use nom::branch::alt;
use nom::bytes::complete::tag;
use nom::character::complete::line_ending;
use nom::character::complete::space0;
use nom::combinator::verify;
use nom::multi::many_till;

use super::Context;
use super::Object;
use crate::error::CustomError;
use crate::error::MyError;
use crate::error::Res;
use crate::parser::exiting::ExitClass;
use crate::parser::object_parser::minimal_set_object;
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::exit_matcher_parser;
use crate::parser::util::get_consumed;
use crate::parser::RadioLink;
use crate::parser::RadioTarget;

#[tracing::instrument(ret, level = "debug")]
pub fn radio_link<'r, 's>(context: Context<'r, 's>, input: &'s str) -> Res<&'s str, RadioLink<'s>> {
    let radio_targets = context
        .iter()
        .filter_map(|context_element| match context_element.get_data() {
            ContextElement::RadioTarget(targets) => Some(targets),
            _ => None,
        })
        .flatten();
    for radio_target in radio_targets {
        let rematched_target = rematch_target(context, radio_target, input);
        if let Ok((remaining, rematched_target)) = rematched_target {
            let (remaining, _) = space0(remaining)?;
            let source = get_consumed(input, remaining);
            return Ok((
                remaining,
                RadioLink {
                    source,
                    children: rematched_target,
                },
            ));
        }
    }
    Err(nom::Err::Error(CustomError::MyError(MyError(
        "NoRadioLink",
    ))))
}

#[tracing::instrument(ret, level = "debug")]
pub fn rematch_target<'x, 'r, 's>(
    context: Context<'r, 's>,
    target: &'x Vec<Object<'x>>,
    input: &'s str,
) -> Res<&'s str, Vec<Object<'s>>> {
    let mut remaining = input;
    let mut new_matches = Vec::with_capacity(target.len());
    for original_object in target {
        match original_object {
            // TODO: The rest of the minimal set of objects.
            Object::Bold(bold) => {
                let (new_remaining, new_match) = bold.rematch_object(context, remaining)?;
                remaining = new_remaining;
                new_matches.push(new_match);
            }
            Object::PlainText(plaintext) => {
                let (new_remaining, new_match) = plaintext.rematch_object(context, remaining)?;
                remaining = new_remaining;
                new_matches.push(new_match);
            }
            _ => {
                return Err(nom::Err::Error(CustomError::MyError(MyError(
                    "OnlyMinimalSetObjectsAllowed",
                ))));
            }
        };
    }
    Ok((remaining, new_matches))
}

#[tracing::instrument(ret, level = "debug")]
pub fn radio_target<'r, 's>(
    context: Context<'r, 's>,
    input: &'s str,
) -> Res<&'s str, RadioTarget<'s>> {
    let (remaining, _opening) = tag("<<<")(input)?;
    let parser_context =
        context.with_additional_node(ContextElement::ExitMatcherNode(ExitMatcherNode {
            class: ExitClass::Beta,
            exit_matcher: &radio_target_end,
        }));

    let (remaining, (children, _exit_contents)) = verify(
        many_till(
            parser_with_context!(minimal_set_object)(&parser_context),
            parser_with_context!(exit_matcher_parser)(&parser_context),
        ),
        |(children, _exit_contents)| !children.is_empty(),
    )(remaining)?;

    let (remaining, _closing) = tag(">>>")(remaining)?;
    let (remaining, _trailing_whitespace) = space0(remaining)?;
    let source = get_consumed(input, remaining);
    Ok((remaining, RadioTarget { source, children }))
}

#[tracing::instrument(ret, level = "debug")]
fn radio_target_end<'r, 's>(context: Context<'r, 's>, input: &'s str) -> Res<&'s str, &'s str> {
    alt((tag("<"), tag(">"), line_ending))(input)
}

pub trait RematchObject<'x> {
    fn rematch_object<'r, 's>(
        &'x self,
        context: Context<'r, 's>,
        input: &'s str,
    ) -> Res<&'s str, Object<'s>>;
}

#[cfg(test)]
mod tests {
    use super::*;
    use crate::parser::element_parser::element;
    use crate::parser::parser_context::ContextElement;
    use crate::parser::parser_context::ContextTree;
    use crate::parser::parser_with_context::parser_with_context;
    use crate::parser::source::Source;
    use crate::parser::Bold;
    use crate::parser::PlainText;

    #[test]
    fn plain_text_radio_target() {
        let input = "foo bar baz";
        let radio_target_match = vec![Object::PlainText(PlainText { source: "bar" })];
        let initial_context: ContextTree<'_, '_> = ContextTree::new();
        let document_context = initial_context
            .with_additional_node(ContextElement::DocumentRoot(input))
            .with_additional_node(ContextElement::RadioTarget(vec![&radio_target_match]));
        let paragraph_matcher = parser_with_context!(element(true))(&document_context);
        let (remaining, first_paragraph) = paragraph_matcher(input).expect("Parse first paragraph");
        let first_paragraph = match first_paragraph {
            crate::parser::Element::Paragraph(paragraph) => paragraph,
            _ => panic!("Should be a paragraph!"),
        };
        assert_eq!(remaining, "");
        assert_eq!(first_paragraph.get_source(), "foo bar baz");
        assert_eq!(first_paragraph.children.len(), 3);
        assert_eq!(
            first_paragraph
                .children
                .get(1)
                .expect("Len already asserted to be 3"),
            &Object::RadioLink(RadioLink {
                source: "bar ",
                children: vec![Object::PlainText(PlainText { source: "bar" })]
            })
        );
    }

    #[test]
    fn bold_radio_target() {
        let input = "foo *bar* baz";
        let radio_target_match = vec![Object::Bold(Bold {
            source: "*bar*",
            children: vec![Object::PlainText(PlainText { source: "bar" })],
        })];
        let initial_context: ContextTree<'_, '_> = ContextTree::new();
        let document_context = initial_context
            .with_additional_node(ContextElement::DocumentRoot(input))
            .with_additional_node(ContextElement::RadioTarget(vec![&radio_target_match]));
        let paragraph_matcher = parser_with_context!(element(true))(&document_context);
        let (remaining, first_paragraph) = paragraph_matcher(input).expect("Parse first paragraph");
        let first_paragraph = match first_paragraph {
            crate::parser::Element::Paragraph(paragraph) => paragraph,
            _ => panic!("Should be a paragraph!"),
        };
        assert_eq!(remaining, "");
        assert_eq!(first_paragraph.get_source(), "foo *bar* baz");
        assert_eq!(first_paragraph.children.len(), 3);
        assert_eq!(
            first_paragraph
                .children
                .get(1)
                .expect("Len already asserted to be 3"),
            &Object::RadioLink(RadioLink {
                source: "*bar* ",
                children: vec![Object::Bold(Bold {
                    source: "*bar* ",
                    children: vec![Object::PlainText(PlainText { source: "bar" })]
                })]
            })
        );
    }
}