/*
* Copyright (c) 2018, Nordic Semiconductor
*
* SPDX-License-Identifier: Apache-2.0
*/
package io.runtime.mcumgr.sample.viewmodel;
import android.app.Application;
import android.bluetooth.BluetoothAdapter;
import android.content.BroadcastReceiver;
import android.content.Context;
import android.content.Intent;
import android.content.IntentFilter;
import android.content.SharedPreferences;
import android.location.LocationManager;
import java.util.List;
import javax.inject.Inject;
import androidx.annotation.NonNull;
import androidx.lifecycle.AndroidViewModel;
import org.jetbrains.annotations.NotNull;
import io.runtime.mcumgr.sample.utils.FilterUtils;
import io.runtime.mcumgr.sample.utils.Utils;
import no.nordicsemi.android.support.v18.scanner.BluetoothLeScannerCompat;
import no.nordicsemi.android.support.v18.scanner.ScanCallback;
import no.nordicsemi.android.support.v18.scanner.ScanResult;
import no.nordicsemi.android.support.v18.scanner.ScanSettings;
public class ScannerViewModel extends AndroidViewModel {
private static final String PREFS_FILTER_UUID_REQUIRED = "filter_uuid";
private static final String PREFS_FILTER_NEARBY_ONLY = "filter_nearby";
/** MutableLiveData containing the list of devices. */
private final DevicesLiveData mDevicesLiveData;
/** MutableLiveData containing the scanner state. */
private final ScannerStateLiveData mScannerStateLiveData;
private final SharedPreferences mPreferences;
public DevicesLiveData getDevices() {
return mDevicesLiveData;
}
public ScannerStateLiveData getScannerState() {
return mScannerStateLiveData;
}
@Inject
public ScannerViewModel(@NonNull final Application application,
@NonNull final SharedPreferences preferences) {
super(application);
mPreferences = preferences;
final boolean filterUuidRequired = isUuidFilterEnabled();
final boolean filerNearbyOnly = isNearbyFilterEnabled();
mScannerStateLiveData = new ScannerStateLiveData(
Utils.isBleEnabled(),
Utils.isLocationEnabled(application)
);
mDevicesLiveData = new DevicesLiveData(filterUuidRequired, filerNearbyOnly);
registerBroadcastReceivers(application);
}
@Override
protected void onCleared() {
super.onCleared();
getApplication().unregisterReceiver(mBluetoothStateBroadcastReceiver);
if (Utils.isMarshmallowOrAbove()) {
getApplication().unregisterReceiver(mLocationProviderChangedReceiver);
}
}
public boolean isUuidFilterEnabled() {
return mPreferences.getBoolean(PREFS_FILTER_UUID_REQUIRED, true);
}
public boolean isNearbyFilterEnabled() {
return mPreferences.getBoolean(PREFS_FILTER_NEARBY_ONLY, false);
}
/**
* Forces the observers to be notified. This method is used to refresh the screen after the
* location permission has been granted. In result, the observer in
* {@link io.runtime.mcumgr.sample.ScannerActivity} will try to start scanning.
*/
public void refresh() {
mScannerStateLiveData.refresh();
}
/**
* Updates the device filter. Devices that once passed the filter will still be shown
* even if they move away from the phone, or change the advertising packet. This is to
* avoid removing devices from the list.
*
* @param uuidRequired if true, the list will display only devices with SMP UUID
* in the advertising packet.
*/
public void filterByUuid(final boolean uuidRequired) {
mPreferences.edit().putBoolean(PREFS_FILTER_UUID_REQUIRED, uuidRequired).apply();
if (mDevicesLiveData.filterByUuid(uuidRequired))
mScannerStateLiveData.recordFound();
else
mScannerStateLiveData.clearRecords();
}
/**
* Updates the device filter. Devices that once passed the filter will still be shown
* even if they move away from the phone, or change the advertising packet. This is to
* avoid removing devices from the list.
*
* @param nearbyOnly if true, the list will show only devices with high RSSI.
*/
public void filterByDistance(final boolean nearbyOnly) {
mPreferences.edit().putBoolean(PREFS_FILTER_NEARBY_ONLY, nearbyOnly).apply();
if (mDevicesLiveData.filterByDistance(nearbyOnly))
mScannerStateLiveData.recordFound();
else
mScannerStateLiveData.clearRecords();
}
/**
* Start scanning for Bluetooth LE devices.
*/
public void startScan() {
if (mScannerStateLiveData.isScanning()) {
return;
}
// Scanning settings
final ScanSettings settings = new ScanSettings.Builder()
.setScanMode(ScanSettings.SCAN_MODE_LOW_LATENCY)
.setLegacy(false)
.setReportDelay(500)
.setUseHardwareBatchingIfSupported(false)
.build();
final BluetoothLeScannerCompat scanner = BluetoothLeScannerCompat.getScanner();
scanner.startScan(null, settings, scanCallback);
mScannerStateLiveData.scanningStarted();
}
/**
* Stop scanning for Bluetooth LE devices.
