opt-in usage notes and a stats dashboard

Release builds ask in setup and Settings whether to send a short note when the app is opened and after each drive: the version, plus the Android version, phone model and cars people tick. Nothing runs in the background. Dev builds always send. The Cloudflare Worker in stats-worker/ stores the notes and serves a private dashboard with GitHub downloads alongside.

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

@@ -27,6 +27,7 @@ import app.seb3thehacker.gearslip.car.CarEnvironment
 import app.seb3thehacker.gearslip.car.CarSettings
 import app.seb3thehacker.gearslip.car.CarUi
 import app.seb3thehacker.gearslip.car.Prefetch
+import app.seb3thehacker.gearslip.stats.UsageStats
 import app.seb3thehacker.gearslip.ui.GearslipApp
 import app.seb3thehacker.gearslip.ui.GearslipTheme
 import java.io.FileInputStream
@@ -150,6 +151,7 @@ class GearslipActivity : ComponentActivity(), Projection {
     override fun onStart() {
         super.onStart()
         Prefetch.warm(this)
+        UsageStats.onAppOpened(this)
     }
 
     override fun onNewIntent(intent: Intent) {

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

@@ -1,6 +1,7 @@
 package app.seb3thehacker.gearslip
 
 import android.content.Context
+import app.seb3thehacker.gearslip.stats.UsageStats
 import android.os.Build
 
 /**
@@ -48,7 +49,10 @@ object SessionReport {
     @Volatile private var lastState = ""
     private var printed = false
 
+    private var appContext: Context? = null
+
     fun init(context: Context) {
+        appContext = context.applicationContext
         val info = runCatching { context.packageManager.getPackageInfo(context.packageName, 0) }.getOrNull()
         appVersion = info?.versionName ?: "?"
         appCode = info?.longVersionCode ?: 0
@@ -59,6 +63,8 @@ object SessionReport {
         category = Category.NONE
         failure = ""; protocolVersion = ""; certSource = ""; certIssuer = ""
         tlsProtocol = ""; tlsCipher = ""; authStatus = null
+        headUnitInfo = null
+        carScreen = ""; carDpi = 0
         headUnit = ""; profile = ""; video = ""; lastStream = ""; lastState = ""
         printed = false
     }
@@ -68,6 +74,14 @@ object SessionReport {
     fun tls(protocol: String, cipher: String) { tlsProtocol = protocol; tlsCipher = cipher }
     fun auth(status: Int) { authStatus = status }
     fun headUnit(info: String) { headUnit = info }
+
+    /** Who the car said it is, for the opt-in usage note; null until service discovery. */
+    @Volatile var headUnitInfo: ServiceDiscovery.HeadUnitInfo? = null
+
+    /** The car screen's usable size once its margins are cropped, and its density; blank before video starts. */
+    @Volatile var carScreen = ""; private set
+    @Volatile var carDpi = 0; private set
+    fun carScreen(size: String, dpi: Int) { carScreen = size; carDpi = dpi }
     fun profile(name: String?) { profile = name ?: "none matched" }
     fun video(summary: String) { video = summary }
     fun audio(summary: String) { audio = summary }
@@ -121,6 +135,18 @@ object SessionReport {
         if (printed || startedAt == 0L) return
         printed = true
         render().lines().forEach { GearslipLog.i(it) }
+        appContext?.let { context ->
+            // Video started means the car showed Gearslip: that's a working car, and unplugging or
+            // switching the car off at the end shows up as a USB or ByeBye "failure" that isn't one.
+            val reached = carScreen.isNotEmpty()
+            val outcome = when {
+                reached && category in setOf(Category.NONE, Category.USB, Category.BYEBYE) -> "connected"
+                reached -> "connected, then ${category.label}"
+                category == Category.NONE -> "ended before video"
+                else -> category.label
+            }
+            runCatching { UsageStats.recordSession(context, headUnitInfo, protocolVersion, outcome, carScreen, carDpi) }
+        }
         GearslipLog.flush()
     }
 

