const express = require('express');
const multer = require('multer');
const path = require('path');
const fs = require('fs');
const { v4: uuidv4 } = require('uuid');
const { optionalAuth } = require('../middleware/auth');

const router = express.Router();

// 确保上传目录存在
const uploadDir = path.join(__dirname, '../uploads');
if (!fs.existsSync(uploadDir)) {
  fs.mkdirSync(uploadDir, { recursive: true });
}

// Multer配置
const storage = multer.diskStorage({
  destination: (req, file, cb) => {
    cb(null, uploadDir);
  },
  filename: (req, file, cb) => {
    const uniqueName = `${uuidv4()}-${file.originalname}`;
    cb(null, uniqueName);
  }
});

const fileFilter = (req, file, cb) => {
  // 检查文件类型
  if (file.mimetype === 'application/pdf') {
    cb(null, true);
  } else {
    cb(new Error('只支持PDF文件格式'), false);
  }
};

const upload = multer({
  storage,
  fileFilter,
  limits: {
    fileSize: 50 * 1024 * 1024, // 50MB限制
  }
});

// 上传文件
router.post('/upload', optionalAuth, upload.single('file'), async (req, res) => {
  try {
    if (!req.file) {
      return res.status(400).json({
        success: false,
        message: '未找到上传的文件'
      });
    }

    const fileInfo = {
      fileId: uuidv4(),
      originalName: req.file.originalname,
      fileName: req.file.filename,
      fileSize: req.file.size,
      mimeType: req.file.mimetype,
      uploadTime: new Date(),
      userId: req.user?.userId || null,
      filePath: req.file.path
    };

    // 这里应该保存到数据库
    // await FileModel.create(fileInfo);

    res.json({
      success: true,
      message: '文件上传成功',
      data: {
        fileId: fileInfo.fileId,
        originalName: fileInfo.originalName,
        fileSize: fileInfo.fileSize,
        uploadTime: fileInfo.uploadTime
      }
    });

  } catch (error) {
    console.error('文件上传错误:', error);
    res.status(500).json({
      success: false,
      message: '文件上传失败'
    });
  }
});

// 获取文件信息
router.get('/:fileId', optionalAuth, async (req, res) => {
  try {
    const { fileId } = req.params;

    // 这里应该从数据库查询
    // const file = await FileModel.findOne({ fileId });
    
    // 模拟数据
    const file = {
      fileId,
      originalName: '示例文档.pdf',
      fileSize: 2048576,
      mimeType: 'application/pdf',
      uploadTime: new Date(),
      status: 'ready'
    };

    if (!file) {
      return res.status(404).json({
        success: false,
        message: '文件未找到'
      });
    }

    res.json({
      success: true,
      data: file
    });

  } catch (error) {
    console.error('获取文件信息错误:', error);
    res.status(500).json({
      success: false,
      message: '获取文件信息失败'
    });
  }
});

// 删除文件
router.delete('/:fileId', optionalAuth, async (req, res) => {
  try {
    const { fileId } = req.params;

    // 这里应该从数据库查询文件信息
    // const file = await FileModel.findOne({ fileId });
    
    // 删除物理文件
    const uploadDir = path.join(__dirname, '../uploads');
    const files = fs.readdirSync(uploadDir);
    const targetFile = files.find(file => file.includes(fileId));
    
    if (targetFile) {
      fs.unlinkSync(path.join(uploadDir, targetFile));
    }

    // 从数据库删除记录
    // await FileModel.deleteOne({ fileId });

    res.json({
      success: true,
      message: '文件删除成功'
    });

  } catch (error) {
    console.error('删除文件错误:', error);
    res.status(500).json({
      success: false,
      message: '删除文件失败'
    });
  }
});

// 下载文件
router.get('/download/:fileName', (req, res) => {
  try {
    const { fileName } = req.params;
    const filePath = path.join(uploadDir, fileName);

    if (!fs.existsSync(filePath)) {
      return res.status(404).json({
        success: false,
        message: '文件不存在'
      });
    }

    res.download(filePath, (err) => {
      if (err) {
        console.error('文件下载错误:', err);
        res.status(500).json({
          success: false,
          message: '文件下载失败'
        });
      }
    });

  } catch (error) {
    console.error('下载文件错误:', error);
    res.status(500).json({
      success: false,
      message: '下载文件失败'
    });
  }
});

module.exports = router;