Add "Mirror" mod to osu!catch

osu.Game.Rulesets.Catch/CatchRuleset.cs

@@ -117,6 +117,7 @@ namespace osu.Game.Rulesets.Catch
                     {
                         new CatchModDifficultyAdjust(),
                         new CatchModClassic(),
+                        new CatchModMirror(),
                     };
 
                 case ModType.Automation:

osu.Game.Rulesets.Catch/Mods/CatchModMirror.cs

@@ -0,0 +1,39 @@
+// Copyright (c) ppy Pty Ltd <contact@ppy.sh>. Licensed under the MIT Licence.
+// See the LICENCE file in the repository root for full licence text.
+
+using System.Linq;
+using osu.Game.Rulesets.Catch.Objects;
+using osu.Game.Rulesets.Mods;
+using osu.Game.Rulesets.Catch.UI;
+using osu.Game.Rulesets.Objects;
+using osuTK;
+
+namespace osu.Game.Rulesets.Catch.Mods
+{
+    public class CatchModMirror : ModMirror, IApplicableToHitObject
+    {
+        public override string Description => "Fruits are flipped horizontally.";
+        
+        public void ApplyToHitObject(HitObject hitObject)
+        {
+            var catchObject = (CatchHitObject)hitObject;
+
+            if (catchObject is BananaShower)
+                return;
+
+            catchObject.OriginalX = CatchPlayfield.WIDTH - catchObject.OriginalX;
+
+            foreach (var nested in catchObject.NestedHitObjects.Cast<CatchHitObject>())
+                nested.OriginalX = CatchPlayfield.WIDTH - nested.OriginalX;
+
+            if (!(catchObject is JuiceStream juiceStream))
+                return;
+
+            var controlPoints = juiceStream.Path.ControlPoints.Select(p => new PathControlPoint(p.Position.Value, p.Type.Value)).ToArray();
+            foreach (var point in controlPoints)
+                point.Position.Value = new Vector2(-point.Position.Value.X, point.Position.Value.Y);
+
+            juiceStream.Path = new SliderPath(controlPoints, juiceStream.Path.ExpectedDistance.Value);
+        }
+    }
+}