public Command ProcessCommand()
{
try
{
Command command = _userInteraction.WaitForUserAction();
if (command == null)
{
_userInteraction.DisplayMessage("Incorrect command, please try again or type HELP");
return(null);
}
if (command is HelpCommand)
{
_userInteraction.DisplayMessage(HELP_MESSAGE);
return(command);
}
if (command is ExchangeCommand)
{
if (!command.HasCorrectArguments)
{
_userInteraction.DisplayMessage(command.GetArgumentHelpMessage());
return(null);
}
var exchangeCommand = (ExchangeCommand)command;
var result = _exchangeService.GetAmount(
exchangeCommand.CurrencyFrom,
exchangeCommand.CurrencyTo,
exchangeCommand.FromAmount
);
_userInteraction.DisplayMessage($"{result:N4}");
}
return(command);
}
catch (InvalidCurrencyException ex)
{
_userInteraction.DisplayMessage($"Currency '{ex.InvalidValue}' is not supported.");
return(null);
}
catch (Exception)
{
_userInteraction.DisplayMessage("Something went wrong, please try again.");
return(null);
}
}
