Create a generic base archive download manager class

osu.Game/Database/ArchiveDownloadModelManager.cs

@@ -0,0 +1,117 @@
+using osu.Framework.Logging;
+using osu.Framework.Platform;
+using osu.Game.Online.API;
+using osu.Game.Overlays.Notifications;
+using System;
+using System.Collections.Generic;
+using System.Threading.Tasks;
+
+namespace osu.Game.Database
+{
+    public abstract class ArchiveDownloadModelManager<TModel, TFileModel, TDownloadRequestModel> : ArchiveModelManager<TModel, TFileModel>
+        where TModel : class, IHasFiles<TFileModel>, IHasPrimaryKey, ISoftDelete
+        where TFileModel : INamedFileInfo, new()
+        where TDownloadRequestModel : ArchiveDownloadModelRequest<TModel>
+    {
+        public event Action<TDownloadRequestModel> DownloadBegan;
+
+        public event Action<TDownloadRequestModel> DownloadFailed;
+
+        private readonly IAPIProvider api;
+
+        private readonly List<TDownloadRequestModel> currentDownloads = new List<TDownloadRequestModel>();
+
+        protected ArchiveDownloadModelManager(Storage storage, IDatabaseContextFactory contextFactory, IAPIProvider api, MutableDatabaseBackedStoreWithFileIncludes<TModel, TFileModel> modelStore, IIpcHost importHost = null)
+            :base(storage, contextFactory, modelStore, importHost)
+        {
+            this.api = api;
+        }
+
+        protected abstract TDownloadRequestModel CreateDownloadRequest(TModel model);
+
+        public bool Download(TModel model)
+        {
+            var existing = GetExistingDownload(model);
+
+            if (existing != null || api == null) return false;
+
+            DownloadNotification notification = new DownloadNotification
+            {
+                Text = $"Downloading {model}",
+            };
+
+            var request = CreateDownloadRequest(model);
+
+            request.DownloadProgressed += progress =>
+            {
+                notification.State = ProgressNotificationState.Active;
+                notification.Progress = progress;
+            };
+
+            request.Success += filename =>
+            {
+                Task.Factory.StartNew(() =>
+                {
+                    Import(notification, filename);
+                    currentDownloads.Remove(request);
+                }, TaskCreationOptions.LongRunning);
+            };
+
+            request.Failure += error =>
+            {
+                DownloadFailed?.Invoke(request);
+
+                if (error is OperationCanceledException) return;
+
+                notification.State = ProgressNotificationState.Cancelled;
+                // TODO: implement a Name for every model that we can use in this message
+                Logger.Error(error, "Download failed!");
+                currentDownloads.Remove(request);
+            };
+
+            notification.CancelRequested += () =>
+            {
+                request.Cancel();
+                currentDownloads.Remove(request);
+                notification.State = ProgressNotificationState.Cancelled;
+                return true;
+            };
+
+            currentDownloads.Add(request);
+            PostNotification?.Invoke(notification);
+
+            Task.Factory.StartNew(() =>
+            {
+                try
+                {
+                    request.Perform(api);
+                }
+                catch
+                {
+                }
+            }, TaskCreationOptions.LongRunning);
+
+            DownloadBegan?.Invoke(request);
+
+            return true;
+        }
+
+        public TDownloadRequestModel GetExistingDownload(TModel model) => currentDownloads.Find(r => r.Info.Equals(model));
+
+        private class DownloadNotification : ProgressNotification
+        {
+            public override bool IsImportant => false;
+
+            protected override Notification CreateCompletionNotification() => new SilencedProgressCompletionNotification
+            {
+                Activated = CompletionClickAction,
+                Text = CompletionText
+            };
+
+            private class SilencedProgressCompletionNotification : ProgressCompletionNotification
+            {
+                public override bool IsImportant => false;
+            }
+        }
+    }
+}

osu.Game/Online/API/ArchiveDownloadModelRequest.cs

@@ -0,0 +1,23 @@
+using System;
+using System.Collections.Generic;
+using System.Text;
+
+namespace osu.Game.Online.API
+{
+    public abstract class ArchiveDownloadModelRequest<TModel> : APIDownloadRequest
+        where TModel : class
+    {
+        public readonly TModel Info;
+
+        public float Progress;
+
+        public event Action<float> DownloadProgressed;
+
+        protected ArchiveDownloadModelRequest(TModel model)
+        {
+            Info = model;
+
+            Progressed += (current, total) => DownloadProgressed?.Invoke(Progress = (float)current / total);
+        }
+    }
+}