// fetch for the demo scripts. A connection that never opened did not reach the server,
// so it is safe to try again; anything that may have been delivered is not retried.
const NEVER_SENT = new Set(['UND_ERR_CONNECT_TIMEOUT', 'ECONNREFUSED', 'ENOTFOUND', 'EAI_AGAIN']);

export async function fetchRetry(url, init = {}, { tries = 4, timeoutMs = 90000 } = {}) {
  for (let attempt = 1; ; attempt++) {
    try {
      return await fetch(url, { ...init, signal: AbortSignal.timeout(timeoutMs) });
    } catch (e) {
      const code = e.cause?.code;
      const idempotent = !init.method || init.method === 'GET';
      const safe = NEVER_SENT.has(code) || (idempotent && code === 'ECONNRESET');
      if (!safe || attempt >= tries) throw e;
      console.log(`  (network: ${code}, retrying)`);
      await new Promise((r) => setTimeout(r, 1500 * attempt));
    }
  }
}