Decouple Lights from Toggleable Visuals (and headphone music notes bugfix) (#35341)

* - Combine enum keys `ToggleableLightVisuals` and `ToggleVisuals` into `ToggleableVisuals`
- Rename `ToggleableLightVisualsComponent` to `ToggleableVisualsComponent` and `ToggleableLightVisualsSystem` to `ToggleableVisualsSystem`
  - (The `SpriteLayer` field on the component is now required because the old default of `light` doesn't make sense anymore)
- Make it so that `ToggleableVisualsComponent` works even when there's not a light attached to the entity
  - (Amazingly this seems to have only applied to  Headphones, but I can only imagine there are many other things people would like to do with simple toggleable visuals)
- Explicitly make `ItemTogglePointLightComponent`'s purpose to make `ToggleVisualsComponent` apply to `PointLightComponent`s on the same entity.
  - Add field `ToggleableVisualsColorModulatesLights`, which makes the `Color` appearance value of `ToggleableVisuals` modulate the color of lights on the same entity
  - Lots of prototype updates to uptake the above

* fix bad merge

* unbork robust

* blindly letting rider reformat stuff

* I guess I never cleaned up these imports at all

Content.Client/Toggleable/ToggleableVisualsSystem.cs

@@ -0,0 +1,140 @@
+using System.Linq;
+using Content.Client.Clothing;
+using Content.Client.Items.Systems;
+using Content.Shared.Clothing;
+using Content.Shared.Hands;
+using Content.Shared.Inventory;
+using Content.Shared.Item;
+using Content.Shared.Light.Components;
+using Content.Shared.Toggleable;
+using Robust.Client.GameObjects;
+using Robust.Shared.Utility;
+
+namespace Content.Client.Toggleable;
+
+/// <summary>
+/// Implements the behavior of <see cref="ToggleableVisualsComponent"/> by reacting to
+/// <see cref="AppearanceChangeEvent"/>, for the sprite directly; <see cref="OnGetHeldVisuals"/> for the
+/// in-hand visuals; and <see cref="OnGetEquipmentVisuals"/> for the clothing visuals.
+/// </summary>
+/// <see cref="ToggleableVisualsComponent"/>
+public sealed class ToggleableVisualsSystem : VisualizerSystem<ToggleableVisualsComponent>
+{
+    [Dependency] private readonly SharedItemSystem _item = default!;
+    [Dependency] private readonly SharedPointLightSystem _pointLight = default!;
+
+    public override void Initialize()
+    {
+        base.Initialize();
+        SubscribeLocalEvent<ToggleableVisualsComponent, GetInhandVisualsEvent>(OnGetHeldVisuals,
+            after: [typeof(ItemSystem)]);
+        SubscribeLocalEvent<ToggleableVisualsComponent, GetEquipmentVisualsEvent>(OnGetEquipmentVisuals,
+            after: [typeof(ClientClothingSystem)]);
+    }
+
+    protected override void OnAppearanceChange(EntityUid uid,
+        ToggleableVisualsComponent component,
+        ref AppearanceChangeEvent args)
+    {
+        if (!AppearanceSystem.TryGetData<bool>(uid, ToggleableVisuals.Enabled, out var enabled, args.Component))
+            return;
+
+        var modulateColor =
+            AppearanceSystem.TryGetData<Color>(uid, ToggleableVisuals.Color, out var color, args.Component);
+
+        // Update the item's sprite
+        if (args.Sprite != null && component.SpriteLayer != null &&
+            SpriteSystem.LayerMapTryGet((uid, args.Sprite), component.SpriteLayer, out var layer, false))
+        {
+            SpriteSystem.LayerSetVisible((uid, args.Sprite), layer, enabled);
+            if (modulateColor)
+                SpriteSystem.LayerSetColor((uid, args.Sprite), component.SpriteLayer, color);
+        }
+
+        // If there's a `ItemTogglePointLightComponent` that says to apply the color to attached lights, do so.
+        if (TryComp<ItemTogglePointLightComponent>(uid, out var toggleLights) &&
+            TryComp(uid, out PointLightComponent? light))
+        {
+            DebugTools.Assert(!light.NetSyncEnabled,
+                $"{typeof(ItemTogglePointLightComponent)} requires point lights without net-sync");
+            _pointLight.SetEnabled(uid, enabled, light);
+            if (modulateColor && toggleLights.ToggleableVisualsColorModulatesLights)
+            {
+                _pointLight.SetColor(uid, color, light);
+            }
+        }
+
+        // update clothing & in-hand visuals.
+        _item.VisualsChanged(uid);
+    }
+
+    private void OnGetEquipmentVisuals(EntityUid uid,
+        ToggleableVisualsComponent component,
+        GetEquipmentVisualsEvent args)
+    {
+        if (!TryComp(uid, out AppearanceComponent? appearance)
+            || !AppearanceSystem.TryGetData<bool>(uid, ToggleableVisuals.Enabled, out var enabled, appearance)
+            || !enabled)
+            return;
+
+        if (!TryComp(args.Equipee, out InventoryComponent? inventory))
+            return;
+        List<PrototypeLayerData>? layers = null;
+
+        // attempt to get species specific data
+        if (inventory.SpeciesId != null)
+            component.ClothingVisuals.TryGetValue($"{args.Slot}-{inventory.SpeciesId}", out layers);
+
+        // No species specific data.  Try to default to generic data.
+        if (layers == null && !component.ClothingVisuals.TryGetValue(args.Slot, out layers))
+            return;
+
+        var modulateColor = AppearanceSystem.TryGetData<Color>(uid, ToggleableVisuals.Color, out var color, appearance);
+
+        var i = 0;
+        foreach (var layer in layers)
+        {
+            var key = layer.MapKeys?.FirstOrDefault();
+            if (key == null)
+            {
+                key = i == 0 ? $"{args.Slot}-toggle" : $"{args.Slot}-toggle-{i}";
+                i++;
+            }
+
+            if (modulateColor)
+                layer.Color = color;
+
+            args.Layers.Add((key, layer));
+        }
+    }
+
+    private void OnGetHeldVisuals(EntityUid uid, ToggleableVisualsComponent component, GetInhandVisualsEvent args)
+    {
+        if (!TryComp(uid, out AppearanceComponent? appearance)
+            || !AppearanceSystem.TryGetData<bool>(uid, ToggleableVisuals.Enabled, out var enabled, appearance)
+            || !enabled)
+            return;
+
+        if (!component.InhandVisuals.TryGetValue(args.Location, out var layers))
+            return;
+
+        var modulateColor = AppearanceSystem.TryGetData<Color>(uid, ToggleableVisuals.Color, out var color, appearance);
+
+        var i = 0;
+        var defaultKey = $"inhand-{args.Location.ToString().ToLowerInvariant()}-toggle";
+        foreach (var layer in layers)
+        {
+            var key = layer.MapKeys?.FirstOrDefault();
+            if (key == null)
+            {
+                key = i == 0 ? defaultKey : $"{defaultKey}-{i}";
+                i++;
+            }
+
+            if (modulateColor)
+                layer.Color = color;
+
+            args.Layers.Add((key, layer));
+        }
+    }
+}