Refactor chemical injection to be ECS (#4296)

Content.Server/Chemistry/EntitySystems/SolutionInjectOnCollideSystem.cs

@@ -0,0 +1,38 @@
+using Content.Server.Body.Circulatory;
+using Content.Server.Chemistry.Components;
+using JetBrains.Annotations;
+using Robust.Shared.GameObjects;
+using Robust.Shared.Physics.Dynamics;
+
+namespace Content.Server.Chemistry.EntitySystems
+{
+    [UsedImplicitly]
+    internal sealed class SolutionInjectOnCollideSystem : EntitySystem
+    {
+        public override void Initialize()
+        {
+            base.Initialize();
+            SubscribeLocalEvent<SolutionInjectOnCollideComponent, ComponentInit>(HandleInit);
+            SubscribeLocalEvent<SolutionInjectOnCollideComponent, StartCollideEvent>(HandleInjection);
+        }
+
+        private void HandleInit(EntityUid uid, SolutionInjectOnCollideComponent component, ComponentInit args)
+        {
+            component.Owner.EnsureComponentWarn<SolutionContainerComponent>($"{nameof(SolutionInjectOnCollideComponent)} requires a SolutionContainer on {component.Owner}!");
+        }
+
+        private void HandleInjection(EntityUid uid, SolutionInjectOnCollideComponent component, StartCollideEvent args)
+        {
+            if (!args.OtherFixture.Body.Owner.TryGetComponent<BloodstreamComponent>(out var bloodstream) ||
+                !ComponentManager.TryGetComponent(uid, out SolutionContainerComponent? solutionContainer)) return;
+
+            var solution = solutionContainer.Solution;
+            var solRemoved = solution.SplitSolution(component.TransferAmount);
+            var solRemovedVol = solRemoved.TotalVolume;
+
+            var solToInject = solRemoved.SplitSolution(solRemovedVol * component.TransferEfficiency);
+
+            bloodstream.TryTransferSolution(solToInject);
+        }
+    }
+}