Pow3r: stage 1 (#4208)

Co-authored-by: 20kdc <asdd2808@gmail.com>

Content.Server/NodeContainer/NodeGroups/PipeNet.cs

@@ -0,0 +1,101 @@
+#nullable enable
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using Content.Server.Atmos;
+using Content.Server.Atmos.Components;
+using Content.Server.Atmos.EntitySystems;
+using Content.Server.Interfaces;
+using Content.Server.NodeContainer.Nodes;
+using Content.Shared.Atmos;
+using Robust.Shared.GameObjects;
+using Robust.Shared.Maths;
+using Robust.Shared.ViewVariables;
+
+namespace Content.Server.NodeContainer.NodeGroups
+{
+    public interface IPipeNet : INodeGroup, IGasMixtureHolder
+    {
+        /// <summary>
+        ///     Causes gas in the PipeNet to react.
+        /// </summary>
+        void Update();
+    }
+
+    [NodeGroup(NodeGroupID.Pipe)]
+    public class PipeNet : BaseNodeGroup, IPipeNet
+    {
+        [ViewVariables] public GasMixture Air { get; set; } = new() {Temperature = Atmospherics.T20C};
+
+        [ViewVariables] private readonly List<PipeNode> _pipes = new();
+
+        [ViewVariables] private AtmosphereSystem? _atmosphereSystem;
+
+        [ViewVariables]
+        private IGridAtmosphereComponent? GridAtmos =>
+            _atmosphereSystem?.GetGridAtmosphere(GridId);
+
+        public override void Initialize(Node sourceNode)
+        {
+            base.Initialize(sourceNode);
+
+            _atmosphereSystem = EntitySystem.Get<AtmosphereSystem>();
+            GridAtmos?.AddPipeNet(this);
+        }
+
+        public void Update()
+        {
+            _atmosphereSystem?.React(Air, this);
+        }
+
+        public override void LoadNodes(List<Node> groupNodes)
+        {
+            base.LoadNodes(groupNodes);
+
+            foreach (var node in groupNodes)
+            {
+                var pipeNode = (PipeNode) node;
+                _pipes.Add(pipeNode);
+                pipeNode.JoinPipeNet(this);
+                Air.Volume += pipeNode.Volume;
+            }
+        }
+
+        public override void RemoveNode(Node node)
+        {
+            base.RemoveNode(node);
+
+            var pipeNode = (PipeNode) node;
+            Air.Volume -= pipeNode.Volume;
+            // TODO: Bad O(n^2)
+            _pipes.Remove(pipeNode);
+        }
+
+        public override void AfterRemake(IEnumerable<IGrouping<INodeGroup?, Node>> newGroups)
+        {
+            RemoveFromGridAtmos();
+
+            var buffer = new GasMixture(Air.Volume) {Temperature = Air.Temperature};
+            var atmosphereSystem = EntitySystem.Get<AtmosphereSystem>();
+
+            foreach (var newGroup in newGroups)
+            {
+                if (newGroup.Key is not IPipeNet newPipeNet)
+                    continue;
+
+                var newAir = newPipeNet.Air;
+                var newVolume = newGroup.Cast<PipeNode>().Sum(n => n.Volume);
+
+                buffer.Clear();
+                atmosphereSystem.Merge(buffer, Air);
+                buffer.Multiply(MathF.Min(newVolume / Air.Volume, 1f));
+                atmosphereSystem.Merge(newAir, buffer);
+            }
+        }
+
+        private void RemoveFromGridAtmos()
+        {
+            GridAtmos?.RemovePipeNet(this);
+        }
+    }
+}