make kill anim patch update resilient

MiraAPI/Patches/Events/KillAnimationMurderEventPatch.cs

@@ -0,0 +1,35 @@
+using System.Reflection;
+using HarmonyLib;
+using Il2CppInterop.Runtime.InteropTypes;
+using MiraAPI.Events;
+using MiraAPI.Events.Vanilla.Gameplay;
+using MiraAPI.Utilities;
+
+namespace MiraAPI.Patches.Events;
+
+/// <summary>
+/// Patch to invoke AfterMurderEvent after a kill animation is performed.
+/// </summary>
+[HarmonyPatch]
+public static class KillAnimationMurderEventPatch
+{
+    public static MethodBase TargetMethod()
+    {
+        return Helpers.GetStateMachineMoveNext<KillAnimation>(nameof(KillAnimation.CoPerformKill))!;
+    }
+
+    public static void Postfix(Il2CppObjectBase __instance)
+    {
+        var wrapper = new StateMachineWrapper<KillAnimation>(__instance);
+        if (wrapper.GetState() != 1)
+        {
+            return;
+        }
+
+        var source = wrapper.GetParameter<PlayerControl>("source");
+        var target = wrapper.GetParameter<PlayerControl>("target");
+
+        var afterMurderEvent = new AfterMurderEvent(source, target, Helpers.GetBodyById(target.PlayerId));
+        MiraEventManager.InvokeEvent(afterMurderEvent);
+    }
+}

MiraAPI/Patches/Events/KillAnimationPatches.cs

@@ -1,30 +0,0 @@
-using HarmonyLib;
-using MiraAPI.Events;
-using MiraAPI.Events.Vanilla.Gameplay;
-using MiraAPI.Utilities;
-
-namespace MiraAPI.Patches.Events;
-
-/// <summary>
-/// General patches for the KillAnimation class.
-/// </summary>
-[HarmonyPatch]
-public static class KillAnimationPatches
-{
-    /// <summary>
-    /// Used to trigger the <see cref="AfterMurderEvent"/>.
-    /// </summary>
-    [HarmonyPostfix]
-    [HarmonyPatch(typeof(KillAnimation._CoPerformKill_d__2), nameof(KillAnimation._CoPerformKill_d__2.MoveNext))]
-    public static void KillAnimPostfix(KillAnimation._CoPerformKill_d__2 __instance)
-    {
-        // Checking if state is -1 to wait for the end of coroutine.
-        if (__instance.__1__state != -1)
-        {
-            return;
-        }
-
-        var afterMurderEvent = new AfterMurderEvent(__instance.source, __instance.target, Helpers.GetBodyById(__instance.target.PlayerId));
-        MiraEventManager.InvokeEvent(afterMurderEvent);
-    }
-}

MiraAPI/Utilities/StateMachineWrapper.cs

@@ -1,4 +1,6 @@
-using System.Reflection;
+using System;
+using System.Collections.Generic;
+using System.Reflection;
 using HarmonyLib;
 using Il2CppInterop.Runtime.InteropTypes;
 
@@ -11,8 +13,11 @@ namespace MiraAPI.Utilities;
 public class StateMachineWrapper<T> where T : Il2CppObjectBase
 {
     private readonly Il2CppObjectBase _stateMachine;
+
+    // normally it is fields, but IL2CPP turns them into properties
     private readonly PropertyInfo _thisProperty;
     private readonly PropertyInfo _stateProperty;
+    private readonly Dictionary<string, PropertyInfo> _propertyCache;
 
     private T? _parentInstance;
 
@@ -32,6 +37,13 @@ public class StateMachineWrapper<T> where T : Il2CppObjectBase
         var type = _stateMachine.GetType();
         _thisProperty = AccessTools.Property(type, "__4__this");
         _stateProperty = AccessTools.Property(type, "__1__state");
+
+        if (_thisProperty == null || _stateProperty == null)
+        {
+            throw new MissingMemberException($"Could not find required properties in type '{type}'.");
+        }
+
+        _propertyCache = [];
     }
 
     /// <summary>
@@ -39,4 +51,25 @@ public class StateMachineWrapper<T> where T : Il2CppObjectBase
     /// </summary>
     /// <returns>The current state as an integer.</returns>
     public int GetState() => (int)_stateProperty.GetValue(_stateMachine)!;
+
+    /// <summary>
+    /// Gets a parameter from the state machine by its name.
+    /// </summary>
+    /// <param name="parameterName">The name of the parameter to retrieve.</param>
+    /// <typeparam name="TField">The type of the parameter to retrieve.</typeparam>
+    /// <returns>>The value of the specified parameter.</returns>
+    /// <exception cref="MissingFieldException">Thrown if the specified parameter does not exist.</exception>
+    public TField GetParameter<TField>(string parameterName)
+    {
+        if (_propertyCache.TryGetValue(parameterName, out var property))
+        {
+            return (TField)property.GetValue(_stateMachine)!;
+        }
+
+        property = AccessTools.Property(_stateMachine.GetType(), parameterName)
+                   ?? throw new MissingFieldException($"Could not find parameter '{parameterName}' in state machine of type '{_stateMachine.GetType()}'.");
+
+        _propertyCache[parameterName] = property;
+        return (TField)property.GetValue(_stateMachine)!;
+    }
 }