Add a dialog offering to import beatmaps from stable

osu.Game/Beatmaps/BeatmapManager.cs

@@ -697,10 +697,12 @@ namespace osu.Game.Beatmaps
             }
         }
 
+        public bool StableInstallationAvailable => GetStableStorage?.Invoke() != null;
+
         /// <summary>
         /// This is a temporary method and will likely be replaced by a full-fledged (and more correctly placed) migration process in the future.
         /// </summary>
-        public void ImportFromStable()
+        public async Task ImportFromStable()
         {
             var stable = GetStableStorage?.Invoke();
 
@@ -710,7 +712,7 @@ namespace osu.Game.Beatmaps
                 return;
             }
 
-            Import(stable.GetDirectories("Songs"));
+            await Task.Factory.StartNew(() => Import(stable.GetDirectories("Songs")), TaskCreationOptions.LongRunning);
         }
 
         public void DeleteAll()

osu.Game/Overlays/Settings/Sections/Maintenance/GeneralSettings.cs

@@ -30,8 +30,7 @@ namespace osu.Game.Overlays.Settings.Sections.Maintenance
                     Action = () =>
                     {
                         importButton.Enabled.Value = false;
-                        Task.Factory.StartNew(beatmaps.ImportFromStable)
-                            .ContinueWith(t => Schedule(() => importButton.Enabled.Value = true), TaskContinuationOptions.LongRunning);
+                        beatmaps.ImportFromStable().ContinueWith(t => Schedule(() => importButton.Enabled.Value = true));
                     }
                 },
                 deleteButton = new DangerousSettingsButton

osu.Game/Screens/Select/ImportFromStablePopup.cs

@@ -0,0 +1,33 @@
+// 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;
+using osu.Game.Graphics;
+using osu.Game.Overlays.Dialog;
+
+namespace osu.Game.Screens.Select
+{
+    public class ImportFromStablePopup : PopupDialog
+    {
+        public ImportFromStablePopup(Action importFromStable)
+        {
+            HeaderText = @"You have no beatmaps!";
+            BodyText = "An existing copy of osu! was found, though.\nWould you like to import your beatmaps?";
+
+            Icon = FontAwesome.fa_trash_o;
+
+            Buttons = new PopupDialogButton[]
+            {
+                new PopupDialogOkButton
+                {
+                    Text = @"Yes please!",
+                    Action = importFromStable
+                },
+                new PopupDialogCancelButton
+                {
+                    Text = @"No, I'd like to start from scratch",
+                },
+            };
+        }
+    }
+}

osu.Game/Screens/Select/PlaySongSelect.cs

@@ -11,6 +11,7 @@ using osu.Framework.Graphics.Containers;
 using osu.Framework.Screens;
 using osu.Game.Beatmaps;
 using osu.Game.Graphics;
+using osu.Game.Overlays;
 using osu.Game.Overlays.Mods;
 using osu.Game.Screens.Edit;
 using osu.Game.Screens.Play;
@@ -45,8 +46,8 @@ namespace osu.Game.Screens.Select
 
         private SampleChannel sampleConfirm;
 
-        [BackgroundDependencyLoader]
-        private void load(OsuColour colours, AudioManager audio)
+        [BackgroundDependencyLoader(true)]
+        private void load(OsuColour colours, AudioManager audio, BeatmapManager beatmaps, DialogOverlay dialogOverlay)
         {
             sampleConfirm = audio.Sample.Get(@"SongSelect/confirm-selection");
 
@@ -59,6 +60,16 @@ namespace osu.Game.Screens.Select
                 ValidForResume = false;
                 Push(new Editor());
             }, Key.Number3);
+
+            if (dialogOverlay != null)
+            {
+                Schedule(() =>
+                {
+                    // if we have no beatmaps but osu-stable is found, let's prompt the user to import.
+                    if (!beatmaps.GetAllUsableBeatmapSets().Any() && beatmaps.StableInstallationAvailable)
+                        dialogOverlay.Push(new ImportFromStablePopup(() => beatmaps.ImportFromStable()));
+                });
+            }
         }
 
         protected override void UpdateBeatmap(WorkingBeatmap beatmap)

osu.Game/osu.Game.csproj

@@ -310,6 +310,7 @@
     <Compile Include="Overlays\Profile\Sections\Ranks\DrawableTotalScore.cs" />
     <Compile Include="Overlays\Profile\Sections\Ranks\ScoreModsContainer.cs" />
     <Compile Include="Overlays\Settings\Sections\Maintenance\DeleteAllBeatmapsDialog.cs" />
+    <Compile Include="Screens\Select\ImportFromStablePopup.cs" />
     <Compile Include="Overlays\Settings\SettingsButton.cs" />
     <Compile Include="Rulesets\Edit\Layers\Selection\OriginHandle.cs" />
     <Compile Include="Rulesets\Edit\Layers\Selection\HitObjectSelectionBox.cs" />