Power Rework (#863)

Co-authored-by: py01 <pyronetics01@gmail.com>

Content.Server/GameObjects/Components/NodeContainer/NodeGroups/INodeGroup.cs

@@ -0,0 +1,121 @@
+using Content.Server.GameObjects.Components.NodeContainer.Nodes;
+using Robust.Shared.ViewVariables;
+using System.Collections.Generic;
+
+namespace Content.Server.GameObjects.Components.NodeContainer.NodeGroups
+{
+    /// <summary>
+    ///     Maintains a collection of <see cref="Node"/>s, and performs operations requiring a list of
+    ///     all connected <see cref="Node"/>s.
+    /// </summary>
+    public interface INodeGroup
+    {
+        public IReadOnlyList<Node> Nodes { get; }
+
+        void AddNode(Node node);
+
+        void RemoveNode(Node node);
+
+        void CombineGroup(INodeGroup newGroup);
+
+        void BeforeCombine();
+
+        void AfterCombine();
+
+        void BeforeRemakeSpread();
+
+        void AfterRemakeSpread();
+    }
+
+    [NodeGroup(NodeGroupID.Default)]
+    public class BaseNodeGroup : INodeGroup
+    {
+        [ViewVariables]
+        public IReadOnlyList<Node> Nodes => _nodes;
+        private readonly List<Node> _nodes = new List<Node>();
+
+        [ViewVariables]
+        public int NodeCount => Nodes.Count;
+
+        public static readonly INodeGroup NullGroup = new NullNodeGroup();
+
+        public void AddNode(Node node)
+        {
+            _nodes.Add(node);
+            OnAddNode(node);
+        }
+
+        public void RemoveNode(Node node)
+        {
+            _nodes.Remove(node);
+            OnRemoveNode(node);
+            RemakeGroup();
+        }
+
+        public void CombineGroup(INodeGroup newGroup)
+        {
+            if (newGroup.Nodes.Count < Nodes.Count)
+            {
+                newGroup.CombineGroup(this);
+                return;
+            }
+            BeforeCombine();
+            newGroup.BeforeCombine();
+            foreach (var node in Nodes)
+            {
+                node.NodeGroup = newGroup;
+            }
+            AfterCombine();
+            newGroup.AfterCombine();
+        }
+
+        /// <summary>
+        ///     Causes all <see cref="Node"/>s to remake their groups. Called when a <see cref="Node"/> is removed
+        ///     and may have split a group in two, so multiple new groups may need to be formed.
+        /// </summary>
+        private void RemakeGroup()
+        {
+            BeforeRemake();
+            foreach (var node in Nodes)
+            {
+                node.ClearNodeGroup();
+            }
+            foreach (var node in Nodes)
+            {
+                if (node.TryAssignGroupIfNeeded())
+                {
+                    node.StartSpreadingGroup();
+                }
+            }
+        }
+
+        protected virtual void OnAddNode(Node node) { }
+        
+        protected virtual void OnRemoveNode(Node node) { }
+
+        protected virtual void BeforeRemake() { }
+
+        protected virtual void AfterRemake() { }
+
+        public virtual void BeforeCombine() { }
+
+        public virtual void AfterCombine() { }
+
+        public virtual void BeforeRemakeSpread() { }
+
+        public virtual void AfterRemakeSpread() { }
+
+        private class NullNodeGroup : INodeGroup
+        {
+            public IReadOnlyList<Node> Nodes => _nodes;
+            private readonly List<Node> _nodes = new List<Node>();
+            public void AddNode(Node node) { }
+            public void CombineGroup(INodeGroup newGroup) { }
+            public void RemoveNode(Node node) { }
+            public void BeforeCombine() { }
+            public void AfterCombine() { }
+            public void BeforeRemakeSpread() { }
+            public void AfterRemakeSpread() { }
+        }
+    }
+}