use crate::obj::{prelude::*, reserved::*};
use once_cell::sync::Lazy;
use shredder::Scan;
use std::fmt::{Debug, Formatter, self};

pub type IntRef = ObjRef<Int>;

#[derive(Scan)]
pub struct Int {
    value: i64,
    vtable: Vtable,
    attrs: Attrs,
}

impl Int {
    pub fn new_obj(value: i64) -> ObjRef<Self> {
        // TODO : cache int values
        self_referring_obj! {
            Self {
                value,
                vtable: Default::default(),
                attrs: Default::default(),
            },
            vtable: |obj_ref: ObjRef| vtable! {
                // TODO needs Method type so this function is given an argument when called
                STR_MEMBER_NAME.sym => Method::new_obj(obj_ref.clone(), INT_STR_FUN.clone()),
            }
        }
    }

    pub fn value(&self) -> i64 {
        self.value
    }
}

impl_obj_readonly!(Int);

impl Debug for Int {
    fn fmt(&self, fmt: &mut Formatter) -> fmt::Result {
        fmt.debug_struct("Int")
            .field("value", &self.value)
            .finish()
    }
}

static INT_STR_FUN: Lazy<NativeFunRef> = Lazy::new(|| {
    NativeFun::new_obj(|_callee, vm, args| {
        read_obj!(let int_obj = &args[0]);
        if let Some(int_obj) = std::any::Any::downcast_ref::<Int>(int_obj.as_any()) {
            vm.push(Str::new_obj(int_obj.value.to_string()));
        } else {
            panic!("{:?} is not an int", int_obj)
        }
        crate::vm::signal::Signal::Return
    })
});