public async Task UpdateTaxAndShippingPrices()

in src/Modules/SimplCommerce.Module.Orders/Services/OrderService.cs [379:433]
49 lines of code
6 McCabe index (conditional complexity)

        public async Task<OrderTaxAndShippingPriceVm> UpdateTaxAndShippingPrices(long cartId, TaxAndShippingPriceRequestVm model)
        {
            var cart = await _cartRepository.Query().FirstOrDefaultAsync(x => x.Id == cartId);
            if (cart == null)
            {
                throw new ApplicationException($"Cart id {cartId} not found");
            }

            Address address;
            if (model.ExistingShippingAddressId != 0)
            {
                address = await _userAddressRepository.Query().Where(x => x.Id == model.ExistingShippingAddressId).Select(x => x.Address).FirstOrDefaultAsync();
                if (address == null)
                {
                    throw new ApplicationException($"Address id {model.ExistingShippingAddressId} not found");
                }
            }
            else
            {
                address = new Address
                {
                    CountryId = model.NewShippingAddress.CountryId,
                    StateOrProvinceId = model.NewShippingAddress.StateOrProvinceId,
                    DistrictId = model.NewShippingAddress.DistrictId,
                    ZipCode = model.NewShippingAddress.ZipCode,
                    AddressLine1 = model.NewShippingAddress.AddressLine1,
                };
            }

            var orderTaxAndShippingPrice = new OrderTaxAndShippingPriceVm
            {
                Cart = await _cartService.GetActiveCartDetails(cart.CustomerId, cart.CreatedById)
            };

            cart.TaxAmount = orderTaxAndShippingPrice.Cart.TaxAmount = await GetTax(cartId, address.CountryId, address.StateOrProvinceId, address.ZipCode);

            var request = new GetShippingPriceRequest
            {
                OrderAmount = orderTaxAndShippingPrice.Cart.OrderTotal,
                ShippingAddress = address
            };

            orderTaxAndShippingPrice.ShippingPrices = await _shippingPriceService.GetApplicableShippingPrices(request);
            var selectedShippingMethod = string.IsNullOrWhiteSpace(model.SelectedShippingMethodName)
                ? orderTaxAndShippingPrice.ShippingPrices.FirstOrDefault()
                : orderTaxAndShippingPrice.ShippingPrices.FirstOrDefault(x => x.Name == model.SelectedShippingMethodName);
            if (selectedShippingMethod != null)
            {
                cart.ShippingAmount = orderTaxAndShippingPrice.Cart.ShippingAmount = selectedShippingMethod.Price;
                cart.ShippingMethod = orderTaxAndShippingPrice.SelectedShippingMethodName = selectedShippingMethod.Name;
            }

            await _cartRepository.SaveChangesAsync();
            return orderTaxAndShippingPrice;
        }