From da9c23f3478356b9183fecbe82d0d416c039a26d Mon Sep 17 00:00:00 2001
From: Salman Ahmed <frenzibyte@gmail.com>
Date: Sat, 16 Jan 2021 23:00:56 +0300
Subject: [PATCH] Add beatmap availability tracker component for multiplayer

---
 .../Online/Rooms/MultiplayerBeatmapTracker.cs | 89 +++++++++++++++++++
 1 file changed, 89 insertions(+)
 create mode 100644 osu.Game/Online/Rooms/MultiplayerBeatmapTracker.cs

diff --git a/osu.Game/Online/Rooms/MultiplayerBeatmapTracker.cs b/osu.Game/Online/Rooms/MultiplayerBeatmapTracker.cs
new file mode 100644
index 0000000000..b22d17f3ef
--- /dev/null
+++ b/osu.Game/Online/Rooms/MultiplayerBeatmapTracker.cs
@@ -0,0 +1,89 @@
+// 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;
+using System.Linq;
+using osu.Framework.Bindables;
+using osu.Game.Beatmaps;
+
+namespace osu.Game.Online.Rooms
+{
+    public class MultiplayerBeatmapTracker : DownloadTrackingComposite<BeatmapSetInfo, BeatmapManager>
+    {
+        public readonly IBindable<PlaylistItem> SelectedItem = new Bindable<PlaylistItem>();
+
+        /// <summary>
+        /// The availability state of the currently selected playlist item.
+        /// </summary>
+        public IBindable<BeatmapAvailability> Availability => availability;
+
+        private readonly Bindable<BeatmapAvailability> availability = new Bindable<BeatmapAvailability>();
+
+        public MultiplayerBeatmapTracker()
+        {
+            State.BindValueChanged(_ => updateAvailability());
+            Progress.BindValueChanged(_ => updateAvailability());
+            updateAvailability();
+        }
+
+        protected override void LoadComplete()
+        {
+            base.LoadComplete();
+
+            SelectedItem.BindValueChanged(item => Model.Value = item.NewValue?.Beatmap.Value.BeatmapSet, true);
+        }
+
+        protected override bool VerifyDatabasedModel(BeatmapSetInfo databasedSet)
+        {
+            int? beatmapId = SelectedItem.Value.Beatmap.Value.OnlineBeatmapID;
+            string checksum = SelectedItem.Value.Beatmap.Value.MD5Hash;
+
+            BeatmapInfo matchingBeatmap;
+
+            if (databasedSet.Beatmaps == null)
+            {
+                // The given databased beatmap set is not passed in a usable state to check with.
+                // Perform a full query instead, as per https://github.com/ppy/osu/pull/11415.
+                matchingBeatmap = Manager.QueryBeatmap(b => b.OnlineBeatmapID == beatmapId && b.MD5Hash == checksum);
+                return matchingBeatmap != null;
+            }
+
+            matchingBeatmap = databasedSet.Beatmaps.FirstOrDefault(b => b.OnlineBeatmapID == beatmapId && b.MD5Hash == checksum);
+            return matchingBeatmap != null;
+        }
+
+        protected override bool IsModelAvailableLocally()
+        {
+            int? beatmapId = SelectedItem.Value.Beatmap.Value.OnlineBeatmapID;
+            string checksum = SelectedItem.Value.Beatmap.Value.MD5Hash;
+
+            var beatmap = Manager.QueryBeatmap(b => b.OnlineBeatmapID == beatmapId && b.MD5Hash == checksum);
+            return beatmap?.BeatmapSet.DeletePending == false;
+        }
+
+        private void updateAvailability()
+        {
+            switch (State.Value)
+            {
+                case DownloadState.NotDownloaded:
+                    availability.Value = BeatmapAvailability.NotDownloaded();
+                    break;
+
+                case DownloadState.Downloading:
+                    availability.Value = BeatmapAvailability.Downloading(Progress.Value);
+                    break;
+
+                case DownloadState.Importing:
+                    availability.Value = BeatmapAvailability.Importing();
+                    break;
+
+                case DownloadState.LocallyAvailable:
+                    availability.Value = BeatmapAvailability.LocallyAvailable();
+                    break;
+
+                default:
+                    throw new ArgumentOutOfRangeException(nameof(State));
+            }
+        }
+    }
+}