chrome/browser/resources/bluetooth_internals/device_broker.js

// Copyright 2017 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

/**
 * Javascript for device_broker, served from chrome://bluetooth-internals/.
 * Provides a single source to access DeviceRemotes. DeviceRemotes are cached
 * for repeated use. Multiple connection requests will result in the same
 * DeviceRemote being shared among all requesters.
 */

import {getAdapterBroker} from './adapter_broker.js';
import {DeviceRemote} from './device.mojom-webui.js';


// Expose for testing.
/**
 * @type {Map<string,
 *     !DeviceRemote|!Promise<!DeviceRemote>>}
 */
export const connectedDevices = new Map();

/**
 * Creates a GATT connection to the device with |address|. If a connection to
 * the device already exists, the promise is resolved with the existing
 * DeviceRemote. If a connection is in progress, the promise resolves when
 * the existing connection request promise is fulfilled.
 * @param {string} address
 * @return {!Promise<!DeviceRemote>}
 */
export function connectToDevice(address) {
  const deviceOrPromise = connectedDevices.get(address) || null;
  if (deviceOrPromise !== null) {
    return Promise.resolve(deviceOrPromise);
  }

  const promise = /** @type {!Promise<!DeviceRemote>} */ (
      getAdapterBroker()
          .then(function(adapterBroker) {
            return adapterBroker.connectToDevice(address);
          })
          .then(function(device) {
            connectedDevices.set(address, device);

            device.onConnectionError.addListener(
                () => connectedDevices.delete(address));

            return device;
          })
          .catch(function(error) {
            connectedDevices.delete(address);
            throw error;
          }));

  connectedDevices.set(address, promise);
  return promise;
}