gearslip/src/main/java/app/seb3thehacker/gearslip/stats/UsageStats.kt

@@ -0,0 +1,235 @@
+package app.seb3thehacker.gearslip.stats
+
+import android.app.job.JobScheduler
+import android.content.Context
+import android.os.Build
+import app.seb3thehacker.gearslip.BuildConfig
+import app.seb3thehacker.gearslip.GearslipLog
+import app.seb3thehacker.gearslip.ServiceDiscovery
+import org.json.JSONArray
+import org.json.JSONObject
+import java.net.HttpURLConnection
+import java.net.URL
+import java.time.LocalDate
+import java.util.UUID
+import java.util.concurrent.atomic.AtomicBoolean
+
+/**
+ * Opt-in usage counts: a short note to the stats Worker (stats-worker/ in the repo). Off until the
+ * driver turns it on in setup or Settings. Only the app version is always sent; everything else
+ * is one of the driver's [Choices]. A random install ID counts a phone once; nothing ties it to a
+ * person, and the Worker keeps no IP addresses.
+ *
+ * Notes go out only while Gearslip is in use: the first time the app is opened each day, and
+ * after every car session. Nothing runs in the background, so a phone that stops using Gearslip
+ * goes quiet. A note that fails waits for the next one. With no [BuildConfig.STATS_URL] set at
+ * build time, nothing is sent.
+ */
+object UsageStats {
+
+    /** What the driver agreed to share beyond the app version. */
+    data class Choices(
+        val android: Boolean = true,
+        val phone: Boolean = true,
+        val cars: Boolean = true,
+    )
+
+    private const val PREFS = "usage_stats"
+    private const val KEY_ENABLED = "enabled"
+    private const val KEY_ASKED = "asked"
+    private const val KEY_ID = "install_id"
+    /** The phone details the server last got, and when, so they go again only on a change. */
+    private const val KEY_SENT_DETAILS = "sent_details"
+    private const val KEY_DETAILS_DAY = "details_day"
+    private const val DETAILS_REFRESH_DAYS = 30L
+    private const val KEY_CARS = "cars"
+    private const val KEY_SENT_DAY = "sent_day"
+    /** The daily background job of earlier builds, cancelled wherever it's still scheduled. */
+    private const val OLD_JOB_ID = 4_207
+    private const val MAX_CARS = 10
+
+    private fun prefs(context: Context) = context.getSharedPreferences(PREFS, Context.MODE_PRIVATE)
+
+    /**
+     * Dev builds are the developer's own, so they always send everything and never ask: no switch
+     * in Settings, no page in setup. Only release builds offer the choice.
+     */
+    val choosable: Boolean get() = !BuildConfig.DEBUG
+
+    fun enabled(context: Context): Boolean = !choosable || prefs(context).getBoolean(KEY_ENABLED, false)
+
+    /** Whether the driver has answered the question in setup, either way. */
+    fun asked(context: Context): Boolean = !choosable || prefs(context).getBoolean(KEY_ASKED, false)
+
+    fun choices(context: Context): Choices {
+        if (!choosable) return Choices()
+        val p = prefs(context)
+        return Choices(
+            android = p.getBoolean("share_android", true),
+            phone = p.getBoolean("share_phone", true),
+            cars = p.getBoolean("share_cars", true),
+        )
+    }
+
+    fun set(context: Context, enabled: Boolean, choices: Choices = choices(context)) {
+        prefs(context).edit()
+            .putBoolean(KEY_ENABLED, enabled)
+            .putBoolean(KEY_ASKED, true)
+            .putBoolean("share_android", choices.android)
+            .putBoolean("share_phone", choices.phone)
+            .putBoolean("share_cars", choices.cars)
+            .apply()
+        if (enabled) sendSoon(context)
+        else prefs(context).edit().remove(KEY_CARS).remove(KEY_SENT_DAY).apply()
+    }
+
+    /** Gearslip was opened: send today's note unless one already went out. */
+    fun onAppOpened(context: Context) {
+        context.getSystemService(JobScheduler::class.java)?.cancel(OLD_JOB_ID)
+        if (prefs(context).getString(KEY_SENT_DAY, null) != LocalDate.now().toString()) sendSoon(context)
+    }
+
+    private val sending = AtomicBoolean(false)
+    @Volatile private var sendAgain = false
+    /** Guards the saved car list, which a session's end and a finished send both rewrite. */
+    private val carsLock = Any()
+
+    /**
+     * Sends off the calling thread. A call while a note is in flight sends once more after it, so
+     * a car recorded mid-send still goes out.
+     */
+    private fun sendSoon(context: Context) {
+        if (!enabled(context)) return
+        if (!sending.compareAndSet(false, true)) { sendAgain = true; return }
+        val app = context.applicationContext
+        Thread({
+            try {
+                do { sendAgain = false } while (send(app) && sendAgain)
+            } finally {
+                sending.set(false)
+            }
+        }, "gearslip-stats").start()
+    }
+
+    private fun installId(context: Context): String {
+        val p = prefs(context)
+        return p.getString(KEY_ID, null) ?: UUID.randomUUID().toString().also { p.edit().putString(KEY_ID, it).apply() }
+    }
+
+    /**
+     * A car session ended. [info] is null when the car hung up before it said who it is, for
+     * instance after rejecting the certificate; the protocol version and [outcome] still say a lot.
+     */
+    fun recordSession(
+        context: Context,
+        info: ServiceDiscovery.HeadUnitInfo?,
