nearby/internal/platform/implementation/windows/bluetooth_classic_medium.cc

// Copyright 2020-2023 Google LLC
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     https://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

#include "internal/platform/implementation/windows/bluetooth_classic_medium.h"

#include <windows.h>

#include <codecvt>
#include <functional>
#include <ios>
#include <locale>
#include <map>
#include <memory>
#include <regex>  // NOLINT
#include <string>
#include <utility>

#include "internal/platform/cancellation_flag.h"
#include "internal/platform/cancellation_flag_listener.h"
#include "internal/platform/exception.h"
#include "internal/platform/feature_flags.h"
#include "internal/platform/implementation/bluetooth_adapter.h"
#include "internal/platform/implementation/bluetooth_classic.h"
#include "internal/platform/implementation/windows/bluetooth_adapter.h"
#include "internal/platform/implementation/windows/bluetooth_classic_device.h"
#include "internal/platform/implementation/windows/bluetooth_classic_server_socket.h"
#include "internal/platform/implementation/windows/bluetooth_classic_socket.h"
#include "internal/platform/implementation/windows/bluetooth_pairing.h"
#include "internal/platform/implementation/windows/generated/winrt/Windows.Devices.Bluetooth.Rfcomm.h"
#include "internal/platform/implementation/windows/generated/winrt/Windows.Devices.Bluetooth.h"
#include "internal/platform/implementation/windows/generated/winrt/Windows.Devices.Enumeration.h"
#include "internal/platform/implementation/windows/generated/winrt/Windows.Foundation.Collections.h"
#include "internal/platform/implementation/windows/generated/winrt/base.h"
#include "internal/platform/implementation/windows/utils.h"
#include "internal/platform/implementation/windows/wifi_lan.h"
#include "internal/platform/logging.h"

namespace nearby {
namespace windows {
namespace {
using ::winrt::Windows::Devices::Bluetooth::Rfcomm::RfcommDeviceService;
using ::winrt::Windows::Devices::Bluetooth::Rfcomm::RfcommServiceId;
using ::winrt::Windows::Devices::Bluetooth::Rfcomm::RfcommServiceProvider;
using ::winrt::Windows::Devices::Enumeration::DeviceAccessInformation;
using ::winrt::Windows::Devices::Enumeration::DeviceAccessStatus;
using ::winrt::Windows::Devices::Enumeration::DeviceInformation;
using ::winrt::Windows::Devices::Enumeration::DeviceInformationKind;
using ::winrt::Windows::Devices::Enumeration::DeviceInformationUpdate;
using ::winrt::Windows::Devices::Enumeration::DeviceWatcher;
using ::winrt::Windows::Devices::Enumeration::DeviceWatcherStatus;
using ::winrt::Windows::Foundation::IInspectable;
using ::winrt::Windows::Foundation::Collections::IMapView;
using ::winrt::Windows::Storage::Streams::DataReader;
using ::winrt::Windows::Storage::Streams::DataWriter;
using ::winrt::Windows::Storage::Streams::UnicodeEncoding;

// Used to control the dump output for device information. It is only for debug
// purpose.
constexpr bool kEnableDumpDeviceInfomation = false;
// The maximum length of Bluetooth device name Android can discover.
constexpr int kAndroidDiscoverableBluetoothNameMaxLength = 37;  // bytes
// Used to select bluetooth devices.
constexpr wchar_t kBluetoothSelector[] =
    L"System.Devices.Aep.ProtocolId:=\"{e0cbf06c-cd8b-4647-bb8a-263b43f0f974}"
    L"\"";

void DumpDeviceInformation(
    const IMapView<winrt::hstring, IInspectable>& properties) {
  if (!kEnableDumpDeviceInfomation) {
    return;
  }

  if (properties == nullptr) {
    return;
  }

  for (const auto& property : properties) {
    if (property.Key() == L"System.ItemNameDisplay") {
      LOG(INFO) << "System.ItemNameDisplay: "
                << InspectableReader::ReadString(property.Value());
    } else if (property.Key() == L"System.Devices.Aep.CanPair") {
      LOG(INFO) << "System.Devices.Aep.CanPair: "
                << InspectableReader::ReadBoolean(property.Value());
    } else if (property.Key() == L"System.Devices.Aep.IsPaired") {
      LOG(INFO) << "System.Devices.Aep.IsPaired: "
                << InspectableReader::ReadBoolean(property.Value());
    } else if (property.Key() == L"System.Devices.Aep.IsPresent") {
      LOG(INFO) << "System.Devices.Aep.IsPresent: "
                << InspectableReader::ReadBoolean(property.Value());
    } else if (property.Key() == L"System.Devices.Aep.DeviceAddress") {
      LOG(INFO) << "System.Devices.Aep.DeviceAddress: "
                << InspectableReader::ReadString(property.Value());
    }
  }
}

