use winnow::Parser;
use winnow::ascii::multispace0;
use winnow::combinator::{Infix, Prefix, peek};
use winnow::combinator::{delimited, dispatch, expression, fail};
use winnow::error::ContextError;
use winnow::token::any;

use crate::binary_repr::parse_binary_repr;
use crate::expr::{BinOp, Expr, UnaryOp};

pub fn parser<'i>(size: usize) -> impl Parser<&'i str, Expr, ContextError> {
    move |i: &mut &str| {
        use Infix::Left;
        expression(delimited(
            multispace0,
            dispatch! {peek(any);
                '(' => delimited('(',  parser(size).map(|e| Expr::Group(Box::new(e))), ')'),
                _ =>                 parse_binary_repr(size).map(Expr::Constant),

            },
            multispace0,
        ))
        .prefix(delimited(
            multispace0,
            dispatch! {any;
                '-' => Prefix(12, |_, a| Ok(Expr::UnaryOp(UnaryOp::Neg, Box::new(a)))),
                '!' => Prefix(12, |_, a| Ok(Expr::UnaryOp(UnaryOp::Not, Box::new(a)))),
                _ => fail,
            },
            multispace0,
        ))
        .infix(delimited(
            multispace0,
            dispatch! {any;
                '+' => Left(5, |_, a, b| Ok(Expr::BinaryOp(Box::new(a), BinOp::Plus, Box::new(b)))),
                '-' => Left(5, |_, a, b| Ok(Expr::BinaryOp(Box::new(a), BinOp::Sub, Box::new(b)))),
                '*' => Left(7, |_, a, b| Ok(Expr::BinaryOp(Box::new(a), BinOp::Mul, Box::new(b)))),
                '/' => Left(7, |_, a, b| Ok(Expr::BinaryOp(Box::new(a), BinOp::Div, Box::new(b)))),
                _ => fail,
            },
            multispace0,
        ))
        .parse_next(i)
    }
}