public Task <OperationResult> CompareExcelDocument(IFormFile file) =>
        Task.Factory.StartNew(() =>
        {
            OperationResult result = _validator.ValidateExcelDocument(file);

            if (result.Success)
            {
                WorkBook workBook   = WorkBookHelper.ConvertFileToWorkbook(file);
                WorkSheet worksheet = workBook.DefaultWorkSheet;

                List <Row> rowsFromDb = (List <Row>)_repository.GetAll();
                WorkSheet dbWorksheet = new WorkbookBuilder().CreateWorkBook(rowsFromDb).DefaultWorkSheet;

                List <Cell> changedCells = (List <Cell>)FindChangedCells(worksheet, dbWorksheet);
                SetRedColor(changedCells);

                workBook.SaveAs(file.FileName);
            }

            return(result);
        });
 public Task <IEnumerable <Row> > GetAllRows() =>
 Task.Factory.StartNew(() =>
 {
     return(_spreadsheetRepository.GetAll());
 });