Http client

http.js

import 'whatwg-fetch';

let uuid = 0;
function getCallbackName() {
  // Note: This does not run in node without a DOM
  // But, if you're in node, why are you using JSONP???

  let name;
  do {
    name = `jsonp_callback_${uuid++}`;
  } while (window[name]);
}

export class MessageHandler {
  send(uri, opts) {
    throw new Error('MessageHandler.handle must be implemented');
  }
}

export class DefaultMessageHandler {
  send(uri, opts) {
    return fetch(uri, opts);
  }
}

export class DelegatingMessageHandler extends MessageHandler {
  constructor(next) {
    this.next = next;
  }

  send(uri, opts) {
    return this.next(uri, opts);
  }
}

export class SimpleClient extends MessageHandler {
  constructor(handler = new DefaultMessageHandler()) {
    this.handler = handler;

    // TODO: Add default values to stuff like common headers etc.
  }

  send(uri, opts = {}) {
    // TODO: Apply default values for headers and base URI etc.

    return this.handler.send(uri, opts);
  }

  /**
   * Sends an HTTP DELETE request.
   *
   * @method delete
   * @param {String} uri The target URI.
   * @param {Object} opts Request options
   * @return {Promise} A promise.
   */
  delete(uri, opts = {}) {
    return this.send(uri, {...opts, method: 'delete'});
  }

  /**
   * Sends an HTTP GET request.
   *
   * @method get
   * @param {String} uri The target URI.
   * @param {Object} opts Request options
   * @return {Promise} A promise.
   */
  get(uri, opts = {}) {
     return this.send(uri, {...opts, method: 'get'});
  }

   /**
   * Sends an HTTP HEAD request.
   *
   * @method head
   * @param {String} uri The target URI.
   * @param {Object} opts Request options
   * @return {Promise} A promise.
   */
  head(uri, opts = {}) {
    return this.send(uri, {...opts, method: 'head'});
  }

   /**
   * Sends an HTTP OPTIONS request.
   *
   * @method options
   * @param {String} uri The target URI.
   * @param {Object} opts Request options
   * @return {Promise} A promise.
   */
  options(uri, opts = {}) {
    return this.send(uri, {...opts, method: 'options'});
  }

   /**
   * Sends an HTTP PUT request.
   *
   * @method put
   * @param {String} uri The target URI.
   * @param {Object} opts Request put
   * @return {Promise} A promise.
   */
  put(uri, opts = {}) {
    return this.send(uri, {...opts, method: 'put'});
  }

   /**
   * Sends an HTTP PATCH request.
   *
   * @method patch
   * @param {String} uri The target URI.
   * @param {Object} opts Request patch
   * @return {Promise} A promise.
   */
  patch(uri, opts = {}) {
    return this.send(uri, {...opts, method: 'patch'});
  }

   /**
   * Sends an HTTP POST request.
   *
   * @method post
   * @param {String} uri The target URI.
   * @param {Object} opts Request post
   * @return {Promise} A promise.
   */
  post(uri, opts = {}) {
    return this.send(uri, {...opts, method: 'post'});
  }

  jsonp(uri, callbackParameterName = 'jsoncallback') {
    return new Promise((resolve, reject) => {
      let resolved = false;
      const callbackName = makeCallbackName();
      window[callbackName] = (data) => {
        resolved = true;
        resolve(data);
        delete window[callbackName];
      };

      const script = document.createElement('script');
      script.src = uri;
      document.body.appendChild(script);

      if (this.timeout && this.timeout > 0) {
        setTimeout(() => {
          reject(new Error('timeout'));
        }, this.timeout);
      }
    });
  }
}