host: car apps get the car's speed, odometer, fuel and range, compass and GPS

gearslip/src/main/java/app/seb3thehacker/gearslip/GearslipRunner.kt

@@ -185,6 +185,7 @@ class GearslipRunner(
         guidanceLink?.close()
         guidanceLink = null
         CarSensors.clear()
+        app.seb3thehacker.gearslip.car.CarData.clear()
         CarMic.current = null
         CarBluetooth.onCarDisconnected()
         BluetoothAudioCheck.onCarDisconnected()
@@ -467,6 +468,7 @@ class GearslipRunner(
         log.i("head unit: $info")
         SessionReport.headUnit(info.toString())
         SessionReport.headUnitInfo = info
+        app.seb3thehacker.gearslip.car.CarData.onModel(info.carModel, info.carYear)
         vehicleProfile = runCatching { vehicleProfileFor(info) }.getOrNull()
         val profile = vehicleProfile
         SessionReport.profile(profile?.name)
@@ -785,6 +787,7 @@ class GearslipRunner(
 
             MSG_SENSOR_EVENT_INDICATION -> {
                 CarSensors.onEvent(body)
+                app.seb3thehacker.gearslip.car.CarData.onEvent(body)
                 logSensorEvent(body)
                 onNightSensor(body)
             }

gearslip/src/main/java/app/seb3thehacker/gearslip/car/CarData.kt

@@ -0,0 +1,110 @@
+package app.seb3thehacker.gearslip.car
+
+import app.seb3thehacker.gearslip.Wire
+import kotlinx.coroutines.flow.MutableStateFlow
+import kotlinx.coroutines.flow.StateFlow
+
+/**
+ * The car's sensors, read into real values for the car apps that ask (a map's speed, an EV app's
+ * range). [CarSensors] keeps the raw readings for the Vehicle data screen; this keeps the few with
+ * a known meaning, decoded the way Android Auto's SensorBatch scales them:
+ *
+ *   gps_location = 1 { latitude_e7 = 2; longitude_e7 = 3; accuracy_e3 = 4; altitude_e2 = 5;
+ *                      speed_e3 = 6; bearing_e6 = 7 }
+ *   compass = 2 { bearing_e6 = 1 }      speed = 3 { speed_e3 = 1 }  (metres per second)
+ *   odometer = 5 { kms_e1 = 1 }         fuel = 6 { level = 1 (percent); range = 2 (km); low = 3 }
+ *
+ * Each value is null until the car first sends it, and the whole lot clears when it disconnects.
+ */
+object CarData {
+
+    class Location(
+        val latitude: Double,
+        val longitude: Double,
+        val accuracyMeters: Float?,
+        val altitudeMeters: Double?,
+        val speedMps: Float?,
+        val bearingDegrees: Float?,
+    )
+
+    data class Snapshot(
+        val speedMps: Float? = null,
+        val odometerKm: Float? = null,
+        val fuelPercent: Int? = null,
+        val rangeKm: Int? = null,
+        val fuelLow: Boolean? = null,
+        val compassDegrees: Float? = null,
+        val location: Location? = null,
+        /** When each kind last changed, by its SensorBatch field number. */
+        val updatedAt: Map<Int, Long> = emptyMap(),
+    )
+
+    /** What the car says it is, from its service discovery: model and year. It names no maker. */
+    class Model(val name: String, val year: Int?)
+
+    private val flow = MutableStateFlow(Snapshot())
+    val state: StateFlow<Snapshot> = flow
+
+    @Volatile var model: Model? = null
+        private set
+
+    fun onModel(name: String, year: String) {
+        model = name.takeIf { it.isNotBlank() }?.let { Model(it, year.toIntOrNull()?.takeIf { y -> y > 0 }) }
+    }
+
+    fun onEvent(body: ByteArray) {
+        val now = System.currentTimeMillis()
+        val batch = Wire.fields(body)
+        var s = flow.value
+        val touched = HashSet<Int>()
+        // Each kind may come several times in one batch: the last is the newest.
+        Wire.allBytes(batch, LOCATION).lastOrNull()?.let { bytes ->
+            val f = Wire.fields(bytes)
+            val lat = Wire.varint(f, 2)?.toInt()
+            val lon = Wire.varint(f, 3)?.toInt()
+            if (lat != null && lon != null) {
+                s = s.copy(
+                    location = Location(
+                        lat / 1e7, lon / 1e7,
+                        Wire.varint(f, 4)?.let { it / 1e3f },
+                        Wire.varint(f, 5)?.let { it.toInt() / 1e2 },
+                        Wire.varint(f, 6)?.let { it.toInt() / 1e3f },
+                        Wire.varint(f, 7)?.let { it.toInt() / 1e6f },
+                    ),
+                )
+                touched += LOCATION
+            }
+        }
+        Wire.allBytes(batch, COMPASS).lastOrNull()?.let { bytes ->
+            Wire.varint(Wire.fields(bytes), 1)?.let { s = s.copy(compassDegrees = it.toInt() / 1e6f); touched += COMPASS }
+        }
+        Wire.allBytes(batch, SPEED).lastOrNull()?.let { bytes ->
+            Wire.varint(Wire.fields(bytes), 1)?.let { s = s.copy(speedMps = it.toInt() / 1e3f); touched += SPEED }
+        }
+        Wire.allBytes(batch, ODOMETER).lastOrNull()?.let { bytes ->
+            Wire.varint(Wire.fields(bytes), 1)?.let { s = s.copy(odometerKm = it.toInt() / 10f); touched += ODOMETER }
+        }
+        Wire.allBytes(batch, FUEL).lastOrNull()?.let { bytes ->
+            val f = Wire.fields(bytes)
+            s = s.copy(
+                fuelPercent = Wire.varint(f, 1)?.toInt() ?: s.fuelPercent,
+                rangeKm = Wire.varint(f, 2)?.toInt() ?: s.rangeKm,
+                fuelLow = Wire.varint(f, 3)?.let { it != 0L } ?: s.fuelLow,
+            )
+            touched += FUEL
+        }
+        if (touched.isEmpty()) return
+        flow.value = s.copy(updatedAt = s.updatedAt + touched.associateWith { now })
+    }
+
+    fun clear() {
+        flow.value = Snapshot()
+        model = null
+    }
+
+    const val LOCATION = 1
+    const val COMPASS = 2
+    const val SPEED = 3
+    const val ODOMETER = 5
+    const val FUEL = 6
+}

