Pow3r: stage 1 (#4208)

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

Content.Server/Power/Components/ApcPowerProviderComponent.cs

@@ -0,0 +1,121 @@
+#nullable enable
+using System;
+using System.Collections.Generic;
+using Content.Server.Power.NodeGroups;
+using Robust.Shared.GameObjects;
+using Robust.Shared.IoC;
+using Robust.Shared.Serialization.Manager.Attributes;
+using Robust.Shared.ViewVariables;
+
+namespace Content.Server.Power.Components
+{
+    [RegisterComponent]
+    public class ApcPowerProviderComponent : BaseApcNetComponent
+    {
+        public override string Name => "PowerProvider";
+
+        public IEntity ProviderOwner => Owner;
+
+        /// <summary>
+        ///     The max distance this can transmit power to <see cref="ApcPowerReceiverComponent"/>s from.
+        /// </summary>
+        [ViewVariables(VVAccess.ReadWrite)]
+        public int PowerTransferRange { get => _powerTransferRange; set => SetPowerTransferRange(value); }
+        [DataField("powerTransferRange")]
+        private int _powerTransferRange = 3;
+
+        [ViewVariables] public List<ApcPowerReceiverComponent> LinkedReceivers { get; } = new();
+
+        /// <summary>
+        ///     If <see cref="ApcPowerReceiverComponent"/>s should consider connecting to this.
+        /// </summary>
+        [ViewVariables(VVAccess.ReadWrite)]
+        public bool Connectable { get; private set; } = true;
+
+        public void AddReceiver(ApcPowerReceiverComponent receiver)
+        {
+            LinkedReceivers.Add(receiver);
+            receiver.NetworkLoad.LinkedNetwork = default;
+
+            Net?.QueueNetworkReconnect();
+        }
+
+        public void RemoveReceiver(ApcPowerReceiverComponent receiver)
+        {
+            LinkedReceivers.Remove(receiver);
+            receiver.NetworkLoad.LinkedNetwork = default;
+
+            Net?.QueueNetworkReconnect();
+        }
+
+        protected override void Startup()
+        {
+            base.Startup();
+
+            foreach (var receiver in FindAvailableReceivers())
+            {
+                receiver.Provider = this;
+            }
+        }
+
+        protected override void OnRemove()
+        {
+            Connectable = false;
+            var receivers = LinkedReceivers.ToArray();
+            foreach (var receiver in receivers)
+            {
+                receiver.Provider = null;
+            }
+            foreach (var receiver in receivers)
+            {
+                receiver.TryFindAndSetProvider();
+            }
+            base.OnRemove();
+        }
+
+        private IEnumerable<ApcPowerReceiverComponent> FindAvailableReceivers()
+        {
+            var nearbyEntities = IoCManager.Resolve<IEntityLookup>()
+                .GetEntitiesInRange(Owner, PowerTransferRange);
+
+            foreach (var entity in nearbyEntities)
+            {
+                if (entity.TryGetComponent<ApcPowerReceiverComponent>(out var receiver) &&
+                    receiver.Connectable &&
+                    receiver.NeedsProvider &&
+                    receiver.Owner.Transform.Coordinates.TryDistance(Owner.EntityManager, Owner.Transform.Coordinates, out var distance) &&
+                    distance < Math.Min(PowerTransferRange, receiver.PowerReceptionRange))
+                {
+                    yield return receiver;
+                }
+            }
+        }
+
+        protected override void AddSelfToNet(IApcNet apcNet)
+        {
+            apcNet.AddPowerProvider(this);
+        }
+
+        protected override void RemoveSelfFromNet(IApcNet apcNet)
+        {
+            apcNet.RemovePowerProvider(this);
+        }
+
+        private void SetPowerTransferRange(int newPowerTransferRange)
+        {
+            var receivers = LinkedReceivers.ToArray();
+
+            foreach (var receiver in receivers)
+            {
+                receiver.Provider = null;
+            }
+
+            _powerTransferRange = newPowerTransferRange;
+
+            foreach (var receiver in receivers)
+            {
+                receiver.TryFindAndSetProvider();
+            }
+        }
+    }
+}