use chumsky::Parser;

use std::fmt::Debug;

use super::super::assertion_error::AssertionError;
use crate::external::litconv::with_lit;
use crate::parse::float_parser;
use crate::representations::{interpreted::ExprInst, Literal};
use crate::{atomic_impl, atomic_redirect, externfn_impl};

/// ParseFloat a number
/// 
/// Next state: [ParseFloat0]

#[derive(Clone)]
pub struct ParseFloat1;
externfn_impl!(ParseFloat1, |_: &Self, x: ExprInst| {Ok(ParseFloat0{x})});

/// Applied to_string function
/// 
/// Prev state: [ParseFloat1]

#[derive(Debug, Clone)]
pub struct ParseFloat0{ x: ExprInst }
atomic_redirect!(ParseFloat0, x);
atomic_impl!(ParseFloat0, |Self{ x }: &Self| {
  let number = with_lit(x, |l| Ok(match l {
    Literal::Str(s) => {
      let parser = float_parser();
      parser.parse(s.as_str())
        .map_err(|_| AssertionError::ext(x.clone(), "cannot be parsed into a float"))?
    }
    Literal::Num(n) => *n,
    Literal::Uint(i) => (*i as u32).into(),
    Literal::Char(char) => char.to_digit(10)
      .ok_or(AssertionError::ext(x.clone(), "is not a decimal digit"))?
      .into()
  }))?;
  Ok(number.into())
});