public ActionResult ShowExpenses()
        {
            // request info about expense
            var extenseHelper = new ExpenseGeneralFunction();
            var allUserExtenses = extenseHelper.AllUserExpenses(User.Identity.Name, DateTime.UtcNow.AddDays(-7),
                                                                               DateTime.UtcNow);
            // total amount
            decimal totalAmount = 0;

            // cut expense by tag
            var statTags = extenseHelper.ExpenseByTag(allUserExtenses, ref totalAmount);

            // return model with statistic
            return View(new ExpenseModels.DisplayStatisticModel()
                            {
                                StatisticsByTag = statTags,
                                AllExpenses = allUserExtenses,
                                TotalAmount = totalAmount,
                                BeginOfPeriod = DateTime.Now.AddDays(-7),
                                EndOfPeriod = DateTime.Now
                            });
        }
        public ActionResult ShowExpenses(ExpenseModels.RequestStatisticModel model)
        {
            // select all Expenses
            var extenseHelper = new ExpenseGeneralFunction();
            var allUserExtenses = extenseHelper.AllUserExpenses(User.Identity.Name, model.BeginOfPeriod.ToUniversalTime(),
                                                                               model.EndOfPeriod.ToUniversalTime());
            // spent sum
            decimal totalAmount = 0;

            // create info by tags
            var statTags = extenseHelper.ExpenseByTag(allUserExtenses, ref totalAmount);

            // create new model, that contain all needing data
            return View(new ExpenseModels.DisplayStatisticModel()
            {
                StatisticsByTag = statTags,
                AllExpenses = allUserExtenses,
                TotalAmount = totalAmount,
                BeginOfPeriod = model.BeginOfPeriod,
                EndOfPeriod = model.EndOfPeriod
            });
        }