use nom::bytes::complete::tag;
use nom::bytes::complete::tag_no_case;
use nom::character::complete::anychar;
use nom::character::complete::line_ending;
use nom::character::complete::one_of;
use nom::character::complete::space0;
use nom::combinator::opt;
use nom::combinator::recognize;
use nom::combinator::verify;
use nom::multi::many_till;
#[cfg(feature = "tracing")]
use tracing::span;

use super::org_source::OrgSource;
use super::Context;
use crate::error::CustomError;
use crate::error::Res;
use crate::parser::exiting::ExitClass;
use crate::parser::parser_context::ContextElement;
use crate::parser::parser_context::ExitMatcherNode;
use crate::parser::parser_context::InlineSourceBlockBracket;
use crate::parser::parser_with_context::parser_with_context;
use crate::parser::util::exit_matcher_parser;
use crate::parser::util::get_consumed;
use crate::parser::InlineSourceBlock;

#[cfg_attr(feature = "tracing", tracing::instrument(ret, level = "debug"))]
pub fn inline_source_block<'r, 's>(
    context: Context<'r, 's>,
    input: OrgSource<'s>,
) -> Res<OrgSource<'s>, InlineSourceBlock<'s>> {
    let (remaining, _) = tag_no_case("src_")(input)?;
    let (remaining, _) = lang(context, remaining)?;
    let (remaining, _header1) = opt(parser_with_context!(header)(context))(remaining)?;
    let (remaining, _body) = body(context, remaining)?;
    let (remaining, _) = space0(remaining)?;
    let source = get_consumed(input, remaining);
    Ok((
        remaining,
        InlineSourceBlock {
            source: source.into(),
        },
    ))
}

#[cfg_attr(feature = "tracing", tracing::instrument(ret, level = "debug"))]
fn lang<'r, 's>(
    context: Context<'r, 's>,
    input: OrgSource<'s>,
) -> Res<OrgSource<'s>, OrgSource<'s>> {
    let parser_context =
        context.with_additional_node(ContextElement::ExitMatcherNode(ExitMatcherNode {
            class: ExitClass::Beta,
            exit_matcher: &lang_end,
        }));
    let (remaining, lang) = recognize(many_till(
        verify(anychar, |c| !(c.is_whitespace() || "[{".contains(*c))),
        parser_with_context!(exit_matcher_parser)(&parser_context),
    ))(input)?;
    Ok((remaining, lang))
}

#[cfg_attr(feature = "tracing", tracing::instrument(ret, level = "debug"))]
fn lang_end<'r, 's>(
    _context: Context<'r, 's>,
    input: OrgSource<'s>,
) -> Res<OrgSource<'s>, OrgSource<'s>> {
    recognize(one_of("[{"))(input)
}

#[cfg_attr(feature = "tracing", tracing::instrument(ret, level = "debug"))]
fn header<'r, 's>(
    context: Context<'r, 's>,
    input: OrgSource<'s>,
) -> Res<OrgSource<'s>, OrgSource<'s>> {
    let (remaining, _) = tag("[")(input)?;

    let parser_context = context
        .with_additional_node(ContextElement::InlineSourceBlockBracket(
            InlineSourceBlockBracket {
                position: remaining,
                depth: 0,
            },
        ))
        .with_additional_node(ContextElement::ExitMatcherNode(ExitMatcherNode {
            class: ExitClass::Beta,
            exit_matcher: &header_end,
        }));

    let (remaining, header_contents) = recognize(many_till(
        anychar,
        parser_with_context!(exit_matcher_parser)(&parser_context),
    ))(remaining)?;
    let (remaining, _) = tag("]")(remaining)?;
    Ok((remaining, header_contents))
}

