Merge pull request #820 from nolt/feature-bots

(cherry picked from commit b10de0645a869485fbb5771a739abd06b5708c2d)

src/GameLogic/ItemExtensions.cs

@@ -137,6 +137,37 @@ public static class ItemExtensions
         return item.Definition?.Group == ShieldItemGroup;
     }
 
+    /// <summary>
+    /// Determines whether equipping an item of this definition into the given hand slot would conflict
+    /// with what the other hand already holds: a two-handed item needs the other hand free (ammunition
+    /// aside), and nothing but ammunition fits next to an already equipped two-handed item.
+    /// </summary>
+    /// <param name="itemDefinition">The definition of the item which would be equipped.</param>
+    /// <param name="inventory">The inventory to check the other hand in.</param>
+    /// <param name="toSlot">The hand slot the item would be equipped into.</param>
+    /// <returns><c>true</c> if the other hand blocks this item; otherwise, <c>false</c>.</returns>
+    public static bool ConflictsWithEquippedHands(this ItemDefinition itemDefinition, IStorage inventory, byte toSlot)
+    {
+        if (itemDefinition.ItemSlot is null)
+        {
+            return false;
+        }
+
+        static bool IsOneHandedOrShield(ItemDefinition definition) =>
+            (definition.ItemSlot!.ItemSlots.Contains(InventoryConstants.RightHandSlot) && definition.ItemSlot.ItemSlots.Contains(InventoryConstants.LeftHandSlot))
+            || definition.Group == ShieldItemGroup;
+
+        var rightHandItemDefinition = inventory.GetItem(InventoryConstants.RightHandSlot)?.Definition;
+
+        return (toSlot == InventoryConstants.LeftHandSlot
+                && itemDefinition.Width >= 2
+                && rightHandItemDefinition is not null
+                && !rightHandItemDefinition.IsAmmunition)
+               || (toSlot == InventoryConstants.RightHandSlot
+                   && IsOneHandedOrShield(itemDefinition)
+                   && inventory.GetItem(InventoryConstants.LeftHandSlot)?.Definition?.Width >= 2);
+    }
+
     /// <summary>
     /// Determines whether this item is a jewelry (pendant or ring) item.
     /// </summary>