From bf4dbf384a99f62df3144690e6aa0307b652d39f Mon Sep 17 00:00:00 2001
From: laurencee <laurence.evanz@gmail.com>
Date: Wed, 3 Aug 2016 21:14:49 +1000
Subject: [PATCH] Refactor refresh timer event hooking to occur during
 activation/deactivation of the livestream list screen.

Attempt to only process errors from refreshes when the screen is active.
---
 GlobalAssemblyInfo.cs                         |  4 +-
 Livestream.Monitor/Core/Extensions.cs         |  7 ++-
 .../ViewModels/LivestreamListViewModel.cs     | 43 +++++++++++--------
 3 files changed, 32 insertions(+), 22 deletions(-)

diff --git a/GlobalAssemblyInfo.cs b/GlobalAssemblyInfo.cs
index e30d306..627fb4e 100644
--- a/GlobalAssemblyInfo.cs
+++ b/GlobalAssemblyInfo.cs
@@ -22,5 +22,5 @@
 // by using the '*' as shown below:
 // [assembly: AssemblyVersion("1.0.*")]
 
-[assembly: AssemblyVersion("2.5.1.0")]
-[assembly: AssemblyFileVersion("2.5.1.0")]
\ No newline at end of file
+[assembly: AssemblyVersion("2.5.2.0")]
+[assembly: AssemblyFileVersion("2.5.2.0")]
\ No newline at end of file
diff --git a/Livestream.Monitor/Core/Extensions.cs b/Livestream.Monitor/Core/Extensions.cs
index 0e6111a..3430aa6 100644
--- a/Livestream.Monitor/Core/Extensions.cs
+++ b/Livestream.Monitor/Core/Extensions.cs
@@ -8,7 +8,6 @@
 using Caliburn.Micro;
 using Livestream.Monitor.Model;
 using Livestream.Monitor.Model.ApiClients;
-using Livestream.Monitor.Model.Monitoring;
 using MahApps.Metro.Controls;
 using MahApps.Metro.Controls.Dialogs;
 
@@ -189,6 +188,12 @@ public static string ExtractErrorMessage(this Exception exception, int skipExcep
         {
             if (exception == null) return null;
 
+            var aggregateException = exception as AggregateException;
+            if (aggregateException != null)
+            {
+                exception = aggregateException.Flatten();
+            }
+
             // Avoiding large recursion... just in case
             int count = 0;
 
diff --git a/Livestream.Monitor/ViewModels/LivestreamListViewModel.cs b/Livestream.Monitor/ViewModels/LivestreamListViewModel.cs
index 43e76f4..7ee9b5f 100644
--- a/Livestream.Monitor/ViewModels/LivestreamListViewModel.cs
+++ b/Livestream.Monitor/ViewModels/LivestreamListViewModel.cs
@@ -23,7 +23,8 @@ public class LivestreamListViewModel : Screen, IHandleWithTask<ExceptionDispatch
         private readonly INavigationService navigationService;
         private readonly DispatcherTimer refreshTimer;
 
-        private bool loading, displayingException;
+        private bool loading;
+        private int refreshErrorCount = 0;
         private LivestreamsLayoutMode layoutModeMode = LivestreamsLayoutMode.Grid;
 
         public LivestreamListViewModel()
@@ -50,7 +51,6 @@ public LivestreamListViewModel(
             this.StreamsModel = monitorStreamsModel;
             FilterModel = filterModel;
             refreshTimer = new DispatcherTimer { Interval = Constants.RefreshPollingTime };
-            refreshTimer.Tick += async (sender, args) => await RefreshLivestreams();
         }
 
         public bool Loading
@@ -85,33 +85,30 @@ public async Task RefreshLivestreams()
             try
             {
                 await StreamsModel.RefreshLivestreams();
-            }
-            catch (AggregateException ex)
-            {
-                if (!displayingException)
-                {
-                    Execute.OnUIThread(async () =>
-                    {
-                        displayingException = true;
-                        await this.ShowMessageAsync("Error refreshing livestreams", ex.Flatten().ExtractErrorMessage());
-                        displayingException = false;
-                    });
-                }
+                refreshErrorCount = 0;
+
+                // only reactive the timer if we're still on this screen
+                if (IsActive) refreshTimer.Start();
             }
             catch (Exception ex)
             {
-                if (!displayingException)
+                if (!IsActive) return;
+                refreshErrorCount++;
+
+                // keep trying to refresh until we hit too many consecutive errors
+                if (refreshErrorCount >= 3)
                 {
                     Execute.OnUIThread(async () =>
                     {
-                        displayingException = true;
                         await this.ShowMessageAsync("Error refreshing livestreams", ex.ExtractErrorMessage());
-                        displayingException = false;
+                        refreshTimer.Start();
                     });
                 }
+                else
+                {
+                    refreshTimer.Start();
+                }
             }
-
-            refreshTimer.Start();
         }
 
         /// <summary> Loads the selected stream through livestreamer and displays a messagebox with the loading process details </summary>
@@ -190,6 +187,8 @@ protected override async void OnActivate()
             Loading = true;
             try
             {
+                refreshErrorCount = 0;
+                refreshTimer.Tick += RefreshTimerOnTick;
                 StreamsModel.LivestreamsRefreshComplete += OnLivestreamsRefreshComplete;
                 FilterModel.PropertyChanged += OnFilterModelOnPropertyChanged;
                 ViewSource.Source = StreamsModel.Livestreams;
@@ -221,6 +220,7 @@ protected override async void OnActivate()
 
         protected override void OnDeactivate(bool close)
         {
+            refreshTimer.Tick -= RefreshTimerOnTick;
             refreshTimer.Stop();
             StreamsModel.LivestreamsRefreshComplete -= OnLivestreamsRefreshComplete;
             FilterModel.PropertyChanged -= OnFilterModelOnPropertyChanged;
@@ -236,6 +236,11 @@ protected override void OnDeactivate(bool close)
             base.OnDeactivate(close);
         }
 
+        private async void RefreshTimerOnTick(object sender, EventArgs args)
+        {
+            await RefreshLivestreams();
+        }
+
         private void LivestreamsOnCollectionChanged(object sender, NotifyCollectionChangedEventArgs e)
         {
             if (e.NewItems != null)