}  // namespace

BluetoothClassicMedium::BluetoothClassicMedium(
    api::BluetoothAdapter& bluetooth_adapter)
    : bluetooth_adapter_(dynamic_cast<BluetoothAdapter&>(bluetooth_adapter)) {
  InitializeDeviceWatcher();
  bluetooth_adapter_.RestoreRadioNameIfNecessary();

  bluetooth_adapter_.SetOnScanModeChanged(std::bind(
      &BluetoothClassicMedium::OnScanModeChanged, this, std::placeholders::_1));
}

BluetoothClassicMedium::~BluetoothClassicMedium() {}

void BluetoothClassicMedium::OnScanModeChanged(
    BluetoothAdapter::ScanMode scan_mode) {
  LOG(INFO) << __func__ << ": OnScanModeChanged is called with scanMode: "
            << static_cast<int>(scan_mode);

  if (scan_mode == scan_mode_) {
    LOG(INFO) << __func__ << ": No change of scan mode.";
    return;
  }

  scan_mode_ = scan_mode;
  bool radio_discoverable =
      scan_mode_ == BluetoothAdapter::ScanMode::kConnectableDiscoverable;

  if (bluetooth_adapter_.GetName().size() >
      kAndroidDiscoverableBluetoothNameMaxLength) {
    // If the name longer than the android limitation, always set the value to
    // false.
    radio_discoverable = false;
  }

  if (is_radio_discoverable_ == radio_discoverable) {
    LOG(INFO) << __func__ << ": No change of radio discovery.";
    return;
  }

  if (rfcomm_provider_ == nullptr) {
    LOG(WARNING) << __func__ << ": No advertising.";
    return;
  }

  try {
    rfcomm_provider_.StopAdvertising();
    rfcomm_provider_.StartAdvertising(
        raw_server_socket_->stream_socket_listener(), radio_discoverable);
    is_radio_discoverable_ = radio_discoverable;
    return;
  } catch (std::exception exception) {
    LOG(ERROR) << __func__
               << ": OnScanModeChanged exception: " << exception.what();
    return;
  } catch (const winrt::hresult_error& ex) {
    LOG(ERROR) << __func__ << ": OnScanModeChanged exception: " << ex.code()
               << ": " << winrt::to_string(ex.message());
    return;
  } catch (...) {
    LOG(ERROR) << __func__ << ": Unknown exception.";
    return;
  }
}

bool BluetoothClassicMedium::StartDiscovery(
    BluetoothClassicMedium::DiscoveryCallback discovery_callback) {
  LOG(INFO) << "StartDiscovery is called.";

  bool result = false;
  discovery_callback_ = std::move(discovery_callback);

  if (!IsWatcherStarted()) {
    result = StartScanning();
  }

  return result;
}

bool BluetoothClassicMedium::StopDiscovery() {
  LOG(INFO) << "StopDiscovery is called.";

  bool result = false;

  if (IsWatcherStarted()) {
    result = StopScanning();
  }

  return result;
}

void BluetoothClassicMedium::InitializeDeviceWatcher() {
  try {
    // create watcher
    const winrt::param::iterable<winrt::hstring> requested_properties =
        winrt::single_threaded_vector<winrt::hstring>(
            {winrt::to_hstring("System.Devices.Aep.IsPresent"),
             winrt::to_hstring("System.Devices.Aep.DeviceAddress")});

    device_watcher_ = DeviceInformation::CreateWatcher(
        kBluetoothSelector,                           // aqsFilter
        requested_properties,                         // additionalProperties
        DeviceInformationKind::AssociationEndpoint);  // kind

    //  An app must subscribe to all of the added, removed, and updated events
    //  to be notified when there are device additions, removals or updates. If
    //  an app handles only the added event, it will not receive an update if a
    //  device is added to the system after the initial device enumeration
    //  completes. register event handlers before starting the watcher

