Fix Antimatter engine maths and overplacing (#2736)

* Antimatter engine parts can't be placed overlapping

* Antimatter engine stability maths fixed

* Antimatter engine: Clean up some unused stuff

Content.Server/GameObjects/Components/NodeContainer/NodeGroups/AMENodeGroup.cs

@@ -5,6 +5,9 @@ using Content.Server.Explosions;
 using Content.Server.GameObjects.Components.NodeContainer.Nodes;
 using Content.Server.GameObjects.Components.Power.AME;
 using Robust.Shared.GameObjects.Components.Transform;
+using Robust.Shared.Interfaces.Random;
+using Robust.Shared.Random;
+using Robust.Shared.IoC;
 using Robust.Shared.ViewVariables;
 
 namespace Content.Server.GameObjects.Components.NodeContainer.NodeGroups
@@ -23,6 +26,9 @@ namespace Content.Server.GameObjects.Components.NodeContainer.NodeGroups
         [ViewVariables]
         private AMEControllerComponent _masterController;
 
+        [Dependency]
+        private readonly IRobustRandom _random = default!;
+
         public AMEControllerComponent MasterController => _masterController;
 
         private readonly List<AMEShieldComponent> _cores = new();
@@ -95,16 +101,42 @@ namespace Content.Server.GameObjects.Components.NodeContainer.NodeGroups
             }
         }
 
-        public int InjectFuel(int injectionAmount)
+        public int InjectFuel(int fuel, out bool overloading)
         {
-            if(injectionAmount > 0 && CoreCount > 0)
+            overloading = false;
+            if(fuel > 0 && CoreCount > 0)
             {
-                var instability = 2 * (injectionAmount / CoreCount);
+                var safeFuelLimit = CoreCount * 2;
-                foreach(AMEShieldComponent core in _cores)
+                if (fuel > safeFuelLimit)
                 {
-                    core.CoreIntegrity -= instability;
+                    // The AME is being overloaded.
+                    // Note about these maths: I would assume the general idea here is to make larger engines less safe to overload.
+                    // In other words, yes, those are supposed to be CoreCount, not safeFuelLimit.
+                    var instability = 0;
+                    var overloadVsSizeResult = fuel - CoreCount;
+
+                    // fuel > safeFuelLimit: Slow damage. Can safely run at this level for burst periods if the engine is small and someone is keeping an eye on it.
+                    if (_random.Prob(0.5f))
+                        instability = 1;
+                    // overloadVsSizeResult > 5: 
+                    if (overloadVsSizeResult > 5)
+                        instability = 5;
+                    // overloadVsSizeResult > 10: This will explode in at most 5 injections.
+                    if (overloadVsSizeResult > 10)
+                        instability = 20;
+
+                    // Apply calculated instability
+                    if (instability != 0)
+                    {
+                        overloading = true;
+                        foreach(AMEShieldComponent core in _cores)
+                        {
+                            core.CoreIntegrity -= instability;
+                        }
+                    }
                 }
-                return CoreCount * injectionAmount * 15000; //2 core engine injecting 2 fuel per core = 60kW(?)
+                // Note the float conversions. The maths will completely fail if not done using floats.
+                return (int) ((((float) fuel) / CoreCount) * fuel * 20000);
             }
             return 0;
         }

Content.Server/GameObjects/Components/Power/AME/AMEControllerComponent.cs

@@ -85,11 +85,12 @@ namespace Content.Server.GameObjects.Components.Power.AME
             }
 
             _jarSlot.ContainedEntity.TryGetComponent<AMEFuelContainerComponent>(out var fuelJar);
-            if(fuelJar != null && _powerSupplier != null && fuelJar.FuelAmount > InjectionAmount)
+            if(fuelJar != null && _powerSupplier != null)
             {
-                _powerSupplier.SupplyRate = group.InjectFuel(InjectionAmount);
+                var availableInject = fuelJar.FuelAmount >= InjectionAmount ? InjectionAmount : fuelJar.FuelAmount;
-                fuelJar.FuelAmount -= InjectionAmount;
+                _powerSupplier.SupplyRate = group.InjectFuel(availableInject, out var overloading);
-                InjectSound();
+                fuelJar.FuelAmount -= availableInject;
+                InjectSound(overloading);
                 UpdateUserInterface();
             }
 
@@ -315,9 +316,9 @@ namespace Content.Server.GameObjects.Components.Power.AME
 
         }
 
-        private void InjectSound()
+        private void InjectSound(bool overloading)
         {
-            EntitySystem.Get<AudioSystem>().PlayFromEntity("/Audio/Effects/bang.ogg", Owner, AudioParams.Default.WithVolume(0f));
+            EntitySystem.Get<AudioSystem>().PlayFromEntity("/Audio/Effects/bang.ogg", Owner, AudioParams.Default.WithVolume(overloading ? 10f : 0f));
         }
 
         async Task<bool> IInteractUsing.InteractUsing(InteractUsingEventArgs args)

Content.Server/GameObjects/Components/Power/AME/AMEPartComponent.cs

@@ -1,4 +1,5 @@
 using System.Threading.Tasks;
+using System.Linq;
 using Content.Server.GameObjects.Components.Interactable;
 using Content.Server.Interfaces.GameObjects.Components.Items;
 using Content.Shared.GameObjects.Components.Interactable;
@@ -35,8 +36,12 @@ namespace Content.Server.GameObjects.Components.Power.AME
             {
 
                 var mapGrid = _mapManager.GetGrid(args.ClickLocation.GetGridId(_serverEntityManager));
-                var tile = mapGrid.GetTileRef(args.ClickLocation);
                 var snapPos = mapGrid.SnapGridCellFor(args.ClickLocation, SnapGridOffset.Center);
+                if (mapGrid.GetSnapGridCell(snapPos, SnapGridOffset.Center).Any(sc => sc.Owner.HasComponent<AMEShieldComponent>()))
+                {
+                    Owner.PopupMessage(args.User, Loc.GetString("Shielding is already there!"));
+                    return true;
+                }
 
                 var ent = _serverEntityManager.SpawnEntity("AMEShielding", mapGrid.GridTileToLocal(snapPos));
                 ent.Transform.LocalRotation = Owner.Transform.LocalRotation;

Content.Server/GameObjects/Components/Power/AME/AMEShieldComponent.cs

@@ -26,11 +26,6 @@ namespace Content.Server.GameObjects.Components.Power.AME
             Owner.TryGetComponent(out _pointLight);
         }
 
-        internal void OnUpdate(float frameTime)
-        {
-            throw new NotImplementedException();
-        }
-
         public void SetCore()
         {
             if(_isCore) { return; }