use nom::branch::alt;
use nom::bytes::complete::is_not;
use nom::bytes::complete::tag;
use nom::bytes::complete::tag_no_case;
use nom::character::complete::line_ending;
use nom::character::complete::space0;
use nom::character::complete::space1;
use nom::combinator::eof;
use nom::combinator::not;
use nom::combinator::peek;
use nom::combinator::recognize;
use nom::sequence::tuple;

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

#[cfg_attr(feature = "tracing", tracing::instrument(ret, level = "debug"))]
pub fn keyword<'r, 's>(
    _context: Context<'r, 's>,
    input: OrgSource<'s>,
) -> Res<OrgSource<'s>, Keyword<'s>> {
    start_of_line(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("#+"),
        not(peek(tag_no_case("call"))),
        not(peek(tag_no_case("begin"))),
        is_not(" \t\r\n:"),
        tag(":"),
        alt((recognize(tuple((space1, is_not("\r\n")))), space0)),
        alt((line_ending, eof)),
    )))(input)?;
    Ok((
        remaining,
        Keyword {
            source: rule.into(),
        },
    ))
}