Implement friend leaderboards (#589)

The query here is extraordinarily slow (~10s in Debug mode on my
machine, with a warmed up JIT). But leaving it as a 404 causes the game
to wait a full 30 seconds between requests, so even though these
requests are serial in LBP, its still faster for users in the end to
have it implemented.

We can optimize the query after Postgres gets in.

Refresh.GameServer/Database/GameDatabaseContext.Leaderboard.cs

@@ -60,8 +60,6 @@ public GameSubmittedScore SubmitScore(SerializedScore score, GameUser user, Game
         return newScore;
     }
 
-    [UsedImplicitly] private record ScoreLevelWithPlayer(GameLevel Level, GameUser Player);
-
     public DatabaseList<GameSubmittedScore> GetTopScoresForLevel(GameLevel level, int count, int skip, byte type, bool showDuplicates = false)
     {
         IEnumerable<GameSubmittedScore> scores = this.GameSubmittedScores
@@ -70,7 +68,7 @@ public DatabaseList<GameSubmittedScore> GetTopScoresForLevel(GameLevel level, in
             .AsEnumerable();
 
         if (!showDuplicates)
-            scores = scores.DistinctBy(s => new ScoreLevelWithPlayer(s.Level, s.Players[0]));
+            scores = scores.DistinctBy(s => s.Players[0]);
 
         return new DatabaseList<GameSubmittedScore>(scores, skip, count);
     }
@@ -86,13 +84,30 @@ public IEnumerable<ScoreWithRank> GetRankedScoresAroundScore(GameSubmittedScore
             .AsEnumerable()
             .ToList();
 
-        scores = scores.DistinctBy(s => new ScoreLevelWithPlayer(s.Level, s.Players[0]))
+        scores = scores.DistinctBy(s => s.Players[0])
             .ToList();
 
         return scores.Select((s, i) => new ScoreWithRank(s, i + 1))
             .Skip(Math.Min(scores.Count, scores.IndexOf(score) - count / 2)) // center user's score around other scores
             .Take(count);
     }
+
+    public IEnumerable<ScoreWithRank> GetLevelTopScoresByFriends(GameUser user, GameLevel level, int count, byte type)
+    {
+        IEnumerable<GameUser> mutuals = this.GetUsersMutuals(user);
+
+        IEnumerable<GameSubmittedScore> scores = this.GameSubmittedScores
+            .Where(s => s.ScoreType == type && s.Level == level)
+            .OrderByDescending(s => s.Score)
+            .AsEnumerable()
+            .DistinctBy(s => s.Players[0].UserId)
+            //TODO: THIS CALL IS EXTREMELY INEFFECIENT!!! once we are in postgres land, figure out a way to do this effeciently
+            .Where(s => s.Players.Any(p => p.UserId == user.UserId || mutuals.Contains(p)))
+            .Take(10)
+            .ToList();
+
+        return scores.Select((s, i) => new ScoreWithRank(s, i + 1));
+    }
 
     [Pure]
     [ContractAnnotation("null => null; notnull => canbenull")]

Refresh.GameServer/Endpoints/Game/Levels/LeaderboardEndpoints.cs

@@ -1,6 +1,7 @@
 using System.Diagnostics;
 using Bunkum.Core;
 using Bunkum.Core.Endpoints;
+using Bunkum.Core.Endpoints.Debugging;
 using Bunkum.Core.RateLimit;
 using Bunkum.Core.Responses;
 using Bunkum.Listener.Protocol;
@@ -11,6 +12,7 @@
 using Refresh.GameServer.Types.Levels;
 using Refresh.GameServer.Types.Lists;
 using Refresh.GameServer.Types.Roles;
+using Refresh.GameServer.Types.Scores;
 using Refresh.GameServer.Types.UserData;
 using Refresh.GameServer.Types.UserData.Leaderboard;
 
@@ -66,6 +68,23 @@ public Response GetUserScores(RequestContext context, GameUser user, GameDatabas
 
         return new Response(SerializedMultiLeaderboardResponse.FromOld(multiLeaderboard), ContentType.Xml);
     }
+
+    [GameEndpoint("scoreboard/friends/{slotType}/{id}", HttpMethods.Post, ContentType.Xml)]
+    [RateLimitSettings(RequestTimeoutDuration, MaxRequestAmount, RequestBlockDuration, BucketName)]
+    [NullStatusCode(NotFound)]
+    public SerializedScoreLeaderboardList? GetLevelFriendLeaderboard(
+        RequestContext context, 
+        GameUser user, 
+        GameDatabaseContext database, 
+        string slotType, 
+        int id, 
+        FriendScoresRequest body)
+    {
+        GameLevel? level = database.GetLevelByIdAndType(slotType, id);
+        if (level == null) return null;
+
+        return SerializedScoreLeaderboardList.FromSubmittedEnumerable(database.GetLevelTopScoresByFriends(user, level, 10, body.Type));
+    }
 
     [GameEndpoint("scoreboard/{slotType}/{id}", ContentType.Xml, HttpMethods.Post)]
     [RateLimitSettings(RequestTimeoutDuration, MaxRequestAmount, RequestBlockDuration, BucketName)]

Refresh.GameServer/Types/Scores/FriendScoresRequest.cs

@@ -0,0 +1,13 @@
+using System.Xml.Serialization;
+
+namespace Refresh.GameServer.Types.Scores;
+
+[XmlRoot("playRecord")]
+public class FriendScoresRequest
+{
+    [XmlElement("playerIds")]
+    public List<string> Usernames { get; set; }
+
+    [XmlElement("type")]
+    public byte Type { get; set; }
+}