Re-organize all projects (#4166)

Content.Server/Light/EntitySystems/HandHeldLightSystem.cs

@@ -0,0 +1,50 @@
+using System.Collections.Generic;
+using System.Linq;
+using Content.Server.Light.Components;
+using JetBrains.Annotations;
+using Robust.Shared.GameObjects;
+
+namespace Content.Server.Light.EntitySystems
+{
+    [UsedImplicitly]
+    internal sealed class HandHeldLightSystem : EntitySystem
+    {
+        // TODO: Ideally you'd be able to subscribe to power stuff to get events at certain percentages.. or something?
+        // But for now this will be better anyway.
+        private HashSet<HandheldLightComponent> _activeLights = new();
+
+        public override void Initialize()
+        {
+            base.Initialize();
+            SubscribeLocalEvent<ActivateHandheldLightMessage>(HandleActivate);
+            SubscribeLocalEvent<DeactivateHandheldLightMessage>(HandleDeactivate);
+        }
+
+        public override void Shutdown()
+        {
+            base.Shutdown();
+            _activeLights.Clear();
+            UnsubscribeLocalEvent<ActivateHandheldLightMessage>();
+            UnsubscribeLocalEvent<DeactivateHandheldLightMessage>();
+        }
+
+        private void HandleActivate(ActivateHandheldLightMessage message)
+        {
+            _activeLights.Add(message.Component);
+        }
+
+        private void HandleDeactivate(DeactivateHandheldLightMessage message)
+        {
+            _activeLights.Remove(message.Component);
+        }
+
+        public override void Update(float frameTime)
+        {
+            foreach (var handheld in _activeLights.ToArray())
+            {
+                if (handheld.Deleted || handheld.Paused) continue;
+                handheld.OnUpdate(frameTime);
+            }
+        }
+    }
+}