From 011223048b129b213003083279a9f6793e930fb5 Mon Sep 17 00:00:00 2001
From: Aergwyn <aergwyn@t-online.de>
Date: Mon, 4 Dec 2017 11:47:27 +0100
Subject: [PATCH] fix crash if any amount of maps were restored from main menu

also fixes preview not playing if an entire set is restored
---
 osu.Game/Screens/Select/BeatmapCarousel.cs | 30 ++++++++++++++--------
 osu.Game/Screens/Select/SongSelect.cs      |  4 +--
 2 files changed, 21 insertions(+), 13 deletions(-)

diff --git a/osu.Game/Screens/Select/BeatmapCarousel.cs b/osu.Game/Screens/Select/BeatmapCarousel.cs
index 3f42ae11ac..47bfe6095f 100644
--- a/osu.Game/Screens/Select/BeatmapCarousel.cs
+++ b/osu.Game/Screens/Select/BeatmapCarousel.cs
@@ -34,7 +34,6 @@ namespace osu.Game.Screens.Select
         public IEnumerable<BeatmapSetInfo> Beatmaps
         {
             get { return groups.Select(g => g.BeatmapSet); }
-
             set
             {
                 scrollableContent.Clear(false);
@@ -44,15 +43,14 @@ namespace osu.Game.Screens.Select
                 List<BeatmapGroup> newGroups = null;
 
                 Task.Run(() =>
-                {
-                    newGroups = value.Select(createGroup).Where(g => g != null).ToList();
-                    criteria.Filter(newGroups);
-                }).ContinueWith(t =>
                 {
                     Schedule(() =>
                     {
+                        newGroups = value.Select(createGroup).Where(g => g != null).ToList();
+                        criteria.Filter(newGroups);
+
                         foreach (var g in newGroups)
-                            if (g != null) addGroup(g);
+                            addGroup(g);
 
                         computeYPositions();
                         BeatmapsChanged?.Invoke();
@@ -135,7 +133,7 @@ namespace osu.Game.Screens.Select
                 if (i >= 0)
                     groups.Insert(i, newGroup);
                 else
-                    groups.Add(newGroup);
+                    addGroup(newGroup);
             }
 
             bool hadSelection = selectedGroup == group;
@@ -149,8 +147,10 @@ namespace osu.Game.Screens.Select
             if (hadSelection && newGroup != null)
             {
                 var newSelection =
-                    newGroup.BeatmapPanels.Find(p => p.Beatmap.ID == selectedPanel?.Beatmap.ID) ??
-                    newGroup.BeatmapPanels[Math.Min(newGroup.BeatmapPanels.Count - 1, group.BeatmapPanels.IndexOf(selectedPanel))];
+                    newGroup.BeatmapPanels.Find(p => p.Beatmap.ID == selectedPanel?.Beatmap.ID);
+
+                if(newSelection == null && group != null && selectedPanel != null)
+                    newSelection = newGroup.BeatmapPanels[Math.Min(newGroup.BeatmapPanels.Count - 1, group.BeatmapPanels.IndexOf(selectedPanel))];
 
                 selectGroup(newGroup, newSelection);
             }
@@ -350,6 +350,8 @@ namespace osu.Game.Screens.Select
 
         private BeatmapGroup createGroup(BeatmapSetInfo beatmapSet)
         {
+            beatmapSet = manager.Refresh(beatmapSet);
+
             if (beatmapSet.Beatmaps.All(b => b.Hidden))
                 return null;
 
@@ -381,6 +383,10 @@ namespace osu.Game.Screens.Select
 
         private void addGroup(BeatmapGroup group)
         {
+            // prevent duplicates by concurrent independent actions trying to add a group
+            if (groups.Any(g => g.BeatmapSet.ID == group.BeatmapSet.ID))
+                return;
+
             groups.Add(group);
             panels.Add(group.Header);
             panels.AddRange(group.BeatmapPanels);
@@ -478,7 +484,8 @@ namespace osu.Game.Screens.Select
                 if (panel == null)
                     panel = group.BeatmapPanels.First();
 
-                if (selectedPanel == panel) return;
+                if (selectedPanel == panel)
+                    return;
 
                 Trace.Assert(group.BeatmapPanels.Contains(panel), @"Selected panel must be in provided group");
 
@@ -490,7 +497,8 @@ namespace osu.Game.Screens.Select
 
                 panel.State = PanelSelectedState.Selected;
 
-                if (selectedPanel == panel) return;
+                if (selectedPanel == panel)
+                    return;
 
                 selectedPanel = panel;
                 selectedGroup = group;
diff --git a/osu.Game/Screens/Select/SongSelect.cs b/osu.Game/Screens/Select/SongSelect.cs
index 46284226d7..0f72e3fd95 100644
--- a/osu.Game/Screens/Select/SongSelect.cs
+++ b/osu.Game/Screens/Select/SongSelect.cs
@@ -255,11 +255,11 @@ namespace osu.Game.Screens.Select
                 UpdateBeatmap(Beatmap.Value);
             };
 
-            selectionChangedDebounce?.Cancel();
-
             if (beatmap?.Equals(beatmapNoDebounce) == true)
                 return;
 
+            selectionChangedDebounce?.Cancel();
+
             beatmapNoDebounce = beatmap;
 
             if (beatmap == null)