/**
 * 备份管理控制器
 * @file backupController.js
 * @description 处理数据备份和恢复相关业务逻辑
 */
const backupService = require('../services/backupService');
const logger = require('../utils/logger');
const { validationResult } = require('express-validator');
const cron = require('node-cron');

/**
 * 创建备份
 * @route POST /api/backup/create
 */
const createBackup = async (req, res) => {
  try {
    const { type = 'full', description } = req.body;
    
    logger.info(`用户 ${req.user.username} 开始创建备份，类型: ${type}`);
    
    const backupResult = await backupService.createFullBackup({
      type,
      description,
      createdBy: req.user.id
    });

    res.json({
      success: true,
      message: '备份创建成功',
      data: backupResult
    });
  } catch (error) {
    logger.error('创建备份失败:', error);
    res.status(500).json({
      success: false,
      message: error.message || '创建备份失败',
      error: error.message
    });
  }
};

/**
 * 获取备份列表
 * @route GET /api/backup/list
 */
const getBackupList = async (req, res) => {
  try {
    const { page = 1, limit = 10, type } = req.query;
    
    let backups = await backupService.getBackupList();
    
    // 按类型过滤
    if (type) {
      backups = backups.filter(backup => backup.type === type);
    }
    
    // 分页
    const startIndex = (page - 1) * limit;
    const endIndex = startIndex + parseInt(limit);
    const paginatedBackups = backups.slice(startIndex, endIndex);
    
    res.json({
      success: true,
      data: paginatedBackups,
      total: backups.length,
      page: parseInt(page),
      limit: parseInt(limit)
    });
  } catch (error) {
    logger.error('获取备份列表失败:', error);
    res.status(500).json({
      success: false,
      message: '获取备份列表失败',
      error: error.message
    });
  }
};

/**
 * 获取备份统计
 * @route GET /api/backup/stats
 */
const getBackupStats = async (req, res) => {
  try {
    const stats = await backupService.getBackupStats();
    
    res.json({
      success: true,
      data: stats
    });
  } catch (error) {
    logger.error('获取备份统计失败:', error);
    res.status(500).json({
      success: false,
      message: '获取备份统计失败',
      error: error.message
    });
  }
};

/**
 * 删除备份
 * @route DELETE /api/backup/:id
 */
const deleteBackup = async (req, res) => {
  try {
    const { id } = req.params;
    
    const result = await backupService.deleteBackup(id);
    
    if (result) {
      logger.info(`用户 ${req.user.username} 删除备份: ${id}`);
      res.json({
        success: true,
        message: '备份删除成功'
      });
    } else {
      res.status(404).json({
        success: false,
        message: '备份不存在或删除失败'
      });
    }
  } catch (error) {
    logger.error('删除备份失败:', error);
    res.status(500).json({
      success: false,
      message: '删除备份失败',
      error: error.message
    });
  }
};

/**
 * 恢复数据库
 * @route POST /api/backup/:id/restore
 */
const restoreBackup = async (req, res) => {
  try {
    const { id } = req.params;
    const { confirm } = req.body;
    
    if (!confirm) {
      return res.status(400).json({
        success: false,
        message: '请确认恢复操作'
      });
    }
    
    logger.info(`用户 ${req.user.username} 开始恢复备份: ${id}`);
    
    const result = await backupService.restoreDatabase(id);
    
    if (result) {
      res.json({
        success: true,
        message: '数据恢复成功'
      });
    } else {
      res.status(500).json({
        success: false,
        message: '数据恢复失败'
      });
    }
  } catch (error) {
    logger.error('恢复备份失败:', error);
    res.status(500).json({
      success: false,
      message: '恢复备份失败',
      error: error.message
    });
  }
};

/**
 * 下载备份文件
 * @route GET /api/backup/:id/download
 */
const downloadBackup = async (req, res) => {
  try {
    const { id } = req.params;
    const path = require('path');
    const fs = require('fs');
    
    const archivePath = path.join(__dirname, '../../backups', `${id}.zip`);
    
    // 检查文件是否存在
    if (!fs.existsSync(archivePath)) {
      return res.status(404).json({
        success: false,
        message: '备份文件不存在'
      });
    }
    
    const stats = fs.statSync(archivePath);
    const filename = `backup_${id}.zip`;
    
    res.setHeader('Content-Type', 'application/zip');
    res.setHeader('Content-Disposition', `attachment; filename="${filename}"`);
    res.setHeader('Content-Length', stats.size);
    
    const readStream = fs.createReadStream(archivePath);
    readStream.pipe(res);
    
    logger.info(`用户 ${req.user.username} 下载备份: ${id}`);
  } catch (error) {
    logger.error('下载备份失败:', error);
    res.status(500).json({
      success: false,
      message: '下载备份失败',
      error: error.message
    });
  }
};

/**
 * 清理过期备份
 * @route POST /api/backup/cleanup
 */
const cleanupBackups = async (req, res) => {
  try {
    const deletedCount = await backupService.cleanupExpiredBackups();
    
    logger.info(`用户 ${req.user.username} 执行备份清理，删除了 ${deletedCount} 个过期备份`);
    
    res.json({
      success: true,
      message: `清理完成，删除了 ${deletedCount} 个过期备份`,
      data: { deletedCount }
    });
  } catch (error) {
    logger.error('清理备份失败:', error);
    res.status(500).json({
      success: false,
      message: '清理备份失败',
      error: error.message
    });
  }
};

