use nom::branch::alt;
use nom::bytes::complete::is_not;
use nom::bytes::complete::tag;
use nom::bytes::complete::tag_no_case;
use nom::bytes::complete::take_while1;
use nom::character::complete::anychar;
use nom::character::complete::line_ending;
use nom::character::complete::space0;
use nom::character::complete::space1;
use nom::combinator::consumed;
use nom::combinator::eof;
use nom::combinator::not;
use nom::combinator::peek;
use nom::combinator::recognize;
use nom::multi::many_till;
use nom::sequence::tuple;

use super::org_source::BracketDepth;
use super::org_source::OrgSource;
use crate::context::Matcher;
use crate::context::RefContext;
use crate::error::CustomError;
use crate::error::MyError;
use crate::error::Res;
use crate::parser::util::start_of_line;
use crate::types::Keyword;

const ORG_ELEMENT_AFFILIATED_KEYWORDS: [&'static str; 13] = [
    "caption", "data", "header", "headers", "label", "name", "plot", "resname", "result",
    "results", "source", "srcname", "tblname",
];
const ORG_ELEMENT_DUAL_KEYWORDS: [&'static str; 2] = ["caption", "results"];

pub fn filtered_keyword<F: Matcher>(
    key_parser: F,
) -> impl for<'s> Fn(OrgSource<'s>) -> Res<OrgSource<'s>, Keyword<'s>> {
    move |input| _filtered_keyword(&key_parser, input)
}

#[cfg_attr(
    feature = "tracing",
    tracing::instrument(ret, level = "debug", skip(key_parser))
)]
fn _filtered_keyword<'s, F: Matcher>(
    key_parser: F,
    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, (consumed_input, (_, _, parsed_key, _))) =
        consumed(tuple((space0, tag("#+"), key_parser, tag(":"))))(input)?;
    match tuple((space0, alt((line_ending, eof))))(remaining) {
        Ok((remaining, _)) => {
            return Ok((
                remaining,
                Keyword {
                    source: consumed_input.into(),
                    key: parsed_key.into(),
                    value: "".into(),
                },
            ));
        }
        err @ Err(_) => err?,
    };
    let (remaining, _ws) = space1(remaining)?;
    let (remaining, parsed_value) = is_not("\r\n")(remaining)?;
    let (remaining, _ws) = tuple((space0, alt((line_ending, eof))))(remaining)?;
    Ok((
        remaining,
        Keyword {
            source: consumed_input.into(),
            key: parsed_key.into(),
            value: parsed_value.into(),
        },
    ))
}

#[cfg_attr(feature = "tracing", tracing::instrument(ret, level = "debug"))]
pub fn keyword<'b, 'g, 'r, 's>(
    _context: RefContext<'b, 'g, 'r, 's>,
    input: OrgSource<'s>,
) -> Res<OrgSource<'s>, Keyword<'s>> {
    filtered_keyword(regular_keyword_key)(input)
}

#[cfg_attr(feature = "tracing", tracing::instrument(ret, level = "debug"))]
pub fn affiliated_keyword<'b, 'g, 'r, 's>(
    _context: RefContext<'b, 'g, 'r, 's>,
    input: OrgSource<'s>,
) -> Res<OrgSource<'s>, Keyword<'s>> {
    filtered_keyword(affiliated_key)(input)
}

#[cfg_attr(feature = "tracing", tracing::instrument(ret, level = "debug"))]
fn regular_keyword_key<'s>(input: OrgSource<'s>) -> Res<OrgSource<'s>, OrgSource<'s>> {
    recognize(tuple((
        not(peek(tag_no_case("call"))),
        not(peek(tag_no_case("begin"))),
        is_not(" \t\r\n:"),
    )))(input)
}

#[cfg_attr(feature = "tracing", tracing::instrument(ret, level = "debug"))]
fn affiliated_key<'s>(input: OrgSource<'s>) -> Res<OrgSource<'s>, OrgSource<'s>> {
    alt((
        recognize(tuple((dual_affiliated_key, tag("["), optval, tag("]")))),
        plain_affiliated_key,
        export_keyword,
    ))(input)
}

#[cfg_attr(feature = "tracing", tracing::instrument(ret, level = "debug"))]
fn plain_affiliated_key<'s>(input: OrgSource<'s>) -> Res<OrgSource<'s>, OrgSource<'s>> {
    for keyword in ORG_ELEMENT_AFFILIATED_KEYWORDS {
        let result = tag_no_case::<_, _, CustomError<_>>(keyword)(input);
        match result {
            Ok((remaining, ent)) => {
                return Ok((remaining, ent));
            }
            Err(_) => {}
        }
    }

    Err(nom::Err::Error(CustomError::MyError(MyError(
        "NoKeywordKey".into(),
    ))))
}

#[cfg_attr(feature = "tracing", tracing::instrument(ret, level = "debug"))]
fn dual_affiliated_key<'s>(input: OrgSource<'s>) -> Res<OrgSource<'s>, OrgSource<'s>> {
    for keyword in ORG_ELEMENT_DUAL_KEYWORDS {
        let result = tag_no_case::<_, _, CustomError<_>>(keyword)(input);
        match result {
            Ok((remaining, ent)) => {
                return Ok((remaining, ent));
            }
            Err(_) => {}
        }
    }

    Err(nom::Err::Error(CustomError::MyError(MyError(
        "NoKeywordKey".into(),
    ))))
}

#[cfg_attr(feature = "tracing", tracing::instrument(ret, level = "debug"))]
fn optval<'s>(input: OrgSource<'s>) -> Res<OrgSource<'s>, OrgSource<'s>> {
    recognize(many_till(
        anychar,
        peek(optval_end(input.get_bracket_depth())),
    ))(input)
}

const fn optval_end(
    starting_bracket_depth: BracketDepth,
) -> impl for<'s> Fn(OrgSource<'s>) -> Res<OrgSource<'s>, OrgSource<'s>> {
    move |input: OrgSource<'_>| _optval_end(input, starting_bracket_depth)
}

#[cfg_attr(feature = "tracing", tracing::instrument(ret, level = "debug"))]
fn _optval_end<'s>(
    input: OrgSource<'s>,
    starting_bracket_depth: BracketDepth,
) -> Res<OrgSource<'s>, OrgSource<'s>> {
    let current_depth = input.get_bracket_depth() - starting_bracket_depth;
    if current_depth < 0 {
        // This shouldn't be possible because if depth is 0 then a closing bracket should end the opval.
        unreachable!("Exceeded optval bracket depth.")
    }
    if current_depth == 0 {
        let close_bracket = tag::<_, _, CustomError<_>>("]")(input);
        if close_bracket.is_ok() {
            return close_bracket;
        }
    }
    tag("\n")(input)
}

#[cfg_attr(feature = "tracing", tracing::instrument(ret, level = "debug"))]
fn export_keyword<'s>(input: OrgSource<'s>) -> Res<OrgSource<'s>, OrgSource<'s>> {
    recognize(tuple((
        tag_no_case("attr_"),
        take_while1(|c: char| c.is_alphanumeric() || "-_".contains(c)),
    )))(input)
}