    //  Event that is raised when a device is added to the collection enumerated
    //  by the DeviceWatcher.
    // https://docs.microsoft.com/en-us/uwp/api/windows.devices.enumeration.devicewatcher.added?view=winrt-20348
    device_watcher_.Added({this, &BluetoothClassicMedium::DeviceWatcher_Added});

    // Event that is raised when a device is updated in the collection of
    // enumerated devices.
    // https://docs.microsoft.com/en-us/uwp/api/windows.devices.enumeration.devicewatcher.updated?view=winrt-20348
    device_watcher_.Updated(
        {this, &BluetoothClassicMedium::DeviceWatcher_Updated});

    // Event that is raised when a device is removed from the collection of
    // enumerated devices.
    // https://docs.microsoft.com/en-us/uwp/api/windows.devices.enumeration.devicewatcher.removed?view=winrt-20348
    device_watcher_.Removed(
        {this, &BluetoothClassicMedium::DeviceWatcher_Removed});
  } catch (std::exception exception) {
    LOG(ERROR) << __func__
               << ": InitializeDeviceWatcher exception: " << exception.what();
  } catch (const winrt::hresult_error& ex) {
    LOG(ERROR) << __func__
               << ": InitializeDeviceWatcher exception: " << ex.code() << ": "
               << winrt::to_string(ex.message());
  } catch (...) {
    LOG(ERROR) << __func__ << ": Unknown exception.";
  }
}

std::unique_ptr<api::BluetoothSocket> BluetoothClassicMedium::ConnectToService(
    api::BluetoothDevice& remote_device, const std::string& service_uuid,
    CancellationFlag* cancellation_flag) {
  try {
    LOG(INFO) << "ConnectToService is called.";
    if (service_uuid.empty()) {
      LOG(ERROR) << __func__ << ": service_uuid not specified.";
      return nullptr;
    }

    const std::regex pattern(
        "^[0-9a-fA-F]{8}-[0-9a-fA-F]{4}-[0-9a-fA-F]{4}-[0-9a-fA-F]{4}-[0-9a-fA-"
        "F]"
        "{12}$");

    // Must check for valid pattern as the guid constructor will throw on an
    // invalid format
    if (!std::regex_match(service_uuid, pattern)) {
      LOG(ERROR) << __func__ << ": invalid service_uuid: " << service_uuid;
      return nullptr;
    }

    winrt::guid service(service_uuid);

    if (cancellation_flag == nullptr) {
      LOG(ERROR) << __func__ << ": cancellation_flag not specified.";
      return nullptr;
    }

    auto remote_device_to_connect_ = dynamic_cast<BluetoothDevice*>(
        GetRemoteDevice(remote_device.GetMacAddress()));

    if (remote_device_to_connect_ == nullptr ||
        remote_device_to_connect_->GetId().empty()) {
      LOG(ERROR) << __func__
                 << ": Failed to get remote device from MAC address.";
      return nullptr;
    }

    winrt::hstring device_id =
        winrt::to_hstring(remote_device_to_connect_->GetId());

    if (!HaveAccess(device_id)) {
      LOG(ERROR) << __func__ << ": Failed to gain access to device: "
                 << winrt::to_string(device_id);
      return nullptr;
    }

    RfcommDeviceService requested_service(
        GetRequestedService(remote_device_to_connect_, service));

    if (!FeatureFlags::GetInstance()
             .GetFlags()
             .skip_service_discovery_before_connecting_to_rfcomm &&
        !CheckSdp(requested_service)) {
      LOG(ERROR) << __func__ << ": Invalid SDP.";
      return nullptr;
    }

    auto rfcomm_socket = std::make_unique<BluetoothSocket>();

    if (cancellation_flag->Cancelled()) {
      LOG(INFO)
          << __func__
          << ": Bluetooth Classic socket connection cancelled for device: "
          << winrt::to_string(device_id) << ", service: " << service_uuid;
      return nullptr;
    }
    nearby::CancellationFlagListener cancellation_flag_listener(
        cancellation_flag, [&rfcomm_socket]() { rfcomm_socket->Close(); });

