Candy Bucket for Halloween (#21257)

* Added candy bucket and component to update appearance of held containers akin to it

* cleanup newline

* newline was load-bearing

* moved component to Shared, cleanup

* newline is spooky

* You build and run without errors, stop pretending otherwise

* Updated for new storage system in master branch

Content.Shared/ContainerHeld/ContainerHeldComponent.cs

@@ -0,0 +1,14 @@
+namespace Content.Shared.ContainerHeld;
+
+[RegisterComponent]
+public sealed partial class ContainerHeldComponent: Component
+{
+    /// <summary>
+    ///     The amount of weight needed to be in the container
+    ///     in order for it to toggle it's appearance
+    ///     to ToggleVisuals.Toggled = true, and
+    ///     SetHeldPrefix() to "full" instead of "empty".
+    /// </summary>
+    [DataField("threshold")]
+    public int Threshold { get; private set; } = 1;
+}

Content.Shared/ContainerHeld/ContainerHeldSystem.cs

@@ -0,0 +1,43 @@
+using Robust.Shared.Containers;
+
+using Content.Shared.Item;
+using Content.Shared.Storage;
+using Content.Shared.Storage.EntitySystems;
+using Content.Shared.Toggleable;
+
+namespace Content.Shared.ContainerHeld;
+
+public sealed class ContainerHeldSystem : EntitySystem
+{
+    [Dependency] private readonly SharedItemSystem _item = default!;
+    [Dependency] private readonly SharedAppearanceSystem _appearance = default!;
+    [Dependency] private readonly SharedStorageSystem _storage = default!;
+
+    public override void Initialize()
+    {
+        base.Initialize();
+
+        SubscribeLocalEvent<ContainerHeldComponent, EntInsertedIntoContainerMessage>(OnContainerModified);
+        SubscribeLocalEvent<ContainerHeldComponent, EntRemovedFromContainerMessage>(OnContainerModified);
+    }
+
+    private void OnContainerModified(EntityUid uid, ContainerHeldComponent comp, ContainerModifiedMessage args)
+    {
+        if (!(TryComp<StorageComponent>(uid, out var storage)
+              && TryComp<AppearanceComponent>(uid, out var appearance)
+              && TryComp<ItemComponent>(uid, out var item)))
+        {
+            return;
+        }
+        if (_storage.GetCumulativeItemSizes(uid, storage) >= comp.Threshold)
+        {
+            _item.SetHeldPrefix(uid, "full", item);
+            _appearance.SetData(uid, ToggleVisuals.Toggled, true, appearance);
+        }
+        else
+        {
+            _item.SetHeldPrefix(uid, "empty", item);
+            _appearance.SetData(uid, ToggleVisuals.Toggled, false, appearance);
+        }
+    }
+}