use std::rc::{Rc, Weak};
use std::cell::RefCell;
use r9_macro::SharedFromSelf;
use r9_macro_derive::SharedFromSelf;

#[derive(SharedFromSelf)]
pub struct Queue<T> {
    msg_list: Rc::<RefCell::<crate::ListHead<T>>>,
    pub work_list: Rc::<RefCell::<crate::ListHead<T>>>,
    _self_wp: Weak::<RefCell::<Self>>,
}

impl<T> Queue<T> {

    pub fn new() -> Rc::<RefCell::<Self>> {
        let this = Rc::new(RefCell::new(Self{
            msg_list: crate::ListHead::<T>::new_head(),
            work_list: crate::ListHead::<T>::new_head(),
            _self_wp: Default::default(),
        }));
        this.borrow_mut()._self_wp = Rc::downgrade(&this);
        return this;
    }

    pub fn push(&self, node: &Rc::<RefCell::<crate::ListHead<T>>>) {
        crate::ListHead::<T>::add_tail(&self.msg_list, node);
    }

    pub fn fetch(&self) {
        if !self.msg_list.borrow().empty() &&
            self.work_list.borrow().empty() {
                crate::ListHead::replace_init(&self.work_list, &self.msg_list);
        }
    }

}