Use default distributor when selecting Instant for the first time

apps/multiplatform/android/src/main/java/chat/simplex/app/SimplexApp.kt

@@ -240,7 +240,14 @@ class SimplexApp: Application(), LifecycleEventObserver {
         }
         if (mode == NotificationsMode.INSTANT) {
           CoroutineScope(Dispatchers.Default).launch {
-            SimplexService.initUnifiedPush(this) {
+            /**
+             * If the user re-selects INSTANT, then we don't use default distributor - so it's possible to use
+             * a non-default distrib
+             */
+            val activity = if (chatModel.controller.appPrefs.notificationsMode.get() != NotificationsMode.INSTANT) {
+              mainActivity.get()
+            } else null
+            SimplexService.initUnifiedPush(activity, this) {
               // Change notifications mode only if everything is correctly setup
               chatModel.controller.appPrefs.notificationsMode.set(mode)
             }

apps/multiplatform/android/src/main/java/chat/simplex/app/SimplexService.kt

@@ -428,8 +428,11 @@ class SimplexService: Service() {
 
     private fun getPreferences(context: Context): SharedPreferences = context.getSharedPreferences(SHARED_PREFS_ID, Context.MODE_PRIVATE)
 
-    suspend fun initUnifiedPush(scope: CoroutineScope, onSuccess: () -> Unit) {
-      PushManager.initUnifiedPush(androidAppContext, scope, onSuccess)
+    /**
+     * @param activity if not null, try default distrib
+     */
+    suspend fun initUnifiedPush(activity: Activity?, scope: CoroutineScope, onSuccess: () -> Unit) {
+      PushManager.initUnifiedPush(androidAppContext, activity, scope, onSuccess)
     }
 
     fun showBackgroundServiceNoticeIfNeeded(showOffAlert: Boolean = true) {

apps/multiplatform/android/src/main/java/chat/simplex/app/platform/PushManager.kt

@@ -1,6 +1,7 @@
 package chat.simplex.app.platform
 
 import SectionItemView
+import android.app.Activity
 import android.content.Context
 import android.content.pm.PackageManager
 import android.os.Build
@@ -36,13 +37,28 @@ object PushManager {
    * If a single distrib is available, use it
    * If many, ask distributor to use with a dialog
    * Else alert about missing service
+   *
+   * @param activity if not null: try to use default distrib
    */
-  suspend fun initUnifiedPush(context: Context, scope: CoroutineScope, onSuccess: () -> Unit) {
+  suspend fun initUnifiedPush(context: Context, activity: Activity?, scope: CoroutineScope, onSuccess: () -> Unit) {
     val vapid = getVapidKey(scope)
       ?: run {
         Log.w(TAG, "Tried to init UnifiedPush but couldn't find VAPID key")
         return
       }
+    activity?.let {
+      UnifiedPush.tryUseDefaultDistributor(activity) { success ->
+        if (success) {
+          register(context, vapid)
+          onSuccess()
+        } else {
+          initUnifiedPushWithDialogs(context, vapid, onSuccess)
+        }
+      }
+    } ?: initUnifiedPushWithDialogs(context, vapid, onSuccess)
+  }
+
+  private fun initUnifiedPushWithDialogs(context: Context, vapid: String, onSuccess: () -> Unit) {
     val distributors = UnifiedPush.getDistributors(context)
     when (distributors.size) {
       0 -> {