#[derive(Debug)]
struct Scene {
    root: Rc<RefCell<SceneNode>>
}

impl Scene {
    pub fn new() -> Scene {
        Scene {
            root: Rc::new(RefCell::new(SceneNode::new(String::from("root"))))
        }
    }

    pub fn root(&self) -> Rc<RefCell<SceneNode>> {
        self.root.clone()
    }
}

#[derive(Debug)]
struct SceneNode {
    identifier: String,
    parent: Option<Weak<RefCell<SceneNode>>>,
    children: HashMap<String, Rc<RefCell<SceneNode>>>
}

impl SceneNode {
    pub fn new(identifier: String) -> SceneNode {
        SceneNode {
            identifier,
            parent: None,
            children: HashMap::new()
        }
    }

    pub fn identifier(&self) -> &String {
        &self.identifier
    }

    pub fn add_child(&mut self, child: SceneNode) {
        // How? child.set_parent(self);
        self.children.insert(child.identifier().clone(), Rc::new(RefCell::new(child)));
    }

    pub fn set_parent(&mut self, parent: Option<Weak<RefCell<SceneNode>>>) {
        self.parent = parent;
    }
}