+        protocol: String,
+        outcome: String,
+        screen: String = "",
+        dpi: Int = 0,
+    ) {
+        if (!enabled(context)) return
+        val p = prefs(context)
+        synchronized(carsLock) { addCar(p, info, protocol, outcome, screen, dpi) }
+        sendSoon(context)
+    }
+
+    private fun addCar(
+        p: android.content.SharedPreferences,
+        info: ServiceDiscovery.HeadUnitInfo?,
+        protocol: String,
+        outcome: String,
+        screen: String,
+        dpi: Int,
+    ) {
+        val cars = runCatching { JSONArray(p.getString(KEY_CARS, "[]")) }.getOrDefault(JSONArray())
+        val car = JSONObject()
+            .put("name", info?.headUnitName.orEmpty())
+            .put("car", info?.carModel.orEmpty())
+            .put("year", info?.carYear.orEmpty())
+            .put("make", info?.headUnitMake.orEmpty())
+            .put("model", info?.headUnitModel.orEmpty())
+            .put("protocol", protocol)
+            .put("result", outcome)
+        if (screen.isNotEmpty()) car.put("screen", screen).put("dpi", dpi)
+        // The same car and outcome twice in a day is one fact, not two.
+        val seen = (0 until cars.length()).any { cars.optJSONObject(it)?.toString() == car.toString() }
+        if (!seen && cars.length() < MAX_CARS) cars.put(car)
+        p.edit().putString(KEY_CARS, cars.toString()).apply()
+    }
+
+    // GrapheneOS reports the same build fields as stock Pixel firmware; its own apps give it away.
+    private fun isGrapheneOs(context: Context) =
+        runCatching { context.packageManager.getPackageInfo("app.grapheneos.setupwizard", 0) }.isSuccess
+
+    private fun details(context: Context, c: Choices) = JSONObject().apply {
+        if (c.android) put("android", Build.VERSION.RELEASE).put("os", if (isGrapheneOs(context)) "GrapheneOS" else "other")
+        if (c.phone) put("phone", "${Build.MANUFACTURER} ${Build.MODEL}")
+    }
+
+    /**
+     * What a note carries. With [everything], every field the driver shares, as Settings shows it;
+     * otherwise exactly what the next note would send, which leaves out unchanged phone details.
+     */
+    fun preview(context: Context, everything: Boolean = false): JSONObject {
+        val c = choices(context)
+        val p = prefs(context)
+        val note = JSONObject()
+            .put("id", installId(context))
+            .put("version", BuildConfig.VERSION_NAME)
+            .put("code", BuildConfig.VERSION_CODE)
+            .put("build", if (BuildConfig.DEBUG) "dev" else "release")
+        // Phone details change rarely, so they ride along only when they differ from what the
+        // server last got, or once a month in case it lost them. Unticked ones are left out, and
+        // the server keeps the last value it had.
+        val details = details(context, c)
+        val stale = p.getString(KEY_DETAILS_DAY, null)?.let { LocalDate.parse(it).plusDays(DETAILS_REFRESH_DAYS) <= LocalDate.now() } ?: true
+        if (details.length() > 0 && (everything || stale || details.toString() != p.getString(KEY_SENT_DETAILS, null))) {
+            details.keys().forEach { note.put(it, details.get(it)) }
+        }
+        if (c.cars) note.put("cars", runCatching { JSONArray(p.getString(KEY_CARS, "[]")) }.getOrDefault(JSONArray()))
+        return note
+    }
+
+    /** Sends the note now; false when it didn't get through. */
+    private fun send(context: Context): Boolean {
+        if (!enabled(context)) return true
+        val endpoint = BuildConfig.STATS_URL
+        if (endpoint.isBlank()) return true
+        val p = prefs(context)
+        val note = synchronized(carsLock) { preview(context) }
+        val sentCars = note.optJSONArray("cars")?.toString()
+        val sentDetails = if (note.has("android") || note.has("phone")) details(context, choices(context)).toString() else null
+        val body = note.toString().toByteArray()
+        return runCatching {
+            val conn = (URL("$endpoint/ping").openConnection() as HttpURLConnection).apply {
+                requestMethod = "POST"
+                doOutput = true
+                connectTimeout = 15_000
+                readTimeout = 15_000
+                setRequestProperty("Content-Type", "application/json")
+            }
+            conn.outputStream.use { it.write(body) }
+            val code = conn.responseCode
+            conn.disconnect()
+            if (code in 200..299) {
+                // Sent: the cars start over, unless a session ended meanwhile and added one, which
+                // stays for the next note.
+                synchronized(carsLock) {
+                    val edit = p.edit().putString(KEY_SENT_DAY, LocalDate.now().toString())
+                    if (sentDetails != null) edit.putString(KEY_SENT_DETAILS, sentDetails).putString(KEY_DETAILS_DAY, LocalDate.now().toString())
+                    if (sentCars == null || p.getString(KEY_CARS, "[]") == sentCars) edit.remove(KEY_CARS)
+                    edit.apply()
+                }
+                GearslipLog.i("stats: note sent")
+                true
+            } else {
+                GearslipLog.w("stats: the server answered $code")
+                false
+            }
+        }.getOrElse {
+            GearslipLog.w("stats: could not send: ${it.message}")
+            false
+        }
+    }
+}

