import http from 'http';
import fs from 'fs';
import path from 'path';
import { fileURLToPath } from 'url';

const __dirname = path.dirname(fileURLToPath(import.meta.url));
const DIST_DIR = path.join(__dirname, 'dist');
const PORT = 5175;
const API_TARGET = 'http://localhost:8080';

const MIME_TYPES = {
  '.html': 'text/html',
  '.js': 'application/javascript',
  '.css': 'text/css',
  '.json': 'application/json',
  '.png': 'image/png',
  '.jpg': 'image/jpeg',
  '.svg': 'image/svg+xml',
  '.ico': 'image/x-icon',
};

function proxyRequest(req, res) {
  const url = API_TARGET + req.url;
  console.log(`[Proxy] ${req.method} ${req.url} -> ${url}`);

  const options = {
    hostname: 'localhost',
    port: 8080,
    path: req.url,
    method: req.method,
    headers: req.headers,
  };

  const proxyReq = http.request(options, (proxyRes) => {
    res.writeHead(proxyRes.statusCode, proxyRes.headers);
    proxyRes.pipe(res);
  });

  proxyReq.on('error', (err) => {
    console.error(`[Proxy Error] ${err.message}`);
    res.writeHead(502, { 'Content-Type': 'application/json' });
    res.end(JSON.stringify({ error: 'Proxy error', message: err.message }));
  });

  req.pipe(proxyReq);
}

const server = http.createServer((req, res) => {
  console.log(`${new Date().toISOString()} ${req.method} ${req.url}`);

  // CORS headers
  res.setHeader('Access-Control-Allow-Origin', '*');
  res.setHeader('Access-Control-Allow-Methods', 'GET, POST, PUT, DELETE, OPTIONS');
  res.setHeader('Access-Control-Allow-Headers', 'Content-Type, Authorization');

  if (req.method === 'OPTIONS') {
    res.writeHead(204);
    res.end();
    return;
  }

  // Proxy API requests
  if (req.url.startsWith('/api')) {
    proxyRequest(req, res);
    return;
  }

  let filePath = path.join(DIST_DIR, req.url === '/' ? 'index.html' : req.url);

  // SPA fallback - 如果文件不存在，返回 index.html
  if (!fs.existsSync(filePath) || fs.statSync(filePath).isDirectory()) {
    filePath = path.join(DIST_DIR, 'index.html');
  }

  const ext = path.extname(filePath);
  const contentType = MIME_TYPES[ext] || 'application/octet-stream';

  try {
    const content = fs.readFileSync(filePath);
    res.writeHead(200, {
      'Content-Type': contentType,
      'Cache-Control': 'no-cache'
    });
    res.end(content);
  } catch (err) {
    res.writeHead(404);
    res.end('Not Found');
  }
});

server.listen(PORT, '127.0.0.1', () => {
  console.log(`Dev server running at http://127.0.0.1:${PORT}/`);
  console.log(`Serving: ${DIST_DIR}`);
  console.log(`API proxy: -> ${API_TARGET}`);
});