const https = require('https');
const http = require('http');

const POLL_URL = process.env.POLICY_POLL_URL || '{{POLICY_POLL_URL}}';
const WEBHOOK_URL = process.env.WEBHOOK_URL || '{{WEBHOOK_URL}}';

exports.handler = async function () {
  const snapshot = await fetchJSON(POLL_URL);
  if (WEBHOOK_URL) {
    await postJSON(WEBHOOK_URL, snapshot);
  }
  return { statusCode: 200, body: JSON.stringify({ ok: true, genesis: snapshot.genesis_version }) };
};

function fetchJSON(url) {
  return new Promise((resolve, reject) => {
    const lib = url.startsWith('https') ? https : http;
    lib.get(url, (res) => {
      let body = '';
      res.on('data', (c) => { body += c; });
      res.on('end', () => {
        try { resolve(JSON.parse(body)); } catch (e) { reject(e); }
      });
    }).on('error', reject);
  });
}

function postJSON(url, obj) {
  return new Promise((resolve, reject) => {
    const data = JSON.stringify(obj);
    const u = new URL(url);
    const lib = u.protocol === 'https:' ? https : http;
    const req = lib.request({
      hostname: u.hostname,
      port: u.port || (u.protocol === 'https:' ? 443 : 80),
      path: u.pathname + u.search,
      method: 'POST',
      headers: { 'Content-Type': 'application/json', 'Content-Length': Buffer.byteLength(data) },
    }, (res) => {
      res.on('data', () => {});
      res.on('end', resolve);
    });
    req.on('error', reject);
    req.write(data);
    req.end();
  });
}