use nom::branch::alt;
use nom::bytes::complete::escaped;
use nom::bytes::complete::tag;
use nom::bytes::complete::take_till1;
use nom::character::complete::anychar;
use nom::combinator::consumed;
use nom::combinator::eof;
use nom::combinator::map_parser;
use nom::combinator::peek;
use nom::combinator::recognize;
use nom::combinator::rest;
use nom::combinator::verify;
use nom::multi::many_till;
use nom::sequence::tuple;

use super::object_parser::regular_link_description_set_object;
use super::org_source::OrgSource;
use super::util::exit_matcher_parser;
use super::util::get_consumed;
use super::util::maybe_consume_object_trailing_whitespace_if_not_exiting;
use crate::context::parser_with_context;
use crate::context::ContextElement;
use crate::context::ExitClass;
use crate::context::ExitMatcherNode;
use crate::context::RefContext;
use crate::error::Res;
use crate::types::LinkType;
use crate::types::Object;
use crate::types::RegularLink;

#[cfg_attr(feature = "tracing", tracing::instrument(ret, level = "debug"))]
pub(crate) fn regular_link<'b, 'g, 'r, 's>(
    context: RefContext<'b, 'g, 'r, 's>,
    input: OrgSource<'s>,
) -> Res<OrgSource<'s>, RegularLink<'s>> {
    alt((
        parser_with_context!(regular_link_without_description)(context),
        parser_with_context!(regular_link_with_description)(context),
    ))(input)
}

#[cfg_attr(feature = "tracing", tracing::instrument(ret, level = "debug"))]
fn regular_link_without_description<'b, 'g, 'r, 's>(
    context: RefContext<'b, 'g, 'r, 's>,
    input: OrgSource<'s>,
) -> Res<OrgSource<'s>, RegularLink<'s>> {
    let (remaining, _opening_bracket) = tag("[[")(input)?;
    let (remaining, path) = pathreg(context, remaining)?;
    let (remaining, _closing_bracket) = tag("]]")(remaining)?;
    let (remaining, _trailing_whitespace) =
        maybe_consume_object_trailing_whitespace_if_not_exiting(context, remaining)?;
    let source = get_consumed(input, remaining);
    Ok((
        remaining,
        RegularLink {
            source: source.into(),
            link_type: path.link_type,
            path: path.path,
            raw_link: path.raw_link,
        },
    ))
}

#[cfg_attr(feature = "tracing", tracing::instrument(ret, level = "debug"))]
fn regular_link_with_description<'b, 'g, 'r, 's>(
    context: RefContext<'b, 'g, 'r, 's>,
    input: OrgSource<'s>,
) -> Res<OrgSource<'s>, RegularLink<'s>> {
    let (remaining, _opening_bracket) = tag("[[")(input)?;
    let (remaining, path) = pathreg(context, remaining)?;
    let (remaining, _closing_bracket) = tag("][")(remaining)?;
    let (remaining, _description) = description(context, remaining)?;
    let (remaining, _closing_bracket) = tag("]]")(remaining)?;
    let (remaining, _trailing_whitespace) =
        maybe_consume_object_trailing_whitespace_if_not_exiting(context, remaining)?;
    let source = get_consumed(input, remaining);
    Ok((
        remaining,
        RegularLink {
            source: source.into(),
            link_type: path.link_type,
            path: path.path,
            raw_link: path.raw_link,
        },
    ))
}

struct PathReg<'s> {
    link_type: LinkType<'s>,
    path: &'s str,
    raw_link: &'s str,
}

#[cfg_attr(feature = "tracing", tracing::instrument(ret, level = "debug"))]
fn pathreg<'b, 'g, 'r, 's>(
    _context: RefContext<'b, 'g, 'r, 's>,
    input: OrgSource<'s>,
) -> Res<OrgSource<'s>, PathReg<'s>> {
    let (remaining, path) = map_parser(
        escaped(
            take_till1(|c| match c {
                '\\' | '[' | ']' => true,
                _ => false,
            }),
            '\\',
            anychar,
        ),
        parse_path_reg,
    )(input)?;
    Ok((remaining, path))
}

fn parse_path_reg<'s>(input: OrgSource<'s>) -> Res<OrgSource<'s>, PathReg<'s>> {
    alt((
        file_path_reg,
        id_path_reg,
        custom_id_path_reg,
        code_ref_path_reg,
        fuzzy_path_reg,
    ))(input)
}

fn file_path_reg<'s>(input: OrgSource<'s>) -> Res<OrgSource<'s>, PathReg<'s>> {
    let (remaining, (raw_link, (_, path))) = consumed(tuple((tag("file:"), rest)))(input)?;
    Ok((
        remaining,
        PathReg {
            link_type: LinkType::File,
            path: path.into(),
            raw_link: raw_link.into(),
        },
    ))
}

fn id_path_reg<'s>(input: OrgSource<'s>) -> Res<OrgSource<'s>, PathReg<'s>> {
    let (remaining, (raw_link, (_, path))) = consumed(tuple((tag("id:"), rest)))(input)?;
    Ok((
        remaining,
        PathReg {
            link_type: LinkType::Id,
            path: path.into(),
            raw_link: raw_link.into(),
        },
    ))
}

fn custom_id_path_reg<'s>(input: OrgSource<'s>) -> Res<OrgSource<'s>, PathReg<'s>> {
    let (remaining, (raw_link, (_, path))) = consumed(tuple((tag("#"), rest)))(input)?;
    Ok((
        remaining,
        PathReg {
            link_type: LinkType::CustomId,
            path: path.into(),
            raw_link: raw_link.into(),
        },
    ))
}

fn code_ref_path_reg<'s>(input: OrgSource<'s>) -> Res<OrgSource<'s>, PathReg<'s>> {
    let (remaining, (raw_link, (_, path, _))) = consumed(tuple((
        tag("("),
        recognize(many_till(anychar, peek(tuple((tag(")"), eof))))),
        tag(")"),
    )))(input)?;
    Ok((
        remaining,
        PathReg {
            link_type: LinkType::CodeRef,
            path: path.into(),
            raw_link: raw_link.into(),
        },
    ))
}

fn fuzzy_path_reg<'s>(input: OrgSource<'s>) -> Res<OrgSource<'s>, PathReg<'s>> {
    let (remaining, body) = rest(input)?;
    Ok((
        remaining,
        PathReg {
            link_type: LinkType::Fuzzy,
            path: body.into(),
            raw_link: body.into(),
        },
    ))
}

#[cfg_attr(feature = "tracing", tracing::instrument(ret, level = "debug"))]
fn description<'b, 'g, 'r, 's>(
    context: RefContext<'b, 'g, 'r, 's>,
    input: OrgSource<'s>,
) -> Res<OrgSource<'s>, Vec<Object<'s>>> {
    let parser_context = ContextElement::ExitMatcherNode(ExitMatcherNode {
        class: ExitClass::Beta,
        exit_matcher: &description_end,
    });
    let parser_context = context.with_additional_node(&parser_context);
    let (remaining, (children, _exit_contents)) = verify(
        many_till(
            parser_with_context!(regular_link_description_set_object)(&parser_context),
            parser_with_context!(exit_matcher_parser)(&parser_context),
        ),
        |(children, _exit_contents)| !children.is_empty(),
    )(input)?;

    Ok((remaining, children))
}

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