dioxus-mirror/packages/fullstack/src/hooks/server_future.rs

use dioxus_core::prelude::*;
use serde::{de::DeserializeOwned, Serialize};
use std::any::Any;
use std::cell::Cell;
use std::cell::Ref;
use std::cell::RefCell;
use std::fmt::Debug;
use std::future::Future;
use std::rc::Rc;
use std::sync::Arc;

/// A future that resolves to a value.
///
/// This runs the future only once - though the future may be regenerated
/// through the [`UseServerFuture::restart`] method.
///
/// This is commonly used for components that cannot be rendered until some
/// asynchronous operation has completed.
///
/// Whenever the hooks dependencies change, the future will be re-evaluated.
/// If a future is pending when the dependencies change, the previous future
/// will be allowed to continue
///
/// - dependencies: a tuple of references to values that are PartialEq + Clone
#[must_use = "Consider using `cx.spawn` to run a future without reading its value"]
pub fn use_server_future<T, F>(future: impl FnOnce() -> F) -> Option<UseServerFuture<T>>
where
    T: 'static + Serialize + DeserializeOwned + Debug,
    F: Future<Output = T> + 'static,
{
    todo!()

    // let state = use_hook(move || UseServerFuture {
    //     update: schedule_update(),
    //     needs_regen: Cell::new(true),
    //     value: Default::default(),
    //     task: Cell::new(None),
    //     dependencies: Vec::new(),
    // });

    // let first_run = { state.value.borrow().as_ref().is_none() && state.task.get().is_none() };

    // #[cfg(not(feature = "ssr"))]
    // {
    //     if first_run {
    //         match crate::html_storage::deserialize::take_server_data() {
    //             Some(data) => {
    //                 tracing::trace!("Loaded {data:?} from server");
    //                 *state.value.borrow_mut() = Some(Box::new(data));
    //                 state.needs_regen.set(false);
    //                 return Some(state);
    //             }
    //             None => {
    //                 tracing::trace!("Failed to load from server... running future");
    //             }
    //         };
    //     }
    // }

    // if dependencies.clone().apply(&mut state.dependencies) || state.needs_regen.get() {
    //     // We don't need regen anymore
    //     state.needs_regen.set(false);

    //     // Create the new future
    //     let fut = future(dependencies.out());

    //     // Clone in our cells
    //     let value = state.value.clone();
    //     let schedule_update = state.update.clone();

    //     // Cancel the current future
    //     if let Some(current) = state.task.take() {
    //         cx.remove_future(current);
    //     }

    //     state.task.set(Some(cx.push_future(async move {
    //         let data;
    //         #[cfg(feature = "ssr")]
    //         {
    //             data = fut.await;
    //             if first_run {
    //                 if let Err(err) = crate::prelude::server_context().push_html_data(&data) {
    //                     tracing::error!("Failed to push HTML data: {}", err);
    //                 };
    //             }
    //         }
    //         #[cfg(not(feature = "ssr"))]
    //         {
    //             data = fut.await;
    //         }
    //         *value.borrow_mut() = Some(Box::new(data));

    //         schedule_update();
    //     })));
    // }

    // if first_run {
    //     #[cfg(feature = "ssr")]
    //     {
    //         tracing::trace!("Suspending first run of use_server_future");
    //         cx.suspend();
    //     }
    //     None
    // } else {
    //     Some(state)
    // }
}

pub struct UseServerFuture<T> {
    update: Arc<dyn Fn()>,
    needs_regen: Cell<bool>,
    task: Cell<Option<Task>>,
    dependencies: Vec<Box<dyn Any>>,
    value: Rc<RefCell<Option<Box<T>>>>,
}

impl<T> UseServerFuture<T> {
    // /// Restart the future with new dependencies.
    // ///
    // /// Will not cancel the previous future, but will ignore any values that it
    // /// generates.
    // pub fn restart(&self) {
    //     self.needs_regen.set(true);
    //     (self.update)();
    // }

    // /// Forcefully cancel a future
    // pub fn cancel(&self) {
    //     if let Some(task) = self.task.take() {
    //         cx.remove_future(task);
    //     }
    // }

    // /// Return any value, even old values if the future has not yet resolved.
    // ///
    // /// If the future has never completed, the returned value will be `None`.
    // pub fn value(&self) -> Ref<'_, T> {
    //     Ref::map(self.value.borrow(), |v| v.as_deref().unwrap())
    // }

    // /// Get the ID of the future in Dioxus' internal scheduler
    // pub fn task(&self) -> Option<Task> {
    //     self.task.get()
    // }

    // /// Get the current state of the future.
    // pub fn reloading(&self) -> bool {
    //     self.task.get().is_some()
    // }
}