add "IPlayCustomPowerSfx" interface

Hooks/IPlayCustomPowerSfx.cs

@@ -0,0 +1,47 @@
+using System.Reflection.Emit;
+using BaseLib.Utils.Patching;
+using HarmonyLib;
+using MegaCrit.Sts2.Core.Commands;
+using MegaCrit.Sts2.Core.Models;
+using MegaCrit.Sts2.Core.Nodes.Combat;
+
+namespace BaseLib.Hooks;
+
+/// <summary>
+/// Interface for a power that plays a sound when applied other than the default
+/// </summary>
+public interface IPlayCustomPowerSfx
+{
+    /// <summary>
+    /// Play the desired custom sfx using <see cref="SfxCmd.Play(string, float)"/>
+    /// </summary>
+    /// <param name="amount">The amount of power applied</param>
+    /// <param name="isBuff">Is true if the buff sfx would have played, otherwise the debuff sfx would have played</param>
+    /// <returns>Whether or not the sound played (if false, the default power apply sound plays)</returns>
+    public bool PlayCustomPowerSfx(int amount, bool isBuff);
+
+    [HarmonyPatch(typeof(NCreature), nameof(NCreature.OnPowerIncreased))]
+    private class IPlayCustomPowerSfxPatch
+    {
+        public static List<CodeInstruction> Transpiler(IEnumerable<CodeInstruction> instructions) => new InstructionPatcher(instructions)
+            .Match(new InstructionMatcher()
+                .callvirt(AccessTools.PropertyGetter(typeof(PowerModel), nameof(PowerModel.ShouldPlayVfx)))
+            )
+            .GetOperandLabel(out var target) // where to go if we want to skip the default power sfx
+            .Step(1)
+            .Insert([
+                CodeInstruction.LoadArgument(1),
+                CodeInstruction.LoadArgument(2),
+                CodeInstruction.LoadLocal(1),
+                CodeInstruction.Call(typeof(IPlayCustomPowerSfxPatch), nameof(PlaySfx)), // check if a custom sound should play and play it if so
+                new CodeInstruction(OpCodes.Brtrue_S, target), // if a custom sound played, skip playing the default one
+            ]);
+
+        private static bool PlaySfx(PowerModel power, int amount, bool isBuff)
+        {
+            if (power is IPlayCustomPowerSfx custom)
+                return custom.PlayCustomPowerSfx(amount, isBuff);
+            return false;
+        }
+    }
+}