Fix background timer: native AlarmManager schedules phase alarms, service plays audio independently of Dart isolate

utsapoddar · utsapoddar · commit 02f1dee9c0ff · 2026-03-25T14:35:40.000+06:00
diff --git a/work_timer/android/app/src/main/AndroidManifest.xml b/work_timer/android/app/src/main/AndroidManifest.xml
@@ -3,6 +3,9 @@
     <uses-permission android:name="android.permission.POST_NOTIFICATIONS"/>
     <uses-permission android:name="android.permission.FOREGROUND_SERVICE"/>
     <uses-permission android:name="android.permission.FOREGROUND_SERVICE_SPECIAL_USE"/>
+    <uses-permission android:name="android.permission.WAKE_LOCK"/>
+    <uses-permission android:name="android.permission.SCHEDULE_EXACT_ALARM" android:maxSdkVersion="32"/>
+    <uses-permission android:name="android.permission.USE_EXACT_ALARM"/>
     <application
         android:label="Sift"
         android:name="${applicationName}"
@@ -37,6 +40,9 @@
                 android:name="android.app.PROPERTY_SPECIAL_USE_FGS_SUBTYPE"
                 android:value="This foreground service keeps the work session timer running so the alarm can ring at each phase boundary even when the app is in the background."/>
         </service>
+        <receiver
+            android:name=".AlarmReceiver"
+            android:exported="false"/>
         <!-- Don't delete the meta-data below.
              This is used by the Flutter tool to generate GeneratedPluginRegistrant.java -->
         <meta-data
diff --git a/work_timer/android/app/src/main/kotlin/com/utsapoddar/sift/AlarmReceiver.kt b/work_timer/android/app/src/main/kotlin/com/utsapoddar/sift/AlarmReceiver.kt
@@ -0,0 +1,20 @@
+package com.utsapoddar.sift
+
+import android.content.BroadcastReceiver
+import android.content.Context
+import android.content.Intent
+import android.os.Build
+
+class AlarmReceiver : BroadcastReceiver() {
+    override fun onReceive(context: Context, intent: Intent) {
+        val serviceIntent = Intent(context, TimerService::class.java).apply {
+            action = TimerService.ACTION_ALARM_FIRED
+            putExtra(TimerService.EXTRA_PHASE_NAME, intent.getStringExtra(TimerService.EXTRA_PHASE_NAME) ?: "")
+        }
+        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {
+            context.startForegroundService(serviceIntent)
+        } else {
+            context.startService(serviceIntent)
+        }
+    }
+}
diff --git a/work_timer/android/app/src/main/kotlin/com/utsapoddar/sift/MainActivity.kt b/work_timer/android/app/src/main/kotlin/com/utsapoddar/sift/MainActivity.kt
@@ -23,6 +23,7 @@ class MainActivity : FlutterActivity() {
             val action = when (intent.action) {
                 TimerService.ACTION_STOP -> "stop"
                 TimerService.ACTION_SILENCE -> "silence"
+                "com.sift.timer.alarm_notify" -> "alarm"
                 else -> return
             }
             runOnUiThread {
@@ -38,7 +39,18 @@ class MainActivity : FlutterActivity() {
         ch.setMethodCallHandler { call, result ->
             when (call.method) {
                 "startTimerService" -> {
-                    val intent = Intent(this, TimerService::class.java)
+                    @Suppress("UNCHECKED_CAST")
+                    val args = call.arguments as? Map<String, Any> ?: emptyMap<String, Any>()
+                    val phaseNames = (args["phaseNames"] as? List<*>)
+                        ?.filterIsInstance<String>()?.toTypedArray() ?: emptyArray()
+                    val phaseEndTimes = (args["phaseEndTimes"] as? List<*>)
+                        ?.map { (it as Number).toLong() }?.toLongArray() ?: LongArray(0)
+
+                    val intent = Intent(this, TimerService::class.java).apply {
+                        action = TimerService.ACTION_SCHEDULE_ALARMS
+                        putExtra(TimerService.EXTRA_PHASE_NAMES, phaseNames)
+                        putExtra(TimerService.EXTRA_PHASE_END_TIMES, phaseEndTimes)
+                    }
                     if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {
                         startForegroundService(intent)
                     } else {
@@ -47,7 +59,10 @@ class MainActivity : FlutterActivity() {
                     result.success(null)
                 }
                 "stopTimerService" -> {
-                    stopService(Intent(this, TimerService::class.java))
+                    val intent = Intent(this, TimerService::class.java).apply {
+                        action = TimerService.ACTION_CANCEL_ALARMS
+                    }
+                    startService(intent)
                     result.success(null)
                 }
                 else -> result.notImplemented()
@@ -57,7 +72,7 @@ class MainActivity : FlutterActivity() {
 
     override fun onCreate(savedInstanceState: Bundle?) {
         super.onCreate(savedInstanceState)
-        // Request notification permission on launch so it's settled before the timer starts
+        // Request notification permission on launch so it's settled before timer starts
         if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.TIRAMISU &&
             ContextCompat.checkSelfPermission(this, Manifest.permission.POST_NOTIFICATIONS)
                 != PackageManager.PERMISSION_GRANTED) {
@@ -67,6 +82,7 @@ class MainActivity : FlutterActivity() {
         val filter = IntentFilter().apply {
             addAction(TimerService.ACTION_STOP)
             addAction(TimerService.ACTION_SILENCE)
+            addAction("com.sift.timer.alarm_notify")
         }
         if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.TIRAMISU) {
             registerReceiver(actionReceiver, filter, RECEIVER_NOT_EXPORTED)
diff --git a/work_timer/android/app/src/main/kotlin/com/utsapoddar/sift/TimerService.kt b/work_timer/android/app/src/main/kotlin/com/utsapoddar/sift/TimerService.kt
@@ -1,5 +1,6 @@
 package com.utsapoddar.sift
 
