michael@0: /* This Source Code Form is subject to the terms of the Mozilla Public
michael@0:  * License, v. 2.0. If a copy of the MPL was not distributed with this
michael@0:  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
michael@0: 
michael@0: 'use strict';
michael@0: 
michael@0: module.metadata = {
michael@0:   'stability': 'experimental'
michael@0: };
michael@0: 
michael@0: let { request: hostReq, response: hostRes } = require('./host');
michael@0: let { defer: async } = require('../lang/functional');
michael@0: let { defer } = require('../core/promise');
michael@0: let { emit: emitSync, on, off } = require('../event/core');
michael@0: let { uuid } = require('../util/uuid');
michael@0: let emit = async(emitSync);
michael@0: 
michael@0: // Map of IDs to deferreds
michael@0: let requests = new Map();
michael@0: 
michael@0: // May not be necessary to wrap this in `async`
michael@0: // once promises are async via bug 881047
michael@0: let receive = async(function ({data, id, error}) {
michael@0:   let request = requests.get(id);
michael@0:   if (request) {
michael@0:     if (error) request.reject(error);
michael@0:     else request.resolve(clone(data));
michael@0:     requests.delete(id);
michael@0:   }
michael@0: });
michael@0: on(hostRes, 'data', receive);
michael@0: 
michael@0: /*
michael@0:  * Send is a helper to be used in client APIs to send
michael@0:  * a request to host
michael@0:  */
michael@0: function send (eventName, data) {
michael@0:   let id = uuid();
michael@0:   let deferred = defer();
michael@0:   requests.set(id, deferred);
michael@0:   emit(hostReq, 'data', {
michael@0:     id: id,
michael@0:     data: clone(data),
michael@0:     event: eventName
michael@0:   });
michael@0:   return deferred.promise;
michael@0: }
michael@0: exports.send = send;
michael@0: 
michael@0: /*
michael@0:  * Implement internal structured cloning algorithm in the future?
michael@0:  * http://www.whatwg.org/specs/web-apps/current-work/multipage/common-dom-interfaces.html#internal-structured-cloning-algorithm
michael@0:  */
michael@0: function clone (obj) JSON.parse(JSON.stringify(obj || {}))