Entity Reagent Reactions v2 (#3714)

* Refactors reactions to be more POWERFUL and DATA-ORIENTED

Content.Shared/Chemistry/ReagentEntityReaction.cs

@@ -0,0 +1,56 @@
+using System;
+using Content.Shared.Interfaces.GameObjects.Components;
+using Robust.Shared.GameObjects;
+using Robust.Shared.Serialization.Manager.Attributes;
+using Robust.Shared.ViewVariables;
+
+namespace Content.Shared.Chemistry
+{
+    public enum ReactionMethod
+    {
+        Touch,
+        Injection,
+        Ingestion,
+    }
+
+    [DataDefinition]
+    public abstract class ReagentEntityReaction
+    {
+        [ViewVariables]
+        [field: DataField("touch")]
+        public bool Touch { get; } = false;
+
+        [ViewVariables]
+        [field: DataField("injection")]
+        public bool Injection { get; } = false;
+
+        [ViewVariables]
+        [field: DataField("ingestion")]
+        public bool Ingestion { get; } = false;
+
+        public void React(ReactionMethod method, IEntity entity, ReagentPrototype reagent, ReagentUnit volume, Solution? source)
+        {
+            switch (method)
+            {
+                case ReactionMethod.Touch:
+                    if (!Touch)
+                        return;
+                    break;
+                case ReactionMethod.Injection:
+                    if(!Injection)
+                        return;
+                    break;
+                case ReactionMethod.Ingestion:
+                    if(!Ingestion)
+                        return;
+                    break;
+                default:
+                    throw new ArgumentOutOfRangeException(nameof(method), method, null);
+            }
+
+            React(entity, reagent, volume, source);
+        }
+
+        protected abstract void React(IEntity entity, ReagentPrototype reagent, ReagentUnit volume, Solution? source);
+    }
+}