class DateGroupingKey

{

    public int Year [ get; set; ]

    public int Month [ get; set; ]

    public int Day [ get; set; ]

}

var baseQuery = _uow.BusinessSalesRepo

    .GetAll(sale => sale.BusinessId == BusinessId && sale.CreatedByBusinessCrew.BranchId == BranchId);

Expression<Func<DateTime, DateGroupingKey>> groupKeySelector;

switch (filterBy)

{

    case (int)BusinessSalesFilteredBy.Month:

        groupKeySelector = sale => new DateGroupingKey { 

            Year = sale.CreateDate.Value.Year, Month = sale.CreateDate.Value.Month 

        }

        break;

    case (int)BusinessSalesFilteredBy.Year:

        groupKeySelector = sale => new DateGroupingKey { 

            Year = sale.CreateDate.Value.Year 

        }

       break;

    default:

        // Default to daily grouping

        groupKeySelector = sale => new DateGroupingKey { 

            Year = sale.CreateDate.Value.Year, Month = sale.CreateDate.Value.Month, Day = sale.CreateDate.Value.Day 

        }

      break;

}

ar summaryQuery = baseQuery

    .GroupBy(groupKeySelector)

    .Select(grouped => new

    {

        SalesOn = grouped.Key,

        SalesCount = grouped.Count(),

        ClientCount = grouped.Select(x => x.ClientProfileId).Distinct().Count(),

        SumPurchases = grouped.Sum(x => x.PurchasedAmount ?? 0)

    });

var pagedSummary = await summaryQuery.ToListAsync();