Bluetooth scan filters (to enable background scanning on Android)

packages/carp_connectivity_package/lib/connectivity_package.dart

@@ -84,3 +84,41 @@ class ConnectivitySamplingPackage extends SmartphoneSamplingPackage {
         .add(WIFI, wifiNameAnonymizer);
   }
 }
+
+/// A sampling configuration specifying how to scan for Bluetooth devices on a
+/// regular basis for a specific period.
+///
+/// Data collection will be started as specified by the [interval] for a time
+/// period specified as the [duration]. Bluetooth scanning is filtering
+/// on the [withServices] and [withRemoteIds] to only collect data from
+/// specific services and remote ids.
+///
+/// Filtering on remoteIds allows Android to scan for devices in the background
+/// without needing to be in the foreground. This is not possible on iOS.
+@JsonSerializable(includeIfNull: false, explicitToJson: true)
+class BluetoothScanPeriodicSamplingConfiguration
+    extends PeriodicSamplingConfiguration {
+  /// List of Bluetooth service UUIDs to filter the scan results.
+  List<String> withServices;
+
+  /// List of remote device IDs to filter the scan results.
+  List<String> withRemoteIds;
+
+  BluetoothScanPeriodicSamplingConfiguration({
+    required super.interval,
+    required super.duration,
+    this.withServices = const [],
+    this.withRemoteIds = const [],
+  });
+
+  @override
+  Map<String, dynamic> toJson() =>
+      _$BluetoothScanPeriodicSamplingConfigurationToJson(this);
+  @override
+  Function get fromJsonFunction =>
+      _$BluetoothScanPeriodicSamplingConfigurationFromJson;
+  factory BluetoothScanPeriodicSamplingConfiguration.fromJson(
+          Map<String, dynamic> json) =>
+      FromJsonFactory()
+          .fromJson<BluetoothScanPeriodicSamplingConfiguration>(json);
+}

packages/carp_connectivity_package/lib/connectivity_probes.dart

@@ -56,8 +56,10 @@ class WifiProbe extends IntervalProbe {
 
 /// The [BluetoothProbe] scans for nearby and visible Bluetooth devices and
 /// collects a [Bluetooth] measurement that lists each device found during the scan.
+///
 /// Uses a [PeriodicSamplingConfiguration] for configuration the [interval]
-/// and [duration] of the scan.
+/// and [duration] of the scan. Can also be configured to filter by
+/// [services] and [remoteIds] by using a [BluetoothScanPeriodicSamplingConfiguration].
 class BluetoothProbe extends BufferingPeriodicStreamProbe {
   /// Default timeout for bluetooth scan - 4 secs
   static const DEFAULT_TIMEOUT = 4 * 1000;
@@ -70,11 +72,32 @@ class BluetoothProbe extends BufferingPeriodicStreamProbe {
   Future<Measurement?> getMeasurement() async =>
       _data != null ? Measurement.fromData(_data!) : null;
 
+  // if a BT-specific sampling configuration is used, we need to
+  // extract the services and remoteIds from it so FlutterBluePlus can
+  // perform filtered scanning
+
+  List<Guid> get services => (samplingConfiguration
+          is BluetoothScanPeriodicSamplingConfiguration)
+      ? (samplingConfiguration as BluetoothScanPeriodicSamplingConfiguration)
+          .withServices
+          .map((e) => Guid(e))
+          .toList()
+      : [];
+
+  List<String> get remoteIds => (samplingConfiguration
+          is BluetoothScanPeriodicSamplingConfiguration)
+      ? (samplingConfiguration as BluetoothScanPeriodicSamplingConfiguration)
+          .withRemoteIds
+      : [];
+
   @override
   void onSamplingStart() {
     _data = Bluetooth();
+
     try {
       FlutterBluePlus.startScan(
+          withServices: services,
+          withRemoteIds: remoteIds,
           timeout: samplingConfiguration?.duration ??
               const Duration(milliseconds: DEFAULT_TIMEOUT));
     } catch (error) {