use crate::{runtime::Runtime, Element, ScopeId, Task};
use futures_util::Future;
use std::sync::Arc;

/// Get the current scope id
pub fn current_scope_id() -> Option<ScopeId> {
    Runtime::with(|rt| rt.current_scope_id()).flatten()
}

#[doc(hidden)]
/// Check if the virtual dom is currently inside of the body of a component
pub fn vdom_is_rendering() -> bool {
    Runtime::with(|rt| rt.rendering.get()).unwrap_or_default()
}

/// Consume context from the current scope
pub fn try_consume_context<T: 'static + Clone>() -> Option<T> {
    Runtime::with_current_scope(|cx| cx.consume_context::<T>()).flatten()
}

/// Consume context from the current scope
pub fn consume_context<T: 'static + Clone>() -> T {
    Runtime::with_current_scope(|cx| cx.consume_context::<T>())
        .flatten()
        .unwrap_or_else(|| panic!("Could not find context {}", std::any::type_name::<T>()))
}

/// Consume context from the current scope
pub fn consume_context_from_scope<T: 'static + Clone>(scope_id: ScopeId) -> Option<T> {
    Runtime::with(|rt| {
        rt.get_state(scope_id)
            .and_then(|cx| cx.consume_context::<T>())
    })
    .flatten()
}

/// Check if the current scope has a context
pub fn has_context<T: 'static + Clone>() -> Option<T> {
    Runtime::with_current_scope(|cx| cx.has_context::<T>()).flatten()
}

/// Provide context to the current scope
pub fn provide_context<T: 'static + Clone>(value: T) -> T {
    Runtime::with_current_scope(|cx| cx.provide_context(value)).expect("to be in a dioxus runtime")
}

/// Provide a context to the root scope
pub fn provide_root_context<T: 'static + Clone>(value: T) -> T {
    Runtime::with_current_scope(|cx| cx.provide_root_context(value))
        .expect("to be in a dioxus runtime")
}

/// Suspended the current component on a specific task and then return None
pub fn suspend(task: Task) -> Element {
    Runtime::with_current_scope(|cx| cx.suspend(task));
    None
}

/// Start a new future on the same thread as the rest of the VirtualDom.
///
/// **You should generally use `spawn` instead of this method unless you specifically need to run a task during suspense**
///
/// This future will not contribute to suspense resolving but it will run during suspense.
///
/// Because this future runs during suspense, you need to be careful to work with hydration. It is not recommended to do any async IO work in this future, as it can easily cause hydration issues. However, you can use isomorphic tasks to do work that can be consistently replicated on the server and client like logging or responding to state changes.
///
/// ```rust, no_run
/// # use dioxus::prelude::*;
/// // ❌ Do not do requests in isomorphic tasks. It may resolve at a different time on the server and client, causing hydration issues.
/// let mut state = use_signal(|| None);
/// spawn_isomorphic(async move {
///     state.set(Some(reqwest::get("https://api.example.com").await));
/// });
///
/// // ✅ You may wait for a signal to change and then log it
/// let mut state = use_signal(|| 0);
/// spawn_isomorphic(async move {
///     loop {
///         tokio::time::sleep(std::time::Duration::from_secs(1)).await;
///         println!("State is {state}");
///     }
/// });
/// ```
pub fn spawn_isomorphic(fut: impl Future<Output = ()> + 'static) -> Task {
    Runtime::with_current_scope(|cx| cx.spawn_isomorphic(fut)).expect("to be in a dioxus runtime")
}

/// Spawns the future but does not return the [`TaskId`]
pub fn spawn(fut: impl Future<Output = ()> + 'static) -> Task {
    Runtime::with_current_scope(|cx| cx.spawn(fut)).expect("to be in a dioxus runtime")
}

/// Queue an effect to run after the next render
pub fn queue_effect(f: impl FnOnce() + 'static) {
    Runtime::with_current_scope(|cx| cx.queue_effect(f)).expect("to be in a dioxus runtime")
}

/// Spawn a future that Dioxus won't clean up when this component is unmounted
///
/// This is good for tasks that need to be run after the component has been dropped.
///
/// **This will run the task in the root scope. Any calls to global methods inside the future (including `context`) will be run in the root scope.**
pub fn spawn_forever(fut: impl Future<Output = ()> + 'static) -> Option<Task> {
    Runtime::with_scope(ScopeId::ROOT, |cx| cx.spawn(fut))
}

