Initial rewrite, moving API logic to SongSelect

osu.Game/Screens/Select/BeatmapCarousel.cs

@@ -34,8 +34,6 @@ namespace osu.Game.Screens.Select
         private const float bleed_top = FilterControl.HEIGHT;
         private const float bleed_bottom = Footer.HEIGHT;
 
-        protected readonly Bindable<double> RecommendedStarDifficulty = new Bindable<double>();
-
         /// <summary>
         /// Triggered when the <see cref="BeatmapSets"/> loaded change and are completely loaded.
         /// </summary>
@@ -122,6 +120,7 @@ namespace osu.Game.Screens.Select
 
         protected List<DrawableCarouselItem> Items = new List<DrawableCarouselItem>();
         private CarouselRoot root;
+        public SongSelect.DifficultyRecommender DifficultyRecommender;
 
         public BeatmapCarousel()
         {
@@ -145,10 +144,10 @@ namespace osu.Game.Screens.Select
         private BeatmapManager beatmaps { get; set; }
 
         [Resolved]
-        private IAPIProvider api { get; set; }
+        private Bindable<RulesetInfo> decoupledRuleset { get; set; }
 
         [BackgroundDependencyLoader(permitNulls: true)]
-        private void load(OsuConfigManager config, Bindable<RulesetInfo> decoupledRuleset)
+        private void load(OsuConfigManager config)
         {
             config.BindWith(OsuSetting.RandomSelectAlgorithm, RandomAlgorithm);
             config.BindWith(OsuSetting.SongSelectRightMouseScroll, RightClickScrollingEnabled);
@@ -162,27 +161,6 @@ namespace osu.Game.Screens.Select
             beatmaps.BeatmapRestored += beatmapRestored;
 
             loadBeatmapSets(GetLoadableBeatmaps());
-
-            decoupledRuleset.BindValueChanged(UpdateRecommendedStarDifficulty, true);
-        }
-
-        protected void UpdateRecommendedStarDifficulty(ValueChangedEvent<RulesetInfo> ruleset)
-        {
-            if (api.LocalUser.Value is GuestUser)
-            {
-                RecommendedStarDifficulty.Value = 0;
-                return;
-            }
-
-            var req = new GetUserRequest(api.LocalUser.Value.Id, ruleset.NewValue);
-
-            req.Success += result =>
-            {
-                // algorithm taken from https://github.com/ppy/osu-web/blob/e6e2825516449e3d0f3f5e1852c6bdd3428c3437/app/Models/User.php#L1505
-                RecommendedStarDifficulty.Value = Math.Pow((double)(result.Statistics.PP ?? 0), 0.4) * 0.195;
-            };
-
-            api.PerformAsync(req);
         }
 
         protected virtual IEnumerable<BeatmapSetInfo> GetLoadableBeatmaps() => beatmaps.GetAllUsableBeatmapSetsEnumerable();
@@ -608,7 +586,12 @@ namespace osu.Game.Screens.Select
                     b.Metadata = beatmapSet.Metadata;
             }
 
-            var set = new CarouselBeatmapSet(beatmapSet, RecommendedStarDifficulty);
+            BeatmapInfo recommender(IEnumerable<BeatmapInfo> beatmaps)
+            {
+                return DifficultyRecommender?.GetRecommendedBeatmap(beatmaps, decoupledRuleset.Value);
+            }
+
+            var set = new CarouselBeatmapSet(beatmapSet, recommender);
 
             foreach (var c in set.Beatmaps)
             {

osu.Game/Screens/Select/Carousel/CarouselBeatmapSet.cs

@@ -13,13 +13,13 @@ namespace osu.Game.Screens.Select.Carousel
 {
     public class CarouselBeatmapSet : CarouselGroupEagerSelect
     {
-        private readonly Bindable<double> recommendedStarDifficulty = new Bindable<double>();
+        private Func<IEnumerable<BeatmapInfo>, BeatmapInfo> getRecommendedBeatmap;
 
         public IEnumerable<CarouselBeatmap> Beatmaps => InternalChildren.OfType<CarouselBeatmap>();
 
         public BeatmapSetInfo BeatmapSet;
 
-        public CarouselBeatmapSet(BeatmapSetInfo beatmapSet, Bindable<double> recommendedStarDifficulty)
+        public CarouselBeatmapSet(BeatmapSetInfo beatmapSet, Func<IEnumerable<BeatmapInfo>, BeatmapInfo> getRecommendedBeatmap)
         {
             BeatmapSet = beatmapSet ?? throw new ArgumentNullException(nameof(beatmapSet));
 
@@ -28,7 +28,7 @@ namespace osu.Game.Screens.Select.Carousel
                       .Select(b => new CarouselBeatmap(b))
                       .ForEach(AddChild);
 
