public AddMeterPage()
 {
     this.InitializeComponent();
     meterModel = new MeterViewModel();
 }
        private void btnCalculate_Click(object sender, RoutedEventArgs e)
        {
            meterView = new MeterViewModel();
            history = new HistoryViewModel();
            DateTime date = DateTime.Today;
            int day = date.Day;
            int month = date.Month;
            int year = date.Year;
            string myDate = day +"//"+ month +"//"+ year;

            applianceViewModel = new ApplianceViewModel();
            CURRENT_UNITS = Convert.ToDouble(txtCurrentUnits.Text);
            double total_units = 0;
            string appliance1 = txtAppliance1Hours.Text;
            string appliance2 = txtAppliance2Hours.Text;
            string appliance3 = txtAppliance3Hours.Text;
            string appliance4 = txtAppliance4Hours.Text;
            string appliance5 = txtAppliance5Hours.Text;
            try { 
            double first_appliance_hours = Convert.ToDouble(appliance1);
            double second_appliance_hours = Convert.ToDouble(appliance2);
            double third_appliance_hours = Convert.ToDouble(appliance3);
            double fourth_appliance_hours = Convert.ToDouble(appliance4);
            double fifth_appliance_hours = Convert.ToDouble(appliance5);

            double total_appliance_hours = first_appliance_hours + second_appliance_hours + third_appliance_hours + fourth_appliance_hours + fifth_appliance_hours;
            Kilo_Watts = (total_watts * total_appliance_hours) * tota_number;

            total_units = Kilo_Watts / 1000;
            REMAINING_UNITS += CURRENT_UNITS - total_units;
            string checkDate = date.ToString("D");
            history.saveHistory(tota_number, total_units, REMAINING_UNITS, checkDate);
            lblRemainingUnits.Text = "You have " + REMAINING_UNITS + " Units Remaining";
            meterView.updateMeterBoxUnits(total_units);
            txtCurrentUnits.Text = ""+REMAINING_UNITS;
            messageBox("Total consumed Units for selected appliances is : " + total_units + " units");
            }
            catch (Exception ex){
                messageBox("Please check your text fields or "+ex.Message);
            }

        }