Add alternative for random beatmap selection

"Never repeat" will not repeat until all songs have been seen by repeatedly pressing F2/Random button

osu.Game/Configuration/OsuConfigManager.cs

@@ -20,6 +20,8 @@ namespace osu.Game.Configuration
             Set(OsuSetting.DisplayStarsMinimum, 0.0, 0, 10);
             Set(OsuSetting.DisplayStarsMaximum, 10.0, 0, 10);
 
+            Set(OsuSetting.SelectionRandomType, SelectionRandomType.Random);
+
             Set(OsuSetting.ChatDisplayHeight, ChatOverlay.DEFAULT_HEIGHT, 0.2, 1);
 
             // Online settings
@@ -102,6 +104,7 @@ namespace osu.Game.Configuration
         SaveUsername,
         DisplayStarsMinimum,
         DisplayStarsMaximum,
+        SelectionRandomType,
         SnakingInSliders,
         SnakingOutSliders,
         ShowFpsDisplay,

osu.Game/Configuration/SelectionRandomType.cs

@@ -0,0 +1,15 @@
+// Copyright (c) 2007-2017 ppy Pty Ltd <contact@ppy.sh>.
+// Licensed under the MIT Licence - https://raw.githubusercontent.com/ppy/osu/master/LICENCE
+
+using System.ComponentModel;
+
+namespace osu.Game.Configuration
+{
+   public enum SelectionRandomType
+    {
+        [Description("Random")]
+        Random,
+        [Description("Never repeat")]
+        RandomPermutation
+    }
+}

osu.Game/Overlays/Settings/Sections/Gameplay/SongSelectSettings.cs

@@ -27,6 +27,11 @@ namespace osu.Game.Overlays.Settings.Sections.Gameplay
                     LabelText = "up to",
                     Bindable = config.GetBindable<double>(OsuSetting.DisplayStarsMaximum)
                 },
+                new SettingsEnumDropdown<SelectionRandomType>
+                {
+                    LabelText = "Random beatmap selection",
+                    Bindable = config.GetBindable<SelectionRandomType>(OsuSetting.SelectionRandomType),
+                },
             };
         }
 

osu.Game/Screens/Select/BeatmapCarousel.cs

@@ -9,6 +9,7 @@ using System;
 using System.Collections.Generic;
 using System.Linq;
 using osu.Game.Beatmaps.Drawables;
+using osu.Game.Configuration;
 using osu.Framework.Input;
 using OpenTK.Input;
 using System.Collections;
@@ -17,6 +18,7 @@ using System.Diagnostics;
 using System.Threading.Tasks;
 using osu.Framework.Allocation;
 using osu.Framework.Threading;
+using osu.Framework.Configuration;
 
 namespace osu.Game.Screens.Select
 {
@@ -70,6 +72,9 @@ namespace osu.Game.Screens.Select
 
         private readonly List<BeatmapGroup> groups = new List<BeatmapGroup>();
 
+        private Bindable<SelectionRandomType> randomType;
+        private HashSet<BeatmapGroup> seenGroups = new HashSet<BeatmapGroup>();
+
         private readonly List<Panel> panels = new List<Panel>();
 
         private BeatmapGroup selectedGroup;
@@ -171,7 +176,22 @@ namespace osu.Game.Screens.Select
             if (visibleGroups.Count < 1)
                 return;
 
-            BeatmapGroup group = visibleGroups[RNG.Next(visibleGroups.Count)];
+            BeatmapGroup group;
+            if (randomType == SelectionRandomType.RandomPermutation)
+            {
+                List<BeatmapGroup> notSeenGroups = visibleGroups.Except(seenGroups).ToList();
+                if (!notSeenGroups.Any())
+                { 
+                    seenGroups.Clear();
+                    notSeenGroups = visibleGroups;
+                }
+
+                group = notSeenGroups[RNG.Next(notSeenGroups.Count())];
+                seenGroups.Add(group);
+            }
+            else
+                group = visibleGroups[RNG.Next(visibleGroups.Count)];
+
             BeatmapPanel panel = group.BeatmapPanels[RNG.Next(group.BeatmapPanels.Count)];
 
             selectGroup(group, panel);
@@ -239,9 +259,10 @@ namespace osu.Game.Screens.Select
         }
 
         [BackgroundDependencyLoader(permitNulls: true)]
-        private void load(BeatmapDatabase database)
+        private void load(BeatmapDatabase database, OsuConfigManager config)
         {
             this.database = database;
+            randomType = config.GetBindable<SelectionRandomType>(OsuSetting.SelectionRandomType);
         }
 
         private void addGroup(BeatmapGroup group)

osu.Game/osu.Game.csproj

@@ -74,6 +74,7 @@
     <Compile Include="Audio\SampleInfoList.cs" />
     <Compile Include="Beatmaps\Drawables\BeatmapBackgroundSprite.cs" />
     <Compile Include="Beatmaps\DifficultyCalculator.cs" />
+    <Compile Include="Configuration\SelectionRandomType.cs" />
     <Compile Include="Online\API\Requests\PostMessageRequest.cs" />
     <Compile Include="Online\Chat\ErrorMessage.cs" />
     <Compile Include="Overlays\Chat\ChatTabControl.cs" />