*/
public void stopScan() {
final BluetoothLeScannerCompat scanner = BluetoothLeScannerCompat.getScanner();
scanner.stopScan(scanCallback);
mScannerStateLiveData.scanningStopped();
}
private final ScanCallback scanCallback = new ScanCallback() {
@Override
public void onScanResult(final int callbackType, @NotNull final ScanResult result) {
// This callback will be called only if the scan report delay is not set or is set to 0.
// If the packet has been obtained while Location was disabled, mark Location as not required
if (Utils.isLocationRequired(getApplication()) && !Utils.isLocationEnabled(getApplication()))
Utils.markLocationNotRequired(getApplication());
if (!isNoise(result) && mDevicesLiveData.deviceDiscovered(result)) {
mDevicesLiveData.applyFilter();
mScannerStateLiveData.recordFound();
}
}
@Override
public void onBatchScanResults(@NotNull final List<ScanResult> results) {
// This callback will be called only if the report delay set above is greater then 0.
// If the packet has been obtained while Location was disabled, mark Location as not required
if (Utils.isLocationRequired(getApplication()) && !Utils.isLocationEnabled(getApplication()))
Utils.markLocationNotRequired(getApplication());
boolean atLeastOneMatchedFilter = false;
for (final ScanResult result : results)
atLeastOneMatchedFilter =
(!isNoise(result) && mDevicesLiveData.deviceDiscovered(result))
|| atLeastOneMatchedFilter;
if (atLeastOneMatchedFilter) {
mDevicesLiveData.applyFilter();
mScannerStateLiveData.recordFound();
}
}
@Override
public void onScanFailed(final int errorCode) {
// TODO This should be handled
stopScan();
mScannerStateLiveData.scanningStopped();
}
};
/**
* Register for required broadcast receivers.
*/
private void registerBroadcastReceivers(@NonNull final Application application) {
application.registerReceiver(mBluetoothStateBroadcastReceiver, new IntentFilter(BluetoothAdapter.ACTION_STATE_CHANGED));
if (Utils.isMarshmallowOrAbove()) {
application.registerReceiver(mLocationProviderChangedReceiver, new IntentFilter(LocationManager.MODE_CHANGED_ACTION));
}
}
/**
* Broadcast receiver to monitor the changes in the location provider
*/
private final BroadcastReceiver mLocationProviderChangedReceiver = new BroadcastReceiver() {
@Override
public void onReceive(final Context context, final Intent intent) {
final boolean enabled = Utils.isLocationEnabled(context);
mScannerStateLiveData.setLocationEnabled(enabled);
}
};
/**
* Broadcast receiver to monitor the changes in the bluetooth adapter
*/
private final BroadcastReceiver mBluetoothStateBroadcastReceiver = new BroadcastReceiver() {
@Override
public void onReceive(final Context context, final Intent intent) {
final int state = intent.getIntExtra(BluetoothAdapter.EXTRA_STATE, BluetoothAdapter.STATE_OFF);
final int previousState = intent.getIntExtra(BluetoothAdapter.EXTRA_PREVIOUS_STATE, BluetoothAdapter.STATE_OFF);
switch (state) {
case BluetoothAdapter.STATE_ON:
mScannerStateLiveData.bluetoothEnabled();
break;
case BluetoothAdapter.STATE_TURNING_OFF:
case BluetoothAdapter.STATE_OFF:
if (previousState != BluetoothAdapter.STATE_TURNING_OFF && previousState != BluetoothAdapter.STATE_OFF) {
stopScan();
mDevicesLiveData.bluetoothDisabled();
mScannerStateLiveData.bluetoothDisabled();
}
break;
}
}
};
/**
* This method returns true if the scan result may be considered as noise.
* This is to make the device list on the scanner screen shorter.
* <p>
* This implementation considers as noise devices that:
* <ul>
* <li>Are not connectable (Android Oreo or newer only),</li>
* <li>Are far away (RSSI < -80),</li>
* <li>Advertise as beacons (iBeacons, Nordic Beacons, Microsoft Advertising Beacons,
* Eddystone,</li>
* <li>Advertise with AirDrop footprint,</li>
* <li>Advertise as Bluetooth Mesh devices.</li>
* </ul>
* Noise devices will no the shown on the scanner screen even with all filters disabled.
*
* @param result the scan result.
* @return true, if the device may be dismissed, false otherwise.
*/
@SuppressWarnings({"BooleanMethodIsAlwaysInverted", "RedundantIfStatement"})
private boolean isNoise(@NonNull final ScanResult result) {
// Do not show non-connectable devices.
// Only Android Oreo or newer can say if a device is connectable. On older Android versions
// the Support Scanner Library assumes all devices are connectable (compatibility mode).
if (!result.isConnectable())
return true;
// Very distant devices are noise.
if (result.getRssi() < -80)
return true;
if (FilterUtils.isBeacon(result))
return true;
if (FilterUtils.isAirDrop(result))
return true;
if (FilterUtils.isMeshDevice(result))
return true;
return false;
}
}