gearslip/src/main/java/app/seb3thehacker/gearslip/host/CarAppConnection.kt

@@ -227,6 +227,7 @@ class CarAppConnection(private val context: Context) {
 
     private fun disconnect(keepLocation: Boolean) {
         main.removeCallbacks(handshakeTimeout)
+        hardware.stop()
         clearToasts()
         lent?.let { sendSurfaceDestroyed(it) }
         lent = null
@@ -684,38 +685,25 @@ class CarAppConnection(private val context: Context) {
     }
 
     /**
-     * Answers car-hardware questions with "this car doesn't have that".
+     * Answers car-hardware questions from what the car itself sends: see [CarHardwareFeed].
      *
-     * A phone knows nothing about a car's sensors, so every answer here is "unsupported" - but
-     * it has to be an actual answer. Returning no binder for this service at all is what made
-     * Organic Maps crash in onAppStart: its CarSensorsManager assumes a host that offers the
-     * service, and the library's own "unsupported" path only runs once a reply arrives.
-     *
-     * The reply's Bundleable is ignored by the library whenever isSupported is false, but the
-     * IBinder must be a real IOnDoneCallback - the app dispatches the reply through it.
+     * Every question has to get an actual answer, even "unsupported". Returning no binder for
+     * this service at all is what made Organic Maps crash in onAppStart: its CarSensorsManager
+     * assumes a host that offers the service, and the library's own "unsupported" path only runs
+     * once a reply arrives. The reply's IBinder must be a real IOnDoneCallback: the app
+     * dispatches the reply through it.
      */
+    private val hardware = CarHardwareFeed { name -> noop(name).asBinder() }
+
     private val hardwareHost = object : ICarHardwareHost.Stub() {
         override fun getInterfaceVersion(): Int = ICarHardwareHost.VERSION
-        override fun getCarHardwareResult(
-            type: Int,
-            params: Bundleable?,
-            result: ICarHardwareResult?,
-        ) = unsupported(type, result)
+        override fun getCarHardwareResult(type: Int, params: Bundleable?, result: ICarHardwareResult?) =
+            hardware.get(type, result)
 