#[cfg_attr(feature = "tracing", tracing::instrument(ret, level = "debug"))]
fn header_end<'r, 's>(
    context: Context<'r, 's>,
    input: OrgSource<'s>,
) -> Res<OrgSource<'s>, OrgSource<'s>> {
    let context_depth = get_bracket_depth(context)
        .expect("This function should only be called from inside an inline source block header.");
    let text_since_context_entry = get_consumed(context_depth.position, input);
    let mut current_depth = context_depth.depth;
    for c in Into::<&str>::into(text_since_context_entry).chars() {
        match c {
            '[' => {
                current_depth += 1;
            }
            ']' if current_depth == 0 => {
                panic!("Exceeded inline source block header bracket depth.")
            }
            ']' if current_depth > 0 => {
                current_depth -= 1;
            }
            _ => {}
        }
    }
    if current_depth == 0 {
        let close_bracket = tag::<&str, OrgSource<'_>, CustomError<OrgSource<'_>>>("]")(input);
        if close_bracket.is_ok() {
            return close_bracket;
        }
    }

    line_ending(input)
}

#[cfg_attr(feature = "tracing", tracing::instrument(ret, level = "debug"))]
fn body<'r, 's>(
    context: Context<'r, 's>,
    input: OrgSource<'s>,
) -> Res<OrgSource<'s>, OrgSource<'s>> {
    let (remaining, _) = tag("{")(input)?;

    let parser_context = context
        .with_additional_node(ContextElement::InlineSourceBlockBracket(
            InlineSourceBlockBracket {
                position: remaining,
                depth: 0,
            },
        ))
        .with_additional_node(ContextElement::ExitMatcherNode(ExitMatcherNode {
            class: ExitClass::Beta,
            exit_matcher: &body_end,
        }));

    let (remaining, body_contents) = recognize(many_till(
        anychar,
        parser_with_context!(exit_matcher_parser)(&parser_context),
    ))(remaining)?;
    let (remaining, _) = {
        #[cfg(feature = "tracing")]
        let span = span!(
            tracing::Level::DEBUG,
            "outside end body",
            remaining = Into::<&str>::into(remaining)
        );
        #[cfg(feature = "tracing")]
        let _enter = span.enter();
        tag("}")(remaining)?
    };
    Ok((remaining, body_contents))
}

#[cfg_attr(feature = "tracing", tracing::instrument(ret, level = "debug"))]
fn body_end<'r, 's>(
    context: Context<'r, 's>,
    input: OrgSource<'s>,
) -> Res<OrgSource<'s>, OrgSource<'s>> {
    let context_depth = get_bracket_depth(context)
        .expect("This function should only be called from inside an inline source block body.");
    let text_since_context_entry = get_consumed(context_depth.position, input);
    let mut current_depth = context_depth.depth;
    for c in Into::<&str>::into(text_since_context_entry).chars() {
        match c {
            '{' => {
                current_depth += 1;
            }
            '}' if current_depth == 0 => {
                panic!("Exceeded inline source block body bracket depth.")
            }
            '}' if current_depth > 0 => {
                current_depth -= 1;
            }
            _ => {}
        }
    }
    {
        #[cfg(feature = "tracing")]
        let span = span!(
            tracing::Level::DEBUG,
            "inside end body",
            remaining = Into::<&str>::into(input),
            current_depth = current_depth
        );
        #[cfg(feature = "tracing")]
        let _enter = span.enter();

        if current_depth == 0 {
            let close_bracket = tag::<&str, OrgSource<'_>, CustomError<OrgSource<'_>>>("}")(input);
            if close_bracket.is_ok() {
                return close_bracket;
            }
        }
    }

    line_ending(input)
}

#[cfg_attr(feature = "tracing", tracing::instrument(ret, level = "debug"))]
pub fn get_bracket_depth<'r, 's>(
    context: Context<'r, 's>,
) -> Option<&'r InlineSourceBlockBracket<'s>> {
    for node in context.iter() {
        match node.get_data() {
            ContextElement::InlineSourceBlockBracket(depth) => return Some(depth),
            _ => {}
        }
    }
    None
}