use emojis::Emoji;
use markdown_it::parser::inline::{InlineRule, InlineState};
use markdown_it::{Node, NodeValue, Renderer};
use maud::{Markup, PreEscaped, Render};

pub struct Markdown<'a>(pub &'a str);

impl Render for Markdown<'_> {
	fn render(&self) -> Markup {
		// TODO: init once
		let md = &mut markdown_it::MarkdownIt::new();
		markdown_it::plugins::cmark::add(md);
		markdown_it::plugins::html::add(md);
		md.inline.add_rule::<InlineEmote>();
		md.inline.add_rule::<InlineMdx>();

		let md = md.parse(&self.0);
		let html = md.render();

		return PreEscaped(html);
	}
}

//
// MARK: extensions
//

#[derive(Debug)]
pub struct InlineEmote(&'static Emoji);

impl NodeValue for InlineEmote {
	fn render(&self, _node: &Node, fmt: &mut dyn Renderer) {
		fmt.text(self.0.as_str());
	}
}

impl InlineRule for InlineEmote {
	const MARKER: char = ':';

	fn run(state: &mut InlineState<'_, '_>) -> Option<(Node, usize)> {
		let input = &state.src[state.pos..state.pos_max];

		if !input.starts_with(':') {
			return None;
		}

		let end_idx = input[1..].find(':')? + 1;
		let emote = emojis::get_by_shortcode(&input[1..end_idx])?;

		Some((Node::new(InlineEmote(emote)), end_idx + 1))
	}
}

#[derive(Debug)]
pub struct InlineMdx(String);

impl NodeValue for InlineMdx {
	fn render(&self, node: &Node, fmt: &mut dyn Renderer) {
		if mdx_style(&self.0, node, fmt) {
			return;
		}

		fmt.open("code", &[]);
		fmt.text(&self.0);
		fmt.close("code");
	}
}

impl InlineRule for InlineMdx {
	const MARKER: char = '{';

	fn run(state: &mut InlineState<'_, '_>) -> Option<(Node, usize)> {
		let input = &state.src[state.pos..state.pos_max];
		if !input.starts_with('{') {
			return None;
		}

		let mut balance = 1;
		let mut end = 1;
		for i in input[1..].bytes() {
			match i {
				b'}' => balance -= 1,
				b'{' => balance += 1,
				_ => {}
			}

			if balance == 0 {
				break;
			}

			end += 1;
		}

		if balance != 0 {
			return None;
		}

		let content = &input[1..end];
		Some((Node::new(InlineMdx(content.to_owned())), content.len() + 2))
	}
}

fn mdx_style(mdx: &str, _node: &Node, fmt: &mut dyn Renderer) -> bool {
	let mdx = mdx.trim();

	if !mdx.starts_with("style(") {
		return false;
	}

	let skip = 6;
	let mut balance = 1;
	let mut end = skip;
	for i in mdx[skip..].bytes() {
		match i {
			b')' => balance -= 1,
			b'(' => balance += 1,
			_ => {}
		}

		if balance == 0 {
			break;
		}

		end += 1;
	}

	if balance != 0 {
		return false;
	}

	let style = &mdx[skip..end].trim();
	let content = &mdx[end + 1..].trim();

	let mut style_str = String::new();

	for kv in style.split(";") {
		let mut s = kv.split(":");
		let k = s.next();
		let v = s.next();

		if k.is_none() || v.is_none() || s.next().is_some() {
			return false;
		}

		let k = k.unwrap().trim();
		let v = v.unwrap().trim();

		match k {
			"color" => {
				style_str.push_str("color:");
				style_str.push_str(v);
				style_str.push_str(";");
			}

			"color_var" => {
				style_str.push_str("color:var(--");
				style_str.push_str(v);
				style_str.push_str(");");
			}

			_ => continue,
		}
	}

	fmt.open("span", &[("style", style_str)]);
	fmt.text(&content);
	fmt.close("span");

	return true;
}