import getEnvelopeBody from './getEnvelopeBody';
import { appendQueryParameters } from './location';
import parseJSON from '../json/parseJson';
import responseHandler from './responseHandler';
import type { NetworkResponse, RequestOptions, SerializableObject } from '../types';

const rnoContent = (method: string): boolean => /^(?:GET|HEAD)$/i.test((method));

const defaultOptions: Partial<RequestOptions> = {
  method: 'GET',
  headers: {},
};

/**
 * XMLHttpRequest transport
 */
export default function xhr<R = unknown>(
  o: RequestOptions,
): Promise<NetworkResponse<R>> {
  return new Promise((resolve, reject) => {
    const options = {
      ...defaultOptions,
      ...o,
    };
    const method = options.method || 'GET';
    const hasContent = !rnoContent(method);
    const headers = options.headers || {};
    const request = new XMLHttpRequest();
    let url = options.url || window.location.href;

    if (!options.envelope && !hasContent && options.data) {
      url = appendQueryParameters(url, options.data as SerializableObject);
    }

    if (options.envelope) {
      url = appendQueryParameters(url, { envelope: 'request' });
    }

    request.open(options.envelope ? 'POST' : method, url, true);

    request.onreadystatechange = () => {
      if (request.readyState === 4) {
        const response = parseJSON<R>(request.responseText);
        responseHandler<R>(request.status, response)
          .then((result) => resolve(result))
          .catch((err) => reject(err));
      }
    };

    if (options.envelope) {
      request.send(getEnvelopeBody(
        method,
        headers,
        options.data,
      ));
      return;
    }

    Object.keys(headers).forEach((header) => {
      if (Object.prototype.hasOwnProperty.call(headers, header)) {
        request.setRequestHeader(header, headers[header]);
      }
    });

    if (hasContent && options.data) {
      request.setRequestHeader('Content-Type', 'application/json');
      request.send(JSON.stringify(options.data));
    } else {
      request.send();
    }
  });
}