Show notification when Syncthing has alerts

app/src/main/java/com/chiller3/basicsync/Notifications.kt

@@ -26,12 +26,14 @@ class Notifications(private val context: Context) {
         private const val CHANNEL_ID_PERSISTENT = "persistent"
         private const val CHANNEL_ID_FAILURE = "failure"
         private const val CHANNEL_ID_CONFLICTS = "conflicts"
+        private const val CHANNEL_ID_ALERTS = "alerts"
 
         private val LEGACY_CHANNEL_IDS = arrayOf<String>()
 
         const val ID_PERSISTENT = -1
         private const val ID_FAILURE = -2
         private const val ID_CONFLICTS = -3
+        private const val ID_ALERTS = -4
     }
 
     private val notificationManager = context.getSystemService(NotificationManager::class.java)
@@ -62,6 +64,14 @@ class Notifications(private val context: Context) {
         description = context.getString(R.string.notification_channel_conflicts_desc)
     }
 
+    private fun createSyncthingAlertsChannel() = NotificationChannel(
+        CHANNEL_ID_ALERTS,
+        context.getString(R.string.notification_channel_alerts_name),
+        NotificationManager.IMPORTANCE_HIGH,
+    ).apply {
+        description = context.getString(R.string.notification_channel_alerts_desc)
+    }
+
     /**
      * Ensure notification channels are up-to-date.
      *
@@ -72,6 +82,7 @@ class Notifications(private val context: Context) {
             createPersistentChannel(),
             createFailureAlertsChannel(),
             createConflictsAlertsChannel(),
+            createSyncthingAlertsChannel(),
         ))
         LEGACY_CHANNEL_IDS.forEach { notificationManager.deleteNotificationChannel(it) }
     }
@@ -240,4 +251,36 @@ class Notifications(private val context: Context) {
 
         notificationManager.notify(ID_CONFLICTS, notification)
     }
+
+    fun sendOrClearAlertsNotification(alertCount: Int) {
+        if (alertCount == 0) {
+            notificationManager.cancel(ID_ALERTS)
+            return
+        }
+
+        val notification = Notification.Builder(context, CHANNEL_ID_ALERTS).run {
+            setContentTitle(context.resources.getQuantityString(
+                R.plurals.notification_syncthing_alerts_title,
+                alertCount,
+                alertCount,
+            ))
+            setSmallIcon(R.drawable.ic_notifications)
+            setOnlyAlertOnce(true)
+
+            val intent = Intent(context, WebUiActivity::class.java).apply {
+                addFlags(Intent.FLAG_ACTIVITY_SINGLE_TOP or Intent.FLAG_ACTIVITY_CLEAR_TOP)
+            }
+            val pendingIntent = PendingIntent.getActivity(
+                context,
+                0,
+                intent,
+                PendingIntent.FLAG_IMMUTABLE or PendingIntent.FLAG_UPDATE_CURRENT,
+            )
+            setContentIntent(pendingIntent)
+
+            build()
+        }
+
+        notificationManager.notify(ID_ALERTS, notification)
+    }
 }

app/src/main/java/com/chiller3/basicsync/syncthing/SyncthingService.kt

@@ -228,6 +228,15 @@ class SyncthingService : Service(), SyncthingStatusReceiver, DeviceStateListener
                 notifications.sendOrClearConflictsNotification(conflicts)
             }
         }
+    @GuardedBy("stateLock")
+    private var syncthingAlerts = 0
+        set(count) {
+            if (field != count) {
+                field = count
+
+                notifications.sendOrClearAlertsNotification(count)
+            }
+        }
 
     private val isResumed: Boolean
         @GuardedBy("stateLock")
@@ -577,6 +586,7 @@ class SyncthingService : Service(), SyncthingStatusReceiver, DeviceStateListener
             deviceStateTracker.updateConnectedDevices(0)
 
             syncthingConflicts = emptyList()
+            syncthingAlerts = 0
             syncthingApp = null
 
             stateChanged()
@@ -599,6 +609,13 @@ class SyncthingService : Service(), SyncthingStatusReceiver, DeviceStateListener
         }
     }
 
+    @WorkerThread
+    override fun onAlertsUpdated(count: Int) {
+        synchronized(stateLock) {
+            syncthingAlerts = count
+        }
+    }
+
     @WorkerThread
     override fun onBusyFoldersUpdated(count: Int) {
         deviceStateTracker.updateBusyFolders(count)

app/src/main/res/values/strings.xml

@@ -226,6 +226,10 @@
     <string name="notification_channel_conflicts_name">Sync conflicts</string>
     <!-- Description of the Android notification channel for notifications about sync conflicts. -->
     <string name="notification_channel_conflicts_desc">Alerts for conflicts encountered during syncing</string>
+    <!-- Name of the Android notification channel for Syncthing's in-app alerts. -->
+    <string name="notification_channel_alerts_name">Syncthing alerts</string>
+    <!-- Description of the Android notification channel for Syncthing's in-app alerts. -->
+    <string name="notification_channel_alerts_desc">Device/folder requests and other alerts reported by Syncthing</string>
     <!-- Status text indicating that Syncthing is running and ready to sync. -->
     <string name="notification_persistent_running_title">Syncthing is running</string>
     <!-- Status text indicating that Syncthing is not running at all (not just paused). -->
@@ -251,6 +255,11 @@
         <item quantity="one">%d sync conflict found</item>
         <item quantity="other">%d sync conflicts found</item>
     </plurals>
+    <!-- Title of the notification shown when Syncthing sends an in-app alert. -->
+    <plurals name="notification_syncthing_alerts_title">
+        <item quantity="one">%d Syncthing alert</item>
+        <item quantity="other">%d Syncthing alerts</item>
+    </plurals>
     <!-- Button shown in the persistent notification to switch from manual mode to auto mode. -->
     <string name="notification_action_auto_mode">Auto mode</string>
     <!-- Button shown in the persistent notification to switch from auto mode to manual mode. -->