import xhr from './xhr';
import fetch from './fetch';
import type { NetworkResponse, RequestOptions } from '../types';

function hasFetchSupport(): boolean {
  return 'fetch' in window && typeof window.fetch === 'function';
}

function hasCorsSupport(): boolean {
  return 'XMLHttpRequest' in window && 'withCredentials' in new XMLHttpRequest();
}

/**
 * http client for browsers. Will attempt to use a CORS capable implementation
 * if available.
 *
 * @param {Object} options
 * @param {string} options.url The url of the request.
 * @param {string} [options.method] The HTTP method to use, ie, GET, POST, etc.
 * @param {Object} [options.data] The data to send with the request. For JSONP
 *                              and methods that do not support bodies, data
 *                              will be converted to URL parameters, otherwise
 *                              sent as the body for applicable HTTP methods.
 * @param {Object} [options.headers] HTTP headers to be sent with the request.
 * @param {boolean} [options.envelope=false] Default false. Fallback to using envelope
 *                                   based POST requests (for all HTTP methods).
 *                                   Use this to avoid leaking sensitive data in query
 *                                   strings for envelope and JSONP requests.
 */
export default function request<T>(
  options: RequestOptions,
): Promise<NetworkResponse<T>> {
  if (hasCorsSupport()) {
    return xhr<T>(options);
  } if (hasFetchSupport()) {
    return fetch<T>(options);
  }
  throw new Error('Unable to determine ajax implementation to use for request.');
}