use nom::{
    character::complete::{char, one_of},
    combinator::{map, recognize},
    multi::{many0, many1},
    sequence::{preceded, terminated},
};

use crate::parser::{IResult, Span};

pub fn hexadecimal(input: Span) -> IResult<Span, u64> {
    map(
        preceded(
            char('h'),
            recognize(many1(terminated(
                one_of("0123456789abcdefABCDEF"),
                many0(char('_')),
            ))),
        ),
        |out: Span| {
            u64::from_str_radix(&str::replace(out.fragment(), "_", ""), 16).expect("error parsing literal")
        },
    )(input)
}

#[cfg(test)]
mod test {
    use super::*;

    #[test]
    fn test_hex() {
        assert_eq!(hexadecimal("hfF".into()).unwrap().1, 0xff);
        assert_eq!(hexadecimal("hF".into()).unwrap().1, 0xf);
    }
}