const Dropbox = require('dropbox').Dropbox;

export default async function handler(req, res) {
  if (req.method === 'GET' && req.query.info === '1') {
    const DBX = new Dropbox({ 
      accessToken: process.env.DROPBOX_ACCESS_TOKEN 
    });
    
    try {
      const fileInfo = await DBX.filesGetInfo({ path: '/Data-Matrix.xlsx' });
      return res.json({
        rev: fileInfo.result.rev,
        size: fileInfo.result.size,
        server_modified: fileInfo.result.server_modified
      });
    } catch (err) {
      return res.status(500).json({ error: err.message });
    }
  }

  const DBX = new Dropbox({ 
    accessToken: process.env.DROPBOX_ACCESS_TOKEN 
  });

  try {
    const upstream = await DBX.filesDownload({ path: '/Data-Matrix.xlsx' });
    const buffer = Buffer.from(upstream.result.fileBinary);
    
    res.setHeader('Content-Type', 'application/octet-stream');
    res.setHeader('Cache-Control', 'no-store');
    res.send(buffer);
  } catch (err) {
    console.error('Dropbox error:', err);
    res.status(500).send('Proxy error: ' + err.message);
  }
}