import net from 'node:net';
const SLOW_MS = 3000;

export function classify({ ok, reachable, latency, error }) {
  if (ok) return { status: latency > SLOW_MS ? 'warn' : 'ok', latency_ms: latency, detail: `${latency}ms` };
  if (reachable) return { status: 'warn', latency_ms: latency ?? null, detail: 'degraded' };
  return { status: 'down', latency_ms: null, detail: error || 'unreachable' };
}

// Default probe: HTTP (status 2xx/3xx) or TCP connect. Only called with
// operator-configured URLs from the registry — never user input.
export async function probe(svc) {
  const started = Date.now();
  const type = svc.check?.type || 'http';
  try {
    if (type === 'tcp') {
      const u = new URL(svc.url);
      await new Promise((resolve, reject) => {
        const sock = net.connect({ host: u.hostname, port: Number(u.port) }, () => { sock.end(); resolve(); });
        sock.setTimeout(5000); sock.on('timeout', () => { sock.destroy(); reject(new Error('timeout')); });
        sock.on('error', reject);
      });
      return { ok: true, latency: Date.now() - started };
    }
    const base = svc.url.replace(/\/$/, '');
    const url = base + (svc.check?.path || '');
    const res = await fetch(url, { redirect: 'manual', signal: AbortSignal.timeout(6000) });
    const reachable = true;
    const ok = res.status >= 200 && res.status < 400;
    return { ok, reachable, latency: Date.now() - started };
  } catch (e) {
    return { ok: false, reachable: false, latency: Date.now() - started, error: e.code || e.message };
  }
}

export async function checkAll(services, probeFn = probe) {
  return Promise.all(services.map(async svc => {
    const c = classify(await probeFn(svc));
    return { service_id: svc.id, ...c };
  }));
}