use orchid_api_derive::Coding;
use orchid_base::error::{OrcRes, mk_errv};
use orchid_base::format::FmtUnit;
use orchid_base::parse::{name_char, name_start};
use orchid_extension::atom::Atomic;
use orchid_extension::atom_thin::{ThinAtom, ThinVariant};
use orchid_extension::context::i;
use orchid_extension::lexer::{LexContext, Lexer, err_not_applicable};
use orchid_extension::tree::{GenTokTree, x_tok};

use crate::macros::mactree::{Ph, PhKind};

#[derive(Clone, Coding)]
pub struct PhAtom(orchid_api::TStr, PhKind);
impl PhAtom {
	pub async fn to_full(&self) -> Ph { Ph { kind: self.1, name: i().ex(self.0).await } }
}
impl Atomic for PhAtom {
	type Data = Self;
	type Variant = ThinVariant;
}
impl ThinAtom for PhAtom {
	async fn print(&self) -> FmtUnit {
		Ph { name: i().ex(self.0).await, kind: self.1 }.to_string().into()
	}
}

#[derive(Default)]
pub struct PhLexer;
impl Lexer for PhLexer {
	const CHAR_FILTER: &'static [std::ops::RangeInclusive<char>] = &['$'..='$', '.'..='.'];
	async fn lex<'a>(line: &'a str, ctx: &'a LexContext<'a>) -> OrcRes<(&'a str, GenTokTree)> {
		let (tail, name, phkind) = if let Some(tail) = line.strip_prefix("$")
			&& tail.starts_with(name_start)
		{
			let name = tail.split_once(|c| !name_char(c)).map_or("", |(h, _)| h);
			let tail = tail.split_at(name.len()).1;
			(tail, name, PhKind::Scalar)
		} else {
			async fn name_and_prio<'a>(
				tail: &'a str,
				ctx: &'a LexContext<'a>,
			) -> OrcRes<(&'a str, u8, &'a str)> {
				let name = tail.split_once(|c| !name_char(c)).map_or("", |(h, _)| h);
				let tail = tail.split_at(name.len()).1;
				let (prio, tail) = match tail.strip_prefix(":") {
					None => (0, tail),
					Some(tail) => {
						let prio = tail.split_once(|c: char| c.is_ascii_digit()).map_or("", |(h, _)| h);
						let tail = tail.split_at(prio.len()).1;
						if let Ok(prio_num) = prio.parse::<u8>() {
							(prio_num, tail)
						} else {
							return Err(mk_errv(
								i().i("Invalid priority, must be 0-255").await,
								format!("{prio} is not a valid placeholder priority"),
								[ctx.pos_lt(prio.len(), tail)],
							));
						}
					},
				};
				Ok((name, prio, tail))
			}
			if let Some(tail) = line.strip_prefix("..$") {
				let (name, priority, tail) = name_and_prio(tail, ctx).await?;
				(tail, name, PhKind::Vector { at_least_one: false, priority })
			} else if let Some(tail) = line.strip_prefix("...$") {
				let (name, priority, tail) = name_and_prio(tail, ctx).await?;
				(tail, name, PhKind::Vector { at_least_one: true, priority })
			} else {
				return Err(err_not_applicable().await);
			}
		};
		let ph_atom = PhAtom(i().i::<String>(name).await.to_api(), phkind);
		Ok((tail, x_tok(ph_atom).await.at(ctx.pos_tt(line, tail))))
	}
}