use crate::{obj::{prelude::*, reserved::*}, vm::{error::*, signal::*}};
use maplit::btreemap;
use once_cell::sync::Lazy;
use std::collections::BTreeMap;

pub static PRINTLN_BUILTIN_FUN: Lazy<NativeFunRef> = Lazy::new(|| NativeFun::new_obj(1, |_, vm, args| {
    // TODO : use __get_attr__ when it gets added
    let to_string = {
        let obj_ref = &args[0];
        read_obj!(let obj = obj_ref);
        obj.get_attr(STR_MEMBER_NAME.sym)
            .ok_or(Error::MissingAttr { attr: STR_MEMBER_NAME.sym })?
    };
    let return_value = vm.call(to_string, vec![])?;
    {
        read_obj!(let str_obj = return_value);
        let str_obj: &Str = str_obj.as_any().downcast_ref()
            .ok_or_else(|| Error::ValueError { error: "expected str value".to_string(), })?; 
        println!("{}", str_obj.value());
    }

    vm.push(NIL_NAME.sym_ref());
    Ok(Signal::Return)
}));

pub static PRINT_BUILTIN_FUN: Lazy<NativeFunRef> = Lazy::new(|| NativeFun::new_obj(1, |_, vm, args| {
    // TODO : use __get_attr__ when it gets added
    let to_string = {
        let obj_ref = &args[0];
        read_obj!(let obj = obj_ref);
        obj.get_attr(STR_MEMBER_NAME.sym)
            .ok_or(Error::MissingAttr { attr: STR_MEMBER_NAME.sym })?
    };
    let return_value = vm.call(to_string, vec![])?;
    {
        read_obj!(let str_obj = return_value);
        let str_obj: &Str = str_obj.as_any().downcast_ref()
            .ok_or_else(|| Error::ValueError { error: "expected str value".to_string(), })?;
        print!("{}", str_obj.value());
    }

    vm.push(NIL_NAME.sym_ref());
    Ok(Signal::Return)
}));

pub static BUILTIN_OBJS: Lazy<BTreeMap<Sym, ObjRef>> = Lazy::new(|| btreemap! {
    PRINTLN_BUILTIN_NAME.sym => PRINTLN_BUILTIN_FUN.clone() as _,
    PRINT_BUILTIN_NAME.sym => PRINT_BUILTIN_FUN.clone() as _,
});