use crate::prelude::*;
use std::marker::{Sized, Unsize};

pub struct WidgetPtr {
    pub inner: Option<StrongWidget>,
}

impl Widget for WidgetPtr {
    fn draw(&mut self, painter: &mut Painter) {
        if let Some(id) = &self.inner {
            painter.widget(id);
        }
    }

    fn desired_width(&mut self, ctx: &mut SizeCtx) -> Len {
        if let Some(id) = &self.inner {
            ctx.width(id)
        } else {
            Len::ZERO
        }
    }

    fn desired_height(&mut self, ctx: &mut SizeCtx) -> Len {
        if let Some(id) = &self.inner {
            ctx.height(id)
        } else {
            Len::ZERO
        }
    }
}

impl WidgetPtr {
    pub fn new() -> Self {
        Self::default()
    }
    pub fn empty() -> Self {
        Self {
            inner: Default::default(),
        }
    }
    pub fn set<W: ?Sized + Unsize<dyn Widget>>(&mut self, to: StrongWidget<W>) {
        self.inner = Some(to)
    }

    pub fn replace<W: ?Sized + Unsize<dyn Widget>>(
        &mut self,
        to: StrongWidget<W>,
    ) -> Option<StrongWidget> {
        self.inner.replace(to)
    }
}

impl Default for WidgetPtr {
    fn default() -> Self {
        Self::empty()
    }
}