From 8204d360a8d84f5ac3fe2eec40155999c23a5ba2 Mon Sep 17 00:00:00 2001
From: Dean Herbert <pe@ppy.sh>
Date: Tue, 9 Feb 2021 13:44:42 +0900
Subject: [PATCH] Always reset local user settings when a mod is deselected in
 ModSelectOverlay

---
 osu.Game/Overlays/Mods/ModButton.cs           |  2 ++
 osu.Game/Overlays/Mods/ModSection.cs          |  4 +++-
 osu.Game/Rulesets/Mods/Mod.cs                 |  5 +++++
 osu.Game/Rulesets/Mods/ModDifficultyAdjust.cs | 11 +++++++++++
 4 files changed, 21 insertions(+), 1 deletion(-)

diff --git a/osu.Game/Overlays/Mods/ModButton.cs b/osu.Game/Overlays/Mods/ModButton.cs
index 8e0d1f5bbd..06f2fea43f 100644
--- a/osu.Game/Overlays/Mods/ModButton.cs
+++ b/osu.Game/Overlays/Mods/ModButton.cs
@@ -69,6 +69,8 @@ private bool changeSelectedIndex(int newIndex)
 
             Mod newSelection = SelectedMod ?? Mods[0];
 
+            newSelection.ResetSettingsToDefaults();
+
             Schedule(() =>
             {
                 if (beforeSelected != Selected)
diff --git a/osu.Game/Overlays/Mods/ModSection.cs b/osu.Game/Overlays/Mods/ModSection.cs
index ecbcba7ad3..08bd3f8622 100644
--- a/osu.Game/Overlays/Mods/ModSection.cs
+++ b/osu.Game/Overlays/Mods/ModSection.cs
@@ -197,8 +197,10 @@ private void updateButtonSelection(ModButton button, IReadOnlyList<Mod> newSelec
                     continue;
 
                 var buttonMod = button.Mods[index];
-                buttonMod.CopyFrom(mod);
                 button.SelectAt(index);
+
+                // the selection above will reset settings to defaults, but as this is an external change we want to copy the new settings across.
+                buttonMod.CopyFrom(mod);
                 return;
             }
 
diff --git a/osu.Game/Rulesets/Mods/Mod.cs b/osu.Game/Rulesets/Mods/Mod.cs
index dec72d94e5..2a11c92223 100644
--- a/osu.Game/Rulesets/Mods/Mod.cs
+++ b/osu.Game/Rulesets/Mods/Mod.cs
@@ -173,5 +173,10 @@ internal virtual void CopyAdjustedSetting(IBindable target, object source)
         }
 
         public bool Equals(IMod other) => GetType() == other?.GetType();
+
+        /// <summary>
+        /// Reset all custom settings for this mod back to their defaults.
+        /// </summary>
+        public virtual void ResetSettingsToDefaults() => CopyFrom((Mod)Activator.CreateInstance(GetType()));
     }
 }
diff --git a/osu.Game/Rulesets/Mods/ModDifficultyAdjust.cs b/osu.Game/Rulesets/Mods/ModDifficultyAdjust.cs
index a531e885db..dbc35569e7 100644
--- a/osu.Game/Rulesets/Mods/ModDifficultyAdjust.cs
+++ b/osu.Game/Rulesets/Mods/ModDifficultyAdjust.cs
@@ -141,5 +141,16 @@ protected virtual void ApplySettings(BeatmapDifficulty difficulty)
             ApplySetting(DrainRate, dr => difficulty.DrainRate = dr);
             ApplySetting(OverallDifficulty, od => difficulty.OverallDifficulty = od);
         }
+
+        public override void ResetSettingsToDefaults()
+        {
+            base.ResetSettingsToDefaults();
+
+            if (difficulty != null)
+            {
+                // base implementation potentially overwrite modified defaults that came from a beatmap selection.
+                TransferSettings(difficulty);
+            }
+        }
     }
 }