-        override fun subscribeCarHardwareResult(
-            type: Int,
-            params: Bundleable?,
-            result: ICarHardwareResult?,
-        ) = unsupported(type, result)
+        override fun subscribeCarHardwareResult(type: Int, params: Bundleable?, result: ICarHardwareResult?) =
+            hardware.subscribe(type, result)
 
-        override fun unsubscribeCarHardwareResult(type: Int, params: Bundleable?) = Unit
-
-        private fun unsupported(type: Int, result: ICarHardwareResult?) {
-            val target = result ?: return
-            runCatching {
-                target.onCarHardwareResult(type, false, null, noop("carHardwareResult").asBinder())
-            }.onFailure { GearslipLog.w("host: could not answer hardware result $type") }
-        }
+        override fun unsubscribeCarHardwareResult(type: Int, params: Bundleable?) = hardware.unsubscribe(type)
     }
 
     /**

gearslip/src/main/java/app/seb3thehacker/gearslip/host/CarHardwareFeed.kt

@@ -0,0 +1,171 @@
+package app.seb3thehacker.gearslip.host
+
+import android.os.IBinder
+import androidx.car.app.hardware.ICarHardwareResult
+import androidx.car.app.hardware.common.CarUnit
+import androidx.car.app.hardware.common.CarValue
+import androidx.car.app.hardware.info.CarHardwareLocation
+import androidx.car.app.hardware.info.Compass
+import androidx.car.app.hardware.info.EnergyLevel
+import androidx.car.app.hardware.info.Mileage
+import androidx.car.app.hardware.info.Model
+import androidx.car.app.hardware.info.Speed
+import androidx.car.app.serialization.Bundleable
+import app.seb3thehacker.gearslip.GearslipLog
+import app.seb3thehacker.gearslip.car.CarData
+import app.seb3thehacker.gearslip.car.CarSettings
+import java.util.concurrent.ConcurrentHashMap
+import java.util.concurrent.CopyOnWriteArrayList
+import kotlinx.coroutines.CoroutineScope
+import kotlinx.coroutines.Dispatchers
+import kotlinx.coroutines.Job
+import kotlinx.coroutines.SupervisorJob
+import kotlinx.coroutines.cancel
+import kotlinx.coroutines.launch
+
+/**
+ * What a car app gets when it asks the car hardware API (CarInfo, CarSensors) about the car:
+ * the model, speed, odometer, fuel and range, compass and the car's own GPS, read from [CarData].
+ * Anything else, or anything the car never sends, is answered "this car doesn't have that".
+ *
+ * A one-off question ([get]) is answered at once. A subscription gets the current value, if
+ * there is one, and then each new one as the car sends it, until the app unsubscribes or the
+ * connection ends ([stop]).
+ */
+internal class CarHardwareFeed(private val callback: (name: String) -> IBinder) {
+
+    private val subscribers = ConcurrentHashMap<Int, CopyOnWriteArrayList<ICarHardwareResult>>()
+    private val scope = CoroutineScope(SupervisorJob() + Dispatchers.Default)
+    @Volatile private var watching: Job? = null
+
+    fun get(type: Int, result: ICarHardwareResult?) {
+        val target = result ?: return
+        send(target, type, valueOf(type, CarData.state.value) ?: return unsupported(target, type))
+    }
+
+    fun subscribe(type: Int, result: ICarHardwareResult?) {
+        val target = result ?: return
+        if (type !in SENSOR_OF) return unsupported(target, type)
+        subscribers.getOrPut(type) { CopyOnWriteArrayList() }.add(target)
+        GearslipLog.i("host: an app subscribed to car hardware ${NAMES[type] ?: type}")
+        valueOf(type, CarData.state.value)?.let { send(target, type, it) }
+        watch()
+    }
+
+    fun unsubscribe(type: Int) {
+        subscribers.remove(type)
+    }
+
+    fun stop() {
+        subscribers.clear()
+        watching?.cancel()
+        watching = null
+    }
+
+    fun close() {
+        stop()
+        scope.cancel()
+    }
+
+    /** Sends each subscribed kind again when the car's reading of it changes. */
+    private fun watch() {
+        if (watching?.isActive == true) return
+        watching = scope.launch {
+            var seen = CarData.state.value.updatedAt
+            CarData.state.collect { s ->
+                for ((type, targets) in subscribers) {
+                    val sensor = SENSOR_OF[type] ?: continue
+                    if (s.updatedAt[sensor] == seen[sensor]) continue
+                    val value = valueOf(type, s) ?: continue
