Fix for holoparasite's ability to attack the host through mech (#36659)

Content.Server/Guardian/GuardianSystem.cs

@@ -10,6 +10,7 @@ using Content.Shared.Hands.EntitySystems;
 using Content.Shared.IdentityManagement;
 using Content.Shared.Interaction;
 using Content.Shared.Interaction.Events;
+using Content.Shared.Mech.EntitySystems;
 using Content.Shared.Mobs;
 using Content.Shared.Popups;
 using Robust.Shared.Audio.Systems;
@@ -56,6 +57,8 @@ namespace Content.Server.Guardian
             SubscribeLocalEvent<GuardianHostComponent, GuardianToggleActionEvent>(OnPerformAction);
 
             SubscribeLocalEvent<GuardianComponent, AttackAttemptEvent>(OnGuardianAttackAttempt);
+
+            SubscribeLocalEvent<GuardianHostComponent, MechPilotRelayedEvent<GettingAttackedAttemptEvent>>(OnPilotAttackAttempt);
         }
 
         private void OnGuardianShutdown(EntityUid uid, GuardianComponent component, ComponentShutdown args)
@@ -144,6 +147,16 @@ namespace Content.Server.Guardian
             args.Cancel();
         }
 
+        private void OnPilotAttackAttempt(Entity<GuardianHostComponent> uid, ref MechPilotRelayedEvent<GettingAttackedAttemptEvent> args)
+        {
+            if (args.Args.Cancelled)
+                return;
+
+            _popupSystem.PopupCursor(Loc.GetString("guardian-attack-host"), args.Args.Attacker, PopupType.LargeCaution);
+
+            args.Args.Cancelled = true;
+        }
+
         public void ToggleGuardian(EntityUid user, GuardianHostComponent hostComponent)
         {
             if (!TryComp<GuardianComponent>(hostComponent.HostedGuardian, out var guardianComponent))

Content.Shared/Guardian/GuardianCreatorDoAfterEvent.cs

@@ -1,4 +1,4 @@
-using Content.Shared.DoAfter;
+using Content.Shared.DoAfter;
 using Robust.Shared.Serialization;
 
 namespace Content.Shared.Guardian;

Content.Shared/Mech/EntitySystems/SharedMechSystem.Relay.cs

@@ -0,0 +1,40 @@
+using Content.Shared.Interaction.Events;
+using Content.Shared.Mech.Components;
+
+namespace Content.Shared.Mech.EntitySystems;
+
+public abstract partial class SharedMechSystem
+{
+    private void InitializeRelay()
+    {
+        SubscribeLocalEvent<MechComponent, GettingAttackedAttemptEvent>(RelayRefToPilot);
+    }
+
+    private void RelayToPilot<T>(Entity<MechComponent> uid, T args) where T : class
+    {
+        if (uid.Comp.PilotSlot.ContainedEntity is not { } pilot)
+            return;
+
+        var ev = new MechPilotRelayedEvent<T>(args);
+
+        RaiseLocalEvent(pilot, ref ev);
+    }
+
+    private void RelayRefToPilot<T>(Entity<MechComponent> uid, ref T args) where T :struct
+    {
+        if (uid.Comp.PilotSlot.ContainedEntity is not { } pilot)
+            return;
+
+        var ev = new MechPilotRelayedEvent<T>(args);
+
+        RaiseLocalEvent(pilot, ref ev);
+
+        args = ev.Args;
+    }
+}
+
+[ByRefEvent]
+public record struct MechPilotRelayedEvent<TEvent>(TEvent Args)
+{
+    public TEvent Args = Args;
+}

Content.Shared/Mech/EntitySystems/SharedMechSystem.cs

@@ -26,7 +26,7 @@ namespace Content.Shared.Mech.EntitySystems;
 /// <summary>
 /// Handles all of the interactions, UI handling, and items shennanigans for <see cref="MechComponent"/>
 /// </summary>
-public abstract class SharedMechSystem : EntitySystem
+public abstract partial class SharedMechSystem : EntitySystem
 {
     [Dependency] private readonly IGameTiming _timing = default!;
     [Dependency] private readonly INetManager _net = default!;
@@ -55,6 +55,8 @@ public abstract class SharedMechSystem : EntitySystem
         SubscribeLocalEvent<MechPilotComponent, GetMeleeWeaponEvent>(OnGetMeleeWeapon);
         SubscribeLocalEvent<MechPilotComponent, CanAttackFromContainerEvent>(OnCanAttackFromContainer);
         SubscribeLocalEvent<MechPilotComponent, AttackAttemptEvent>(OnAttackAttempt);
+
+        InitializeRelay();
     }
 
     private void OnToggleEquipmentAction(EntityUid uid, MechComponent component, MechToggleEquipmentEvent args)