Change all of body system to use entities and components (#2074)

* Early commit

* Early commit 2

* merging master broke my git

* does anyone even read these

* life is fleeting

* it just works

* this time passing integration tests

* Remove hashset yaml serialization for now

* You got a license for those nullables?

* No examine, no context menu, part and mechanism parenting and visibility

* Fix wrong brain sprite state

* Removing layers was a mistake

* just tear body system a new one and see if it still breathes

* Remove redundant code

* Add that comment back

* Separate damage and body, component states, stomach rework

* Add containers for body parts

* Bring layers back pls

* Fix parts magically changing color

* Reimplement sprite layer visibility

* Fix tests

* Add leg test

* Active legs is gone

Crab rave

* Merge fixes, rename DamageState to CurrentState

* Remove IShowContextMenu and ICanExamine

Content.Server/GameObjects/Components/Body/Behavior/LungBehaviorComponent.cs

@@ -0,0 +1,188 @@
+#nullable enable
+using System;
+using System.Linq;
+using Content.Server.Atmos;
+using Content.Server.GameObjects.Components.Body.Circulatory;
+using Content.Server.Utility;
+using Content.Shared.Atmos;
+using Content.Shared.GameObjects.Components.Body.Behavior;
+using Robust.Shared.GameObjects;
+using Robust.Shared.Serialization;
+using Robust.Shared.ViewVariables;
+
+namespace Content.Server.GameObjects.Components.Body.Behavior
+{
+    [RegisterComponent]
+    [ComponentReference(typeof(SharedLungBehaviorComponent))]
+    public class LungBehaviorComponent : SharedLungBehaviorComponent
+    {
+        private float _accumulatedFrameTime;
+
+        [ViewVariables] public GasMixture Air { get; set; } = default!;
+
+        [ViewVariables] public override float Temperature => Air.Temperature;
+
+        [ViewVariables] public override float Volume => Air.Volume;
+
+        public override void ExposeData(ObjectSerializer serializer)
+        {
+            base.ExposeData(serializer);
+
+            Air = new GasMixture {Temperature = Atmospherics.NormalBodyTemperature};
+
+            serializer.DataReadWriteFunction(
+                "volume",
+                6,
+                vol => Air.Volume = vol,
+                () => Air.Volume);
+
+            serializer.DataReadWriteFunction(
+                "temperature",
+                Atmospherics.NormalBodyTemperature,
+                temp => Air.Temperature = temp,
+                () => Air.Temperature);
+        }
+
+        public override void Gasp()
+        {
+            Owner.PopupMessageEveryone("Gasp");
+            Inhale(CycleDelay);
+        }
+
+        public void Transfer(GasMixture from, GasMixture to, float ratio)
+        {
+            var removed = from.RemoveRatio(ratio);
+            var toOld = to.Gases.ToArray();
+
+            to.Merge(removed);
+
+            for (var gas = 0; gas < Atmospherics.TotalNumberOfGases; gas++)
+            {
+                var newAmount = to.GetMoles(gas);
+                var oldAmount = toOld[gas];
+                var delta = newAmount - oldAmount;
+
+                removed.AdjustMoles(gas, -delta);
+            }
+
+            from.Merge(removed);
+        }
+
+        public void ToBloodstream(GasMixture mixture)
+        {
+            if (Body == null)
+            {
+                return;
+            }
+
+            if (!Body.Owner.TryGetComponent(out BloodstreamComponent? bloodstream))
+            {
+                return;
+            }
+
+            var to = bloodstream.Air;
+
+            to.Merge(mixture);
+            mixture.Clear();
+        }
+
+        public override void Update(float frameTime)
+        {
+            if (Status == LungStatus.None)
+            {
+                Status = LungStatus.Inhaling;
+            }
+
+            _accumulatedFrameTime += Status switch
+            {
+                LungStatus.Inhaling => frameTime,
+                LungStatus.Exhaling => -frameTime,
+                _ => throw new ArgumentOutOfRangeException()
+            };
+
+            var absoluteTime = Math.Abs(_accumulatedFrameTime);
+            var delay = CycleDelay;
+
+            if (absoluteTime < delay)
+            {
+                return;
+            }
+
+            switch (Status)
+            {
+                case LungStatus.Inhaling:
+                    Inhale(absoluteTime);
+                    Status = LungStatus.Exhaling;
+                    break;
+                case LungStatus.Exhaling:
+                    Exhale(absoluteTime);
+                    Status = LungStatus.Inhaling;
+                    break;
+                default:
+                    throw new ArgumentOutOfRangeException();
+            }
+
+            _accumulatedFrameTime = absoluteTime - delay;
+        }
+
+        public override void Inhale(float frameTime)
+        {
+            if (!Owner.Transform.Coordinates.TryGetTileAir(out var tileAir))
+            {
+                return;
+            }
+
+            Inhale(frameTime, tileAir);
+        }
+
+        public void Inhale(float frameTime, GasMixture from)
+        {
+            var ratio = Atmospherics.BreathPercentage * frameTime;
+
+            Transfer(from, Air, ratio);
+            ToBloodstream(Air);
+        }
+
+        public override void Exhale(float frameTime)
+        {
+            if (!Owner.Transform.Coordinates.TryGetTileAir(out var tileAir))
+            {
+                return;
+            }
+
+            Exhale(frameTime, tileAir);
+        }
+
+        public void Exhale(float frameTime, GasMixture to)
+        {
+            // TODO: Make the bloodstream separately pump toxins into the lungs, making the lungs' only job to empty.
+            if (Body == null)
+            {
+                return;
+            }
+
+            if (!Body.Owner.TryGetComponent(out BloodstreamComponent? bloodstream))
+            {
+                return;
+            }
+
+            bloodstream.PumpToxins(Air);
+
+            var lungRemoved = Air.RemoveRatio(0.5f);
+            var toOld = to.Gases.ToArray();
+
+            to.Merge(lungRemoved);
+
+            for (var gas = 0; gas < Atmospherics.TotalNumberOfGases; gas++)
+            {
+                var newAmount = to.GetMoles(gas);
+                var oldAmount = toOld[gas];
+                var delta = newAmount - oldAmount;
+
+                lungRemoved.AdjustMoles(gas, -delta);
+            }
+
+            Air.Merge(lungRemoved);
+        }
+    }
+}