feat: Add Saving By Anti207 event

EXILED/Exiled.Events/EventArgs/Player/SavingByAntiScp207EventArgs.cs

@@ -0,0 +1,74 @@
+// -----------------------------------------------------------------------
+// <copyright file="SavingByAntiScp207EventArgs.cs" company="ExMod Team">
+// Copyright (c) ExMod Team. All rights reserved.
+// Licensed under the CC BY-SA 3.0 license.
+// </copyright>
+// -----------------------------------------------------------------------
+
+namespace Exiled.Events.EventArgs.Player
+{
+    using CustomPlayerEffects;
+    using Exiled.API.Features;
+    using Exiled.API.Features.DamageHandlers;
+    using Exiled.Events.EventArgs.Interfaces;
+
+    /// <summary>
+    /// Contains all information before a player is saved from death by the Anti-SCP-207 effect.
+    /// </summary>
+    public class SavingByAntiScp207EventArgs : IPlayerEvent, IDeniableEvent
+    {
+        /// <summary>
+        /// Initializes a new instance of the <see cref="SavingByAntiScp207EventArgs"/> class.
+        /// </summary>
+        /// <param name="player">The player who is being saved.</param>
+        /// <param name="damageAmount">The amount of damage that would have been applied.</param>
+        /// <param name="handler">The damage handler that describes the damage.</param>
+        /// <param name="hitboxType">The hitbox that was hit.</param>
+        public SavingByAntiScp207EventArgs(ReferenceHub player, float damageAmount, DamageHandlerBase handler, HitboxType hitboxType)
+        {
+            Player = Player.Get(player);
+
+            Handler = handler;
+            HitboxType = hitboxType;
+            DamageAmount = damageAmount;
+            DamageMultiplier = (Player.Health + Player.ArtificialHealth - AntiScp207.DeathSaveHealth) / damageAmount;
+            IsAllowed = true;
+        }
+
+        /// <summary>
+        /// Gets the player who is being saved.
+        /// </summary>
+        public Player Player { get; }
+
+        /// <summary>
+        /// Gets the amount of damage that would have been applied.
+        /// </summary>
+        public float DamageAmount { get; }
+
+        /// <summary>
+        /// Gets or sets the multiplier for the damage that is applied when the event is allowed.
+        /// </summary>
+        public float DamageMultiplier { get; set; }
+
+        /// <summary>
+        /// Gets or sets the multiplier for the damage that if event denied.
+        /// </summary>
+        public float DeniedDamageMultiplier { get; set; } = 1;
+
+        /// <summary>
+        /// Gets the damage handler that describes the incoming damage.
+        /// </summary>
+        public DamageHandlerBase Handler { get; }
+
+        /// <summary>
+        /// Gets the hitbox that was hit.
+        /// </summary>
+        public HitboxType HitboxType { get; }
+
+        /// <summary>
+        /// Gets or sets a value indicating whether the event is allowed.
+        /// If set to <c>false</c>, the event will be denied.
+        /// </summary>
+        public bool IsAllowed { get; set; }
+    }
+}

EXILED/Exiled.Events/Handlers/Player.cs

@@ -113,6 +113,11 @@ public class Player
         /// </summary>
         public static Event<InteractedEventArgs> Interacted { get; set; } = new();
 
+        /// <summary>
+        /// Invoked before a <see cref="API.Features.Player"/> is saved from death by the Anti-SCP-207 effect.
+        /// </summary>
+        public static Event<SavingByAntiScp207EventArgs> SavingByAntiScp207 { get; set; } = new();
+
         /// <summary>
         /// Invoked before spawning a <see cref="API.Features.Player"/> <see cref="API.Features.Ragdoll"/>.
         /// </summary>
@@ -1239,6 +1244,12 @@ public static void OnItemRemoved(ReferenceHub referenceHub, InventorySystem.Item
         /// <param name="ev">The <see cref="HealedEventArgs"/> instance. </param>
         public static void OnHealed(HealedEventArgs ev) => Healed.InvokeSafely(ev);
 
+        /// <summary>
+        /// Called before a <see cref="API.Features.Player"/> is saved from death by the Anti-SCP-207 effect.
+        /// </summary>
+        /// <param name="ev">The <see cref="SavingByAntiScp207EventArgs"/> instance.</param>
+        public static void OnSavingByAntiScp207(SavingByAntiScp207EventArgs ev) => SavingByAntiScp207.InvokeSafely(ev);
+
         /// <summary>
         /// Called before a <see cref="API.Features.Player"/> dies.
         /// </summary>