    bool success =
        rfcomm_socket->Connect(requested_service.ConnectionHostName(),
                               requested_service.ConnectionServiceName());
    if (!success) {
      return nullptr;
    }

    return std::move(rfcomm_socket);
  } catch (std::exception exception) {
    // We will log and eat the exception since the caller
    // expects nullptr if it fails
    LOG(ERROR) << __func__ << ": Exception connecting bluetooth async: "
               << exception.what();
    return nullptr;
  } catch (const winrt::hresult_error& ex) {
    LOG(ERROR) << __func__
               << ": Exception connecting bluetooth async, error code: "
               << ex.code()
               << ", error message: " << winrt::to_string(ex.message());
    return nullptr;
  } catch (...) {
    LOG(ERROR) << __func__ << ": Unknown exception.";
    return nullptr;
  }
}

std::unique_ptr<api::BluetoothPairing> BluetoothClassicMedium::CreatePairing(
    api::BluetoothDevice& remote_device) {
  VLOG(1) << __func__ << ": Start to createPairing with device: "
          << remote_device.GetMacAddress();
  try {
    winrt::Windows::Devices::Bluetooth::BluetoothDevice bluetooth_device =
        winrt::Windows::Devices::Bluetooth::BluetoothDevice::
            FromBluetoothAddressAsync(
                mac_address_string_to_uint64(remote_device.GetMacAddress()))
                .get();
    winrt::Windows::Devices::Enumeration::DeviceInformationCustomPairing
        custom_pairing =
            bluetooth_device.DeviceInformation().Pairing().Custom();
    if (custom_pairing) {
      return std::make_unique<BluetoothPairing>(bluetooth_device,
                                                custom_pairing);
    }
    VLOG(1) << __func__ << ": Failed to get DeviceInformationCustomPairing.";
  } catch (std::exception exception) {
    LOG(ERROR) << __func__ << " : Failed to create pairing. exception: "
               << exception.what();
  } catch (const winrt::hresult_error& error) {
    LOG(ERROR) << __func__ << ": Failed to create pairing. WinRT exception: "
               << error.code() << ": " << winrt::to_string(error.message());
  } catch (...) {
    LOG(ERROR) << __func__ << ": Unknown exception.";
  }
  return nullptr;
}

bool BluetoothClassicMedium::HaveAccess(winrt::hstring device_id) {
  if (device_id.empty()) {
    return false;
  }

  DeviceAccessInformation access_information =
      DeviceAccessInformation::CreateFromId(device_id);

  if (access_information == nullptr) {
    return false;
  }

  DeviceAccessStatus access_status = access_information.CurrentStatus();

  if (access_status == DeviceAccessStatus::DeniedByUser ||
      // This status is most likely caused by app permissions (did not declare
      // the device in the app's package.appxmanifest)
      // This status does not cover the case where the device is already
      // opened by another app.
      access_status == DeviceAccessStatus::DeniedBySystem ||
      // Most likely the device is opened by another app, but cannot be sure
      access_status == DeviceAccessStatus::Unspecified) {
    return false;
  }

  return true;
}

RfcommDeviceService BluetoothClassicMedium::GetRequestedService(
    BluetoothDevice* device, winrt::guid service) {
  RfcommServiceId rfcomm_service_id = RfcommServiceId::FromUuid(service);
  return device->GetRfcommServiceForIdAsync(rfcomm_service_id);
}

bool BluetoothClassicMedium::CheckSdp(RfcommDeviceService requested_service) {
  // Do various checks of the SDP record to make sure you are talking to a
  // device that actually supports the Bluetooth Rfcomm Service
  // https://docs.microsoft.com/en-us/uwp/api/windows.devices.bluetooth.rfcomm.rfcommdeviceservice.getsdprawattributesasync?view=winrt-20348
  try {
    if (requested_service == nullptr) {
      LOG(WARNING) << __func__ << ": Request service is empty.";
      return false;
    }

    auto attributes = requested_service.GetSdpRawAttributesAsync().get();
    if (!attributes.HasKey(Constants::SdpServiceNameAttributeId)) {
      LOG(ERROR) << __func__ << ": Missing SdpServiceNameAttributeId.";
      return false;
    }

    auto attribute_reader = DataReader::FromBuffer(
        attributes.Lookup(Constants::SdpServiceNameAttributeId));

    auto attribute_type = attribute_reader.ReadByte();

    if (attribute_type != Constants::SdpServiceNameAttributeType) {
      LOG(ERROR) << __func__ << ": Missing SdpServiceNameAttributeType.";
      return false;
    }

    return true;
  } catch (...) {
    LOG(ERROR) << "Failed to get SDP information.";
    return false;
  }
}

