import { EventEmitter } from 'events';

export const bus = new EventEmitter();

function Deferred() {
  const result = {};

  result.promise = new Promise((resolve, reject) => {
    result.resolve = resolve;
    result.reject = reject;
  });

  return result;
}

export default function once(resetKey, callback) {
  let defer = null,
    result = null;

  const doAction = () => {
    defer = Deferred();
    result = defer.promise.then(callback);

    const errorHandler = () =>
      result.catch(e => {
        defer = Deferred();
        result = defer.promise.then(callback);

        errorHandler();

        throw e;
      });
    errorHandler();
  };

  doAction();
  if (resetKey) {
    bus.on(resetKey, doAction);
  }

  return function(...args) {
    defer.resolve(...args);

    return result;
  };
}