/*
 * Copyright 2017 Google Inc.
 *
 * Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except
 * in compliance with the License. You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software distributed under the
 * License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either
 * express or implied. See the License for the specific language governing permissions and
 * limitations under the License.
 */

import {AppAuthError} from './errors';

/**
 * An class that abstracts away the ability to make an XMLHttpRequest.
 */
export abstract class Requestor {
  abstract xhr<T>(settings: JQueryAjaxSettings): Promise<T>;
}

/**
 * Uses $.ajax to makes the Ajax requests.
 */
export class JQueryRequestor extends Requestor {
  xhr<T>(settings: JQueryAjaxSettings): Promise<T> {
    // NOTE: using jquery to make XHR's as whatwg-fetch requires
    // that I target ES6.
    const xhr = $.ajax(settings);
    return new Promise<T>((resolve, reject) => {
      xhr.then(
          (data, textStatus, jqXhr) => {
            resolve(data as T);
          },
          (jqXhr, textStatus, error) => {
            reject(new AppAuthError(error));
          });
    });
  }
}


/**
 * Uses fetch API to make Ajax requests
 */
export class FetchRequestor extends Requestor {
  xhr<T>(settings: JQueryAjaxSettings): Promise<T> {
    if (!settings.url) {
      return Promise.reject(new AppAuthError('A URL must be provided.'));
    }
    let url: URL = new URL(<string>settings.url);
    let requestInit: RequestInit = {};
    requestInit.method = settings.method;
    requestInit.mode = 'cors';

    if (settings.data) {
      if (settings.method && settings.method.toUpperCase() === 'POST') {
        requestInit.body = <string>settings.data;
      } else {
        let searchParams = new URLSearchParams(settings.data);
        searchParams.forEach((value, key) => {
          url.searchParams.append(key, value);
        });
      }
    }

    // Set the request headers
    requestInit.headers = {};
    if (settings.headers) {
      for (let i in settings.headers) {
        if (settings.headers.hasOwnProperty(i)) {
          requestInit.headers[i] = <string>settings.headers[i];
        }
      }
    }

    const isJsonDataType = settings.dataType && settings.dataType.toLowerCase() === 'json';

    // Set 'Accept' header value for json requests (Taken from
    // https://github.com/jquery/jquery/blob/e0d941156900a6bff7c098c8ea7290528e468cf8/src/ajax.js#L644
    // )
    if (isJsonDataType) {
      requestInit.headers['Accept'] = 'application/json, text/javascript, */*; q=0.01';
    }

    return fetch(url.toString(), requestInit).then(response => {
      if (response.status >= 200 && response.status < 300) {
        const contentType = response.headers.get('content-type');
        if (isJsonDataType || (contentType && contentType.indexOf('application/json') !== -1)) {
          return response.json();
        } else {
          return response.text();
        }
      } else {
        return Promise.reject(new AppAuthError(response.status.toString(), response.statusText));
      }
    });
  }
}

/**
 * Should be used only in the context of testing. Just uses the underlying
 * Promise to mock the behavior of the Requestor.
 */
export class TestRequestor extends Requestor {
  constructor(public promise: Promise<any>) {
    super();
  }
  xhr<T>(settings: JQueryAjaxSettings): Promise<T> {
    return this.promise;  // unsafe cast
  }
}