Proper conditions for push reregistration. Added fix for app compat crash on resume from sleep while app was open.

src/Android/MainActivity.cs

@@ -1,5 +1,4 @@
 using System;
-
 using Android.App;
 using Android.Content.PM;
 using Android.Views;
@@ -10,28 +9,33 @@ using Plugin.Fingerprint.Abstractions;
 using Plugin.Settings.Abstractions;
 using Plugin.Connectivity.Abstractions;
 using Acr.UserDialogs;
-using PushNotification.Plugin.Abstractions;
 using Android.Content;
 using System.Reflection;
 using Xamarin.Forms.Platform.Android;
 using Xamarin.Forms;
+using System.Threading.Tasks;
 
 namespace Bit.Android
 {
     [Activity(Label = "bitwarden",
-        Icon = "@drawable/icon", 
+        Icon = "@drawable/icon",
         ConfigurationChanges = ConfigChanges.ScreenSize | ConfigChanges.Orientation,
         WindowSoftInputMode = SoftInput.StateHidden)]
     public class MainActivity : FormsAppCompatActivity
     {
         private const string HockeyAppId = "d3834185b4a643479047b86c65293d42";
 
-        protected override void OnCreate(Bundle bundle)
+        protected async override void OnCreate(Bundle bundle)
         {
             ToolbarResource = Resource.Layout.toolbar;
             TabLayoutResource = Resource.Layout.tabs;
 
             base.OnCreate(bundle);
+
+            // workaround for app compat bug
+            // ref https://forums.xamarin.com/discussion/62414/app-resuming-results-in-crash-with-formsappcompatactivity
+            await Task.Delay(10);
+
             Console.WriteLine("A OnCreate");
             Window.SetSoftInputMode(SoftInput.StateHidden);
             Window.AddFlags(WindowManagerFlags.Secure);
@@ -59,8 +63,7 @@ namespace Bit.Android
                 Resolver.Resolve<ILockService>(),
                 Resolver.Resolve<IGoogleAnalyticsService>()));
 
-            Xamarin.Forms.MessagingCenter.Subscribe<Xamarin.Forms.Application>(
-                Xamarin.Forms.Application.Current, "RateApp", (sender) =>
+            MessagingCenter.Subscribe<Xamarin.Forms.Application>(Xamarin.Forms.Application.Current, "RateApp", (sender) =>
             {
                 RateApp();
             });

src/Android/MainApplication.cs

@@ -17,16 +17,21 @@ using PushNotification.Plugin;
 using PushNotification.Plugin.Abstractions;
 using XLabs.Ioc;
 using XLabs.Ioc.Unity;
+using System.Threading.Tasks;
+using Plugin.Settings.Abstractions;
 
 namespace Bit.Android
 {
 #if DEBUG
     [Application(Debuggable = true)]
 #else
-    [Application(Debuggable=false)]
+    [Application(Debuggable = false)]
 #endif
     public class MainApplication : Application, Application.IActivityLifecycleCallbacks
     {
+        private const string FirstLaunchKey = "firstLaunch";
+        private const string LastVersionCodeKey = "lastVersionCode";
+
         public static Context AppContext;
 
         public MainApplication(IntPtr handle, JniHandleOwnership transer)
@@ -38,23 +43,76 @@ namespace Bit.Android
             }
         }
 
-        public override void OnCreate()
+        public async override void OnCreate()
         {
             base.OnCreate();
+
+            // workaround for app compat bug
+            // ref https://forums.xamarin.com/discussion/62414/app-resuming-results-in-crash-with-formsappcompatactivity
+            await Task.Delay(10);
+
             RegisterActivityLifecycleCallbacks(this);
             AppContext = ApplicationContext;
             StartPushService();
+            HandlePushReregistration();
+        }
 
+        private void HandlePushReregistration()
+        {
             var pushNotification = Resolver.Resolve<IPushNotification>();
-            // Must unregister the previous instance first or else things wont work
+            var settings = Resolver.Resolve<ISettings>();
+
+            // Reregister for push token based on certain conditions
             // ref https://github.com/rdelrosario/xamarin-plugins/issues/65
-            if(Resolver.Resolve<IAuthService>().IsAuthenticated)
+
+            var reregister = false;
+
+            // 1. First time starting the app after a new install
+            if(settings.GetValueOrDefault(FirstLaunchKey, true))
+            {
+                settings.AddOrUpdateValue(FirstLaunchKey, false);
+                reregister = true;
+            }
+
+            // 2. App version changed (installed update)
+            var versionCode = Context.ApplicationContext.PackageManager.GetPackageInfo(Context.PackageName, 0).VersionCode;
+            if(settings.GetValueOrDefault(LastVersionCodeKey, -1) != versionCode)
+            {
+                settings.AddOrUpdateValue(LastVersionCodeKey, versionCode);
+                reregister = true;
+            }
+
+            // 3. In debug mode
+            if(InDebugMode())
+            {
+                reregister = true;
+            }
+
+            // 4. Doesn't have a push token currently
+            if(string.IsNullOrWhiteSpace(pushNotification.Token))
+            {
+                reregister = true;
+            }
+
+            if(reregister)
             {
                 pushNotification.Unregister();
-                pushNotification.Register();
+                if(Resolver.Resolve<IAuthService>().IsAuthenticated)
+                {
+                    pushNotification.Register();
+                }
             }
         }
 
+        private bool InDebugMode()
+        {
+#if DEBUG
+            return true;
+#else
+            return false;
+#endif
+        }
+
         public override void OnTerminate()
         {
             base.OnTerminate();

src/Android/Services/AppInfoService.cs

@@ -1,14 +1,14 @@
 using Bit.App.Abstractions;
-using AndrodApp = Android.App.Application;
+using AndroidApp = Android.App.Application;
 
 namespace Bit.Android.Services
 {
     public class AppInfoService : IAppInfoService
     {
-        public string Version => AndrodApp.Context.ApplicationContext.PackageManager
-            .GetPackageInfo(AndrodApp.Context.PackageName, 0).VersionName;
+        public string Version => AndroidApp.Context.ApplicationContext.PackageManager
+            .GetPackageInfo(AndroidApp.Context.PackageName, 0).VersionName;
 
-        public string Build => AndrodApp.Context.ApplicationContext.PackageManager
-            .GetPackageInfo(AndrodApp.Context.PackageName, 0).VersionCode.ToString();
+        public string Build => AndroidApp.Context.ApplicationContext.PackageManager
+            .GetPackageInfo(AndroidApp.Context.PackageName, 0).VersionCode.ToString();
     }
 }

src/App/App.cs

@@ -102,6 +102,12 @@ namespace Bit.App
 
         protected async override void OnResume()
         {
+            base.OnResume();
+
+            // workaround for app compat bug
+            // ref https://forums.xamarin.com/discussion/62414/app-resuming-results-in-crash-with-formsappcompatactivity
+            await Task.Delay(10);
+
             // Handle when your app resumes
             Debug.WriteLine("OnResume");
 

src/App/Pages/LoginPage.cs

@@ -205,7 +205,6 @@ namespace Bit.App.Pages
 
             if(Device.OS == TargetPlatform.Android)
             {
-                _pushNotification.Unregister();
                 _pushNotification.Register();
             }