func configureItemFetchedResultsController() {
        print("configureItemFetchedResultsController(): started")
        let itemFetchRequest = NSFetchRequest<NSFetchRequestResult>(entityName: "Item")
        itemFetchRequest.sortDescriptors = [NSSortDescriptor(key: "category", ascending: true),NSSortDescriptor(key: "itemId", ascending: true)]
        let user = NSPredicate(format: "order.user.name == %@", UserDetails.fullName ?? "")
        let dateFrom = Conversions.dateConvert(dateString: dateToFetchMin)!
        let dateTo = Conversions.dateConvert(dateString: dateToFetchMax)!
        print(dateFrom)
        let from = NSPredicate(format: "date >= %@", dateFrom as CVarArg)
        let to = NSPredicate(format: "date <= %@", dateTo as CVarArg)
        itemFetchRequest.predicate = NSCompoundPredicate(andPredicateWithSubpredicates: [user,from,to])
        itemFetchRequest.propertiesToFetch = ["category","itemId","itemName"]]
        itemFetchRequest.returnsDistinctResults = true
        itemFetchRequest.propertiesToGroupBy = ["category","itemId","itemName"]
        itemFetchRequest.resultType = NSFetchRequestResultType.dictionaryResultType

        itemFetchedResultController = NSFetchedResultsController(fetchRequest: itemFetchRequest, managedObjectContext: context, sectionNameKeyPath: "category", cacheName: nil) as? NSFetchedResultsController<Item>
        do {
            try itemFetchedResultController?.performFetch()
            let resultsDict = itemFetchedResultController!.fetchedObjects!
            print(resultsDict as NSArray)
            print("configureItemFetchedResultsController(): sold items fetched")
        } catch  {
            //            fatalError("failed to fetch entities: (error)")
            print("configureItemFetchedResultsController(): failed to fetch Item entities: (error)")
        }
        self.statisticsTableView.reloadData()
    }


func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {

        let cell = tableView.dequeueReusableCell(withIdentifier: "statisticsCell", for: indexPath) as! StatisticsTableViewCell
        let item = itemFetchedResultController?.object(at: indexPath).itemName!
        //        let item = itemResultsArray[indexPath.row]
        let productRequest: NSFetchRequest<Product> = Product.fetchRequest()
        productRequest.sortDescriptors = [NSSortDescriptor(key: "name", ascending: true)]
        productRequest.predicate = NSPredicate(format: "name == %@", item!)
        productRequest.fetchLimit = 1
        do {
            let fetch = try context.fetch(productRequest)
            cell.idInfoLabel.text = fetch[0].productId
            cell.nameInfoLabel.text = fetch[0].name
            cell.productImageView.image = UIImage(data: (fetch[0].productImage! as Data))
            cell.minimumStockInfoLabel.text = fetch[0].minimumStock
            let productPrice = fetch[0].price
            //fetch item for amount of single object
            let itemId = itemFetchedResultController?.object(at: indexPath).itemId!
            let itemRequest = NSFetchRequest<Item>(entityName: "Item")
            itemRequest.sortDescriptors = [NSSortDescriptor(key: "itemName", ascending: true)]
            itemRequest.predicate = NSPredicate(format: "date BEGINSWITH %@", dateToFetchMin)
            itemRequest.predicate = NSPredicate(format: "itemId == %@", itemId!)
            do {
                let itemFetch = try context.fetch(itemRequest)
                print(productPrice!)
                print(itemFetch, itemFetch.count)
                cell.soldQuantityInfoLabel.text = String(describing: itemFetch.count)
                let amount = Double(productPrice!)! * Double(itemFetch.count)
                cell.salesAmountInfoLabel.text = String(describing: amount)
            } catch  {
                print("Error in fetching sold items for cell: (error)")
            }
        } catch  {
            print("Error in fetching product for cell: (error)")
        }
        return cell
    }