-            this.recommendedStarDifficulty.BindTo(recommendedStarDifficulty);
+            this.getRecommendedBeatmap = getRecommendedBeatmap;
         }
 
         protected override DrawableCarouselItem CreateDrawableRepresentation() => new DrawableCarouselBeatmapSet(this);
@@ -37,14 +37,8 @@ namespace osu.Game.Screens.Select.Carousel
         {
             if (LastSelected == null)
             {
-                return Children.OfType<CarouselBeatmap>()
+                var recommendedBeatmapInfo = getRecommendedBeatmap(Children.OfType<CarouselBeatmap>().Where(b => !b.Filtered.Value).Select(b => b.Beatmap));
-                               .Where(b => !b.Filtered.Value)
+                return Children.OfType<CarouselBeatmap>().Where(b => b.Beatmap == recommendedBeatmapInfo).First();
-                               .OrderBy(b =>
-                               {
-                                   var difference = b.Beatmap.StarDifficulty - recommendedStarDifficulty.Value;
-                                   return difference >= 0 ? difference * 2 : difference * -1; // prefer easier over harder
-                               })
-                               .FirstOrDefault();
             }
 
             return base.GetNextToSelect();

osu.Game/Screens/Select/SongSelect.cs

@@ -36,6 +36,9 @@ using osu.Framework.Graphics.Sprites;
 using osu.Framework.Input.Bindings;
 using osu.Game.Overlays.Notifications;
 using osu.Game.Scoring;
+using osu.Game.Online.API;
+using osu.Framework.Extensions.IEnumerableExtensions;
+using osu.Game.Online.API.Requests;
 
 namespace osu.Game.Screens.Select
 {
@@ -80,6 +83,7 @@ namespace osu.Game.Screens.Select
         protected override BackgroundScreen CreateBackground() => new BackgroundScreenBeatmap(Beatmap.Value);
 
         protected BeatmapCarousel Carousel { get; private set; }
+        private DifficultyRecommender difficultyRecommender;
 
         private BeatmapInfoWedge beatmapInfoWedge;
         private DialogOverlay dialogOverlay;
@@ -107,6 +111,8 @@ namespace osu.Game.Screens.Select
             // initial value transfer is required for FilterControl (it uses our re-cached bindables in its async load for the initial filter).
             transferRulesetValue();
 
+            AddInternal(difficultyRecommender = new DifficultyRecommender());
+
             AddRangeInternal(new Drawable[]
             {
                 new ResetScrollContainer(() => Carousel.ScrollToSelected())
@@ -156,6 +162,7 @@ namespace osu.Game.Screens.Select
                                             RelativeSizeAxes = Axes.Both,
                                             SelectionChanged = updateSelectedBeatmap,
                                             BeatmapSetsChanged = carouselBeatmapsLoaded,
+                                            DifficultyRecommender = difficultyRecommender,
                                         },
                                     }
                                 },
@@ -780,6 +787,64 @@ namespace osu.Game.Screens.Select
             return base.OnKeyDown(e);
         }
 
+        public class DifficultyRecommender : Component
+        {
+            [Resolved]
+            private IAPIProvider api { get; set; }
+
+            [Resolved]
+            private RulesetStore rulesets { get; set; }
+
+            private Dictionary<RulesetInfo, double> recommendedStarDifficulty = new Dictionary<RulesetInfo, double>();
+
+            private int pendingAPIRequests = 0;
+
+            [BackgroundDependencyLoader]
+            private void load()
+            {
+                updateRecommended();
+            }
+
+            private void updateRecommended()
+            {
+                if (pendingAPIRequests > 0)
+                    return;
+                if (api.LocalUser.Value is GuestUser)
+                    return;
+                rulesets.AvailableRulesets.ForEach(rulesetInfo =>
+                {
+                    var req = new GetUserRequest(api.LocalUser.Value.Id, rulesetInfo);
+
+                    req.Success += result =>
+                    {
+                        // algorithm taken from https://github.com/ppy/osu-web/blob/e6e2825516449e3d0f3f5e1852c6bdd3428c3437/app/Models/User.php#L1505
+                        recommendedStarDifficulty[rulesetInfo] = Math.Pow((double)(result.Statistics.PP ?? 0), 0.4) * 0.195;
+                        pendingAPIRequests--;
+                    };
+
+                    req.Failure += _ => pendingAPIRequests--;
+
+                    pendingAPIRequests++;
+                    api.Queue(req);
+                });
+            }
+
+            public BeatmapInfo GetRecommendedBeatmap(IEnumerable<BeatmapInfo> beatmaps, RulesetInfo currentRuleset)
+            {
+                if (!recommendedStarDifficulty.ContainsKey(currentRuleset))
+                {
+                    updateRecommended();
+                    return null;
+                }
+
+                return beatmaps.OrderBy(b =>
+                {
+                    var difference = b.StarDifficulty - recommendedStarDifficulty[currentRuleset];
+                    return difference >= 0 ? difference * 2 : difference * -1; // prefer easier over harder
+                }).FirstOrDefault();
+            }
+        }
+
         private class VerticalMaskingContainer : Container
         {
             private const float panel_overflow = 1.2f;