(props.courseId);
      await learningRecordApi.createRecord({
        userID: userInfo.value.id,
        resourceType: 2, // 课程
        resourceID: props.courseId,
        progress: 0,
        duration: 0,
        isComplete: false
      });
      isEnrolled.value = true;
    }
    
    // 跳转到学习页面，默认从第一章第一节开始
    emit('start-learning', props.courseId, 0, 0);
  } catch (error) {
    console.error('开始学习失败:', error);
    ElMessage.error('开始学习失败');
  } finally {
    enrolling.value = false;
  }
}

// 点击节点
function handleNodeClick(chapterIndex: number, nodeIndex: number) {
  if (!userInfo.value?.id) {
    ElMessage.warning('请先登录');
    router.push('/login');
    return;
  }
  
  emit('start-learning', props.courseId, chapterIndex, nodeIndex);
}

// 返回
function handleBack() {
  emit('back');
}

// 格式化时长
function formatDuration(minutes?: number): string {
  if (!minutes) return '0分钟';
  
  const hours = Math.floor(minutes / 60);
  const mins = minutes % 60;
  
  if (hours > 0) {
    return `${hours}小时${mins}分钟`;
  }
  return `${mins}分钟`;
}
</script>

<style lang="scss" scoped>
.course-detail {
  min-height: 100vh;
  background: #f5f7fa;
  padding-bottom: 60px;
}

.back-header {
  padding: 16px 24px;
  background: #fff;
  border-bottom: 1px solid #e4e7ed;
  margin-bottom: 0;
}

.loading {
  padding: 24px;
  background: #fff;
  margin: 16px;
  border-radius: 8px;
}

.course-content {
  max-width: 1200px;
  margin: 0 auto;
  padding: 24px;
}

.course-header {
  background: #fff;
  border-radius: 8px;
  padding: 24px;
  margin-bottom: 24px;
  display: flex;
  gap: 24px;
  box-shadow: 0 2px 12px rgba(0, 0, 0, 0.08);

  @media (max-width: 768px) {
    flex-direction: column;
  }
}

.cover-section {
  flex-shrink: 0;
  
  .cover-image {
    width: 320px;
    height: 240px;
    object-fit: cover;
    border-radius: 8px;
    
    @media (max-width: 768px) {
      width: 100%;
      height: auto;
    }
  }
}

.info-section {
  flex: 1;
  display: flex;
  flex-direction: column;
  gap: 16px;
}

.course-title {
  font-size: 28px;
  font-weight: 600;
  color: #303133;
  margin: 0;
  line-height: 1.4;
}

.course-meta {
  display: flex;
  flex-wrap: wrap;
  gap: 24px;
  
  .meta-item {
    display: flex;
    align-items: center;
    gap: 8px;
    color: #606266;
    font-size: 14px;
    
    .el-icon {
      color: #909399;
    }
  }
}

.course-description {
  color: #606266;
  font-size: 14px;
  line-height: 1.8;
  
  p {
    margin: 0;
  }
}

.action-buttons {
  display: flex;
  gap: 16px;
  margin-top: 8px;
}

.learning-progress {
  padding: 16px;
  background: #f5f7fa;
  border-radius: 8px;
  
  .progress-header {
    display: flex;
    justify-content: space-between;
    margin-bottom: 12px;
    font-size: 14px;
    
    .progress-text {
      color: #409eff;
      font-weight: 600;
    }
  }
}

.chapter-card {
  :deep(.el-card__header) {
    background: #fafafa;
  }
  
  .card-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    font-size: 18px;
    font-weight: 600;
    
    .chapter-count {
      font-size: 14px;
      color: #909399;
      font-weight: normal;
    }
  }
}

.chapter-title-bar {
  display: flex;
  justify-content: space-between;
  align-items: center;
  width: 100%;
  padding-right: 20px;
  
  .chapter-name {
    display: flex;
    align-items: center;
    gap: 8px;
    font-size: 16px;
    font-weight: 500;
  }
  
  .chapter-meta {
    font-size: 14px;
    color: #909399;
  }
}

.node-list {
  padding: 8px 0;
}

.node-item {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 12px 16px;
  margin: 8px 0;
  background: #fafafa;
  border-radius: 6px;
  cursor: pointer;
  transition: all 0.3s;
  
  &:hover {
    background: #f0f2f5;
    transform: translateX(4px);
  }
  
  .node-info {
    display: flex;
    align-items: center;
    gap: 12px;
    flex: 1;
    
    .node-icon {
      color: #409eff;
      font-size: 18px;
    }
    
    .node-name {
      font-size: 14px;
      color: #303133;
    }
  }
  
  .node-meta {
    display: flex;
    align-items: center;
    gap: 12px;
    
    .node-duration {
      display: flex;
      align-items: center;
      gap: 4px;
      font-size: 13px;
      color: #909399;
    }
    
    .arrow-icon {
      color: #c0c4cc;
      transition: transform 0.3s;
    }
  }
  
  &:hover .arrow-icon {
    transform: translateX(4px);
  }
}

.empty-tip {
  text-align: center;
  padding: 40px;
  color: #909399;
  font-size: 14px;
}

.error-tip {
  padding: 40px;
}

.floating-collect {
  position: fixed;
  bottom: 80px;
  right: 40px;
  z-index: 100;
  
  @media (max-width: 768px) {
    bottom: 60px;
    right: 20px;
  }
}
</style>

