const loopbackPorts = [4499, 4498, 4497, 4496, 4495, 4494];

async function discoverBridge() {
  for (const port of loopbackPorts) {
    try {
      const response = await fetch(
        `http://127.0.0.1:${port}/v1/discover`,
        { method: 'SGDISC' }
      );
      if (!response.ok) continue;
      const metadata = await response.json();
      const expectedBase = `http://127.0.0.1:${port}`;
      if (metadata.product === 'SecuGen Connect' &&
          metadata.protocol === 'secugen-connect/1' &&
          metadata.method === 'SGDISC' &&
          metadata.baseUrl === expectedBase) return expectedBase;
    } catch (_) { /* try the next bounded loopback port */ }
  }
  throw new Error('connect_bridge_not_found');
}

async function readJson(response) {
  const body = await response.json();
  if (!response.ok || body.ok === false) {
    throw new Error(body.error || `http_${response.status}`);
  }
  return body;
}

// enrolledTemplate: { format: 'ISO19794_2', dataBase64: '...' }
async function captureAndMatch(serverNonce, enrolledTemplate) {
  const base = await discoverBridge();

  const health = await fetch(base + '/v1/health').then(readJson);
  if (!health.ok) throw new Error('connect_bridge_not_ready');

  const session = await fetch(base + '/v1/session/start', {
    method: 'POST',
    headers: { 'Content-Type': 'application/json' },
    body: JSON.stringify({ client: { name: 'my-app', version: '1.0.0' } })
  }).then(readJson);

  const capture = await fetch(base + '/v1/fingerprint/capture', {
    method: 'POST',
    headers: {
      Authorization: 'Bearer ' + session.sessionToken,
      'Content-Type': 'application/json'
    },
    body: JSON.stringify({
      nonce: serverNonce,
      timeoutMs: 10000,
      minQuality: 50,
      templateFormat: 'ISO19794_2',
      returnImage: false,
      smartCapture: true,
      blinkLed: true,
      touchGate: true
    })
  }).then(readJson);

  if (enrolledTemplate.format !== capture.templateFormat) {
    throw new Error('template_format_mismatch');
  }

  return fetch(base + '/v1/match/score', {
    method: 'POST',
    headers: {
      Authorization: 'Bearer ' + session.sessionToken,
      'Content-Type': 'application/json'
    },
    body: JSON.stringify({
      template1: {
        format: capture.templateFormat,
        dataBase64: capture.templateBase64
      },
      template2: enrolledTemplate,
      securityLevel: 5
    })
  }).then(readJson);
}