EXILED/Exiled.Events/Patches/Events/Player/SavingByAntiScp207.cs

@@ -0,0 +1,96 @@
+// -----------------------------------------------------------------------
+// <copyright file="SavingByAntiScp207.cs" company="ExMod Team">
+// Copyright (c) ExMod Team. All rights reserved.
+// Licensed under the CC BY-SA 3.0 license.
+// </copyright>
+// -----------------------------------------------------------------------
+
+namespace Exiled.Events.Patches.Events.Player
+{
+    using System.Collections.Generic;
+    using System.Reflection.Emit;
+
+    using CustomPlayerEffects;
+    using Exiled.API.Features.Pools;
+    using Exiled.Events.Attributes;
+    using Exiled.Events.EventArgs.Player;
+
+    using HarmonyLib;
+
+    using static HarmonyLib.AccessTools;
+
+    /// <summary>
+    /// Patches <see cref="AntiScp207.GetDamageModifier"/>.
+    /// Adds the <see cref="Handlers.Player.SavingByAntiScp207"/> event before the player is saved from Anti-SCP-207 damage.
+    /// </summary>
+    [EventPatch(typeof(Handlers.Player), nameof(Handlers.Player.SavingByAntiScp207))]
+    [HarmonyPatch(typeof(AntiScp207), nameof(AntiScp207.GetDamageModifier))]
+    internal class SavingByAntiScp207
+    {
+        private static IEnumerable<CodeInstruction> Transpiler(IEnumerable<CodeInstruction> instructions, ILGenerator generator)
+        {
+            List<CodeInstruction> newInstructions = ListPool<CodeInstruction>.Pool.Get(instructions);
+
+            LocalBuilder ev = generator.DeclareLocal(typeof(SavingByAntiScp207EventArgs));
+
+            int offset = -1;
+            int index = newInstructions.FindLastIndex(i => i.Calls(Method(typeof(StatusEffectBase), nameof(StatusEffectBase.DisableEffect)))) + offset;
+
+            Label skipLabel = generator.DefineLabel();
+            Label gotoEventLabel = newInstructions[index].labels[0];
+
+            newInstructions[index].labels = new List<Label> { skipLabel };
+
+            newInstructions.InsertRange(index, new CodeInstruction[]
+            {
+                // this.Hub
+                new CodeInstruction(OpCodes.Ldarg_0).WithLabels(gotoEventLabel),
+                new(OpCodes.Call, PropertyGetter(typeof(StatusEffectBase), nameof(StatusEffectBase.Hub))),
+
+                // damageAmount
+                new(OpCodes.Ldarg_1),
+
+                // handler
+                new(OpCodes.Ldarg_2),
+
+                // hitboxType
+                new(OpCodes.Ldarg_3),
+
+                // SavingByAntiScp207EventArgs ev = new SavingByAntiScp207EventArgs(ReferenceHub, float, DamageHandlerBase, HitboxType)
+                new(OpCodes.Newobj, GetDeclaredConstructors(typeof(SavingByAntiScp207EventArgs))[0]),
+                new(OpCodes.Dup),
+                new(OpCodes.Stloc_S, ev.LocalIndex),
+
+                // Handlers.Player.OnSavingByAntiScp207(ev);
+                new(OpCodes.Call, Method(typeof(Handlers.Player), nameof(Handlers.Player.OnSavingByAntiScp207))),
+
+                // if (!ev.IsAllowed)
+                // return ev.DeniedDamageMultiplier;
+                new(OpCodes.Ldloc_S, ev.LocalIndex),
+                new(OpCodes.Callvirt, PropertyGetter(typeof(SavingByAntiScp207EventArgs), nameof(SavingByAntiScp207EventArgs.IsAllowed))),
+                new(OpCodes.Brtrue_S, skipLabel),
+
+                new(OpCodes.Ldloc_S, ev.LocalIndex),
+                new(OpCodes.Callvirt, PropertyGetter(typeof(SavingByAntiScp207EventArgs), nameof(SavingByAntiScp207EventArgs.DeniedDamageMultiplier))),
+                new(OpCodes.Ret),
+            });
+
+            index = newInstructions.FindLastIndex(i => i.opcode == OpCodes.Ldloc_2);
+
+            newInstructions.InsertRange(index, new CodeInstruction[]
+            {
+                // return ev.DamageMultiplier;
+                new(OpCodes.Ldloc_S, ev.LocalIndex),
+                new(OpCodes.Callvirt, PropertyGetter(typeof(SavingByAntiScp207EventArgs), nameof(SavingByAntiScp207EventArgs.DamageMultiplier))),
+                new(OpCodes.Ret),
+            });
+
+            for (int i = 0; i < newInstructions.Count; i++)
+            {
+                yield return newInstructions[i];
+            }
+
+            ListPool<CodeInstruction>.Pool.Return(newInstructions);
+        }
+    }
+}