/**
 * 获取备份健康状态
 * @route GET /api/backup/health
 */
const getBackupHealth = async (req, res) => {
  try {
    const health = await backupService.checkBackupHealth();
    
    res.json({
      success: true,
      data: health
    });
  } catch (error) {
    logger.error('获取备份健康状态失败:', error);
    res.status(500).json({
      success: false,
      message: '获取备份健康状态失败',
      error: error.message
    });
  }
};

/**
 * 自动备份任务调度器
 */
class BackupScheduler {
  constructor() {
    this.tasks = new Map();
  }

  /**
   * 启动自动备份调度
   */
  start() {
    // 每日备份（凌晨2点）
    const dailyTask = cron.schedule('0 2 * * *', async () => {
      try {
        logger.info('开始执行自动日备份');
        await backupService.createFullBackup({ type: 'daily', description: '自动日备份' });
        logger.info('自动日备份完成');
      } catch (error) {
        logger.error('自动日备份失败:', error);
      }
    }, {
      scheduled: false
    });

    // 每周备份（周日凌晨3点）
    const weeklyTask = cron.schedule('0 3 * * 0', async () => {
      try {
        logger.info('开始执行自动周备份');
        await backupService.createFullBackup({ type: 'weekly', description: '自动周备份' });
        logger.info('自动周备份完成');
      } catch (error) {
        logger.error('自动周备份失败:', error);
      }
    }, {
      scheduled: false
    });

    // 每月备份（每月1号凌晨4点）
    const monthlyTask = cron.schedule('0 4 1 * *', async () => {
      try {
        logger.info('开始执行自动月备份');
        await backupService.createFullBackup({ type: 'monthly', description: '自动月备份' });
        logger.info('自动月备份完成');
      } catch (error) {
        logger.error('自动月备份失败:', error);
      }
    }, {
      scheduled: false
    });

    // 自动清理任务（每天凌晨5点）
    const cleanupTask = cron.schedule('0 5 * * *', async () => {
      try {
        logger.info('开始执行自动备份清理');
        const deletedCount = await backupService.cleanupExpiredBackups();
        logger.info(`自动备份清理完成，删除了 ${deletedCount} 个过期备份`);
      } catch (error) {
        logger.error('自动备份清理失败:', error);
      }
    }, {
      scheduled: false
    });

    this.tasks.set('daily', dailyTask);
    this.tasks.set('weekly', weeklyTask);
    this.tasks.set('monthly', monthlyTask);
    this.tasks.set('cleanup', cleanupTask);

    // 启动所有任务
    this.tasks.forEach((task, name) => {
      task.start();
      logger.info(`备份调度任务已启动: ${name}`);
    });
  }

  /**
   * 停止自动备份调度
   */
  stop() {
    this.tasks.forEach((task, name) => {
      task.stop();
      logger.info(`备份调度任务已停止: ${name}`);
    });
  }

  /**
   * 获取调度状态
   */
  getStatus() {
    const status = {};
    this.tasks.forEach((task, name) => {
      status[name] = {
        running: task.running,
        lastExecution: task.lastExecution,
        nextExecution: task.nextExecution
      };
    });
    return status;
  }
}

// 创建调度器实例
const scheduler = new BackupScheduler();

/**
 * 启动自动备份调度
 * @route POST /api/backup/schedule/start
 */
const startScheduler = async (req, res) => {
  try {
    scheduler.start();
    logger.info(`用户 ${req.user.username} 启动自动备份调度`);
    
    res.json({
      success: true,
      message: '自动备份调度已启动'
    });
  } catch (error) {
    logger.error('启动备份调度失败:', error);
    res.status(500).json({
      success: false,
      message: '启动备份调度失败',
      error: error.message
    });
  }
};

/**
 * 停止自动备份调度
 * @route POST /api/backup/schedule/stop
 */
const stopScheduler = async (req, res) => {
  try {
    scheduler.stop();
    logger.info(`用户 ${req.user.username} 停止自动备份调度`);
    
    res.json({
      success: true,
      message: '自动备份调度已停止'
    });
  } catch (error) {
    logger.error('停止备份调度失败:', error);
    res.status(500).json({
      success: false,
      message: '停止备份调度失败',
      error: error.message
    });
  }
};

/**
 * 获取调度状态
 * @route GET /api/backup/schedule/status
 */
const getSchedulerStatus = async (req, res) => {
  try {
    const status = scheduler.getStatus();
    
    res.json({
      success: true,
      data: status
    });
  } catch (error) {
    logger.error('获取调度状态失败:', error);
    res.status(500).json({
      success: false,
      message: '获取调度状态失败',
      error: error.message
    });
  }
};

module.exports = {
  createBackup,
  getBackupList,
  getBackupStats,
  deleteBackup,
  restoreBackup,
  downloadBackup,
  cleanupBackups,
  getBackupHealth,
  startScheduler,
  stopScheduler,
  getSchedulerStatus,
  scheduler
};