use bstr::{BStr, ByteSlice};
use nom::{
    branch::alt,
    bytes::complete::{tag, take_while_m_n},
    error::ParseError,
    IResult,
};

fn is_hex_digit_lc(b: u8) -> bool {
    matches!(b, b'0'..=b'9' | b'a'..=b'f')
}

/// Copy from https://github.com/Byron/gitoxide/blob/f270850ff92eab15258023b8e59346ec200303bd/git-object/src/immutable/parse.rs#L64
pub fn hex_hash<'a, E: ParseError<&'a [u8]>>(i: &'a [u8]) -> IResult<&'a [u8], &'a BStr, E> {
    take_while_m_n(
        git_hash::Kind::shortest().len_in_hex(),
        git_hash::Kind::longest().len_in_hex(),
        is_hex_digit_lc,
    )(i)
    .map(|(i, hex)| (i, hex.as_bstr()))
}

pub fn newline<'a, E: ParseError<&'a [u8]>>(i: &'a [u8]) -> IResult<&'a [u8], &'a [u8], E> {
    alt((tag(b"\r\n"), tag(b"\n")))(i)
}