From 69352214637b9b5ef6f7e9d56da30da98455584a Mon Sep 17 00:00:00 2001
From: smoogipoo <smoogipoo@smgi.me>
Date: Tue, 14 Apr 2020 21:05:07 +0900
Subject: [PATCH] Improve logic for CSB transfer

---
 osu.Game/Beatmaps/Formats/LegacyDecoder.cs    |  8 ++++--
 .../Objects/Legacy/ConvertHitObjectParser.cs  | 28 ++++++++++++++++---
 2 files changed, 30 insertions(+), 6 deletions(-)

diff --git a/osu.Game/Beatmaps/Formats/LegacyDecoder.cs b/osu.Game/Beatmaps/Formats/LegacyDecoder.cs
index 90a5d0dcba..5b2b213322 100644
--- a/osu.Game/Beatmaps/Formats/LegacyDecoder.cs
+++ b/osu.Game/Beatmaps/Formats/LegacyDecoder.cs
@@ -8,6 +8,7 @@ using osu.Framework.Logging;
 using osu.Game.Audio;
 using osu.Game.Beatmaps.ControlPoints;
 using osu.Game.IO;
+using osu.Game.Rulesets.Objects.Legacy;
 using osuTK.Graphics;
 
 namespace osu.Game.Beatmaps.Formats
@@ -168,8 +169,11 @@ namespace osu.Game.Beatmaps.Formats
             {
                 var baseInfo = base.ApplyTo(hitSampleInfo);
 
-                if (string.IsNullOrEmpty(baseInfo.Suffix) && CustomSampleBank > 0)
-                    baseInfo.Suffix = CustomSampleBank.ToString();
+                if (baseInfo is ConvertHitObjectParser.LegacyHitSampleInfo legacy
+                    && legacy.CustomSampleBank == 0)
+                {
+                    legacy.CustomSampleBank = CustomSampleBank;
+                }
 
                 return baseInfo;
             }
diff --git a/osu.Game/Rulesets/Objects/Legacy/ConvertHitObjectParser.cs b/osu.Game/Rulesets/Objects/Legacy/ConvertHitObjectParser.cs
index 1dca4a5c02..95cbf3ab40 100644
--- a/osu.Game/Rulesets/Objects/Legacy/ConvertHitObjectParser.cs
+++ b/osu.Game/Rulesets/Objects/Legacy/ConvertHitObjectParser.cs
@@ -409,26 +409,46 @@ namespace osu.Game.Rulesets.Objects.Legacy
             public SampleBankInfo Clone() => (SampleBankInfo)MemberwiseClone();
         }
 
-        private class LegacyHitSampleInfo : HitSampleInfo
+        internal class LegacyHitSampleInfo : HitSampleInfo
         {
+            private int customSampleBank;
+
             public int CustomSampleBank
             {
+                get => customSampleBank;
                 set
                 {
+                    customSampleBank = value;
+
+                    // A 0 custom sample bank should cause LegacyBeatmapSkin to always fall back to the user skin. This is done by giving a null suffix.
                     if (value > 0)
                         Suffix = value.ToString();
                 }
             }
+
+            public override IEnumerable<string> LookupNames
+            {
+                get
+                {
+                    // The lookup should only contain the suffix for custom sample bank 2 and beyond.
+                    // For custom sample bank 1 and 0, the lookup should not contain the suffix as only the lookup source (beatmap or user skin) is changed.
+                    if (CustomSampleBank >= 2)
+                        yield return $"{Bank}-{Name}{Suffix}";
+
+                    yield return $"{Bank}-{Name}";
+                }
+            }
         }
 
-        private class FileHitSampleInfo : HitSampleInfo
+        private class FileHitSampleInfo : LegacyHitSampleInfo
         {
             public string Filename;
 
             public FileHitSampleInfo()
             {
-                // Has no effect since LookupNames is overridden, however prompts LegacyBeatmapSkin to not fallback.
-                Suffix = "0";
+                // Make sure that the LegacyBeatmapSkin does not fall back to the user skin.
+                // Note that this does not change the lookup names, as they are overridden locally.
+                CustomSampleBank = 1;
             }
 
             public override IEnumerable<string> LookupNames => new[]