From 82a847b820e11adb2bbbfccd4c0778d3e9ca9638 Mon Sep 17 00:00:00 2001
From: smoogipoo <smoogipoo@smgi.me>
Date: Mon, 2 Apr 2018 15:16:10 +0900
Subject: [PATCH] Extract random selection logic into CarouselRoot

---
 osu.Game/Screens/Select/BeatmapCarousel.cs    |  6 ++---
 .../Carousel/CarouselGroupEagerSelect.cs      | 27 +++++++++----------
 .../Screens/Select/Carousel/CarouselRoot.cs   | 23 ++++++++++++++++
 3 files changed, 39 insertions(+), 17 deletions(-)
 create mode 100644 osu.Game/Screens/Select/Carousel/CarouselRoot.cs

diff --git a/osu.Game/Screens/Select/BeatmapCarousel.cs b/osu.Game/Screens/Select/BeatmapCarousel.cs
index 12791eb193..dfbbc2b5d5 100644
--- a/osu.Game/Screens/Select/BeatmapCarousel.cs
+++ b/osu.Game/Screens/Select/BeatmapCarousel.cs
@@ -66,7 +66,7 @@ namespace osu.Game.Screens.Select
             get { return beatmapSets.Select(g => g.BeatmapSet); }
             set
             {
-                CarouselGroup newRoot = new CarouselGroupEagerSelect(this);
+                CarouselRoot newRoot = new CarouselRoot(this);
 
                 Task.Run(() =>
                 {
@@ -102,11 +102,11 @@ namespace osu.Game.Screens.Select
         private readonly Stack<CarouselBeatmap> randomSelectedBeatmaps = new Stack<CarouselBeatmap>();
 
         protected List<DrawableCarouselItem> Items = new List<DrawableCarouselItem>();
-        private CarouselGroup root;
+        private CarouselRoot root;
 
         public BeatmapCarousel()
         {
-            root = new CarouselGroupEagerSelect(this);
+            root = new CarouselRoot(this);
             Child = new OsuContextMenuContainer
             {
                 RelativeSizeAxes = Axes.X,
diff --git a/osu.Game/Screens/Select/Carousel/CarouselGroupEagerSelect.cs b/osu.Game/Screens/Select/Carousel/CarouselGroupEagerSelect.cs
index 7f64af8216..fabf333461 100644
--- a/osu.Game/Screens/Select/Carousel/CarouselGroupEagerSelect.cs
+++ b/osu.Game/Screens/Select/Carousel/CarouselGroupEagerSelect.cs
@@ -11,11 +11,8 @@ namespace osu.Game.Screens.Select.Carousel
     /// </summary>
     public class CarouselGroupEagerSelect : CarouselGroup
     {
-        private readonly BeatmapCarousel parent;
-
-        public CarouselGroupEagerSelect(BeatmapCarousel parent = null)
+        public CarouselGroupEagerSelect()
         {
-            this.parent = parent;
             State.ValueChanged += v =>
             {
                 if (v == CarouselItemState.Selected)
@@ -23,13 +20,16 @@ namespace osu.Game.Screens.Select.Carousel
             };
         }
 
+        /// <summary>
+        /// The last selected item.
+        /// </summary>
+        protected CarouselItem LastSelected { get; private set; }
+
         /// <summary>
         /// We need to keep track of the index for cases where the selection is removed but we want to select a new item based on its old location.
         /// </summary>
         private int lastSelectedIndex;
 
-        private CarouselItem lastSelected;
-
         /// <summary>
         /// To avoid overhead during filter operations, we don't attempt any selections until after all
         /// children have been filtered. This bool will be true during the base <see cref="Filter(FilterCriteria)"/>
@@ -50,7 +50,7 @@ namespace osu.Game.Screens.Select.Carousel
         {
             base.RemoveChild(i);
 
-            if (i != lastSelected)
+            if (i != LastSelected)
                 updateSelectedIndex();
         }
 
@@ -86,12 +86,11 @@ namespace osu.Game.Screens.Select.Carousel
             // we only perform eager selection if none of our children are in a selected state already.
             if (Children.Any(i => i.State == CarouselItemState.Selected)) return;
 
-            if (parent != null && lastSelected == null)
-            {
-                parent.SelectNextRandom();
-                return;
-            }
+            PerformSelection();
+        }
 
+        protected virtual void PerformSelection()
+        {
             CarouselItem nextToSelect =
                 Children.Skip(lastSelectedIndex).FirstOrDefault(i => !i.Filtered) ??
                 Children.Reverse().Skip(InternalChildren.Count - lastSelectedIndex).FirstOrDefault(i => !i.Filtered);
@@ -104,10 +103,10 @@ namespace osu.Game.Screens.Select.Carousel
 
         private void updateSelected(CarouselItem newSelection)
         {
-            lastSelected = newSelection;
+            LastSelected = newSelection;
             updateSelectedIndex();
         }
 
-        private void updateSelectedIndex() => lastSelectedIndex = lastSelected == null ? 0 : Math.Max(0, InternalChildren.IndexOf(lastSelected));
+        private void updateSelectedIndex() => lastSelectedIndex = LastSelected == null ? 0 : Math.Max(0, InternalChildren.IndexOf(LastSelected));
     }
 }
diff --git a/osu.Game/Screens/Select/Carousel/CarouselRoot.cs b/osu.Game/Screens/Select/Carousel/CarouselRoot.cs
new file mode 100644
index 0000000000..b23d7631c9
--- /dev/null
+++ b/osu.Game/Screens/Select/Carousel/CarouselRoot.cs
@@ -0,0 +1,23 @@
+// Copyright (c) 2007-2018 ppy Pty Ltd <contact@ppy.sh>.
+// Licensed under the MIT Licence - https://raw.githubusercontent.com/ppy/osu/master/LICENCE
+
+namespace osu.Game.Screens.Select.Carousel
+{
+    public class CarouselRoot : CarouselGroupEagerSelect
+    {
+        private readonly BeatmapCarousel carousel;
+
+        public CarouselRoot(BeatmapCarousel carousel)
+        {
+            this.carousel = carousel;
+        }
+
+        protected override void PerformSelection()
+        {
+            if (LastSelected == null)
+                carousel.SelectNextRandom();
+            else
+                base.PerformSelection();
+        }
+    }
+}