import Transport from "@ledgerhq/hw-transport";
import type { Observer, DescriptorEvent, Subscription } from "@ledgerhq/hw-transport";
import hidFraming from "@ledgerhq/devices/hid-framing";
import { identifyUSBProductId, ledgerUSBVendorId } from "@ledgerhq/devices";
import type { DeviceModel } from "@ledgerhq/devices";
import { log } from "@ledgerhq/logs";
import {
  TransportOpenUserCancelled,
  DisconnectedDeviceDuringOperation,
  DisconnectedDevice,
  TransportError,
} from "@ledgerhq/errors";

const ledgerDevices = [
  {
    vendorId: ledgerUSBVendorId,
  },
];

const isSupported = () => Promise.resolve(!!(window.navigator && window.navigator.hid));

const getHID = (): HID => {
  // $FlowFixMe
  const { hid } = navigator;
  if (!hid) throw new TransportError("navigator.hid is not supported", "HIDNotSupported");
  return hid;
};

async function requestLedgerDevices(): Promise<HIDDevice[]> {
  const device = await getHID().requestDevice({
    filters: ledgerDevices,
  });
  if (Array.isArray(device)) return device;
  return [device];
}

async function getLedgerDevices(): Promise<HIDDevice[]> {
  const devices = await getHID().getDevices();
  return devices.filter(d => d.vendorId === ledgerUSBVendorId);
}

async function getFirstLedgerDevice(): Promise<HIDDevice> {
  const existingDevices = await getLedgerDevices();
  if (existingDevices.length > 0) return existingDevices[0];
  const devices = await requestLedgerDevices();
  return devices[0];
}
/**
 * WebHID Transport implementation
 * @example
 * import TransportWebHID from "@ledgerhq/hw-transport-webhid";
 * ...
 * TransportWebHID.create().then(transport => ...)
 */

export default class TransportWebHID extends Transport {
  device: HIDDevice;
  deviceModel: DeviceModel | null | undefined;
  channel = Math.floor(Math.random() * 0xffff);
  packetSize = 64;

  constructor(device: HIDDevice) {
    super();
    this.device = device;
    this.deviceModel =
      typeof device.productId === "number" ? identifyUSBProductId(device.productId) : undefined;
    device.addEventListener("inputreport", this.onInputReport);
  }

  inputs: Buffer[] = [];
  inputCallback: ((arg0: Buffer) => void) | null | undefined;
  read = (): Promise<Buffer> => {
    if (this.inputs.length) {
      const value = this.inputs.shift();
      if (value !== undefined) return Promise.resolve(value);
      throw new Error("Unreachable: non-empty inputs");
    }

    return new Promise(success => {
      this.inputCallback = success;
    });
  };
  onInputReport = (e: HIDInputReportEvent) => {
    const buffer = Buffer.from(e.data.buffer);

    if (this.inputCallback) {
      this.inputCallback(buffer);
      this.inputCallback = null;
    } else {
      this.inputs.push(buffer);
    }
  };

  /**
   * Check if WebUSB transport is supported.
   */
  static isSupported = isSupported;

  /**
   * List the WebUSB devices that was previously authorized by the user.
   */
  static list = getLedgerDevices;

  /**
   * Actively listen to WebUSB devices and emit ONE device
   * that was either accepted before, if not it will trigger the native permission UI.
   *
   * Important: it must be called in the context of a UI click!
   */
  static listen = (observer: Observer<DescriptorEvent<HIDDevice>>): Subscription => {
    let unsubscribed = false;
    getFirstLedgerDevice().then(
      device => {
        if (!device) {
          observer.error(new TransportOpenUserCancelled("Access denied to use Ledger device"));
        } else if (!unsubscribed) {
          const deviceModel =
            typeof device.productId === "number"
              ? identifyUSBProductId(device.productId)
              : undefined;
          observer.next({
            type: "add",
            descriptor: device,
            deviceModel,
          });
          observer.complete();
        }
      },
      error => {
        observer.error(new TransportOpenUserCancelled(error.message));
      },
    );

    function unsubscribe() {
      unsubscribed = true;
    }

    return {
      unsubscribe,
    };
  };

  /**
   * Similar to create() except it will always display the device permission (even if some devices are already accepted).
   */
  static async request() {
    const [device] = await requestLedgerDevices();
    return TransportWebHID.open(device);
  }

  /**
   * Similar to create() except it will never display the device permission (it returns a Promise<?Transport>, null if it fails to find a device).
   */
  static async openConnected() {
    const devices = await getLedgerDevices();
    if (devices.length === 0) return null;
    return TransportWebHID.open(devices[0]);
  }

  /**
   * Create a Ledger transport with a HIDDevice
   */
  static async open(device: HIDDevice) {
    await device.open();
    const transport = new TransportWebHID(device);

    const onDisconnect = e => {
      if (device === e.device) {
        getHID().removeEventListener("disconnect", onDisconnect);

        transport._emitDisconnect(new DisconnectedDevice());
      }
    };

    getHID().addEventListener("disconnect", onDisconnect);
    return transport;
  }

  _disconnectEmitted = false;
  _emitDisconnect = (e: Error) => {
    if (this._disconnectEmitted) return;
    this._disconnectEmitted = true;
    this.emit("disconnect", e);
  };

  /**
   * Release the transport device
   */
  async close(): Promise<void> {
    await this.exchangeBusyPromise;
    this.device.removeEventListener("inputreport", this.onInputReport);
    await this.device.close();
  }

  /**
   * Exchange with the device using APDU protocol.
   * @param apdu
   * @returns a promise of apdu response
   */
  exchange = async (apdu: Buffer): Promise<Buffer> => {
    const b = await this.exchangeAtomicImpl(async () => {
      const { channel, packetSize } = this;
      log("apdu", "=> " + apdu.toString("hex"));
      const framing = hidFraming(channel, packetSize);
      // Write...
      const blocks = framing.makeBlocks(apdu);

      for (let i = 0; i < blocks.length; i++) {
        await this.device.sendReport(0, blocks[i]);
      }

      // Read...
      let result;
      let acc;

      while (!(result = framing.getReducedResult(acc))) {
        try {
          const buffer = await this.read();
          acc = framing.reduceResponse(acc, buffer);
        } catch (e) {
          if (e instanceof TransportError && e.id === "InvalidChannel") {
            // this can happen if the device is connected
            // on a different channel (like another app)
            // in this case we just filter out the event
            continue;
          }

          throw e;
        }
      }

      log("apdu", "<= " + result.toString("hex"));
      return result;
    }).catch(e => {
      if (e && e.message && e.message.includes("write")) {
        this._emitDisconnect(e);

        throw new DisconnectedDeviceDuringOperation(e.message);
      }

      throw e;
    });
    return b as Buffer;
  };

  setScrambleKey() {}
}