signal router (#20802)

* add signal router sprite

* DisposalSignalRouter logic

* add disposal signal router

* add disposal signal router

* how did it work without this

* death

---------

Co-authored-by: deltanedas <@deltanedas:kde.org>

Content.Server/Disposal/Tube/Systems/DisposalSignalRouterSystem.cs

@@ -0,0 +1,52 @@
+using Content.Server.DeviceLinking.Events;
+using Content.Server.DeviceLinking.Systems;
+using Content.Server.Disposal.Tube;
+using Content.Server.Disposal.Tube.Components;
+
+namespace Content.Server.Disposal.Tube.Systems;
+
+/// <summary>
+/// Handles signals and the routing get next direction event.
+/// </summary>
+public sealed class DisposalSignalRouterSystem : EntitySystem
+{
+    [Dependency] private readonly DeviceLinkSystem _deviceLink = default!;
+
+    public override void Initialize()
+    {
+        base.Initialize();
+
+        SubscribeLocalEvent<DisposalSignalRouterComponent, ComponentInit>(OnInit);
+        SubscribeLocalEvent<DisposalSignalRouterComponent, SignalReceivedEvent>(OnSignalReceived);
+        SubscribeLocalEvent<DisposalSignalRouterComponent, GetDisposalsNextDirectionEvent>(OnGetNextDirection, after: new[] { typeof(DisposalTubeSystem) });
+    }
+
+    private void OnInit(EntityUid uid, DisposalSignalRouterComponent comp, ComponentInit args)
+    {
+        _deviceLink.EnsureSinkPorts(uid, comp.OnPort, comp.OffPort, comp.TogglePort);
+    }
+
+    private void OnSignalReceived(EntityUid uid, DisposalSignalRouterComponent comp, ref SignalReceivedEvent args)
+    {
+        // TogglePort flips it
+        // OnPort sets it to true
+        // OffPort sets it to false
+        comp.Routing = args.Port == comp.TogglePort
+            ? !comp.Routing
+            : args.Port == comp.OnPort;
+    }
+
+    private void OnGetNextDirection(EntityUid uid, DisposalSignalRouterComponent comp, ref GetDisposalsNextDirectionEvent args)
+    {
+        if (!comp.Routing)
+        {
+            args.Next = Transform(uid).LocalRotation.GetDir();
+            return;
+        }
+
+        // use the junction side direction when a tag matches
+        var ev = new GetDisposalsConnectableDirectionsEvent();
+        RaiseLocalEvent(uid, ref ev);
+        args.Next = ev.Connectable[1];
+    }
+}