/// <summary>
/// This loads the items using the <see cref="CalcHistoryHelper"/>. It does not need to be a task or async becuase this
/// is a simple operation (There is no file I/O).
/// </summary>
private void ExecuteLoadItemsCommand()
{
//
if (IsBusy)
{
return;
}
//Set this to true so the app knows we are attempting to load a list. If the user tries to refresh the ListView while
//it's already being refreshed in a previous request, there could be an error. This prevents that.
IsBusy = true;
Items.Clear();
var historyLogs = CalcHistoryHelper.ReadHistoryLog();
foreach (var log in historyLogs)
{
Items.Add(log);
}
IsBusy = false;
}
/// <summary>
/// Calculator logic handling. This processes the button input. This also calls <see cref="UpdateCalculatorExpression"/> to update
/// the displayed expression.
/// </summary>
/// <param name="inpt">The value of the button that was pressed.</param>
public string HandleCalculatorInput(string inpt)
{
//Handle operators
//Note that ÷ and × are special HTML characters.
if (OPERATORS.Contains(inpt))
{
if (calculatorExpression != "" && !ExpressionEndsWithOperator(calculatorExpression) && !calculatorExpression.EndsWith("."))
{
//Reset the decimal tracker
doesCurrentWordHaveDot = false;
calculatorExpression += inpt;
}
}
//Handle decimal points
else if (inpt == ".")
{
//Skip this If there is already a decimal for this number, if the calculator expression is blank, or if the
//expression ends with an operator.
if (!doesCurrentWordHaveDot && calculatorExpression != "" && !ExpressionEndsWithOperator(calculatorExpression))
{
calculatorExpression += ".";
doesCurrentWordHaveDot = true;
}
else
{
return(calculatorExpression);
}
}
//Handle equals
else if (inpt == "=")
{
//If the current expression ends with an operator, do not process it.
if (calculatorExpression != "" && !ExpressionEndsWithOperator(calculatorExpression))
{
//TODO: Save the calculation in a log.
//Calculate the input
string calculated = Calculate(ConvertExpression(calculatorExpression));
//Save it in the history
CalcHistoryHelper.LogEntry(calculatorExpression + " = " + calculated);
calculatorExpression = calculated;
}
}
//Handle CLEAR
else if (inpt == "CLEAR")
{
doesCurrentWordHaveDot = false;
calculatorExpression = "";
}
//Handle all digits
else if (Regex.IsMatch(inpt, "[0-9]+"))
{
calculatorExpression += inpt;
}
//Handle miscellaneous cases for debugging. The program should never flow here, but in the event
//I missed a case, I'll be able to debug it.
else
{
Console.WriteLine("Input case unaccounted for: " + inpt + " when current expression is: " + calculatorExpression);
}
return(calculatorExpression);
}
