Add LegacyOnlineID handling to places that definitely need it

Mostly places that can interact with imported replays.

There are other places that use the online ID as a sort tiebreaker, or
to check presence of a score on results screens, but they should
probably still continue to only use `OnlineID`, since all scores with a
legacy online ID should have an online ID, but the converse is not
generally true.

osu.Game/Extensions/ModelExtensions.cs

@@ -114,8 +114,24 @@ namespace osu.Game.Extensions
         /// </summary>
         /// <param name="instance">The instance to compare.</param>
         /// <param name="other">The other instance to compare against.</param>
-        /// <returns>Whether online IDs match. If either instance is missing an online ID, this will return false.</returns>
-        public static bool MatchesOnlineID(this IScoreInfo? instance, IScoreInfo? other) => matchesOnlineID(instance, other);
+        /// <returns>
+        /// Whether online IDs match.
+        /// Both <see cref="IHasOnlineID{T}.OnlineID"/> and <see cref="IScoreInfo.LegacyOnlineID"/> are checked, in that order.
+        /// If either instance is missing an online ID, this will return false.
+        /// </returns>
+        public static bool MatchesOnlineID(this IScoreInfo? instance, IScoreInfo? other)
+        {
+            if (matchesOnlineID(instance, other))
+                return true;
+
+            if (instance == null || other == null)
+                return false;
+
+            if (instance.LegacyOnlineID < 0 || other.LegacyOnlineID < 0)
+                return false;
+
+            return instance.LegacyOnlineID.Equals(other.LegacyOnlineID);
+        }
 
         private static bool matchesOnlineID(this IHasOnlineID<long>? instance, IHasOnlineID<long>? other)
         {

osu.Game/Online/ScoreDownloadTracker.cs

@@ -39,7 +39,8 @@ namespace osu.Game.Online
             var scoreInfo = new ScoreInfo
             {
                 ID = TrackedItem.ID,
-                OnlineID = TrackedItem.OnlineID
+                OnlineID = TrackedItem.OnlineID,
+                LegacyOnlineID = TrackedItem.LegacyOnlineID
             };
 
             Downloader.DownloadBegan += downloadBegan;
@@ -47,6 +48,7 @@ namespace osu.Game.Online
 
             realmSubscription = realm.RegisterForNotifications(r => r.All<ScoreInfo>().Where(s =>
                 ((s.OnlineID > 0 && s.OnlineID == TrackedItem.OnlineID)
+                 || (s.LegacyOnlineID > 0 && s.LegacyOnlineID == TrackedItem.LegacyOnlineID)
                  || (!string.IsNullOrEmpty(s.Hash) && s.Hash == TrackedItem.Hash))
                 && !s.DeletePending), (items, _) =>
             {

osu.Game/OsuGame.cs

@@ -678,6 +678,9 @@ namespace osu.Game
             if (score.OnlineID > 0)
                 databasedScoreInfo = ScoreManager.Query(s => s.OnlineID == score.OnlineID);
 
+            if (score.LegacyOnlineID > 0)
+                databasedScoreInfo ??= ScoreManager.Query(s => s.LegacyOnlineID == score.LegacyOnlineID);
+
             if (score is ScoreInfo scoreInfo)
                 databasedScoreInfo ??= ScoreManager.Query(s => s.Hash == scoreInfo.Hash);
 

osu.Game/Scoring/IScoreInfo.cs

@@ -24,6 +24,8 @@ namespace osu.Game.Scoring
 
         bool HasReplay { get; }
 
+        long LegacyOnlineID { get; }
+
         DateTimeOffset Date { get; }
 
         double? PP { get; }

osu.Game/Scoring/ScoreManager.cs

@@ -150,7 +150,11 @@ namespace osu.Game.Scoring
 
         public Task Import(ImportTask[] imports, ImportParameters parameters = default) => scoreImporter.Import(imports, parameters);
 
-        public override bool IsAvailableLocally(ScoreInfo model) => Realm.Run(realm => realm.All<ScoreInfo>().Any(s => s.OnlineID == model.OnlineID));
+        public override bool IsAvailableLocally(ScoreInfo model)
+            => Realm.Run(realm => realm.All<ScoreInfo>()
+                                       // this basically inlines `ModelExtension.MatchesOnlineID(IScoreInfo, IScoreInfo)`,
+                                       // because that method can't be used here, as realm can't translate it to its query language.
+                                       .Any(s => s.OnlineID == model.OnlineID || s.LegacyOnlineID == model.LegacyOnlineID));
 
         public IEnumerable<string> HandledExtensions => scoreImporter.HandledExtensions;