@aleworm/hw-transport-node-hid/src/TransportNodeHid.js

Ledger Hardware Wallet Node implementation of the communication layer, using node-hid

//@flow

import HID from "@aleworm/node-hid";
import TransportNodeHidNoEvents, {
  getDevices,
} from "@ledgerhq/hw-transport-node-hid-noevents";
import type {
  Observer,
  DescriptorEvent,
  Subscription,
} from "@ledgerhq/hw-transport";
import { identifyUSBProductId } from "@ledgerhq/devices";
import { TransportError } from "@ledgerhq/errors";
import listenDevices from "./listenDevices";

let listenDevicesDebounce = 500;
let listenDevicesPollingSkip = () => false;

/**
 * node-hid Transport implementation
 * @example
 * import TransportNodeHid from "@ledgerhq/hw-transport-node-hid";
 * ...
 * TransportNodeHid.create().then(transport => ...)
 */
export default class TransportNodeHid extends TransportNodeHidNoEvents {
  /**
   *
   */
  static isSupported = TransportNodeHidNoEvents.isSupported;

  /**
   *
   */
  static list = TransportNodeHidNoEvents.list;

  /**
   *
   */
  static setListenDevicesDebounce = (delay: number) => {
    listenDevicesDebounce = delay;
  };

  /**
   *
   */
  static setListenDevicesPollingSkip = (conditionToSkip: () => boolean) => {
    listenDevicesPollingSkip = conditionToSkip;
  };

  /**
   *
   */
  static setListenDevicesDebug = () => {
    console.warn(
      "setListenDevicesDebug is deprecated. Use @ledgerhq/logs instead. No logs will get emitted there anymore."
    );
  };

  /**
   */
  static listen = (
    observer: Observer<DescriptorEvent<?string>>
  ): Subscription => {
    let unsubscribed = false;
    Promise.resolve(getDevices()).then((devices) => {
      // this needs to run asynchronously so the subscription is defined during this phase
      for (const device of devices) {
        if (!unsubscribed) {
          const descriptor: string = device.path;
          const deviceModel = identifyUSBProductId(device.productId);
          observer.next({ type: "add", descriptor, device, deviceModel });
        }
      }
    });
    const { events, stop } = listenDevices(
      listenDevicesDebounce,
      listenDevicesPollingSkip
    );

    const onAdd = (device) => {
      if (unsubscribed || !device) return;
      const deviceModel = identifyUSBProductId(device.productId);
      observer.next({
        type: "add",
        descriptor: device.path,
        deviceModel,
        device,
      });
    };
    const onRemove = (device) => {
      if (unsubscribed || !device) return;
      const deviceModel = identifyUSBProductId(device.productId);
      observer.next({
        type: "remove",
        descriptor: device.path,
        deviceModel,
        device,
      });
    };
    events.on("add", onAdd);
    events.on("remove", onRemove);
    function unsubscribe() {
      unsubscribed = true;
      events.removeListener("add", onAdd);
      events.removeListener("remove", onRemove);
      stop();
    }
    return { unsubscribe };
  };

  /**
   * if path="" is not provided, the library will take the first device
   */
  static open(path: ?string) {
    return Promise.resolve().then(() => {
      if (path) {
        return new TransportNodeHid(new HID.HID(path));
      }
      const device = getDevices()[0];
      if (!device) throw new TransportError("NoDevice", "NoDevice");
      return new TransportNodeHid(new HID.HID(device.path));
    });
  }
}