// https://developer.android.com/reference/android/bluetooth/BluetoothAdapter.html#listenUsingInsecureRfcommWithServiceRecord
//
// service_uuid is the canonical textual representation
// (https://en.wikipedia.org/wiki/Universally_unique_identifier#Format) of a
// type 3 name-based
// (https://en.wikipedia.org/wiki/Universally_unique_identifier#Versions_3_and_5_(namespace_name-based))
// UUID.
//
//  Returns nullptr error.
std::unique_ptr<api::BluetoothServerSocket>
BluetoothClassicMedium::ListenForService(const std::string& service_name,
                                         const std::string& service_uuid) {
  LOG(INFO) << "ListenForService is called with service name: " << service_name
            << ".";
  if (service_uuid.empty()) {
    LOG(ERROR) << __func__ << ": service_uuid was empty.";
    return nullptr;
  }

  if (service_name.empty()) {
    LOG(ERROR) << __func__ << ": service_name was empty.";
    return nullptr;
  }

  service_name_ = service_name;
  service_uuid_ = service_uuid;

  scan_mode_ = bluetooth_adapter_.GetScanMode();

  LOG(INFO) << __func__ << ": scan_mode: " << static_cast<int>(scan_mode_);
  bool radio_discoverable =
      scan_mode_ == BluetoothAdapter::ScanMode::kConnectableDiscoverable;

  bool result = StartAdvertising(radio_discoverable);

  if (!result) {
    LOG(ERROR) << __func__ << ": Failed to start listening.";
    return nullptr;
  }

  return std::move(server_socket_);
}

api::BluetoothDevice* BluetoothClassicMedium::GetRemoteDevice(
    const std::string& mac_address) {
  auto it = mac_address_to_bluetooth_device_map_.find(mac_address);

  if (it == mac_address_to_bluetooth_device_map_.end()) {
    LOG(WARNING) << __func__ << ": Bluetooth device " << mac_address
                 << " is not in list. create it";
    auto bluetooth_device = std::make_unique<BluetoothDevice>(mac_address);

    mac_address_to_bluetooth_device_map_[mac_address] =
        std::move(bluetooth_device);
    return mac_address_to_bluetooth_device_map_[mac_address].get();
  }

  LOG(INFO) << __func__ << ": Bluetooth device " << mac_address
            << " is in cache";

  return it->second.get();
}

bool BluetoothClassicMedium::StartScanning() {
  if (!IsWatcherStarted()) {
    if (device_watcher_ == nullptr) {
      LOG(ERROR) << __func__
                 << ": Failed to start scanning due to no available watcher.";
      return false;
    }

    mac_address_to_bluetooth_device_map_.clear();
    removed_bluetooth_devices_map_.clear();

    // The Start method can only be called when the DeviceWatcher is in the
    // Created, Stopped or Aborted state.
    auto status = device_watcher_.Status();

    if (status == DeviceWatcherStatus::Created ||
        status == DeviceWatcherStatus::Stopped ||
        status == DeviceWatcherStatus::Aborted) {
      device_watcher_.Start();

      return true;
    }
  }

  LOG(ERROR) << __func__
             << ": Attempted to start scanning when watcher already started.";
  return false;
}

bool BluetoothClassicMedium::StopScanning() {
  if (IsWatcherRunning()) {
    device_watcher_.Stop();
    return true;
  }
  LOG(ERROR) << __func__
             << ": Attempted to stop scanning when watcher already stopped.";
  return false;
}

winrt::fire_and_forget BluetoothClassicMedium::DeviceWatcher_Added(
    DeviceWatcher sender, DeviceInformation device_info) {
  LOG(INFO) << "Device added " << winrt::to_string(device_info.Id());
  IMapView<winrt::hstring, IInspectable> properties = device_info.Properties();
  DumpDeviceInformation(properties);

  if (!IsWatcherStarted()) {
    return winrt::fire_and_forget();
  }

  // If device no item name, ignore it.
  if (!properties.HasKey(L"System.ItemNameDisplay")) {
    LOG(WARNING) << __func__ << ": Ignore the Bluetooth device "
                 << winrt::to_string(device_info.Id()) << " due to no name.";
    return winrt::fire_and_forget();
  }

  if (properties.Lookup(L"System.ItemNameDisplay") == nullptr) {
    LOG(WARNING) << __func__ << ": Ignore the Bluetooth device "
                 << winrt::to_string(device_info.Id()) << " due to empty name.";
    return winrt::fire_and_forget();
  }

