use std::collections::VecDeque;

use super::Document;
use super::Element;
use super::Heading;
use super::Object;
use super::PlainListItem;
use super::Section;
use super::TableCell;
use super::TableRow;
use crate::parser::DocumentElement;

pub enum Token<'r, 's> {
    Document(&'r Document<'s>),
    Heading(&'r Heading<'s>),
    Section(&'r Section<'s>),
    Object(&'r Object<'s>),
    Element(&'r Element<'s>),
    PlainListItem(&'r PlainListItem<'s>),
    TableRow(&'r TableRow<'s>),
    TableCell(&'r TableCell<'s>),
}

impl<'r, 's> Token<'r, 's> {
    pub fn iter_tokens(&self) -> Box<dyn Iterator<Item = Token<'r, 's>> + '_> {
        match self {
            Token::Document(document) => Box::new(
                document
                    .zeroth_section
                    .iter()
                    .map(Token::Section)
                    .chain(document.children.iter().map(Token::Heading)),
            ),
            Token::Heading(heading) => Box::new(heading.title.iter().map(Token::Object).chain(
                heading.children.iter().map(|de| match de {
                    DocumentElement::Heading(ref obj) => Token::Heading(obj),
                    DocumentElement::Section(ref obj) => Token::Section(obj),
                }),
            )),
            Token::Section(section) => Box::new(section.children.iter().map(Token::Element)),
            Token::Object(obj) => match obj {
                Object::Bold(inner) => Box::new(inner.children.iter().map(Token::Object)),
                Object::Italic(inner) => Box::new(inner.children.iter().map(Token::Object)),
                Object::Underline(inner) => Box::new(inner.children.iter().map(Token::Object)),
                Object::StrikeThrough(inner) => Box::new(inner.children.iter().map(Token::Object)),
                Object::Code(_) => Box::new(std::iter::empty()),
                Object::Verbatim(_) => Box::new(std::iter::empty()),
                Object::PlainText(_) => Box::new(std::iter::empty()),
                Object::RegularLink(_) => Box::new(std::iter::empty()),
                Object::RadioLink(inner) => Box::new(inner.children.iter().map(Token::Object)),
                Object::RadioTarget(inner) => Box::new(inner.children.iter().map(Token::Object)),
                Object::PlainLink(_) => Box::new(std::iter::empty()),
                Object::AngleLink(_) => Box::new(std::iter::empty()),
                Object::OrgMacro(_) => Box::new(std::iter::empty()),
                Object::Entity(_) => Box::new(std::iter::empty()),
                Object::LatexFragment(_) => Box::new(std::iter::empty()),
                Object::ExportSnippet(_) => Box::new(std::iter::empty()),
                Object::FootnoteReference(inner) => {
                    Box::new(inner.definition.iter().map(Token::Object))
                }
            },
            Token::Element(elem) => match elem {
                Element::Paragraph(inner) => Box::new(inner.children.iter().map(Token::Object)),
                Element::PlainList(inner) => {
                    Box::new(inner.children.iter().map(Token::PlainListItem))
                }
                Element::GreaterBlock(inner) => Box::new(inner.children.iter().map(Token::Element)),
                Element::DynamicBlock(inner) => Box::new(inner.children.iter().map(Token::Element)),
                Element::FootnoteDefinition(inner) => {
                    Box::new(inner.children.iter().map(Token::Element))
                }
                Element::Comment(_) => Box::new(std::iter::empty()),
                Element::Drawer(inner) => Box::new(inner.children.iter().map(Token::Element)),
                Element::PropertyDrawer(_) => Box::new(std::iter::empty()),
                Element::Table(inner) => Box::new(inner.children.iter().map(Token::TableRow)),
                Element::VerseBlock(inner) => Box::new(inner.children.iter().map(Token::Object)),
                Element::CommentBlock(_) => Box::new(std::iter::empty()),
                Element::ExampleBlock(_) => Box::new(std::iter::empty()),
                Element::ExportBlock(_) => Box::new(std::iter::empty()),
                Element::SrcBlock(_) => Box::new(std::iter::empty()),
                Element::Clock(_) => Box::new(std::iter::empty()),
                Element::DiarySexp(_) => Box::new(std::iter::empty()),
                Element::Planning(_) => Box::new(std::iter::empty()),
                Element::FixedWidthArea(_) => Box::new(std::iter::empty()),
                Element::HorizontalRule(_) => Box::new(std::iter::empty()),
                Element::Keyword(_) => Box::new(std::iter::empty()),
                Element::LatexEnvironment(_) => Box::new(std::iter::empty()),
            },
            Token::PlainListItem(elem) => Box::new(elem.children.iter().map(Token::Element)),
            Token::TableRow(elem) => Box::new(elem.children.iter().map(Token::TableCell)),
            Token::TableCell(elem) => Box::new(elem.children.iter().map(Token::Object)),
        }
    }
}

pub struct AllTokensIterator<'r, 's> {
    queued_tokens: VecDeque<Token<'r, 's>>,
}

impl<'r, 's> AllTokensIterator<'r, 's> {
    pub fn new(tkn: Token<'r, 's>) -> Self {
        let mut queued_tokens = VecDeque::new();
        queued_tokens.push_back(tkn);
        AllTokensIterator { queued_tokens }
    }
}

impl<'r, 's> Iterator for AllTokensIterator<'r, 's> {
    type Item = Token<'r, 's>;

    fn next(&mut self) -> Option<Self::Item> {
        let next_token = match self.queued_tokens.pop_front() {
            Some(tkn) => tkn,
            None => return None,
        };
        self.queued_tokens.extend(next_token.iter_tokens());
        Some(next_token)
    }
}