(Re)add healing items (#1918)

* (Re)add healing component

* Do range check only when healing someone else

Content.Server/GameObjects/Components/Medical/HealingComponent.cs

@@ -0,0 +1,71 @@
+using System.Collections.Generic;
+using Content.Server.GameObjects.Components.Stack;
+using Content.Shared.Damage;
+using Content.Shared.GameObjects.Components.Body;
+using Content.Shared.GameObjects.EntitySystems;
+using Content.Shared.Interfaces.GameObjects.Components;
+using Robust.Shared.GameObjects;
+using Robust.Shared.GameObjects.Systems;
+using Robust.Shared.Interfaces.GameObjects;
+using Robust.Shared.Serialization;
+
+namespace Content.Server.GameObjects.Components.Medical
+{
+    [RegisterComponent]
+    public class HealingComponent : Component, IAfterInteract
+    {
+        public override string Name => "Healing";
+
+        public Dictionary<DamageType, int> Heal { get; private set; }
+
+        public override void ExposeData(ObjectSerializer serializer)
+        {
+            base.ExposeData(serializer);
+
+            serializer.DataField(this, h => h.Heal, "heal", new Dictionary<DamageType, int>());
+        }
+
+        public void AfterInteract(AfterInteractEventArgs eventArgs)
+        {
+            if (eventArgs.Target == null)
+            {
+                return;
+            }
+
+            if (!eventArgs.Target.TryGetComponent(out IBodyManagerComponent body))
+            {
+                return;
+            }
+
+            if (!ActionBlockerSystem.CanInteract(eventArgs.User))
+            {
+                return;
+            }
+
+            if (eventArgs.User != eventArgs.Target)
+            {
+                var interactionSystem = EntitySystem.Get<SharedInteractionSystem>();
+                var from = eventArgs.User.Transform.MapPosition;
+                var to = eventArgs.Target.Transform.MapPosition;
+                bool Ignored(IEntity entity) => entity == eventArgs.User || entity == eventArgs.Target;
+                var inRange = interactionSystem.InRangeUnobstructed(from, to, predicate: Ignored);
+
+                if (!inRange)
+                {
+                    return;
+                }
+            }
+
+            if (Owner.TryGetComponent(out StackComponent stack) &&
+                !stack.Use(1))
+            {
+                return;
+            }
+
+            foreach (var (type, amount) in Heal)
+            {
+                body.ChangeDamage(type, -amount, true);
+            }
+        }
+    }
+}