use nom::branch::alt;
use nom::bytes::complete::tag;
use nom::bytes::complete::tag_no_case;
use nom::character::complete::satisfy;
use nom::character::complete::space0;
use nom::combinator::eof;
use nom::combinator::peek;
use nom::combinator::recognize;

use super::Context;
use crate::error::Res;
use crate::parser::object::Entity;
use crate::parser::parser_with_context::parser_with_context;
use crate::parser::util::get_consumed;

#[cfg_attr(feature = "tracing", tracing::instrument(ret, level = "debug"))]
pub fn entity<'r, 's>(context: Context<'r, 's>, input: &'s str) -> Res<&'s str, Entity<'s>> {
    let (remaining, _) = tag("\\")(input)?;
    let (remaining, entity_name) = name(context, remaining)?;
    let (remaining, _) = alt((
        tag("{}"),
        peek(recognize(parser_with_context!(entity_end)(context))),
    ))(remaining)?;
    let (remaining, _) = space0(remaining)?;

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

#[cfg_attr(feature = "tracing", tracing::instrument(ret, level = "debug"))]
fn name<'r, 's>(context: Context<'r, 's>, input: &'s str) -> Res<&'s str, &'s str> {
    // TODO: This should be defined by org-entities and optionally org-entities-user

    // TODO: Add the rest of the entities, this is a very incomplete list
    let (remaining, proto) = alt((alt((tag_no_case("delta"), tag_no_case("pi"))),))(input)?;
    Ok((remaining, proto))
}

#[cfg_attr(feature = "tracing", tracing::instrument(ret, level = "debug"))]
fn entity_end<'r, 's>(context: Context<'r, 's>, input: &'s str) -> Res<&'s str, ()> {
    let (remaining, _) = alt((eof, recognize(satisfy(|c| !c.is_alphabetic()))))(input)?;

    Ok((remaining, ()))
}