use std::ops::RangeInclusive;

use orchid_base::error::OrcRes;
use orchid_base::number::{num_to_errv, parse_num};
use orchid_extension::conv::ToExpr;
use orchid_extension::lexer::{LexContext, Lexer};
use orchid_extension::tree::{GenTokTree, x_tok};

use super::num_atom::Num;

#[derive(Debug, Default)]
pub struct NumLexer;
impl Lexer for NumLexer {
	const CHAR_FILTER: &'static [RangeInclusive<char>] = &['0'..='9'];
	async fn lex<'a>(all: &'a str, lxcx: &'a LexContext<'a>) -> OrcRes<(&'a str, GenTokTree)> {
		let ends_at = all.find(|c: char| !c.is_ascii_hexdigit() && !"xX._pP".contains(c));
		let (chars, tail) = all.split_at(ends_at.unwrap_or(all.len()));
		match parse_num(chars) {
			Ok(numeric) =>
				Ok((tail, x_tok(Num(numeric).to_gen().await).await.at(lxcx.pos_lt(chars.len(), tail)))),
			Err(e) => Err(num_to_errv(e, lxcx.pos(all), lxcx.src()).await),
		}
	}
}