From a4551dc1eeb2eb6afb9dec61752559eaa6e5632c Mon Sep 17 00:00:00 2001
From: smoogipoo <smoogipoo@smgi.me>
Date: Fri, 5 Feb 2021 14:31:22 +0900
Subject: [PATCH] Add object-ordered hit policy

---
 .../UI/ObjectOrderedHitPolicy.cs              | 55 +++++++++++++++++++
 osu.Game.Rulesets.Osu/UI/OsuPlayfield.cs      |  4 +-
 2 files changed, 57 insertions(+), 2 deletions(-)
 create mode 100644 osu.Game.Rulesets.Osu/UI/ObjectOrderedHitPolicy.cs

diff --git a/osu.Game.Rulesets.Osu/UI/ObjectOrderedHitPolicy.cs b/osu.Game.Rulesets.Osu/UI/ObjectOrderedHitPolicy.cs
new file mode 100644
index 0000000000..fdab241a9b
--- /dev/null
+++ b/osu.Game.Rulesets.Osu/UI/ObjectOrderedHitPolicy.cs
@@ -0,0 +1,55 @@
+// 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.Collections.Generic;
+using System.Linq;
+using osu.Game.Rulesets.Objects;
+using osu.Game.Rulesets.Objects.Drawables;
+using osu.Game.Rulesets.Osu.Objects.Drawables;
+
+namespace osu.Game.Rulesets.Osu.UI
+{
+    /// <summary>
+    /// Ensures that <see cref="HitObject"/>s are hit in order of appearance. The classic note lock.
+    /// <remarks>
+    /// Hits will be blocked until the previous <see cref="HitObject"/>s have been judged.
+    /// </remarks>
+    /// </summary>
+    public class ObjectOrderedHitPolicy : IHitPolicy
+    {
+        private IEnumerable<DrawableHitObject> hitObjects;
+
+        public void SetHitObjects(IEnumerable<DrawableHitObject> hitObjects) => this.hitObjects = hitObjects;
+
+        public bool IsHittable(DrawableHitObject hitObject, double time) => enumerateHitObjectsUpTo(hitObject.HitObject.StartTime).All(obj => obj.AllJudged);
+
+        public void HandleHit(DrawableHitObject hitObject)
+        {
+        }
+
+        private IEnumerable<DrawableHitObject> enumerateHitObjectsUpTo(double targetTime)
+        {
+            foreach (var obj in hitObjects)
+            {
+                if (obj.HitObject.StartTime >= targetTime)
+                    yield break;
+
+                switch (obj)
+                {
+                    case DrawableSpinner _:
+                        continue;
+
+                    case DrawableSlider slider:
+                        yield return slider.HeadCircle;
+
+                        break;
+
+                    default:
+                        yield return obj;
+
+                        break;
+                }
+            }
+        }
+    }
+}
diff --git a/osu.Game.Rulesets.Osu/UI/OsuPlayfield.cs b/osu.Game.Rulesets.Osu/UI/OsuPlayfield.cs
index c7900558a0..6cb890323b 100644
--- a/osu.Game.Rulesets.Osu/UI/OsuPlayfield.cs
+++ b/osu.Game.Rulesets.Osu/UI/OsuPlayfield.cs
@@ -31,7 +31,7 @@ namespace osu.Game.Rulesets.Osu.UI
         private readonly ProxyContainer spinnerProxies;
         private readonly JudgementContainer<DrawableOsuJudgement> judgementLayer;
         private readonly FollowPointRenderer followPoints;
-        private readonly StartTimeOrderedHitPolicy hitPolicy;
+        private readonly IHitPolicy hitPolicy;
 
         public static readonly Vector2 BASE_SIZE = new Vector2(512, 384);
 
@@ -54,7 +54,7 @@ namespace osu.Game.Rulesets.Osu.UI
                 approachCircles = new ProxyContainer { RelativeSizeAxes = Axes.Both },
             };
 
-            hitPolicy = new StartTimeOrderedHitPolicy();
+            hitPolicy = new ObjectOrderedHitPolicy();
             hitPolicy.SetHitObjects(HitObjectContainer.AliveObjects);
 
             var hitWindows = new OsuHitWindows();