Add functionality to mass reset offsets

osu.Game/Beatmaps/BeatmapManager.cs

@@ -313,6 +313,22 @@ public void DeleteAllVideos()
             });
         }
 
+        public void ResetAllOffsets()
+        {
+            const string reset_complete_message = "All offsets have been reset!";
+            Realm.Write(r =>
+            {
+                var items = r.All<BeatmapInfo>();
+
+                foreach (var beatmap in items)
+                {
+                    beatmap.UserSettings.Offset = 0.0;
+                }
+
+                PostNotification?.Invoke(new ProgressCompletionNotification { Text = reset_complete_message });
+            });
+        }
+
         public void Delete(Expression<Func<BeatmapSetInfo, bool>>? filter = null, bool silent = false)
         {
             Realm.Run(r =>

osu.Game/Localisation/DeleteConfirmationContentStrings.cs

@@ -19,6 +19,11 @@ public static class DeleteConfirmationContentStrings
         /// </summary>
         public static LocalisableString BeatmapVideos => new TranslatableString(getKey(@"beatmap_videos"), @"Are you sure you want to delete all beatmaps videos? This cannot be undone!");
 
+        /// <summary>
+        /// "Are you sure you want to reset all local beatmap offsets? This cannot be undone!"
+        /// </summary>
+        public static LocalisableString Offsets => new TranslatableString(getKey(@"offsets"), @"Are you sure you want to reset all local beatmap offsets? This cannot be undone!");
+
         /// <summary>
         /// "Are you sure you want to delete all skins? This cannot be undone!"
         /// </summary>

osu.Game/Localisation/MaintenanceSettingsStrings.cs

@@ -59,6 +59,11 @@ public static class MaintenanceSettingsStrings
         /// </summary>
         public static LocalisableString DeleteAllBeatmapVideos => new TranslatableString(getKey(@"delete_all_beatmap_videos"), @"Delete ALL beatmap videos");
 
+        /// <summary>
+        /// "Reset ALL beatmap offsets"
+        /// </summary>
+        public static LocalisableString ResetAllOffsets => new TranslatableString(getKey(@"reset_all_offsets"), @"Reset ALL beatmap offsets");
+
         /// <summary>
         /// "Delete ALL scores"
         /// </summary>

osu.Game/Overlays/Settings/Sections/Maintenance/BeatmapSettings.cs

@@ -16,6 +16,7 @@ public partial class BeatmapSettings : SettingsSubsection
 
         private SettingsButton deleteBeatmapsButton = null!;
         private SettingsButton deleteBeatmapVideosButton = null!;
+        private SettingsButton resetOffsetsButton = null!;
         private SettingsButton restoreButton = null!;
         private SettingsButton undeleteButton = null!;
 
@@ -47,6 +48,20 @@ private void load(BeatmapManager beatmaps, IDialogOverlay? dialogOverlay)
                     }, DeleteConfirmationContentStrings.BeatmapVideos));
                 }
             });
+
+            Add(resetOffsetsButton = new DangerousSettingsButton
+            {
+                Text = MaintenanceSettingsStrings.ResetAllOffsets,
+                Action = () =>
+                {
+                    dialogOverlay?.Push(new MassDeleteConfirmationDialog(() =>
+                    {
+                        resetOffsetsButton.Enabled.Value = false;
+                        Task.Run(beatmaps.ResetAllOffsets).ContinueWith(_ => Schedule(() => resetOffsetsButton.Enabled.Value = true));
+                    }, DeleteConfirmationContentStrings.Offsets));
+                }
+            });
+
             AddRange(new Drawable[]
             {
                 restoreButton = new SettingsButton