From b10240d7ef41f1a41edbfa6d0717a907823be6ff Mon Sep 17 00:00:00 2001
From: Dean Herbert <pe@ppy.sh>
Date: Mon, 11 Dec 2017 21:31:26 +0900
Subject: [PATCH] Handle the case where the selected panel is no longer a valid
 selection better

---
 osu.Game/Beatmaps/Drawables/BeatmapGroup.cs | 45 +++++++++++----------
 osu.Game/Screens/Select/BeatmapCarousel.cs  | 10 +++--
 2 files changed, 31 insertions(+), 24 deletions(-)

diff --git a/osu.Game/Beatmaps/Drawables/BeatmapGroup.cs b/osu.Game/Beatmaps/Drawables/BeatmapGroup.cs
index 59ff7b06e5..e0536584bd 100644
--- a/osu.Game/Beatmaps/Drawables/BeatmapGroup.cs
+++ b/osu.Game/Beatmaps/Drawables/BeatmapGroup.cs
@@ -47,31 +47,34 @@ namespace osu.Game.Beatmaps.Drawables
             set
             {
                 state = value;
-
-                switch (value)
-                {
-                    case BeatmapGroupState.Expanded:
-                        Header.State = PanelSelectedState.Selected;
-                        foreach (BeatmapPanel panel in BeatmapPanels)
-                            panel.State = panel == SelectedPanel ? PanelSelectedState.Selected :
-                                !panel.Filtered ? PanelSelectedState.NotSelected : PanelSelectedState.Hidden;
-                        break;
-                    case BeatmapGroupState.Collapsed:
-                        Header.State = PanelSelectedState.NotSelected;
-                        foreach (BeatmapPanel panel in BeatmapPanels)
-                            panel.State = PanelSelectedState.Hidden;
-                        break;
-                    case BeatmapGroupState.Hidden:
-                        Header.State = PanelSelectedState.Hidden;
-                        foreach (BeatmapPanel panel in BeatmapPanels)
-                            panel.State = PanelSelectedState.Hidden;
-                        break;
-                }
-
+                UpdateState();
                 StateChanged?.Invoke(state);
             }
         }
 
+        public void UpdateState()
+        {
+            switch (state)
+            {
+                case BeatmapGroupState.Expanded:
+                    Header.State = PanelSelectedState.Selected;
+                    foreach (BeatmapPanel panel in BeatmapPanels)
+                        panel.State = panel == SelectedPanel ? PanelSelectedState.Selected :
+                            !panel.Filtered ? PanelSelectedState.NotSelected : PanelSelectedState.Hidden;
+                    break;
+                case BeatmapGroupState.Collapsed:
+                    Header.State = PanelSelectedState.NotSelected;
+                    foreach (BeatmapPanel panel in BeatmapPanels)
+                        panel.State = PanelSelectedState.Hidden;
+                    break;
+                case BeatmapGroupState.Hidden:
+                    Header.State = PanelSelectedState.Hidden;
+                    foreach (BeatmapPanel panel in BeatmapPanels)
+                        panel.State = PanelSelectedState.Hidden;
+                    break;
+            }
+        }
+
         public BeatmapGroup(BeatmapSetInfo beatmapSet, BeatmapManager manager)
         {
             if (beatmapSet == null)
diff --git a/osu.Game/Screens/Select/BeatmapCarousel.cs b/osu.Game/Screens/Select/BeatmapCarousel.cs
index aa41cad67e..f6b832d0f7 100644
--- a/osu.Game/Screens/Select/BeatmapCarousel.cs
+++ b/osu.Game/Screens/Select/BeatmapCarousel.cs
@@ -327,6 +327,8 @@ namespace osu.Game.Screens.Select
 
                 computeYPositions();
 
+                selectedGroup?.UpdateState();
+
                 if (selectedGroup == null || selectedGroup.State == BeatmapGroupState.Hidden)
                     SelectNext();
                 else
@@ -441,11 +443,13 @@ namespace osu.Game.Screens.Select
 
                         panel.MoveToX(-50, 500, Easing.OutExpo);
 
+                        bool isHidden = panel.State == PanelSelectedState.Hidden;
+
                         //on first display we want to begin hidden under our group's header.
-                        if (panel.Filtered || panel.Alpha == 0)
+                        if (isHidden || panel.Alpha == 0)
                             panel.MoveToY(headerY);
 
-                        movePanel(panel, !panel.Filtered, animated, ref currentY);
+                        movePanel(panel, !isHidden, animated, ref currentY);
                     }
                 }
                 else
@@ -479,7 +483,7 @@ namespace osu.Game.Screens.Select
         {
             try
             {
-                if (panel == null)
+                if (panel == null || panel.Filtered == true)
                     panel = group.BeatmapPanels.First(p => !p.Filtered);
 
                 if (selectedPanel == panel) return;