import express from 'express';
import fetch from 'node-fetch';
import { URL } from 'url';

const app = express();
const port = 3000;

// 允许跨域请求
app.use((req, res, next) => {
  res.header('Access-Control-Allow-Origin', '*');
  next();
});

// 通用代理路由
app.get('/proxy', async (req, res) => {
  console.log('Received Range header:', req.headers.range);
  // 获取目标 URL
  const targetUrl = req.query.url;
  console.log('Fetching data from:', targetUrl);
  if (!targetUrl) {
    return res.status(400).send('URL parameter is required');
  }

  try {
    // 设置请求头
    const headers = {};
    if (req.headers.range) {
      headers['Range'] = req.headers.range; // 转发 Range 请求头
    }

    // 向目标 URL 发起请求
    const response = await fetch(targetUrl, { headers });

    // 设置响应头
    response.headers.forEach((value, key) => {
      if (key !== 'content-encoding') { // 避免某些头信息导致问题
        res.setHeader(key, value);
      }
    });

    // 特殊处理 Transfer-Encoding 和 Content-Length
    if (response.headers.get('transfer-encoding') === 'chunked') {
      res.removeHeader('Content-Length');
    }

    // 将响应体直接流式传输给客户端
    response.body.pipe(res, { end: true });

    // 错误处理
    response.body.on('error', (err) => {
      console.error('Error during data transfer:', err);
      res.status(500).send('Error during data transfer');
    });
  } catch (error) {
    console.error('Error fetching data:', error);
    res.status(500).send('Error fetching data');
  }
});

app.listen(port, () => {
  console.log(`Proxy server running at http://localhost:${port}`);
});