Event-based emergency lights (#2217)

Co-authored-by: Metal Gear Sloth <metalgearsloth@gmail.com>

Content.Server/GameObjects/Components/Power/ApcNetComponents/PowerReceiverUsers/EmergencyLightComponent.cs

@@ -3,6 +3,7 @@ using System.Collections.Generic;
 using Content.Shared.GameObjects.EntitySystems;
 using Robust.Server.GameObjects;
 using Robust.Shared.GameObjects;
+using Robust.Shared.GameObjects.Systems;
 using Robust.Shared.Localization;
 using Robust.Shared.Log;
 using Robust.Shared.Serialization;
@@ -20,7 +21,20 @@ namespace Content.Server.GameObjects.Components.Power.ApcNetComponents.PowerRece
         public override string Name => "EmergencyLight";
 
         [ViewVariables]
-        private EmergencyLightState _lightState = EmergencyLightState.Charging;
+        private EmergencyLightState State
+        {
+            get => _state;
+            set
+            {
+                if (_state == value)
+                    return;
+
+                _state = value;
+                Owner.EntityManager.EventBus.RaiseEvent(EventSource.Local, new EmergencyLightMessage(this, _state));
+            }
+        }
+
+        private EmergencyLightState _state = EmergencyLightState.Charging;
 
         [ViewVariables(VVAccess.ReadWrite)]
         private float _wattage;
@@ -59,30 +73,27 @@ namespace Content.Server.GameObjects.Components.Power.ApcNetComponents.PowerRece
             {
                 receiver.Load = (int) Math.Abs(_wattage);
                 TurnOff();
-                _lightState = EmergencyLightState.Charging;
+                State = EmergencyLightState.Charging;
             }
             else
             {
                 TurnOn();
-                _lightState = EmergencyLightState.On;
+                State = EmergencyLightState.On;
             }
         }
 
         public void OnUpdate(float frameTime)
         {
-            if (_lightState == EmergencyLightState.Empty
-                || _lightState == EmergencyLightState.Full) return;
-
             if (!Owner.TryGetComponent(out BatteryComponent battery))
             {
                 return;
             }
 
-            if(_lightState == EmergencyLightState.On)
+            if(State == EmergencyLightState.On)
             {
                 if (!battery.TryUseCharge(_wattage * frameTime))
                 {
-                    _lightState = EmergencyLightState.Empty;
+                    State = EmergencyLightState.Empty;
                     TurnOff();
                 }
             }
@@ -96,7 +107,7 @@ namespace Content.Server.GameObjects.Components.Power.ApcNetComponents.PowerRece
                         receiver.Load = 1;
                     }
 
-                    _lightState = EmergencyLightState.Full;
+                    State = EmergencyLightState.Full;
                 }
             }
         }
@@ -137,6 +148,7 @@ namespace Content.Server.GameObjects.Components.Power.ApcNetComponents.PowerRece
             }
 
             receiver.OnPowerStateChanged += UpdateState;
+            State = EmergencyLightState.Charging;
         }
 
         public override void OnRemove()
@@ -151,7 +163,7 @@ namespace Content.Server.GameObjects.Components.Power.ApcNetComponents.PowerRece
 
         void IExamine.Examine(FormattedMessage message, bool inDetailsRange)
         {
-            message.AddMarkup(Loc.GetString($"The battery indicator displays: {BatteryStateText[_lightState]}."));
+            message.AddMarkup(Loc.GetString($"The battery indicator displays: {BatteryStateText[State]}."));
         }
 
         public enum EmergencyLightState
@@ -170,4 +182,17 @@ namespace Content.Server.GameObjects.Components.Power.ApcNetComponents.PowerRece
             { EmergencyLightState.On, "[color=darkorange]Discharging[/color]"}
         };
     }
+
+    public sealed class EmergencyLightMessage : EntitySystemMessage
+    {
+        public EmergencyLightComponent Component { get; }
+        
+        public EmergencyLightComponent.EmergencyLightState State { get; }
+
+        public EmergencyLightMessage(EmergencyLightComponent component, EmergencyLightComponent.EmergencyLightState state)
+        {
+            Component = component;
+            State = state;
+        }
+    }
 }

Content.Server/GameObjects/EntitySystems/EmergencyLightSystem.cs

@@ -1,4 +1,6 @@
-using Content.Server.GameObjects.Components.Power.ApcNetComponents.PowerReceiverUsers;
+using System;
+using System.Collections.Generic;
+using Content.Server.GameObjects.Components.Power.ApcNetComponents.PowerReceiverUsers;
 using JetBrains.Annotations;
 using Robust.Shared.GameObjects.Systems;
 
@@ -7,10 +9,42 @@ namespace Content.Server.GameObjects.EntitySystems
     [UsedImplicitly]
     internal sealed class EmergencyLightSystem : EntitySystem
     {
+        private List<EmergencyLightComponent> _activeLights = new List<EmergencyLightComponent>();
+
+        public override void Initialize()
+        {
+            base.Initialize();
+            SubscribeLocalEvent<EmergencyLightMessage>(HandleEmergencyLightMessage);
+        }
+
+        private void HandleEmergencyLightMessage(EmergencyLightMessage message)
+        {
+            switch (message.State)
+            {
+                case EmergencyLightComponent.EmergencyLightState.Charging:
+                    if (_activeLights.Contains(message.Component))
+                        _activeLights.Add(message.Component);
+                    
+                    break;
+                case EmergencyLightComponent.EmergencyLightState.Full:
+                case EmergencyLightComponent.EmergencyLightState.Empty:
+                    _activeLights.Remove(message.Component);
+                    break;
+                case EmergencyLightComponent.EmergencyLightState.On:
+                    if (!_activeLights.Contains(message.Component))
+                        _activeLights.Add(message.Component);
+
+                    break;
+                default:
+                    throw new ArgumentOutOfRangeException();
+            }
+        }
+
         public override void Update(float frameTime)
         {
-            foreach (var comp in ComponentManager.EntityQuery<EmergencyLightComponent>())
+            for (var i = _activeLights.Count - 1; i >= 0; i--)
             {
+                var comp = _activeLights[i];
                 comp.OnUpdate(frameTime);
             }
         }