import http from 'node:http';
import httpProxy from 'http-proxy';

const PORT = Number(process.env.PORT || 8080);
const TARGET = process.env.SUPABASE_TARGET || 'https://cksuehzcimitsxmeloes.supabase.co';
const allowedOrigins = new Set([
  'https://app.caterium.ru',
  'https://caterium.ru',
  'https://www.caterium.ru'
]);

const proxy = httpProxy.createProxyServer({
  target: TARGET,
  changeOrigin: true,
  xfwd: true,
  secure: true,
  ws: true
});

proxy.on('proxyReq', (proxyReq) => {
  proxyReq.setHeader('host', new URL(TARGET).host);
});

proxy.on('error', (err, req, res) => {
  console.error('[proxy:error]', err?.message || err);
  if (res && !res.headersSent) {
    res.writeHead(502, {'content-type':'application/json; charset=utf-8'});
  }
  try { res?.end(JSON.stringify({error:'upstream_unavailable'})); } catch (_) {}
});

function cors(req, res) {
  const origin = req.headers.origin;
  if (origin && !allowedOrigins.has(origin)) return false;
  if (origin) {
    res.setHeader('Access-Control-Allow-Origin', origin);
    res.setHeader('Vary', 'Origin');
  }
  res.setHeader('Access-Control-Allow-Credentials', 'true');
  res.setHeader('Access-Control-Allow-Headers', req.headers['access-control-request-headers'] || 'authorization,apikey,content-type,x-client-info,prefer,range');
  res.setHeader('Access-Control-Allow-Methods', 'GET,HEAD,POST,PUT,PATCH,DELETE,OPTIONS');
  return true;
}

const server = http.createServer((req, res) => {
  if (!cors(req, res)) {
    res.writeHead(403, {'content-type':'application/json; charset=utf-8'});
    return res.end(JSON.stringify({error:'origin_not_allowed'}));
  }
  if (req.method === 'OPTIONS') {
    res.writeHead(204);
    return res.end();
  }
  if (req.url === '/health' || req.url === '/healthz') {
    res.writeHead(200, {'content-type':'application/json; charset=utf-8'});
    return res.end(JSON.stringify({ok:true,target:'supabase'}));
  }
  if (!/^\/(rest|auth|storage|functions|realtime)\/v1(?:\/|\?|$)/.test(req.url || '')) {
    res.writeHead(404, {'content-type':'application/json; charset=utf-8'});
    return res.end(JSON.stringify({error:'route_not_allowed'}));
  }
  proxy.web(req, res);
});

server.on('upgrade', (req, socket, head) => {
  const origin = req.headers.origin;
  if (origin && !allowedOrigins.has(origin)) return socket.destroy();
  if (!/^\/realtime\/v1(?:\/|\?|$)/.test(req.url || '')) return socket.destroy();
  proxy.ws(req, socket, head);
});

server.listen(PORT, '0.0.0.0', () => {
  console.log(`[caterium-proxy] listening on ${PORT} -> ${TARGET}`);
});