gearslip/src/main/java/app/seb3thehacker/gearslip/ui/UsageStatsChoices.kt

@@ -0,0 +1,148 @@
+package app.seb3thehacker.gearslip.ui
+
+import androidx.compose.animation.AnimatedVisibility
+import androidx.compose.foundation.clickable
+import androidx.compose.foundation.layout.Column
+import androidx.compose.foundation.layout.ColumnScope
+import androidx.compose.foundation.layout.Row
+import androidx.compose.foundation.layout.fillMaxWidth
+import androidx.compose.foundation.layout.padding
+import androidx.compose.foundation.selection.toggleable
+import androidx.compose.material.icons.Icons
+import androidx.compose.material.icons.filled.Info
+import androidx.compose.material.icons.filled.KeyboardArrowDown
+import androidx.compose.material.icons.filled.KeyboardArrowUp
+import androidx.compose.material.icons.filled.Send
+import androidx.compose.material3.Checkbox
+import androidx.compose.material3.Icon
+import androidx.compose.material3.MaterialTheme
+import androidx.compose.material3.Surface
+import androidx.compose.material3.Switch
+import androidx.compose.material3.Text
+import androidx.compose.runtime.Composable
+import androidx.compose.runtime.getValue
+import androidx.compose.runtime.mutableStateOf
+import androidx.compose.runtime.remember
+import androidx.compose.runtime.setValue
+import androidx.compose.ui.Alignment
+import androidx.compose.ui.Modifier
+import androidx.compose.ui.platform.LocalContext
+import androidx.compose.ui.semantics.Role
+import androidx.compose.ui.text.AnnotatedString
+import androidx.compose.ui.text.SpanStyle
+import androidx.compose.ui.text.buildAnnotatedString
+import androidx.compose.ui.text.font.FontFamily
+import androidx.compose.ui.text.font.FontWeight
+import androidx.compose.ui.text.withStyle
+import androidx.compose.ui.unit.dp
+import app.seb3thehacker.gearslip.BuildConfig
+import app.seb3thehacker.gearslip.stats.UsageStats
+
+internal const val USAGE_STATS_TITLE = "Help show which cars work"
+
+private const val INTRO_START =
+    "Gearslip can't tell which cars it works in unless drivers say so. Turn this on, and Gearslip " +
+        "sends a short note when you open it and after each drive, never in the background. The " +
+        "note carries the Gearslip version and whatever you tick below. "
+private const val INTRO_PRIVACY =
+    "It holds no name, account, or location, only a random number so your phone counts once. " +
+        "Cloudflare carries the note, and the server keeps no IP address."
+private const val INTRO_END =
+    " Nothing helps the project more: these notes tell the next driver whether their car " +
+        "will work before they install."
+
+/** The pitch for the usage notes, with the privacy promise in bold so it isn't missed. */
+internal val USAGE_STATS_INTRO: AnnotatedString = buildAnnotatedString {
+    append(INTRO_START)
+    withStyle(SpanStyle(fontWeight = FontWeight.Bold)) { append(INTRO_PRIVACY) }
+    append(INTRO_END)
+}
+
+/** The usage notes card for the setup guide: the same rows Settings shows, minus the note. */
+@Composable
+internal fun UsageStatsChoices(modifier: Modifier = Modifier) {
+    SettingsCard(modifier) { UsageStatsRows(showNote = false) }
+}
+
+/**
+ * The on switch, what to share, and (with [showNote]) the note itself, saved as they change.
+ * Rows only: the caller puts them in a card.
+ */
+@Composable
+internal fun ColumnScope.UsageStatsRows(showNote: Boolean) {
+    val context = LocalContext.current
+    var on by remember { mutableStateOf(UsageStats.enabled(context)) }
+    var choices by remember { mutableStateOf(UsageStats.choices(context)) }
+    var noteOpen by remember { mutableStateOf(false) }
