hands ECS (#7081)

Content.Shared/Hands/EntitySystems/SharedHandsSystem.AI.cs

@@ -0,0 +1,39 @@
+using Content.Shared.Hands.Components;
+using System.Diagnostics.CodeAnalysis;
+
+namespace Content.Shared.Hands.EntitySystems;
+
+// These functions are mostly unused except for some AI operator stuff
+// Nothing stops them from being used in general. If they ever get used elsewhere, then this file probably needs to be renamed.
+
+public abstract partial class SharedHandsSystem : EntitySystem
+{
+    public bool TrySelect(EntityUid uid, EntityUid? entity, SharedHandsComponent? handsComp = null)
+    {
+        if (!Resolve(uid, ref handsComp, false))
+            return false;
+
+        if (!IsHolding(uid, entity, out var hand, handsComp))
+            return false;
+
+        SetActiveHand(uid, hand, handsComp);
+        return true;
+    }
+
+    public bool TrySelect<TComponent>(EntityUid uid, [NotNullWhen(true)] out TComponent? component, SharedHandsComponent? handsComp = null) where TComponent : Component
+    {
+        component = null;
+        if (!Resolve(uid, ref handsComp, false))
+            return false;
+
+        foreach (var hand in handsComp.Hands.Values)
+        {
+            if (TryComp(hand.HeldEntity, out component))
+                return true;
+        }
+
+        return false;
+    }
+
+    public bool TrySelectEmptyHand(EntityUid uid, SharedHandsComponent? handsComp = null) => TrySelect(uid, null, handsComp);
+}