Cluster grenade refactor and contra markings (#31108)

* Cluster grenade refactor

* oopsies on the name

* Solve client-side errors

* reviews addressed

* filling scattering grenades is now predicted

* reviews addressed

Content.Shared/Explosion/EntitySystems/SharedScatteringGrenadeSystem.cs

@@ -0,0 +1,70 @@
+using Content.Shared.Explosion.Components;
+using Content.Shared.Interaction;
+using Content.Shared.Whitelist;
+using Robust.Shared.Containers;
+
+namespace Content.Shared.Explosion.EntitySystems;
+
+public abstract class SharedScatteringGrenadeSystem : EntitySystem
+{
+    [Dependency] private readonly EntityWhitelistSystem _whitelistSystem = default!;
+    [Dependency] private readonly SharedAppearanceSystem _appearance = default!;
+    [Dependency] private readonly SharedContainerSystem _container = default!;
+
+    public override void Initialize()
+    {
+        base.Initialize();
+
+        SubscribeLocalEvent<ScatteringGrenadeComponent, ComponentInit>(OnScatteringInit);
+        SubscribeLocalEvent<ScatteringGrenadeComponent, ComponentStartup>(OnScatteringStartup);
+        SubscribeLocalEvent<ScatteringGrenadeComponent, InteractUsingEvent>(OnScatteringInteractUsing);
+    }
+
+    private void OnScatteringInit(Entity<ScatteringGrenadeComponent> entity, ref ComponentInit args)
+    {
+        entity.Comp.Container = _container.EnsureContainer<Container>(entity.Owner, "cluster-payload");
+    }
+
+    /// <summary>
+    /// Setting the unspawned count based on capacity, so we know how many new entities to spawn
+    /// Update appearance based on initial fill amount
+    /// </summary>
+    private void OnScatteringStartup(Entity<ScatteringGrenadeComponent> entity, ref ComponentStartup args)
+    {
+        if (entity.Comp.FillPrototype == null)
+            return;
+
+        entity.Comp.UnspawnedCount = Math.Max(0, entity.Comp.Capacity - entity.Comp.Container.ContainedEntities.Count);
+        UpdateAppearance(entity);
+        Dirty(entity, entity.Comp);
+
+    }
+
+    /// <summary>
+    /// There are some scattergrenades you can fill up with more grenades (like clusterbangs)
+    /// This covers how you insert more into it
+    /// </summary>
+    private void OnScatteringInteractUsing(Entity<ScatteringGrenadeComponent> entity, ref InteractUsingEvent args)
+    {
+        if (entity.Comp.Whitelist == null)
+            return;
+
+        if (args.Handled || !_whitelistSystem.IsValid(entity.Comp.Whitelist, args.Used))
+            return;
+
+        _container.Insert(args.Used, entity.Comp.Container);
+        UpdateAppearance(entity);
+        args.Handled = true;
+    }
+
+    /// <summary>
+    /// Update appearance based off of total count of contents
+    /// </summary>
+    private void UpdateAppearance(Entity<ScatteringGrenadeComponent> entity)
+    {
+        if (!TryComp<AppearanceComponent>(entity, out var appearanceComponent))
+            return;
+
+        _appearance.SetData(entity, ClusterGrenadeVisuals.GrenadesCounter, entity.Comp.UnspawnedCount + entity.Comp.Container.ContainedEntities.Count, appearanceComponent);
+    }
+}