+    fun save() = UsageStats.set(context, on, choices)
+
+    SettingsRow(
+        "Send usage notes",
+        Modifier.toggleable(on, role = Role.Switch) { on = it; save() },
+        subtitle = if (BuildConfig.STATS_URL.isBlank()) "This build has no stats server, so it sends nothing" else null,
+        icon = Icons.Filled.Send,
+        trailing = { Switch(checked = on, onCheckedChange = null) },
+    )
+    AnimatedVisibility(on) {
+        Column {
+            SettingsDivider()
+            Text(
+                "Also share",
+                style = MaterialTheme.typography.labelLarge,
+                color = MaterialTheme.colorScheme.primary,
+                modifier = Modifier.padding(start = 56.dp, end = 16.dp, top = 12.dp, bottom = 4.dp),
+            )
+            Choice("Android version, and whether it's GrapheneOS", choices.android) { choices = choices.copy(android = it); save() }
+            Choice("Phone model", choices.phone) { choices = choices.copy(phone = it); save() }
+            Choice("Each car's head unit, model, year, and screen size, and whether it connected", choices.cars) {
+                choices = choices.copy(cars = it)
+                save()
+            }
+            if (showNote) {
+                SettingsDivider()
+                SettingsRow(
+                    "What gets sent",
+                    Modifier.clickable { noteOpen = !noteOpen },
+                    subtitle = "The Android version and phone model go only when they change, and once a month",
+                    icon = Icons.Filled.Info,
+                    trailing = {
+                        Icon(
+                            if (noteOpen) Icons.Filled.KeyboardArrowUp else Icons.Filled.KeyboardArrowDown,
+                            contentDescription = if (noteOpen) "Hide the note" else "Show the note",
+                            tint = MaterialTheme.colorScheme.onSurfaceVariant,
+                        )
+                    },
+                )
+                AnimatedVisibility(noteOpen) {
+                    // Rebuilt from the saved choices each time one changes, so it always matches.
+                    val note = remember(choices) { UsageStats.preview(context, everything = true).toString(2) }
+                    Surface(
+                        color = MaterialTheme.colorScheme.surfaceContainerLowest,
+                        shape = MaterialTheme.shapes.medium,
+                        modifier = Modifier.fillMaxWidth().padding(start = 16.dp, end = 16.dp, bottom = 16.dp),
+                    ) {
+                        Text(
+                            note,
+                            style = MaterialTheme.typography.bodySmall,
+                            fontFamily = FontFamily.Monospace,
+                            modifier = Modifier.padding(12.dp),
+                        )
+                    }
+                }
+            }
+        }
+    }
+}
+
+/** A share choice: the label lines up with the rows' titles, the checkbox sits at the end. */
+@Composable
+private fun Choice(label: String, checked: Boolean, onChange: (Boolean) -> Unit) {
+    Row(
+        Modifier.fillMaxWidth().toggleable(checked, role = Role.Checkbox, onValueChange = onChange)
+            .padding(start = 56.dp, end = 16.dp, top = 4.dp, bottom = 4.dp),
+        verticalAlignment = Alignment.CenterVertically,
+    ) {
+        Text(label, style = MaterialTheme.typography.bodyLarge, modifier = Modifier.weight(1f).padding(end = 12.dp))
+        Checkbox(checked = checked, onCheckedChange = null, modifier = Modifier.padding(vertical = 8.dp))
+    }
+}