+import android.app.AlarmManager
 import android.app.Notification
 import android.app.NotificationChannel
 import android.app.NotificationManager
@@ -8,9 +9,13 @@ import android.app.Service
 import android.content.Context
 import android.content.Intent
 import android.content.pm.ServiceInfo
+import android.media.AudioAttributes
+import android.media.MediaPlayer
+import android.net.Uri
 import android.os.Build
 import android.os.IBinder
 import androidx.core.app.NotificationCompat
+import java.io.File
 
 class TimerService : Service() {
 
@@ -19,8 +24,17 @@ class TimerService : Service() {
         const val NOTIF_ID = 42
         const val ACTION_STOP = "com.sift.timer.stop"
         const val ACTION_SILENCE = "com.sift.timer.silence"
+        const val ACTION_ALARM_FIRED = "com.sift.timer.alarm_fired"
+        const val ACTION_SCHEDULE_ALARMS = "com.sift.timer.schedule_alarms"
+        const val ACTION_CANCEL_ALARMS = "com.sift.timer.cancel_alarms"
+        const val EXTRA_PHASE_NAMES = "phase_names"
+        const val EXTRA_PHASE_END_TIMES = "phase_end_times"
+        const val EXTRA_PHASE_NAME = "phase_name"
     }
 
+    private var mediaPlayer: MediaPlayer? = null
+    private var currentPhaseName: String = "Work"
+
     override fun onBind(intent: Intent?): IBinder? = null
 
     override fun onCreate() {
@@ -34,11 +48,35 @@ class TimerService : Service() {
     }
 
     override fun onStartCommand(intent: Intent?, flags: Int, startId: Int): Int {
+        when (intent?.action) {
+            ACTION_ALARM_FIRED -> {
+                currentPhaseName = intent.getStringExtra(EXTRA_PHASE_NAME) ?: currentPhaseName
+                updateNotification()
+                playAlarm()
+                // Notify Flutter if it's alive
+                sendBroadcast(Intent(ACTION_STOP).setPackage(packageName).apply {
+                    action = "com.sift.timer.alarm_notify"
+                })
+            }
+            ACTION_SCHEDULE_ALARMS -> {
+                val names = intent.getStringArrayExtra(EXTRA_PHASE_NAMES) ?: return START_STICKY
+                val times = intent.getLongArrayExtra(EXTRA_PHASE_END_TIMES) ?: return START_STICKY
+                currentPhaseName = if (names.isNotEmpty()) names[0] else "Work"
+                updateNotification()
+                scheduleAlarms(names, times)
+            }
+            ACTION_CANCEL_ALARMS -> {
+                cancelAlarms()
+                stopAlarmSound()
+                stopSelf()
+            }
+        }
         return START_STICKY
     }
 
     override fun onDestroy() {
         super.onDestroy()
+        stopAlarmSound()
         if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.N) {
             stopForeground(STOP_FOREGROUND_REMOVE)
         } else {
@@ -47,6 +85,79 @@ class TimerService : Service() {
         }
     }
 