  // If device doesn't support pair, ignore it.
  if (!properties.HasKey(L"System.Devices.Aep.CanPair")) {
    LOG(WARNING) << __func__ << ": Ignore the Bluetooth device "
                 << winrt::to_string(device_info.Id())
                 << " due to no pair property.";
    return winrt::fire_and_forget();
  }

  if (!InspectableReader::ReadBoolean(
          properties.Lookup(L"System.Devices.Aep.CanPair"))) {
    LOG(WARNING) << __func__ << ": Ignore the Bluetooth device "
                 << winrt::to_string(device_info.Id())
                 << " due to not support pair.";
    return winrt::fire_and_forget();
  }

  // Create a bluetooth device out of this id
  auto native_bluetooth_device =
      ::winrt::Windows::Devices::Bluetooth::BluetoothDevice::FromIdAsync(
          device_info.Id())
          .get();

  std::string mac_address =
      uint64_to_mac_address_string(native_bluetooth_device.BluetoothAddress());

  // Create an iterator for the internal list
  auto it = mac_address_to_bluetooth_device_map_.find(mac_address);

  // Add to our internal list if necessary
  if (it != mac_address_to_bluetooth_device_map_.end()) {
    // We're already tracking this one
    LOG(WARNING) << __func__ << ": Bluetooth device " << mac_address
                 << " is alreay added.";
    return winrt::fire_and_forget();
  }

  auto bluetooth_device =
      std::make_unique<BluetoothDevice>(native_bluetooth_device);

  mac_address_to_bluetooth_device_map_[mac_address] =
      std::move(bluetooth_device);

  LOG(INFO) << __func__ << ": Notifying bluetooth device " << mac_address
            << " added";
  if (discovery_callback_.device_discovered_cb != nullptr) {
    discovery_callback_.device_discovered_cb(
        *mac_address_to_bluetooth_device_map_[mac_address]);
  }
  for (auto& observer : observers_.GetObservers()) {
    observer->DeviceAdded(*mac_address_to_bluetooth_device_map_[mac_address]);
  }
  return winrt::fire_and_forget();
}

winrt::fire_and_forget BluetoothClassicMedium::DeviceWatcher_Updated(
    DeviceWatcher sender, DeviceInformationUpdate device_update_info) {
  auto native_bluetooth_device =
      ::winrt::Windows::Devices::Bluetooth::BluetoothDevice::FromIdAsync(
          device_update_info.Id())
          .get();
  std::string mac_address =
      uint64_to_mac_address_string(native_bluetooth_device.BluetoothAddress());

  auto it = mac_address_to_bluetooth_device_map_.find(mac_address);

  if (it == mac_address_to_bluetooth_device_map_.end()) {
    LOG(WARNING) << __func__ << ": Bluetooth device " << mac_address
                 << " is not in list.";
    return winrt::fire_and_forget();
  }

  LOG(INFO) << "Device updated name: "
            << mac_address_to_bluetooth_device_map_[mac_address]->GetName()
            << " (" << mac_address << ")";
  IMapView<winrt::hstring, IInspectable> properties =
      device_update_info.Properties();
  DumpDeviceInformation(properties);

  if (!IsWatcherStarted()) {
    // Spurious call, watcher has stopped or wasn't started
    return winrt::fire_and_forget();
  }

  // https://learn.microsoft.com/en-us/windows/uwp/devices-sensors/device-information-properties#associationendpoint-properties
  if (properties.HasKey(L"System.ItemNameDisplay")) {
    // we need to really change the name of the bluetooth device
    std::string new_device_name = InspectableReader::ReadString(
        properties.Lookup(L"System.ItemNameDisplay"));

    if (it->second->GetName() == new_device_name) {
      LOG(INFO) << "Device name is same as old name, ignore the update.";
    } else {
      it->second->SetName(new_device_name);

