public static string ConvertCurrency(string parameter)
{
if (parameter.IndexOf(' ') == -1)
{
return(usage()); // TODO: try 1.23USD
}
string firstPart = parameter.Substring(0, parameter.IndexOf(' '));
string secondPart = parameter.Substring(parameter.IndexOf(' ') + 1);
string to, from;
if (double.TryParse(firstPart, out double value))
{
from = secondPart;
to = "EUR";
}
else
{
to = firstPart;
if (secondPart.IndexOf(' ') == -1)
{
return(usage()); // TODO: try 1.23USD
}
if (!double.TryParse(secondPart.Substring(0, secondPart.IndexOf(' ')), out value))
{
return(usage());
}
from = secondPart.Substring(secondPart.IndexOf(' ') + 1);
}
// TODO: convert symbols?
return($"{value} {from} = {ExchangeRate.ConvertCurrency(value, from, to).Result} {to}");
string usage() => "Parameter format: `<amount> `<from>` or `<to> <amount> <from>`";
}
