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::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::error::CustomError;
use crate::error::MyError;
use crate::error::Res;
use crate::parser::util::start_of_line;
use crate::parser::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"];

#[cfg_attr(feature = "tracing", tracing::instrument(ret, level = "debug"))]
pub fn keyword<'r, 's>(
    _context: RefContext<'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(),
        },
    ))
}

#[cfg_attr(feature = "tracing", tracing::instrument(ret, level = "debug"))]
pub fn affiliated_keyword<'r, 's>(
    _context: RefContext<'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("#+"),
        affiliated_key,
        tag(":"),
        alt((recognize(tuple((space1, is_not("\r\n")))), space0)),
        alt((line_ending, eof)),
    )))(input)?;
    Ok((
        remaining,
        Keyword {
            source: rule.into(),
        },
    ))
}

#[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)
}