import { MAX_REQUESTS } from './config/env.js';

const sseClients = new Set();
const requests = [];

export function registerSse(req, res, initialStatus = {}) {
  res.setHeader('Content-Type', 'text/event-stream');
  res.setHeader('Cache-Control', 'no-cache');
  res.setHeader('Cache-Control', 'no-transform');
  res.setHeader('Connection', 'keep-alive');
  // Disable proxy buffering in Nginx
  res.setHeader('X-Accel-Buffering', 'no');
  res.flushHeaders?.();
  res.write(`event: hello\n`);
  res.write(`data: {"ok":true}\n\n`);
  if (initialStatus && Object.keys(initialStatus).length) {
    res.write(`event: status\n`);
    res.write(`data: ${JSON.stringify(initialStatus)}\n\n`);
  }
  sseClients.add(res);
  // Heartbeat to keep proxies/load balancers from timing out idle SSE
  // Send a comment line every 20s
  const hb = setInterval(() => {
    try { res.write(`: ping\n\n`); } catch { /* ignore */ }
  }, 20000);
  req.on('close', () => {
    clearInterval(hb);
    sseClients.delete(res);
  });
}

export function pushRequest(rec) {
  requests.push(rec);
  while (requests.length > MAX_REQUESTS) requests.shift();
  const payload = `data: ${JSON.stringify(rec)}\n\n`;
  for (const res of sseClients) {
    try { res.write(payload); } catch { /* ignore */ }
  }
}

export function broadcastStatus(payload) {
  const ev = `event: status\n` + `data: ${JSON.stringify(payload)}\n\n`;
  for (const res of sseClients) {
    try { res.write(ev); } catch { /* ignore */ }
  }
}

export function clearRequests() {
  requests.length = 0;
  const payload = `event: clear\n` + `data: {"ok":true}\n\n`;
  for (const res of sseClients) {
    try { res.write(payload); } catch { /* ignore */ }
  }
}

export function getRecentRequests() {
  return requests.slice(-MAX_REQUESTS);
}