Prevent willful deconversion of Revolutionaries

Content.Server/Implants/ImplanterSystem.cs

@@ -48,10 +48,17 @@ private void OnImplanterAfterInteract(EntityUid uid, ImplanterComponent componen
                 if (implant == null)
                     return;
 
-                // show popup to the user saying implant failed
-                var name = Identity.Name(target, EntityManager, args.User);
-                var msg = Loc.GetString("implanter-component-implant-failed", ("implant", implant), ("target", name));
-                _popup.PopupEntity(msg, target, args.User);
+                // optionally, show popup to explain why the implant failed
+                var ev = new PopupAfterFailedImplantEvent(args.User, target, implant.Value);
+                RaiseLocalEvent(target, ev);
+                if (!ev.Handled)
+                {
+                    // show generic popup saying the implant failed
+                    var name = Identity.Name(target, EntityManager, args.User);
+                    var msg = Loc.GetString("implanter-component-implant-failed", ("implant", implant), ("target", name));
+                    _popup.PopupEntity(msg, target, args.User);
+                }
+
                 // prevent further interaction since popup was shown
                 args.Handled = true;
                 return;

Content.Shared/Implants/SharedImplanterSystem.cs

@@ -225,3 +225,18 @@ public AddImplantAttemptEvent(EntityUid user, EntityUid target, EntityUid implan
         Implanter = implanter;
     }
 }
+
+public sealed class PopupAfterFailedImplantEvent : CancellableEntityEventArgs
+{
+    public readonly EntityUid User;
+    public readonly EntityUid Target;
+    public readonly EntityUid Implant;
+    public bool Handled = false;
+
+    public PopupAfterFailedImplantEvent(EntityUid user, EntityUid target, EntityUid implant)
+    {
+        User = user;
+        Target = target;
+        Implant = implant;
+    }
+}

Content.Shared/Revolutionary/SharedRevolutionarySystem.cs

@@ -1,22 +1,61 @@
 using Content.Shared.IdentityManagement;
+using Content.Shared.Implants;
 using Content.Shared.Mindshield.Components;
 using Content.Shared.Popups;
 using Content.Shared.Revolutionary.Components;
 using Content.Shared.Stunnable;
+using Content.Shared.Tag;
 
 namespace Content.Shared.Revolutionary;
 
 public sealed class SharedRevolutionarySystem : EntitySystem
 {
     [Dependency] private readonly SharedPopupSystem _popupSystem = default!;
     [Dependency] private readonly SharedStunSystem _sharedStun = default!;
+    [Dependency] private readonly TagSystem _tag = default!;
+
+    [ValidatePrototypeId<TagPrototype>]
+    public const string MindShieldTag = "MindShield";
 
     public override void Initialize()
     {
         base.Initialize();
+        SubscribeLocalEvent<RevolutionaryComponent, AddImplantAttemptEvent>(PreventSelfDeconvert);
+        SubscribeLocalEvent<RevolutionaryComponent, PopupAfterFailedImplantEvent>(InformTargetWasSelf);
         SubscribeLocalEvent<MindShieldComponent, MapInitEvent>(MindShieldImplanted);
     }
 
+    /// <summary>
+    /// Prevents Revs from attempting to implant themselves with a mindshield.
+    /// </summary>
+    public void PreventSelfDeconvert(EntityUid uid, RevolutionaryComponent comp, ref AddImplantAttemptEvent ev)
+    {
+        if (IsMindshieldTargetSelf(ev.User, ev.Target, ev.Implant))
+        {
+            ev.Cancel();
+        }
+    }
+
+    /// <summary>
+    /// Informs the Rev why the implant failed.
+    /// </summary>
+    public void InformTargetWasSelf(EntityUid uid, RevolutionaryComponent comp, ref PopupAfterFailedImplantEvent ev)
+    {
+        if (IsMindshieldTargetSelf(ev.User, ev.Target, ev.Implant))
+        {
+            _popupSystem.PopupEntity(Loc.GetString("rev-fail-self-mindshield"), ev.User);
+            ev.Handled = true;
+        }
+    }
+
+    /// <summary>
+    /// Checks if a Rev is attempting to implant themselves with a mindshield.
+    /// </summary>
+    public bool IsMindshieldTargetSelf(EntityUid user, EntityUid target, EntityUid implant)
+    {
+        return _tag.HasTag(implant, MindShieldTag) && HasComp<RevolutionaryComponent>(user) && !HasComp<HeadRevolutionaryComponent>(user) && user == target;
+    }
+
     /// <summary>
     /// When the mindshield is implanted in the rev it will popup saying they were deconverted. In Head Revs it will remove the mindshield component.
     /// </summary>

Resources/Locale/en-US/game-ticking/game-presets/preset-revolutionary.ftl

@@ -31,6 +31,8 @@ rev-role-greeting =
 
 rev-briefing = Help your head revolutionaries kill every head to take over the station.
 
+rev-fail-self-mindshield = You cannot bring yourself to betray the revolution!
+
 ## General
 
 rev-title = Revolutionaries