      LOG(INFO) << "Updated device name:"
                << mac_address_to_bluetooth_device_map_[mac_address]->GetName();

      discovery_callback_.device_name_changed_cb(
          *mac_address_to_bluetooth_device_map_[mac_address]);
    }
  }

  // Indicates if the device is currently paired.
  if (properties.HasKey(L"System.Devices.Aep.IsPaired")) {
    bool new_paired_status = InspectableReader::ReadBoolean(
        properties.Lookup(L"System.Devices.Aep.IsPaired"));
    LOG(INFO) << __func__
              << ": Notifying device paired changed: " << std::boolalpha
              << new_paired_status;
    for (auto& observer : observers_.GetObservers()) {
      observer->DevicePairedChanged(
          *mac_address_to_bluetooth_device_map_[mac_address],
          new_paired_status);
    }
  }

  return winrt::fire_and_forget();
}

winrt::fire_and_forget BluetoothClassicMedium::DeviceWatcher_Removed(
    DeviceWatcher sender, DeviceInformationUpdate device_update_info) {
  auto native_bluetooth_device =
      ::winrt::Windows::Devices::Bluetooth::BluetoothDevice::FromIdAsync(
          device_update_info.Id())
          .get();

  if (native_bluetooth_device == nullptr) {
    LOG(WARNING) << __func__ << ": cannot get native bluetooth device.";
    return winrt::fire_and_forget();
  }

  std::string mac_address =
      uint64_to_mac_address_string(native_bluetooth_device.BluetoothAddress());
  auto it = mac_address_to_bluetooth_device_map_.find(mac_address);

  if (it == mac_address_to_bluetooth_device_map_.end()) {
    LOG(WARNING) << __func__ << ": Bluetooth device " << mac_address
                 << " is not in list.";
    return winrt::fire_and_forget();
  }

  LOG(INFO) << "Device removed "
            << mac_address_to_bluetooth_device_map_[mac_address]->GetName()
            << " (" << mac_address << ")";

  if (!IsWatcherStarted()) {
    return winrt::fire_and_forget();
  }

  LOG(INFO) << __func__ << ": Notifying bluetooth device removed";
  if (discovery_callback_.device_lost_cb != nullptr) {
    discovery_callback_.device_lost_cb(
        *mac_address_to_bluetooth_device_map_[mac_address]);
  }

  for (auto& observer : observers_.GetObservers()) {
    observer->DeviceRemoved(*mac_address_to_bluetooth_device_map_[mac_address]);
  }

  auto node = mac_address_to_bluetooth_device_map_.extract(mac_address);
  removed_bluetooth_devices_map_[mac_address] = std::move(node.mapped());

  return winrt::fire_and_forget();
}

bool BluetoothClassicMedium::IsWatcherStarted() {
  if (device_watcher_ == nullptr) {
    return false;
  }

  DeviceWatcherStatus status = device_watcher_.Status();
  return (status == DeviceWatcherStatus::Started) ||
         (status == DeviceWatcherStatus::EnumerationCompleted);
}

bool BluetoothClassicMedium::IsWatcherRunning() {
  if (device_watcher_ == nullptr) {
    return false;
  }

  DeviceWatcherStatus status = device_watcher_.Status();
  return (status == DeviceWatcherStatus::Started) ||
         (status == DeviceWatcherStatus::EnumerationCompleted) ||
         (status == DeviceWatcherStatus::Stopping);
}

bool BluetoothClassicMedium::StartAdvertising(bool radio_discoverable) {
  LOG(INFO) << __func__
            << ": StartAdvertising is called with radio_discoverable: "
            << radio_discoverable << ".";

  try {
    if (rfcomm_provider_ != nullptr &&
        is_radio_discoverable_ == radio_discoverable) {
      LOG(WARNING) << __func__
                   << ": Ignore StartAdvertising due to no change to "
                      "current advertising.";
      return true;
    }

    if (rfcomm_provider_ != nullptr && !StopAdvertising()) {
      LOG(WARNING) << __func__
                   << ": Failed to StartAdvertising due to cannot stop "
                      "running advertising.";
      return false;
    }

    rfcomm_provider_ =
        RfcommServiceProvider::CreateAsync(
            RfcommServiceId::FromUuid(winrt::guid(service_uuid_)))
            .get();

    server_socket_ = std::make_unique<BluetoothServerSocket>(
        winrt::to_string(rfcomm_provider_.ServiceId().AsString()));

    raw_server_socket_ = server_socket_.get();

    if (!server_socket_->listen()) {
      LOG(ERROR) << __func__
                 << ": Failed to StartAdvertising due to cannot start socket.";
      server_socket_->Close();
      server_socket_ = nullptr;
      rfcomm_provider_ = nullptr;
      return false;
    }

    server_socket_->SetCloseNotifier([&]() { StopAdvertising(); });

