use crate::error::CustomError;
use crate::error::MyError;
use crate::error::Res;
use nom::branch::alt;
use nom::bytes::complete::tag;
use nom::bytes::complete::tag_no_case;
use nom::bytes::complete::take_while;
use nom::character::complete::line_ending;
use nom::character::complete::space0;
use nom::combinator::consumed;
use nom::combinator::eof;
use nom::combinator::recognize;
use nom::multi::many_till;
use nom::sequence::tuple;

use super::Context;
use crate::parser::element_parser::element;
use crate::parser::exiting::ExitClass;
use crate::parser::parser_context::ContextElement;
use crate::parser::parser_context::ExitMatcherNode;
use crate::parser::parser_with_context::parser_with_context;
use crate::parser::util::blank_line;
use crate::parser::util::exit_matcher_parser;
use crate::parser::util::get_consumed;
use crate::parser::util::immediate_in_section;

use crate::parser::util::start_of_line;
use crate::parser::util::WORD_CONSTITUENT_CHARACTERS;
use crate::parser::Drawer;
use crate::parser::Element;
use crate::parser::Paragraph;

#[tracing::instrument(ret, level = "debug")]
pub fn drawer<'r, 's>(context: Context<'r, 's>, input: &'s str) -> Res<&'s str, Drawer<'s>> {
    if immediate_in_section(context, "drawer") {
        return Err(nom::Err::Error(CustomError::MyError(MyError(
            "Cannot nest objects of the same element",
        ))));
    }
    start_of_line(context, input)?;
    let (remaining, _leading_whitespace) = space0(input)?;
    let (remaining, (_open_colon, drawer_name, _close_colon, _new_line)) = tuple((
        tag(":"),
        name,
        tag(":"),
        recognize(tuple((space0, line_ending))),
    ))(remaining)?;

    let parser_context = context
        .with_additional_node(ContextElement::ConsumeTrailingWhitespace(true))
        .with_additional_node(ContextElement::Context("drawer"))
        .with_additional_node(ContextElement::ExitMatcherNode(ExitMatcherNode {
            class: ExitClass::Alpha,
            exit_matcher: &drawer_end,
        }));

    let element_matcher = parser_with_context!(element(true))(&parser_context);
    let exit_matcher = parser_with_context!(exit_matcher_parser)(&parser_context);
    let (remaining, children) = match consumed(many_till(blank_line, exit_matcher))(remaining) {
        Ok((remaining, (whitespace, (_children, _exit_contents)))) => (
            remaining,
            vec![Element::Paragraph(Paragraph::of_text(whitespace))],
        ),
        Err(_) => {
            let (remaining, (children, _exit_contents)) =
                many_till(element_matcher, exit_matcher)(remaining)?;
            (remaining, children)
        }
    };
    let (remaining, _end) = drawer_end(&parser_context, remaining)?;

    let source = get_consumed(input, remaining);

    Ok((
        remaining,
        Drawer {
            source,
            name: drawer_name,
            children,
        },
    ))
}

#[tracing::instrument(ret, level = "debug")]
fn name<'s>(input: &'s str) -> Res<&'s str, &'s str> {
    take_while(|c| WORD_CONSTITUENT_CHARACTERS.contains(c) || "-_".contains(c))(input)
}

#[tracing::instrument(ret, level = "debug")]
fn drawer_end<'r, 's>(context: Context<'r, 's>, input: &'s str) -> Res<&'s str, &'s str> {
    start_of_line(context, input)?;
    recognize(tuple((
        space0,
        tag_no_case(":end:"),
        space0,
        alt((line_ending, eof)),
    )))(input)
}