'use strict';

const API_EXCHANGE = {
  host: 'openexchangerates.org',
  path: 'api/latest.json?app_id=',
  key: '1f43ea96b1e343fe94333dd2b97a109d',
};

const DEFAULT_RETRY = 3;

const getRate = async (currency, retry = DEFAULT_RETRY) => {
  console.log({ currency, retry });
  const { host, path, key } = API_EXCHANGE;
  const url = `https://${host}/${path}${key}`;
  const res = await fetch(url).catch(() => ({ ok: false }));
  if (!res.ok) {
    const attemptsLeft = retry - 1;
    if (attemptsLeft > 0) return getRate(currency, retry - 1);
    throw new Error('Can not get data');
  }
  const data = await res.json();
  const rate = data.rates[currency];
  return rate;
};

const main = async () => {
  try {
    const rate = await getRate('UAH');
    console.log({ rate });
  } catch (err) {
    console.error({ err });
  }
};

main();

const sumAsync = (a, b, callback) => {
  if (typeof a !== 'number') return;
  if (typeof b !== 'number') return;
  setImmediate(() => {
    callback(a + b);
  });
};

let resolve, reject;
const promise = new Promise((resolved, rejected) => {
  resolve = resolved;
  reject = rejected;
});
setTimeout(reject, 1000, new Error('Timed out'));
sumAsync(2, 3, resolve);
const result = await promise;
console.log({ result });

const promise = new Promise((resolve, reject) => {
  sumAsync(4, 5, resolve);
  setTimeout(reject, 1000, new Error('Timed out'));
});
const result = await promise;
console.log({ result });

const { promise, resolve, reject } = Promise.withResolvers();
setTimeout(reject, 1000, new Error('Timed out'));
sumAsync(6, 7, resolve);
const result = await promise;
console.log({ result });