+                    targets.forEach { send(it, type, value) }
+                }
+                seen = s.updatedAt
+            }
+        }
+    }
+
+    private fun valueOf(type: Int, s: CarData.Snapshot): Any? {
+        val imperial = CarSettings.imperial()
+        val distanceUnit = known(if (imperial) CarUnit.MILE else CarUnit.KILOMETER)
+        val at = s.updatedAt[SENSOR_OF[type]] ?: System.currentTimeMillis()
+        fun <T : Any> v(value: T) = CarValue(value, at, CarValue.STATUS_SUCCESS)
+        return when (type) {
+            TYPE_MODEL -> CarData.model?.let { m ->
+                Model.Builder().setName(v(m.name)).apply { m.year?.let { setYear(v(it)) } }.build()
+            }
+            TYPE_SPEED -> s.speedMps?.let {
+                Speed.Builder()
+                    .setRawSpeedMetersPerSecond(v(it))
+                    .setDisplaySpeedMetersPerSecond(v(it))
+                    .setSpeedDisplayUnit(known(if (imperial) CarUnit.MILES_PER_HOUR else CarUnit.KILOMETERS_PER_HOUR))
+                    .build()
+            }
+            TYPE_MILEAGE -> s.odometerKm?.let {
+                Mileage.Builder().setOdometerMeters(v(it * 1000f)).setDistanceDisplayUnit(distanceUnit).build()
+            }
+            TYPE_ENERGY_LEVEL -> if (s.fuelPercent == null && s.rangeKm == null && s.fuelLow == null) null else {
+                EnergyLevel.Builder().apply {
+                    s.fuelPercent?.let { setFuelPercent(v(it.toFloat())) }
+                    s.rangeKm?.let { setRangeRemainingMeters(v(it * 1000f)) }
+                    s.fuelLow?.let { setEnergyIsLow(v(it)) }
+                    setDistanceDisplayUnit(distanceUnit)
+                }.build()
+            }
+            TYPE_COMPASS -> s.compassDegrees?.let { Compass(v(listOf(it))) }
+            TYPE_CAR_LOCATION -> s.location?.let { l ->
+                val location = android.location.Location("car").apply {
+                    latitude = l.latitude
+                    longitude = l.longitude
+                    l.accuracyMeters?.let { accuracy = it }
+                    l.altitudeMeters?.let { altitude = it }
+                    l.speedMps?.let { speed = it }
+                    l.bearingDegrees?.let { bearing = it }
+                    time = at
+                }
+                CarHardwareLocation(v(location))
+            }
+            else -> null
+        }
+    }
+
+    private fun known(value: Int) = CarValue(value, System.currentTimeMillis(), CarValue.STATUS_SUCCESS)
+
+    private fun send(target: ICarHardwareResult, type: Int, value: Any) {
+        runCatching {
+            target.onCarHardwareResult(type, true, Bundleable.create(value), callback("carHardwareResult"))
+        }.onFailure {
+            // The app went away: stop telling it.
+            subscribers.values.forEach { list -> list.remove(target) }
+            GearslipLog.w("host: could not send car hardware ${NAMES[type] ?: type}: ${it.javaClass.simpleName}")
+        }
+    }
+
+    private fun unsupported(target: ICarHardwareResult, type: Int) {
+        runCatching { target.onCarHardwareResult(type, false, null, callback("carHardwareResult")) }
+            .onFailure { GearslipLog.w("host: could not answer hardware result $type") }
+    }
+
+    companion object {
+        // ICarHardwareResultTypes in the car library.
+        private const val TYPE_MODEL = 1
+        private const val TYPE_ENERGY_LEVEL = 4
+        private const val TYPE_SPEED = 5
+        private const val TYPE_MILEAGE = 6
+        private const val TYPE_COMPASS = 21
+        private const val TYPE_CAR_LOCATION = 23
+
+        /** Which of the car's sensors each kind comes from, for knowing when it changed. */
+        private val SENSOR_OF = mapOf(
+            TYPE_ENERGY_LEVEL to CarData.FUEL,
+            TYPE_SPEED to CarData.SPEED,
+            TYPE_MILEAGE to CarData.ODOMETER,
+            TYPE_COMPASS to CarData.COMPASS,
+            TYPE_CAR_LOCATION to CarData.LOCATION,
+        )
+
+        private val NAMES = mapOf(
+            TYPE_MODEL to "model", TYPE_ENERGY_LEVEL to "energy level", TYPE_SPEED to "speed",
+            TYPE_MILEAGE to "mileage", TYPE_COMPASS to "compass", TYPE_CAR_LOCATION to "car location",
+        )
+    }
+}

