Add basic skin database model layout and importing

osu.Game/Skinning/SkinManager.cs

@@ -0,0 +1,39 @@
+// Copyright (c) 2007-2018 ppy Pty Ltd <contact@ppy.sh>.
+// Licensed under the MIT Licence - https://raw.githubusercontent.com/ppy/osu/master/LICENCE
+
+using System.Collections.Generic;
+using System.Linq;
+using osu.Framework.Configuration;
+using osu.Framework.Platform;
+using osu.Game.Database;
+using osu.Game.IO.Archives;
+
+namespace osu.Game.Skinning
+{
+    public class SkinManager : ArchiveModelManager<SkinInfo, SkinFileInfo>
+    {
+        public readonly Bindable<SkinInfo> CurrentSkinInfo = new Bindable<SkinInfo>(SkinInfo.Default) { Default = SkinInfo.Default };
+
+        public override string[] HandledExtensions => new[] { ".osk" };
+
+        /// <summary>
+        /// Returns a list of all usable <see cref="SkinInfo"/>s.
+        /// </summary>
+        /// <returns>A list of available <see cref="SkinInfo"/>.</returns>
+        public List<SkinInfo> GetAllUsableSkins()
+        {
+            var userSkins = ModelStore.ConsumableItems.Where(s => !s.DeletePending).ToList();
+            userSkins.Insert(0, SkinInfo.Default);
+            return userSkins;
+        }
+
+        protected override SkinInfo CreateModel(ArchiveReader archive) => new SkinInfo { Name = archive.Name };
+
+        private SkinStore store;
+
+        public SkinManager(Storage storage, DatabaseContextFactory contextFactory, IIpcHost importHost)
+            : base(storage, contextFactory, new SkinStore(contextFactory, storage), importHost)
+        {
+        }
+    }
+}