use std::fmt;

use super::types::Type;

#[derive(PartialEq, Debug)]
pub enum SExpr {
    Atom(Type),
    Sexpr(Vec<SExpr>)
}

impl fmt::Display for SExpr {
    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
        match self {
            SExpr::Atom(ref t) => write!(f, "{}", t),
            SExpr::Sexpr(ref s) => write!(f, "{:?}", s)
        }
    }
}

#[test]
fn construct() {
    let atom1 = SExpr::Atom(Type::Number(Number::Int(1)));
    let atom2 = SExpr::Atom(Type::Number(Number::Int(2)));
    let atom3 = SExpr::Atom(Type::Number(Number::Int(3)));
    let atom4 = SExpr::Atom(Type::Number(Number::Int(4)));
    let sexp = SExpr::Sexpr(vec!(atom1, atom2, atom3, atom4));
    match sexp {
        SExpr::Sexpr(ref x) => {
            assert_eq!(x[0], SExpr::Atom(Type::Number(Number::Int(1))));
        },
        _ => panic!("What")
    }
}

#[test]
fn mutability() {
    let atom1 = SExpr::Atom(Type::Number(Number::Int(1)));
    let atom2 = SExpr::Atom(Type::Number(Number::Int(2)));
    let atom3 = SExpr::Atom(Type::Number(Number::Int(3)));
    let atom4 = SExpr::Atom(Type::Number(Number::Int(4)));
    let mut sexp = SExpr::Sexpr(vec!(atom1, atom2, atom3, atom4));
    match sexp {
        SExpr::Sexpr(ref mut x) => match x[0] {
            SExpr::Atom(Type::Number(Number::Int(ref mut x))) => *x += 7,
            _ => panic!("What")
        },
        _ => panic!("What")
    }

    match sexp {
        SExpr::Sexpr(ref x) => {
            assert_eq!(x[0], SExpr::Atom(Type::Number(Number::Int(8))));
        },
        _ => panic!("What")
    }
}