/**
  * Move item to given wishlist.
  * Check whether item belongs to one of customer's wishlists
  *
  * @param Mage_Wishlist_Model_Item $item
  * @param Mage_Wishlist_Model_Wishlist $wishlist
  * @param Mage_Wishlist_Model_Resource_Wishlist_Collection $customerWishlists
  * @param int $qty
  * @throws InvalidArgumentException|DomainException
  */
 protected function _moveItem(Mage_Wishlist_Model_Item $item, Mage_Wishlist_Model_Wishlist $wishlist, Mage_Wishlist_Model_Resource_Wishlist_Collection $customerWishlists, $qty = null)
 {
     if (!$item->getId()) {
         throw new InvalidArgumentException();
     }
     if ($item->getWishlistId() == $wishlist->getId()) {
         throw new DomainException(null, 1);
     }
     if (!$customerWishlists->getItemById($item->getWishlistId())) {
         throw new DomainException(null, 2);
     }
     $buyRequest = $item->getBuyRequest();
     if ($qty) {
         $buyRequest->setQty($qty);
     }
     $wishlist->addNewItem($item->getProduct(), $buyRequest);
     $qtyDiff = $item->getQty() - $qty;
     if ($qty && $qtyDiff > 0) {
         $item->setQty($qtyDiff);
         $item->save();
     } else {
         $item->delete();
     }
 }