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

use super::sexp::sexp;
use super::Context;
use crate::error::Res;
use crate::parser::util::get_consumed;
use crate::parser::util::maybe_consume_trailing_whitespace_if_not_exiting;
use crate::parser::util::start_of_line;
use crate::parser::DiarySexp;

#[tracing::instrument(ret, level = "debug")]
pub fn diary_sexp<'r, 's>(context: Context<'r, 's>, input: &'s str) -> Res<&'s str, DiarySexp<'s>> {
    start_of_line(context, input)?;
    let (remaining, _leading_whitespace) = space0(input)?;
    let (remaining, _clock) = tag("%%")(remaining)?;
    let (remaining, _gap_whitespace) = space0(remaining)?;
    let (remaining, _sexp) = recognize(sexp)(remaining)?;
    let (remaining, _trailing_whitespace) =
        recognize(tuple((space0, alt((line_ending, eof)))))(remaining)?;

    let (remaining, _trailing_ws) =
        maybe_consume_trailing_whitespace_if_not_exiting(context, remaining)?;

    let source = get_consumed(input, remaining);
    Ok((remaining, DiarySexp { source }))
}