//! RequestAnimationFrame and RequestIdleCallback port and polyfill.

use gloo_timers::future::TimeoutFuture;
use js_sys::Function;
use wasm_bindgen::JsCast;
use wasm_bindgen::{prelude::Closure, JsValue};
use web_sys::Window;

pub struct RafLoop {
    window: Window,
    ric_receiver: async_channel::Receiver<u32>,
    raf_receiver: async_channel::Receiver<()>,
    ric_closure: Closure<dyn Fn(JsValue)>,
    raf_closure: Closure<dyn Fn(JsValue)>,
}

impl RafLoop {
    pub fn new() -> Self {
        let (raf_sender, raf_receiver) = async_channel::unbounded();

        let raf_closure: Closure<dyn Fn(JsValue)> = Closure::wrap(Box::new(move |_v: JsValue| {
            raf_sender.try_send(()).unwrap()
        }));

        let (ric_sender, ric_receiver) = async_channel::unbounded();

        let ric_closure: Closure<dyn Fn(JsValue)> = Closure::wrap(Box::new(move |_v: JsValue| {
            //
            let deadline = _v.dyn_into::<web_sys::IdleDeadline>().unwrap();
            let time_remaining = deadline.time_remaining() as u32;
            ric_sender.try_send(time_remaining).unwrap()
        }));

        // execute the polyfill for safari
        Function::new_no_args(include_str!("./ricpolyfill.js"))
            .call0(&JsValue::NULL)
            .unwrap();

        let window = web_sys::window().unwrap();

        Self {
            window,
            raf_receiver,
            raf_closure,
            ric_receiver,
            ric_closure,
        }
    }
    /// waits for some idle time and returns a timeout future that expires after the idle time has passed
    pub async fn wait_for_idle_time(&self) -> TimeoutFuture {
        let ric_fn = self.ric_closure.as_ref().dyn_ref::<Function>().unwrap();
        let _cb_id: u32 = self.window.request_idle_callback(ric_fn).unwrap();
        let deadline = self.ric_receiver.recv().await.unwrap();
        let deadline = TimeoutFuture::new(deadline);
        deadline
    }

    pub async fn wait_for_raf(&self) {
        let raf_fn = self.raf_closure.as_ref().dyn_ref::<Function>().unwrap();
        let _id: i32 = self.window.request_animation_frame(raf_fn).unwrap();
        self.raf_receiver.recv().await.unwrap();
    }
}