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use std::future::Future;

/// Spawns and runs a thread-local [`Future`] in a platform-independent way.
///
/// This can be used to interface with any `async` code by spawning a task
/// to run a `Future`.
pub fn spawn_local<F>(fut: F)
where
    F: Future<Output = ()> + 'static,
{
    cfg_if! {
        if #[cfg(target_arch = "wasm32")] {
            wasm_bindgen_futures::spawn_local(fut)
        } else if #[cfg(any(test, doctest))] {
            tokio_test::block_on(fut);
        } else if #[cfg(all(feature = "web-ssr", not(feature = "__single_holder")))] {
            tokio::task::block_in_place(move || {
                tokio::runtime::Handle::current().block_on(async move {
                    let local = tokio::task::LocalSet::new();
                    local.spawn_local(fut);
                    local.await;
                });
            });
        }  else {
            futures::executor::block_on(fut)
        }
    }
}

/// The microtask is a short function which will run after the current task has
/// completed its work and when there is no other code waiting to be run before
/// control of the execution context is returned to the browser's event loop.
///
/// Microtasks are especially useful for libraries and frameworks that need
/// to perform final cleanup or other just-before-rendering tasks.
///
/// [MDN queueMicrotask](https://developer.mozilla.org/en-US/docs/Web/API/queueMicrotask)
pub fn queue_microtask(task: impl FnOnce() + 'static) {
    #[cfg(not(all(target_arch = "wasm32", feature = "web-csr")))]
    {
        task();
    }

    #[cfg(all(target_arch = "wasm32", feature = "web-csr"))]
    {
        use js_sys::{Function, Reflect};
        use wasm_bindgen::prelude::*;

        let task = Closure::once_into_js(task);
        let window = web_sys::window().expect("window not available");
        let queue_microtask = Reflect::get(&window, &JsValue::from_str("queueMicrotask")).expect("queueMicrotask not available");
        let queue_microtask = queue_microtask.unchecked_into::<Function>();
        _ = queue_microtask.call1(&JsValue::UNDEFINED, &task);
    }
}