module model.currency;

struct Currency {
    const char[3] code;
    const ubyte fractionalDigits;
    const ushort numericCode;

    import std.traits : isSomeString, EnumMembers;
    static Currency ofCode(S)(S code) if (isSomeString!S) {
        if (code.length != 3) {
            throw new Exception("Invalid currency code: " ~ code);
        }
        static foreach (c; EnumMembers!Currencies) {
            if (c.code == code) return c;
        }
        throw new Exception("Unknown currency code: " ~ code);
    }
}

enum Currencies : Currency {
    USD = Currency("USD", 2, 840),
    CAD = Currency("CAD", 2, 124),
    GBP = Currency("GBP", 2, 826),
    EUR = Currency("EUR", 2, 978),
    CHF = Currency("CHF", 2, 756),
    ZAR = Currency("ZAR", 2, 710),
    JPY = Currency("JPY", 0, 392),
    INR = Currency("INR", 2, 356)
}

unittest {
    assert(Currency.ofCode("USD") == Currencies.USD);
}