const fs = require('fs');
const path = require('path');

// 持久化文件路径
const STORAGE_FILE = path.join(__dirname, '../../data/viewHistory.json');

// 确保数据目录存在
const ensureDataDir = () => {
  const dir = path.dirname(STORAGE_FILE);
  if (!fs.existsSync(dir)) {
    fs.mkdirSync(dir, { recursive: true });
  }
};

// 从文件加载观看历史数据
const loadViewHistory = () => {
  try {
    ensureDataDir();
    if (fs.existsSync(STORAGE_FILE)) {
      const data = fs.readFileSync(STORAGE_FILE, 'utf8');
      return JSON.parse(data);
    }
  } catch (e) {
    console.warn('[ViewHistoryStore] Failed to load view history from file:', e.message);
  }
  return [];
};

// 保存观看历史数据到文件
const saveViewHistory = (history) => {
  try {
    ensureDataDir();
    fs.writeFileSync(STORAGE_FILE, JSON.stringify(history, null, 2), 'utf8');
  } catch (e) {
    console.error('[ViewHistoryStore] Failed to save view history to file:', e.message);
  }
};

// 内存存储（从文件加载）
let viewHistory = loadViewHistory();
console.log(`[ViewHistoryStore] Loaded ${viewHistory.length} view history records from storage`);

const viewHistoryStore = {
  // 记录观看历史
  record(data) {
    const { userId, targetType, targetId, targetTitle, coverImage, streamerName, authorName, viewDuration } = data;
    
    // 查找是否已存在相同的记录
    const existingIndex = viewHistory.findIndex(
      h => h.userId === userId && h.targetType === targetType && h.targetId === targetId
    );
    
    const now = new Date().toISOString();
    
    if (existingIndex >= 0) {
      // 更新现有记录
      viewHistory[existingIndex] = {
        ...viewHistory[existingIndex],
        targetTitle: targetTitle || viewHistory[existingIndex].targetTitle,
        coverImage: coverImage || viewHistory[existingIndex].coverImage,
        streamerName: streamerName || viewHistory[existingIndex].streamerName,
        authorName: authorName || viewHistory[existingIndex].authorName,
        viewDuration: viewDuration || viewHistory[existingIndex].viewDuration,
        updateTime: now,
        viewCount: (viewHistory[existingIndex].viewCount || 0) + 1
      };
    } else {
      // 创建新记录
      viewHistory.push({
        id: Date.now(),
        userId,
        targetType,
        targetId,
        targetTitle,
        coverImage,
        streamerName,
        authorName,
        viewDuration,
        createTime: now,
        updateTime: now,
        viewCount: 1
      });
    }
    
    saveViewHistory(viewHistory);
    return true;
  },

  // 获取用户的观看历史
  getUserHistory(userId, type, page = 1, pageSize = 20) {
    let filtered = viewHistory.filter(h => h.userId === userId);
    
    // 按类型过滤
    if (type) {
      filtered = filtered.filter(h => h.targetType === type);
    }
    
    // 按更新时间倒序排序
    filtered.sort((a, b) => new Date(b.updateTime) - new Date(a.updateTime));
    
    // 分页
    const total = filtered.length;
    const start = (page - 1) * pageSize;
    const end = start + pageSize;
    const list = filtered.slice(start, end);
    
    return {
      list,
      total,
      page,
      pageSize,
      totalPages: Math.ceil(total / pageSize)
    };
  },

  // 清除用户的观看历史
  clearUserHistory(userId, type) {
    if (type) {
      viewHistory = viewHistory.filter(h => !(h.userId === userId && h.targetType === type));
    } else {
      viewHistory = viewHistory.filter(h => h.userId !== userId);
    }
    saveViewHistory(viewHistory);
    return true;
  },

  // 删除单条观看历史
  deleteRecord(userId, id) {
    const index = viewHistory.findIndex(h => h.id === id && h.userId === userId);
    if (index >= 0) {
      viewHistory.splice(index, 1);
      saveViewHistory(viewHistory);
      return true;
    }
    return false;
  },

  // 清空所有观看历史 (测试用)
  clear() {
    viewHistory = [];
    saveViewHistory(viewHistory);
  }
};

module.exports = viewHistoryStore;