use nom::branch::alt;
use nom::bytes::complete::is_not;
use nom::bytes::complete::tag;
use nom::character::complete::line_ending;
use nom::character::complete::space0;
use nom::character::complete::space1;
use nom::combinator::eof;
use nom::combinator::recognize;
use nom::sequence::tuple;

use super::Context;
use crate::error::Res;
use crate::parser::util::start_of_line;
use crate::parser::Keyword;

#[tracing::instrument(ret, level = "debug")]
pub fn keyword<'r, 's>(context: Context<'r, 's>, input: &'s str) -> Res<&'s str, Keyword<'s>> {
    start_of_line(context, input)?;
    // TODO: When key is a member of org-element-parsed-keywords, value can contain the standard set objects, excluding footnote references.
    let (remaining, rule) = recognize(tuple((
        space0,
        tag("#+"),
        is_not(" \t\r\n:"),
        tag(":"),
        space1,
        is_not("\r\n"),
        alt((line_ending, eof)),
    )))(input)?;
    Ok((remaining, Keyword { source: rule }))
}