+    private fun scheduleAlarms(names: Array<String>, times: LongArray) {
+        val alarmManager = getSystemService(Context.ALARM_SERVICE) as AlarmManager
+        times.forEachIndexed { i, timeMs ->
+            val alarmIntent = Intent(this, AlarmReceiver::class.java).apply {
+                putExtra(EXTRA_PHASE_NAME, if (i + 1 < names.size) names[i + 1] else "Done")
+            }
+            val pi = PendingIntent.getBroadcast(
+                this, i, alarmIntent,
+                PendingIntent.FLAG_IMMUTABLE or PendingIntent.FLAG_UPDATE_CURRENT
+            )
+            if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.M) {
+                alarmManager.setExactAndAllowWhileIdle(AlarmManager.RTC_WAKEUP, timeMs, pi)
+            } else {
+                alarmManager.setExact(AlarmManager.RTC_WAKEUP, timeMs, pi)
+            }
+        }
+    }
+
+    private fun cancelAlarms() {
+        val alarmManager = getSystemService(Context.ALARM_SERVICE) as AlarmManager
+        for (i in 0..6) {
+            val pi = PendingIntent.getBroadcast(
+                this, i, Intent(this, AlarmReceiver::class.java),
+                PendingIntent.FLAG_IMMUTABLE or PendingIntent.FLAG_NO_CREATE
+            )
+            pi?.let { alarmManager.cancel(it) }
+        }
+    }
+
+    private fun playAlarm() {
+        stopAlarmSound()
+        val prefs = getSharedPreferences("FlutterSharedPreferences", Context.MODE_PRIVATE)
+        val ringtonePath = prefs.getString("flutter.ringtone_path", null)
+
+        try {
+            mediaPlayer = if (ringtonePath != null && File(ringtonePath).exists()) {
+                MediaPlayer().apply {
+                    setAudioAttributes(AudioAttributes.Builder()
+                        .setUsage(AudioAttributes.USAGE_ALARM)
+                        .setContentType(AudioAttributes.CONTENT_TYPE_SONIFICATION)
+                        .build())
+                    setDataSource(ringtonePath)
+                    prepare()
+                }
+            } else {
+                val afd = assets.openFd("flutter_assets/assets/alarm.mp3")
+                MediaPlayer().apply {
+                    setAudioAttributes(AudioAttributes.Builder()
+                        .setUsage(AudioAttributes.USAGE_ALARM)
+                        .setContentType(AudioAttributes.CONTENT_TYPE_SONIFICATION)
+                        .build())
+                    setDataSource(afd.fileDescriptor, afd.startOffset, afd.length)
+                    prepare()
+                }
+            }
+            mediaPlayer?.apply {
+                isLooping = false
+                setOnCompletionListener { mp -> mp.release(); mediaPlayer = null }
+                start()
+            }
+        } catch (_: Exception) {}
+    }
+
+    private fun stopAlarmSound() {
+        mediaPlayer?.apply { if (isPlaying) stop(); release() }
+        mediaPlayer = null
+    }
+
+    private fun updateNotification() {
+        val nm = getSystemService(Context.NOTIFICATION_SERVICE) as NotificationManager
+        nm.notify(NOTIF_ID, buildNotification())
+    }
+
     private fun buildNotification(): Notification {
         val stopIntent = Intent(ACTION_STOP).setPackage(packageName)
         val stopPi = PendingIntent.getBroadcast(
@@ -59,7 +170,7 @@ class TimerService : Service() {
             PendingIntent.FLAG_IMMUTABLE or PendingIntent.FLAG_UPDATE_CURRENT
         )
         return NotificationCompat.Builder(this, CHANNEL_ID)
-            .setContentTitle("Sift")
+            .setContentTitle("Sift — $currentPhaseName")
             .setContentText("Timer running")
             .setSmallIcon(R.drawable.ic_notification)
             .setOngoing(true)
@@ -70,12 +181,8 @@ class TimerService : Service() {
 
     private fun createChannel() {
         val channel = NotificationChannel(
-            CHANNEL_ID,
-            "Timer Service",
-            NotificationManager.IMPORTANCE_LOW
-        ).apply {
-            description = "Keeps timer running in background"
-        }
+            CHANNEL_ID, "Timer Service", NotificationManager.IMPORTANCE_LOW
+        ).apply { description = "Keeps timer running in background" }
         val nm = getSystemService(Context.NOTIFICATION_SERVICE) as NotificationManager
         nm.createNotificationChannel(channel)
     }
diff --git a/work_timer/lib/screens/home_screen.dart b/work_timer/lib/screens/home_screen.dart
@@ -72,6 +72,8 @@ class _HomeScreenState extends State<HomeScreen>
             _stop();
           } else if (action == 'silence') {
             _stopAlarm();
+          } else if (action == 'alarm') {
+            _tick(); // sync UI with current phase
           }
         }
       });
@@ -315,7 +317,10 @@ class _HomeScreenState extends State<HomeScreen>
     _ticker = Timer.periodic(const Duration(seconds: 1), (_) => _tick());
     _tick();
     unawaited(startTimerAudio());
-    unawaited(startTimerService());
+    unawaited(startTimerService(
+      phaseNames: schedule.phases.map((p) => p.phase.name).toList(),
+      phaseEndTimes: schedule.phases.map((p) => p.endTime).toList(),
+    ));
     final phase = schedule.phases.first;
     final laErr = await startLiveActivity(
       phaseName: phase.phase.name,
diff --git a/work_timer/lib/services/live_activity.dart b/work_timer/lib/services/live_activity.dart
@@ -70,10 +70,18 @@ Future<void> stopTimerAudio() async {
   try { await _channel.invokeMethod('stopTimerAudio'); } catch (_) {}
 }
 
-/// Start Android foreground service — keeps process alive so alarm fires even on silent.
-Future<void> startTimerService() async {
+/// Start Android foreground service and schedule exact alarms at each phase boundary.
+Future<void> startTimerService({
+  required List<String> phaseNames,
+  required List<DateTime> phaseEndTimes,
+}) async {
   if (!Platform.isAndroid) return;
-  try { await _channel.invokeMethod('startTimerService'); } catch (_) {}
+  try {
+    await _channel.invokeMethod('startTimerService', {
+      'phaseNames': phaseNames,
+      'phaseEndTimes': phaseEndTimes.map((t) => t.millisecondsSinceEpoch).toList(),
+    });
+  } catch (_) {}
 }
 
 /// Stop the Android foreground service.
