private void PrepareInvoiceDocument(Worksheet worksheet, int itemsCount)
{
int lastItemIndexRow = IndexRowItemStart + itemsCount;
CellIndex firstUsedCellIndex = new CellIndex(0, 0);
CellIndex lastUsedCellIndex = new CellIndex(lastItemIndexRow + 1, IndexColumnSubTotal);
CellBorder border = new CellBorder(CellBorderStyle.DashDot, InvoiceBackground);
worksheet.Cells[firstUsedCellIndex, lastUsedCellIndex].SetBorders(new CellBorders(border, border, border, border, null, null, null, null));
worksheet.Cells[firstUsedCellIndex].SetValue("INVOICE");
worksheet.Cells[firstUsedCellIndex].SetFontSize(20);
worksheet.Cells[firstUsedCellIndex].SetHorizontalAlignment(RadHorizontalAlignment.Center);
worksheet.Cells[0, 0, 0, IndexColumnSubTotal].MergeAcross();
worksheet.Columns[IndexColumnUnitPrice].SetWidth(new ColumnWidth(125, true));
worksheet.Columns[IndexColumnSubTotal].SetWidth(new ColumnWidth(125, true));
worksheet.Cells[IndexRowItemStart, 0].SetValue("Item");
worksheet.Cells[IndexRowItemStart, IndexColumnQuantity].SetValue("QTY");
worksheet.Cells[IndexRowItemStart, IndexColumnUnitPrice].SetValue("Unit Price");
worksheet.Cells[IndexRowItemStart, IndexColumnSubTotal].SetValue("SubTotal");
worksheet.Cells[IndexRowItemStart, 0, lastItemIndexRow, IndexColumnQuantity - 1].MergeAcross();
worksheet.Cells[IndexRowItemStart, 0, IndexRowItemStart, IndexColumnSubTotal].SetFill
(new GradientFill(GradientType.Horizontal, InvoiceBackground, InvoiceBackground));
worksheet.Cells[IndexRowItemStart, 0, IndexRowItemStart, IndexColumnSubTotal].SetForeColor(InvoiceHeaderForeground);
worksheet.Cells[IndexRowItemStart, IndexColumnUnitPrice, lastItemIndexRow, IndexColumnSubTotal].SetFormat(
new CellValueFormat(AccountFormatString));
worksheet.Cells[lastItemIndexRow + 1, 6].SetValue("TOTAL: ");
worksheet.Cells[lastItemIndexRow + 1, 7].SetFormat(new CellValueFormat(AccountFormatString));
string subTotalColumnCellRange = NameConverter.ConvertCellRangeToName(
new CellIndex(IndexRowItemStart + 1, IndexColumnSubTotal),
new CellIndex(lastItemIndexRow, IndexColumnSubTotal));
worksheet.Cells[lastItemIndexRow + 1, IndexColumnSubTotal].SetValue(string.Format("=SUM({0})", subTotalColumnCellRange));
worksheet.Cells[lastItemIndexRow + 1, IndexColumnUnitPrice, lastItemIndexRow + 1, IndexColumnSubTotal].SetFontSize(20);
}