feat: New Player Changed Room events (#557)

* Create RoomChangedEventArgs.cs

* Create ZoneChangedEventArgs.cs

* Added Room / Zone Changed handlers

* Create ChangedRoomZone.cs

* Repeated referencehub references simplified

* Simplify

* Deleted ZoneChangedEventArgs.cs

* Deleted ZoneChanged event handler

* Deleted ChangedZone event codes

* Update and rename ChangedRoomZone.cs to ChangedRoom.cs

* More Comment

* More Fast method

* Micro Optimization

Author: MS-crew

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

@@ -0,0 +1,44 @@
+// -----------------------------------------------------------------------
+// <copyright file="RoomChangedEventArgs.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 Exiled.API.Features;
+    using Exiled.Events.EventArgs.Interfaces;
+    using MapGeneration;
+
+    /// <summary>
+    /// Contains the information when a player changes rooms.
+    /// </summary>
+    public class RoomChangedEventArgs : IPlayerEvent
+    {
+        /// <summary>
+        /// Initializes a new instance of the <see cref="RoomChangedEventArgs"/> class.
+        /// </summary>
+        /// <param name="player">The player whose room has changed.</param>
+        /// <param name="oldRoom">The room identifier before the change (Can be null on round start).</param>
+        /// <param name="newRoom">The room identifier after the change.</param>
+        public RoomChangedEventArgs(ReferenceHub player, RoomIdentifier oldRoom, RoomIdentifier newRoom)
+        {
+            Player = Player.Get(player);
+            OldRoom = Room.Get(oldRoom);
+            NewRoom = Room.Get(newRoom);
+        }
+
+        /// <inheritdoc/>
+        public Player Player { get; }
+
+        /// <summary>
+        /// Gets the previous room the player was in.
+        /// </summary>
+        public Room OldRoom { get; }
+
+        /// <summary>
+        /// Gets the new room the player entered.
+        /// </summary>
+        public Room NewRoom { get; }
+    }
+}

EXILED/Exiled.Events/Handlers/Player.cs

@@ -494,6 +494,11 @@ public class Player
         /// </summary>
         public static Event<ChangingSpectatedPlayerEventArgs> ChangingSpectatedPlayer { get; set; } = new();
 
+        /// <summary>
+        /// Invoked when a <see cref="API.Features.Player"/> changes rooms.
+        /// </summary>
+        public static Event<RoomChangedEventArgs> RoomChanged { get; set; } = new();
+
         /// <summary>
         /// Invoked before a <see cref="API.Features.Player"/> toggles the NoClip mode.
         /// </summary>
@@ -810,6 +815,12 @@ public class Player
         /// <param name="ev">The <see cref="RemovedHandcuffsEventArgs"/> instance.</param>
         public static void OnRemovedHandcuffs(RemovedHandcuffsEventArgs ev) => RemovedHandcuffs.InvokeSafely(ev);
 
+        /// <summary>
+        /// Called when a <see cref="API.Features.Player"/> changes rooms.
+        /// </summary>
+        /// <param name="ev">The <see cref="RoomChangedEventArgs"/> instance.</param>
+        public static void OnRoomChanged(RoomChangedEventArgs ev) => RoomChanged.InvokeSafely(ev);
+
         /// <summary>
         /// Called before a <see cref="API.Features.Player"/> escapes.
         /// </summary>

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

@@ -0,0 +1,91 @@
+// -----------------------------------------------------------------------
+// <copyright file="ChangedRoom.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 Exiled.API.Features.Pools;
+    using Exiled.Events.Attributes;
+    using Exiled.Events.EventArgs.Player;
+    using Exiled.Events.Handlers;
+    using HarmonyLib;
+    using MapGeneration;
+    using UnityEngine;
+
+    using static HarmonyLib.AccessTools;
+
+    /// <summary>
+    /// Patches <see cref="CurrentRoomPlayerCache.ValidateCache"/> to add the <see cref="Player.RoomChanged"/> event.
+    /// </summary>
+    [EventPatch(typeof(Player), nameof(Player.RoomChanged))]
+    [HarmonyPatch(typeof(CurrentRoomPlayerCache), nameof(CurrentRoomPlayerCache.ValidateCache))]
+    internal class ChangedRoom
+    {
+        private static IEnumerable<CodeInstruction> Transpiler(IEnumerable<CodeInstruction> instructions, ILGenerator generator)
+        {
+            List<CodeInstruction> newInstructions = ListPool<CodeInstruction>.Pool.Get(instructions);
+
+            Label returnLabel = generator.DefineLabel();
+
+            LocalBuilder oldRoom = generator.DeclareLocal(typeof(RoomIdentifier));
+            LocalBuilder newRoom = generator.DeclareLocal(typeof(RoomIdentifier));
+
+            int index = newInstructions.FindIndex(i => i.opcode == OpCodes.Ldloca_S);
+
+            newInstructions.InsertRange(index, new CodeInstruction[]
+            {
+                // RoomIdentifier oldRoom = this._lastDetected
+                new(OpCodes.Ldarg_0),
+                new(OpCodes.Ldfld, Field(typeof(CurrentRoomPlayerCache), nameof(CurrentRoomPlayerCache._lastDetected))),
+                new(OpCodes.Stloc_S, oldRoom),
+            });
+
+            int lastIndex = newInstructions.Count - 1;
+
+            newInstructions[lastIndex].WithLabels(returnLabel);
+
+            newInstructions.InsertRange(lastIndex, new CodeInstruction[]
+            {
+                // newRoom = lastDetected
+                new(OpCodes.Ldloc_1),
+                new(OpCodes.Dup),
+                new(OpCodes.Stloc_S, newRoom),
+
+                // oldRoom
+                new(OpCodes.Ldloc_S, oldRoom),
+
+                // if (oldRoom == newRoom) return;
+                new(OpCodes.Call, Method(typeof(object), nameof(object.ReferenceEquals), new[] { typeof(object), typeof(object) })),
+                new(OpCodes.Brtrue_S, returnLabel),
+
+                // this._roleManager.gameObject.GetComponent<ReferenceHub>();
+                new(OpCodes.Ldarg_0),
+                new(OpCodes.Ldfld, Field(typeof(CurrentRoomPlayerCache), nameof(CurrentRoomPlayerCache._roleManager))),
+                new(OpCodes.Call, Method(typeof(Component), nameof(Component.GetComponent)).MakeGenericMethod(typeof(ReferenceHub))),
+
+                // oldRoom
+                new(OpCodes.Ldloc_S, oldRoom),
+
+                // newRoom
+                new(OpCodes.Ldloc_S, newRoom),
+
+                // RoomChangedEventArgs ev = new RoomChangedEventArgs(hub, oldRoom, newRoom);
+                new(OpCodes.Newobj, GetDeclaredConstructors(typeof(RoomChangedEventArgs))[0]),
+
+                // Handlers.Player.OnRoomChanged(ev);
+                new(OpCodes.Call, Method(typeof(Player), nameof(Player.OnRoomChanged))),
+            });
+
+            for (int i = 0; i < newInstructions.Count; i++)
+                yield return newInstructions[i];
+
+            ListPool<CodeInstruction>.Pool.Return(newInstructions);
+        }
+    }
+}