enum Type {
    Visa,
    Discover,
    MasterCard,
    AmericanExpress
}

impl ToString for Type {
    fn to_string(&self) -> String {
        match self {
            Type::Visa => "Visa".into(),
            Type::Discover => "Discover".into(),
            Type::MasterCard => "MasterCard".into(),
            Type::AmericanExpress => "AmericanExpress".into(),
        }
    }
}

type Rule = (Type, Vec<Vec<String>>);

const RULES: Vec<Rule> = vec![
    (Type::Visa, vec![vec!["4"]]),
    (Type::Discover, vec![vec!["6011"], range_of_strings(622126, 622925), range_of_strings(644, 649), ["65"]]),
    (Type::MasterCard, vec![range_of_strings(50, 55), range_of_strings(222100, 272099)]),
    (Type::AmericanExpress, vec![vec!["34"], vec!["37"]]),
];

fn range_of_strings(start: u32, end: u32) -> Vec<String> {
    (start..=end).map(|n| n.to_string()).collect()
}

fn card_matches_rule(card: String, rule: Rule) -> boolean {

}

fn to_matching_type(card: String, matched: Option<Type>, type: Type) -> Option<Type> {

}

fn detect_type(card: Option<String>) -> Maybe<Type> {
    return if card.is_none() { card } else {

    }
}

fn main() {
    println!("Hello, world!");
}