Added RoundStartingEventArgs

Exiled.Events/EventArgs/Server/RoundStartingEventArgs.cs

@@ -0,0 +1,31 @@
+// -----------------------------------------------------------------------
+// <copyright file="RoundStartingEventArgs.cs" company="Exiled Team">
+// Copyright (c) Exiled Team. All rights reserved.
+// Licensed under the CC BY-SA 3.0 license.
+// </copyright>
+// -----------------------------------------------------------------------
+
+namespace Exiled.Events.EventArgs.Server
+{
+    /// <summary>
+    /// Contains all information before the start of the round.
+    /// </summary>
+    public class RoundStartingEventArgs
+    {
+        /// <summary>
+        /// Initializes a new instance of the <see cref="RoundStartingEventArgs" /> class.
+        /// </summary>
+        /// <param name="isAllowed">
+        /// <inheritdoc cref="IsAllowed" />
+        /// </param>
+        public RoundStartingEventArgs(bool isAllowed = true)
+        {
+            IsAllowed = isAllowed;
+        }
+
+        /// <summary>
+        /// Gets or sets a value indicating whether the round can start or not.
+        /// </summary>
+        public bool IsAllowed { get; set; }
+    }
+}

Exiled.Events/Handlers/Server.cs

@@ -103,6 +103,11 @@ public static class Server
         /// </summary>
         public static Event ReloadedPermissions { get; set; } = new();
 
+        /// <summary>
+        /// Invoked before the round starts.
+        /// </summary>
+        public static Event<RoundStartingEventArgs> RoundStarting { get; set; } = new();
+
         /// <summary>
         /// Called before waiting for players.
         /// </summary>
@@ -195,5 +200,11 @@ public static class Server
         /// </summary>
         /// <param name="ev">The <see cref="SelectingRespawnTeamEventArgs"/> instance.</param>
         public static void OnSelectingRespawnTeam(SelectingRespawnTeamEventArgs ev) => SelectingRespawnTeam.InvokeSafely(ev);
+
+        /// <summary>
+        /// Called before round started.
+        /// </summary>
+        /// <param name="ev">The <see cref="RoundStartingEventArgs"/> instance.</param>
+        public static void OnRoundStarting(RoundStartingEventArgs ev) => RoundStarting.InvokeSafely(ev);
     }
-}
+}

Exiled.Events/Patches/Events/Server/RoundStarting.cs

@@ -0,0 +1,78 @@
+// -----------------------------------------------------------------------
+// <copyright file="RoundStarting.cs" company="Exiled Team">
+// Copyright (c) Exiled Team. All rights reserved.
+// Licensed under the CC BY-SA 3.0 license.
+// </copyright>
+// -----------------------------------------------------------------------
+
+namespace Exiled.Events.Patches.Events.Server
+{
+    using System.Collections.Generic;
+    using System.Reflection.Emit;
+
+    using API.Features.Pools;
+    using Exiled.Events.Attributes;
+    using Exiled.Events.EventArgs.Server;
+    using Exiled.Events.Handlers;
+
+    using GameCore;
+
+    using HarmonyLib;
+
+    using static HarmonyLib.AccessTools;
+
+    /// <summary>
+    /// Patch the <see cref="RoundStart.NetworkTimer" />.
+    /// Adds the <see cref="Server.RoundStarting" /> event.
+    /// </summary>
+    [EventPatch(typeof(Server), nameof(Server.RoundStarting))]
+    [HarmonyPatch(typeof(RoundStart), nameof(RoundStart.NetworkTimer), MethodType.Setter)]
+    internal static class RoundStarting
+    {
+        private static IEnumerable<CodeInstruction> Transpiler(IEnumerable<CodeInstruction> instructions, ILGenerator generator)
+        {
+            List<CodeInstruction> newInstructions = ListPool<CodeInstruction>.Pool.Get(instructions);
+
+            Label ret = generator.DefineLabel();
+            Label contlabel = generator.DefineLabel();
+
+            newInstructions[newInstructions.Count - 1].labels.Add(ret);
+            LocalBuilder ev = generator.DeclareLocal(typeof(RoundStartingEventArgs));
+
+            newInstructions.InsertRange(
+                0,
+                new CodeInstruction[]
+                {
+                    // Getting a old value
+                    new CodeInstruction(OpCodes.Ldarg_1),
+
+                    // Getting a new value
+                    new CodeInstruction(OpCodes.Ldc_I4, -1),
+
+                    // If the value is not equal, jump
+                    new CodeInstruction(OpCodes.Bne_Un, contlabel),
+
+                    // RoundStartingEventArgs ev = new
+                    new CodeInstruction(OpCodes.Newobj, GetDeclaredConstructors(typeof(RoundStartingEventArgs))[0]),
+                    new CodeInstruction(OpCodes.Dup),
+                    new CodeInstruction(OpCodes.Stloc_S, ev.LocalIndex),
+
+                    // Handlers.Server.OnRoundStarting(ev)
+                    new CodeInstruction(OpCodes.Call, Method(typeof(Server), nameof(Server.OnRoundStarting))),
+                    new CodeInstruction(OpCodes.Ldloc_S, ev.LocalIndex),
+
+                    // If isallowed = false
+                    new CodeInstruction(OpCodes.Callvirt, PropertyGetter(typeof(RoundStartingEventArgs), nameof(RoundStartingEventArgs.IsAllowed))),
+                    new CodeInstruction(OpCodes.Brfalse_S, ret),
+
+                    // Empty opcode for jump
+                    new CodeInstruction(OpCodes.Nop).WithLabels(contlabel),
+                });
+
+            for (int z = 0; z < newInstructions.Count; z++)
+                yield return newInstructions[z];
+
+            ListPool<CodeInstruction>.Pool.Return(newInstructions);
+        }
+    }
+}