Rename base class to LegacyModelImporter

osu.Game/Database/LegacyModelImporter.cs

@@ -0,0 +1,60 @@
+// Copyright (c) ppy Pty Ltd <contact@ppy.sh>. Licensed under the MIT Licence.
+// See the LICENCE file in the repository root for full licence text.
+
+using System.Collections.Generic;
+using System.Linq;
+using System.Threading.Tasks;
+using osu.Framework.Logging;
+using osu.Framework.Platform;
+using osu.Game.IO;
+
+namespace osu.Game.Database
+{
+    /// <summary>
+    /// A class which handles importing legacy user data of a single type from osu-stable.
+    /// </summary>
+    public abstract class LegacyModelImporter<TModel>
+        where TModel : class
+    {
+        /// <summary>
+        /// The relative path from osu-stable's data directory to import items from.
+        /// </summary>
+        protected virtual string ImportFromStablePath => null;
+
+        /// <summary>
+        /// Select paths to import from stable where all paths should be absolute. Default implementation iterates all directories in <see cref="ImportFromStablePath"/>.
+        /// </summary>
+        protected virtual IEnumerable<string> GetStableImportPaths(Storage storage) => storage.GetDirectories(ImportFromStablePath)
+                                                                                              .Select(path => storage.GetFullPath(path));
+
+        protected readonly IModelImporter<TModel> Importer;
+
+        protected LegacyModelImporter(IModelImporter<TModel> importer)
+        {
+            Importer = importer;
+        }
+
+        public Task ImportFromStableAsync(StableStorage stableStorage)
+        {
+            var storage = PrepareStableStorage(stableStorage);
+
+            // Handle situations like when the user does not have a Skins folder.
+            if (!storage.ExistsDirectory(ImportFromStablePath))
+            {
+                string fullPath = storage.GetFullPath(ImportFromStablePath);
+
+                Logger.Log(@$"Folder ""{fullPath}"" not available in the target osu!stable installation to import {Importer.HumanisedModelName}s.", LoggingTarget.Information, LogLevel.Error);
+                return Task.CompletedTask;
+            }
+
+            return Task.Run(async () => await Importer.Import(GetStableImportPaths(storage).ToArray()).ConfigureAwait(false));
+        }
+
+        /// <summary>
+        /// Run any required traversal operations on the stable storage location before performing operations.
+        /// </summary>
+        /// <param name="stableStorage">The stable storage.</param>
+        /// <returns>The usable storage. Return the unchanged <paramref name="stableStorage"/> if no traversal is required.</returns>
+        protected virtual Storage PrepareStableStorage(StableStorage stableStorage) => stableStorage;
+    }
+}