gearslip/src/test/java/app/seb3thehacker/gearslip/car/CarDataTest.kt

@@ -0,0 +1,63 @@
+package app.seb3thehacker.gearslip.car
+
+import app.seb3thehacker.gearslip.Protobuf
+import org.junit.After
+import org.junit.Assert.*
+import org.junit.Test
+
+class CarDataTest {
+    @After fun reset() = CarData.clear()
+
+    private fun batch(field: Int, body: ByteArray) = Protobuf.bytesField(field, body)
+
+    @Test fun `speed odometer and fuel come out in real units`() {
+        CarData.onEvent(
+            batch(CarData.SPEED, Protobuf.varintField(1, 12_500)) +
+                batch(CarData.ODOMETER, Protobuf.varintField(1, 123_456)) +
+                batch(CarData.FUEL, Protobuf.varintField(1, 42) + Protobuf.varintField(2, 380) + Protobuf.varintField(3, 0)),
+        )
+        val s = CarData.state.value
+        assertEquals(12.5f, s.speedMps!!, 0.001f)
+        assertEquals(12_345.6f, s.odometerKm!!, 0.01f)
+        assertEquals(42, s.fuelPercent)
+        assertEquals(380, s.rangeKm)
+        assertEquals(false, s.fuelLow)
+        assertTrue(s.updatedAt.keys.containsAll(listOf(CarData.SPEED, CarData.ODOMETER, CarData.FUEL)))
+    }
+
+    @Test fun `a location west and south of zero keeps its sign`() {
+        CarData.onEvent(
+            batch(
+                CarData.LOCATION,
+                Protobuf.varintField(2, -337_000_000) + Protobuf.varintField(3, -706_000_000) +
+                    Protobuf.varintField(7, 90_000_000),
+            ),
+        )
+        val l = CarData.state.value.location!!
+        assertEquals(-33.7, l.latitude, 1e-6)
+        assertEquals(-70.6, l.longitude, 1e-6)
+        assertEquals(90f, l.bearingDegrees!!, 0.001f)
+        assertNull(l.accuracyMeters)
+    }
+
+    @Test fun `the newest reading in a batch wins, and fuel keeps what a later batch leaves out`() {
+        CarData.onEvent(batch(CarData.FUEL, Protobuf.varintField(1, 50) + Protobuf.varintField(2, 400)))
+        CarData.onEvent(
+            batch(CarData.COMPASS, Protobuf.varintField(1, 10_000_000)) +
+                batch(CarData.COMPASS, Protobuf.varintField(1, 20_000_000)) +
+                batch(CarData.FUEL, Protobuf.varintField(1, 49)),
+        )
+        val s = CarData.state.value
+        assertEquals(20f, s.compassDegrees!!, 0.001f)
+        assertEquals(49, s.fuelPercent)
+        assertEquals(400, s.rangeKm)
+    }
+
+    @Test fun `a car that names no model or year leaves them unknown`() {
+        CarData.onModel("", "0")
+        assertNull(CarData.model)
+        CarData.onModel("Clio", "0")
+        assertEquals("Clio", CarData.model?.name)
+        assertNull(CarData.model?.year)
+    }
+}