/**
 * Health-Probe für die RustyCMS API. Ergebnisse werden kurz gecacht, damit nicht
 * jeder Request einen extra Roundtrip auslöst. Bei Negativ-Status kürzere TTL,
 * damit das Frontend zügig wieder hochkommt sobald das CMS antwortet.
 */
import { env } from '$env/dynamic/public';

const HEALTHY_TTL_MS = 10_000;
const UNHEALTHY_TTL_MS = 3_000;
const PROBE_TIMEOUT_MS = 1_500;

type CacheEntry = { healthy: boolean; expires: number };
let cached: CacheEntry | null = null;
let inflight: Promise<boolean> | null = null;

function getBaseUrl(): string {
  const url = env.PUBLIC_CMS_URL || 'http://localhost:3000';
  return url.replace(/\/$/, '');
}

async function probe(): Promise<boolean> {
  const base = getBaseUrl();
  const ctrl = new AbortController();
  const timer = setTimeout(() => ctrl.abort(), PROBE_TIMEOUT_MS);
  try {
    const res = await fetch(`${base}/api-docs/openapi.json`, {
      method: 'GET',
      signal: ctrl.signal,
    });
    return res.ok;
  } catch {
    return false;
  } finally {
    clearTimeout(timer);
  }
}

export async function isCmsAvailable(): Promise<boolean> {
  const now = Date.now();
  if (cached && cached.expires > now) return cached.healthy;
  if (inflight) return inflight;

  const p = (async () => {
    const healthy = await probe();
    cached = {
      healthy,
      expires: Date.now() + (healthy ? HEALTHY_TTL_MS : UNHEALTHY_TTL_MS),
    };
    return healthy;
  })();
  inflight = p;
  p.finally(() => {
    if (inflight === p) inflight = null;
  });
  return p;
}

export function resetCmsHealthCache(): void {
  cached = null;
}