    // Set the SDP attributes and start Bluetooth advertising
    InitializeServiceSdpAttributes(rfcomm_provider_, service_name_);

    // Start to advertising.
    rfcomm_provider_.StartAdvertising(server_socket_->stream_socket_listener(),
                                      radio_discoverable);
    is_radio_discoverable_ = radio_discoverable;

    LOG(INFO) << ": StartListening completed successfully.";
    return true;
  } catch (std::exception exception) {
    // We will log and eat the exception since the caller
    // expects nullptr if it fails
    LOG(ERROR) << __func__
               << ": Exception setting up for listen: " << exception.what();

    if (server_socket_ != nullptr) {
      server_socket_->Close();
      server_socket_ = nullptr;
    }

    if (rfcomm_provider_ != nullptr) {
      rfcomm_provider_ = nullptr;
    }

    return false;
  } catch (const winrt::hresult_error& ex) {
    LOG(ERROR) << __func__ << ": Exception setting up for listen: " << ex.code()
               << ": " << winrt::to_string(ex.message());
    if (server_socket_ != nullptr) {
      server_socket_->Close();
      server_socket_ = nullptr;
    }

    if (rfcomm_provider_ != nullptr) {
      rfcomm_provider_ = nullptr;
    }

    return false;
  } catch (...) {
    LOG(ERROR) << __func__ << ": Unknown exception.";
    if (server_socket_ != nullptr) {
      server_socket_->Close();
      server_socket_ = nullptr;
    }

    if (rfcomm_provider_ != nullptr) {
      rfcomm_provider_ = nullptr;
    }

    return false;
  }
}

bool BluetoothClassicMedium::StopAdvertising() {
  LOG(INFO) << __func__ << ": StopAdvertising is called";

  try {
    if (rfcomm_provider_ == nullptr) {
      LOG(ERROR) << __func__
                 << ": Ignore StopAdvertising due to no advertising.";
      return true;
    }

    rfcomm_provider_.StopAdvertising();
    rfcomm_provider_ = nullptr;
    raw_server_socket_ = nullptr;
    server_socket_ = nullptr;

    LOG(INFO) << ": StopAdvertising completed successfully.";
    return true;
  } catch (std::exception exception) {
    LOG(ERROR) << __func__
               << ": StopAdvertising exception: " << exception.what();
    return false;
  } catch (const winrt::hresult_error& ex) {
    LOG(ERROR) << __func__ << ": StopAdvertising exception: " << ex.code()
               << ": " << winrt::to_string(ex.message());
    return false;
  } catch (...) {
    LOG(ERROR) << __func__ << ": Unknown exception.";
    return false;
  }
}

bool BluetoothClassicMedium::InitializeServiceSdpAttributes(
    RfcommServiceProvider rfcomm_provider, std::string service_name) {
  try {
    auto sdp_writer = DataWriter();

    // Write the Service Name Attribute.
    sdp_writer.WriteByte(Constants::SdpServiceNameAttributeType);

    // The length of the UTF-8 encoded Service Name SDP Attribute.
    sdp_writer.WriteByte(service_name.size());

    // The UTF-8 encoded Service Name value.
    sdp_writer.UnicodeEncoding(UnicodeEncoding::Utf8);
    sdp_writer.WriteString(winrt::to_hstring(service_name));

    // Set the SDP Attribute on the RFCOMM Service Provider.
    rfcomm_provider.SdpRawAttributes().Insert(
        Constants::SdpServiceNameAttributeId, sdp_writer.DetachBuffer());

    return true;
  } catch (...) {
    LOG(ERROR) << __func__ << ": Failed to InitializeServiceSdpAttributes.";
    return false;
  }
}

}  // namespace windows
}  // namespace nearby