public CalculatorViewModel()
{
CalculateCommand = new RelayCommand <string>(param =>
OutputText = IsValidInput(InputText) ? _model.Calculate(InputText) : "Invalid Input"
);
InputCommand = new RelayCommand <string>(input =>
{
InputText += input;
InputTextBackground = IsValidInput(InputText) ? Brushes.White : Brushes.Crimson;
});
EarseCommand = new RelayCommand <string>(param => InputText = "");
BackspaceCommand = new RelayCommand <string>(param =>
{
if (InputText.Length > 0)
{
InputText = InputText.Remove(InputText.Length - 1);
}
InputTextBackground = IsValidInput(InputText) ? Brushes.White : Brushes.Crimson;
});
_model = new CalculatorModel();
WindowCloseCommand = new RelayCommand <object>(o => _model.CloseService());
}
