Add the ability to import into ArchiveModelManagers from a stream

osu.Game/Database/ImportTask.cs

@@ -0,0 +1,73 @@
+// 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.IO;
+using osu.Game.IO.Archives;
+using osu.Game.Utils;
+using SharpCompress.Common;
+
+namespace osu.Game.Database
+{
+    /// <summary>
+    /// An encapsulated import task to be imported to an <see cref="ArchiveModelManager{TModel,TFileModel}"/>.
+    /// </summary>
+    public class ImportTask
+    {
+        /// <summary>
+        /// The path to the file (or filename in the case a stream is provided).
+        /// </summary>
+        public string Path { get; }
+
+        /// <summary>
+        /// An optional stream which provides the file content.
+        /// </summary>
+        public Stream Stream { get; }
+
+        /// <summary>
+        /// Construct a new import task from a path (on a local filesystem).
+        /// </summary>
+        public ImportTask(string path)
+        {
+            Path = path;
+        }
+
+        /// <summary>
+        /// Construct a new import task from a stream.
+        /// </summary>
+        public ImportTask(Stream stream, string filename)
+        {
+            Path = filename;
+            Stream = stream;
+        }
+
+        /// <summary>
+        /// Retrieve an archive reader from this task.
+        /// </summary>
+        public ArchiveReader GetReader()
+        {
+            if (Stream != null)
+                return new ZipArchiveReader(Stream, Path);
+
+            return getReaderFrom(Path);
+        }
+
+        /// <summary>
+        /// Creates an <see cref="ArchiveReader"/> from a valid storage path.
+        /// </summary>
+        /// <param name="path">A file or folder path resolving the archive content.</param>
+        /// <returns>A reader giving access to the archive's content.</returns>
+        private ArchiveReader getReaderFrom(string path)
+        {
+            if (ZipUtils.IsZipArchive(path))
+                return new ZipArchiveReader(File.Open(path, FileMode.Open, FileAccess.Read, FileShare.Read), System.IO.Path.GetFileName(path));
+            if (Directory.Exists(path))
+                return new LegacyDirectoryArchiveReader(path);
+            if (File.Exists(path))
+                return new LegacyFileArchiveReader(path);
+
+            throw new InvalidFormatException($"{path} is not a valid archive");
+        }
+
+        public override string ToString() => System.IO.Path.GetFileName(Path);
+    }
+}