Utilise TokenManager and ExpiryManager

app/src/main/java/org/thoughtcrime/securesms/ApplicationContext.java

@@ -508,7 +508,6 @@ public class ApplicationContext extends Application implements DefaultLifecycleO
     }
 
     public void clearAllData(boolean isMigratingToV2KeyPair) {
-        PushNotificationAPI.unregister();
         if (firebaseInstanceIdJob != null && firebaseInstanceIdJob.isActive()) {
             firebaseInstanceIdJob.cancel(null);
         }

app/src/main/java/org/thoughtcrime/securesms/notifications/FcmTokenManager.kt

@@ -0,0 +1,26 @@
+package org.thoughtcrime.securesms.notifications
+
+import android.content.Context
+import org.session.libsession.utilities.TextSecurePreferences
+
+class FcmTokenManager(
+    private val context: Context,
+    private val expiryManager: ExpiryManager
+) {
+    val isUsingFCM get() = TextSecurePreferences.isUsingFCM(context)
+
+    var fcmToken
+        get() = TextSecurePreferences.getFCMToken(context)
+        set(value) {
+            TextSecurePreferences.setFCMToken(context, value)
+            if (value != null) markTime() else clearTime()
+        }
+
+    val requiresUnregister get() = fcmToken != null
+
+    private fun clearTime() = expiryManager.clearTime()
+    private fun markTime() = expiryManager.markTime()
+    private fun isExpired() = expiryManager.isExpired()
+
+    fun isInvalid(): Boolean = fcmToken == null || isExpired()
+}