/**
 * Utils.js
 *
 * Released under LGPL License.
 * Copyright (c) 1999-2017 Ephox Corp. All rights reserved
 *
 * License: http://www.tinymce.com/license
 * Contributing: http://www.tinymce.com/contributing
 */
import { FileReader, XMLHttpRequest } from '@ephox/sand';

import Promise from 'tinymce/core/api/util/Promise';
import Tools from 'tinymce/core/api/util/Tools';

const isValue = function (obj) {
  return obj !== null && obj !== undefined;
};

const traverse = function (json, path) {
  let value;

  value = path.reduce(function (result, key) {
    return isValue(result) ? result[key] : undefined;
  }, json);

  return isValue(value) ? value : null;
};

const requestUrlAsBlob = function (url: string, headers: Record<string, string>, withCredentials: boolean) {
  return new Promise<{status: number, blob: Blob}>(function (resolve) {
    let xhr;

    xhr = new XMLHttpRequest();

    xhr.onreadystatechange = function () {
      if (xhr.readyState === 4) {
        resolve({
          status: xhr.status,
          blob: this.response
        });
      }
    };

    xhr.open('GET', url, true);

    xhr.withCredentials = withCredentials;

    Tools.each(headers, function (value, key) {
      xhr.setRequestHeader(key, value);
    });

    xhr.responseType = 'blob';
    xhr.send();
  });
};

const readBlob = function (blob) {
  return new Promise(function (resolve) {
    const fr = new FileReader();

    fr.onload = function (e) {
      const data = e.target;
      resolve(data.result);
    };

    fr.readAsText(blob);
  });
};

const parseJson = function (text) {
  let json;

  try {
    json = JSON.parse(text);
  } catch (ex) {
    // Ignore
  }

  return json;
};

export default {
  traverse,
  readBlob,
  requestUrlAsBlob,
  parseJson
};