Add framework for deleting difficulties

osu.Game/Beatmaps/BeatmapManager.cs

@@ -170,7 +170,7 @@ namespace osu.Game.Beatmaps
         /// Delete a beatmap from the manager.
         /// Is a no-op for already deleted beatmaps.
         /// </summary>
-        /// <param name="beatmapSet">The beatmap to delete.</param>
+        /// <param name="beatmapSet">The beatmap set to delete.</param>
         public void Delete(BeatmapSetInfo beatmapSet)
         {
             lock (beatmaps)
@@ -180,6 +180,16 @@ namespace osu.Game.Beatmaps
                 files.Dereference(beatmapSet.Files.Select(f => f.FileInfo).ToArray());
         }
 
+        /// <summary>
+        /// Delete a beatmap from the manager.
+        /// Is a no-op for already deleted beatmaps.
+        /// </summary>
+        /// <param name="beatmap">The beatmap difficulty to delete.</param>
+        public void Delete(BeatmapInfo beatmap)
+        {
+            //todo: implement
+        }
+
         /// <summary>
         /// Returns a <see cref="BeatmapSetInfo"/> to a usable state if it has previously been deleted but not yet purged.
         /// Is a no-op for already usable beatmaps.

osu.Game/Beatmaps/Drawables/BeatmapGroup.cs

@@ -25,6 +25,8 @@ namespace osu.Game.Beatmaps.Drawables
 
         public Action<BeatmapSetInfo> DeleteRequested;
 
+        public Action<BeatmapInfo> DeleteDifficultyRequested;
+
         public BeatmapSetHeader Header;
 
         private BeatmapGroupState state;
@@ -77,6 +79,7 @@ namespace osu.Game.Beatmaps.Drawables
             {
                 Alpha = 0,
                 GainedSelection = panelGainedSelection,
+                DeleteRequested = p => DeleteDifficultyRequested?.Invoke(p),
                 StartRequested = p => { StartRequested?.Invoke(p.Beatmap); },
                 RelativeSizeAxes = Axes.X,
             }).ToList();

osu.Game/Screens/Select/BeatmapCarousel.cs

@@ -140,7 +140,9 @@ namespace osu.Game.Screens.Select
 
         public Action StartRequested;
 
-        public Action<WorkingBeatmap> DeleteRequested;
+        public Action<BeatmapSetInfo> DeleteRequested;
+
+        public Action<BeatmapInfo> DeleteDifficultyRequested;
 
         public void SelectNext(int direction = 1, bool skipDifficulties = true)
         {
@@ -308,6 +310,7 @@ namespace osu.Game.Screens.Select
                 SelectionChanged = (g, p) => selectGroup(g, p),
                 StartRequested = b => StartRequested?.Invoke(),
                 DeleteRequested = b => DeleteRequested?.Invoke(b),
+                DeleteDifficultyRequested = b => DeleteDifficultyRequested?.Invoke(b),
                 State = BeatmapGroupState.Collapsed
             };
         }

osu.Game/Screens/Select/BeatmapDeleteDialog.cs

@@ -13,29 +13,36 @@ namespace osu.Game.Screens.Select
     {
         private BeatmapManager manager;
 
+        private readonly Action deleteAction;
+
         [BackgroundDependencyLoader]
         private void load(BeatmapManager beatmapManager)
         {
             manager = beatmapManager;
         }
 
-        public BeatmapDeleteDialog(WorkingBeatmap beatmap)
+        public BeatmapDeleteDialog(BeatmapSetInfo beatmap) : this()
         {
-            if (beatmap == null) throw new ArgumentNullException(nameof(beatmap));
+            BodyText = $@"{beatmap.Metadata?.Artist} - {beatmap.Metadata?.Title} (ALL DIFFICULTIES)";
+            deleteAction = () => manager.Delete(beatmap);
+        }
 
+        public BeatmapDeleteDialog(BeatmapInfo beatmap) : this()
+        {
+            BodyText = $@"{beatmap.Metadata?.Artist} - {beatmap.Metadata?.Title} [{beatmap.Version}]";
+            deleteAction = () => manager.Delete(beatmap);
+        }
+
+        public BeatmapDeleteDialog()
+        {
             Icon = FontAwesome.fa_trash_o;
             HeaderText = @"Confirm deletion of";
-            BodyText = $@"{beatmap.Metadata?.Artist} - {beatmap.Metadata?.Title}";
             Buttons = new PopupDialogButton[]
             {
                 new PopupDialogOkButton
                 {
                     Text = @"Yes. Totally. Delete it.",
-                    Action = () =>
+                    Action = () => deleteAction(),
-                    {
-                        beatmap.Dispose();
-                        manager.Delete(beatmap.BeatmapSetInfo);
-                    },
                 },
                 new PopupDialogCancelButton
                 {

osu.Game/Screens/Select/SongSelect.cs

@@ -107,6 +107,7 @@ namespace osu.Game.Screens.Select
                 SelectionChanged = carouselSelectionChanged,
                 BeatmapsChanged = carouselBeatmapsLoaded,
                 DeleteRequested = b => promptDelete(b),
+                DeleteDifficultyRequested = b => promptDelete(b),
                 StartRequested = () => carouselRaisedStart(),
             });
             Add(FilterControl = new FilterControl
@@ -164,7 +165,7 @@ namespace osu.Game.Screens.Select
                 Footer.AddButton(@"random", colours.Green, triggerRandom, Key.F2);
                 Footer.AddButton(@"options", colours.Blue, BeatmapOptions.ToggleVisibility, Key.F3);
 
-                BeatmapOptions.AddButton(@"Delete", @"Beatmap", FontAwesome.fa_trash, colours.Pink, () => promptDelete(Beatmap), Key.Number4, float.MaxValue);
+                BeatmapOptions.AddButton(@"Delete", @"Beatmap", FontAwesome.fa_trash, colours.Pink, () => promptDelete(Beatmap.Value.BeatmapSetInfo), Key.Number4, float.MaxValue);
             }
 
             if (manager == null)
@@ -399,6 +400,14 @@ namespace osu.Game.Screens.Select
             dialogOverlay?.Push(new BeatmapDeleteDialog(beatmap));
         }
 
+        private void promptDelete(BeatmapInfo beatmap)
+        {
+            if (beatmap == null)
+                return;
+
+            dialogOverlay?.Push(new BeatmapDeleteDialog(beatmap));
+        }
+
         protected override bool OnKeyDown(InputState state, KeyDownEventArgs args)
         {
             if (args.Repeat) return false;