Implement machine linking (#1784)

* Implement machine linking

* Cleanup and rename Signals

* Implement signal button

* Add machine linking signal mapping

* Fix signallink command help

* Add localization to signal linking and allow infinite range

* Add feedback for when a transmitter is not connected to any receivers

Refactor PopupMessage to use the entity extension
Refactor dependencies to not have to disable warnings

Content.Server/GameObjects/Components/MachineLinking/SignalReceiverComponent.cs

@@ -0,0 +1,118 @@
+using Content.Server.GameObjects.Components.Interactable;
+using Content.Shared.GameObjects.Components.Interactable;
+using Content.Shared.Interfaces;
+using Content.Shared.Interfaces.GameObjects.Components;
+using Robust.Shared.GameObjects;
+using Robust.Shared.Interfaces.GameObjects;
+using Robust.Shared.Interfaces.Map;
+using Robust.Shared.IoC;
+using Robust.Shared.Localization;
+using System.Collections.Generic;
+using System.Threading.Tasks;
+
+namespace Content.Server.GameObjects.Components.MachineLinking
+{
+    [RegisterComponent]
+    public class SignalReceiverComponent : Component, IInteractUsing
+    {
+        [Dependency] private readonly IMapManager _mapManager = default!;
+
+        public override string Name => "SignalReceiver";
+
+        private List<SignalTransmitterComponent> _transmitters;
+
+        public override void Initialize()
+        {
+            base.Initialize();
+
+            _transmitters = new List<SignalTransmitterComponent>();
+        }
+
+        public void DistributeSignal(SignalState state)
+        {
+            foreach (var comp in Owner.GetAllComponents<ISignalReceiver>())
+            {
+                comp.TriggerSignal(state);
+            }
+        }
+
+        public void Subscribe(SignalTransmitterComponent transmitter)
+        {
+            if (_transmitters.Contains(transmitter))
+            {
+                return;
+            }
+
+            transmitter.Subscribe(this);
+            _transmitters.Add(transmitter);
+        }
+
+        public void Unsubscribe(SignalTransmitterComponent transmitter)
+        {
+            transmitter.Unsubscribe(this);
+            _transmitters.Remove(transmitter);
+        }
+
+        /// <summary>
+        /// Subscribes/Unsubscribes a transmitter to this component. Returns whether it was successful.
+        /// </summary>
+        /// <param name="user"></param>
+        /// <param name="transmitter"></param>
+        /// <returns></returns>
+        public bool Interact(IEntity user, SignalTransmitterComponent transmitter)
+        {
+            if (transmitter == null)
+            {
+                user.PopupMessage(user, Loc.GetString("Signal not set."));
+                return false;
+            }
+
+            if (_transmitters.Contains(transmitter))
+            {
+                Unsubscribe(transmitter);
+                Owner.PopupMessage(user, Loc.GetString("Unlinked."));
+                return true;
+            }
+
+            if (transmitter.Range > 0 && !Owner.Transform.GridPosition.InRange(_mapManager, transmitter.Owner.Transform.GridPosition, transmitter.Range))
+            {
+                Owner.PopupMessage(user, Loc.GetString("Out of range."));
+                return false;
+            }
+
+            Subscribe(transmitter);
+            Owner.PopupMessage(user, Loc.GetString("Linked!"));
+            return true;
+        }
+
+        public async Task<bool> InteractUsing(InteractUsingEventArgs eventArgs)
+        {
+            if (!eventArgs.Using.TryGetComponent<ToolComponent>(out var tool))
+                return false;
+
+            if (tool.HasQuality(ToolQuality.Multitool)
+                && eventArgs.Using.TryGetComponent<SignalLinkerComponent>(out var linker))
+            {
+                return Interact(eventArgs.User, linker.Link);
+            }
+
+            return false;
+        }
+
+        protected override void Shutdown()
+        {
+            base.Shutdown();
+
+            foreach (var transmitter in _transmitters)
+            {
+                if (transmitter.Deleted)
+                {
+                    continue;
+                }
+
+                transmitter.Unsubscribe(this);
+            }
+            _transmitters.Clear();
+        }
+    }
+}