/// Informs the scheduler that this task is no longer needed and should be removed.
///
/// This drops the task immediately.
pub fn remove_future(id: Task) {
    Runtime::with(|rt| rt.remove_task(id)).expect("Runtime to exist");
}

/// Store a value between renders. The foundational hook for all other hooks.
///
/// Accepts an `initializer` closure, which is run on the first use of the hook (typically the initial render).
/// `use_hook` will return a clone of the value on every render.
///
/// In order to clean up resources you would need to implement the [`Drop`] trait for an inner value stored in a RC or similar (Signals for instance),
/// as these only drop their inner value once all references have been dropped, which only happens when the component is dropped.
///
/// # Example
///
/// ```rust
/// use dioxus::prelude::*;
///
/// // prints a greeting on the initial render
/// pub fn use_hello_world() {
///     use_hook(|| println!("Hello, world!"));
/// }
/// ```
///
/// # Custom Hook Example
///
/// ```rust
/// use dioxus::prelude::*;
///
/// pub struct InnerCustomState(usize);
///
/// impl Drop for InnerCustomState {
///     fn drop(&mut self){
///         println!("Component has been dropped.");
///     }
/// }
///
/// #[derive(Clone, Copy)]
/// pub struct CustomState {
///     inner: Signal<InnerCustomState>
/// }
///
/// pub fn use_custom_state() -> CustomState {
///     use_hook(|| CustomState {
///         inner: Signal::new(InnerCustomState(0))
///     })
/// }
/// ```
pub fn use_hook<State: Clone + 'static>(initializer: impl FnOnce() -> State) -> State {
    Runtime::with_current_scope(|cx| cx.use_hook(initializer)).expect("to be in a dioxus runtime")
}

/// Get the current render since the inception of this component
///
/// This can be used as a helpful diagnostic when debugging hooks/renders, etc
pub fn generation() -> usize {
    Runtime::with_current_scope(|cx| cx.generation()).expect("to be in a dioxus runtime")
}

/// Get the parent of the current scope if it exists
pub fn parent_scope() -> Option<ScopeId> {
    Runtime::with_current_scope(|cx| cx.parent_id()).flatten()
}

/// Mark the current scope as dirty, causing it to re-render
pub fn needs_update() {
    Runtime::with_current_scope(|cx| cx.needs_update());
}

/// Mark the current scope as dirty, causing it to re-render
pub fn needs_update_any(id: ScopeId) {
    Runtime::with_current_scope(|cx| cx.needs_update_any(id));
}

/// Schedule an update for the current component
///
/// Note: Unlike [`needs_update`], the function returned by this method will work outside of the dioxus runtime.
///
/// You should prefer [`schedule_update_any`] if you need to update multiple components.
pub fn schedule_update() -> Arc<dyn Fn() + Send + Sync> {
    Runtime::with_current_scope(|cx| cx.schedule_update()).expect("to be in a dioxus runtime")
}

/// Schedule an update for any component given its [`ScopeId`].
///
/// A component's [`ScopeId`] can be obtained from the [`current_scope_id`] method.
///
/// Note: Unlike [`needs_update`], the function returned by this method will work outside of the dioxus runtime.
pub fn schedule_update_any() -> Arc<dyn Fn(ScopeId) + Send + Sync> {
    Runtime::with_current_scope(|cx| cx.schedule_update_any()).expect("to be in a dioxus runtime")
}

/// Creates a callback that will be run before the component is removed.
/// This can be used to clean up side effects from the component
/// (created with [`use_effect`](crate::use_effect)).
///
/// Example:
/// ```rust, ignore
/// use dioxus::prelude::*;
///
/// fn app() -> Element {
///     let state = use_signal(|| true);
///     rsx! {
///         for _ in 0..100 {
///             h1 {
///                 "spacer"
///             }
///         }
///         if **state {
///             rsx! {
///                 child_component {}
///             }
///         }
///         button {
///             onclick: move |_| {
///                 state.set(!*state.get());
///             },
///             "Unmount element"
///         }
///     }
/// }
///
/// fn child_component() -> Element {
///     let original_scroll_position = use_signal(|| 0.0);
///
///     use_effect(move |_| async move {
///         let window = web_sys::window().unwrap();
///         let document = window.document().unwrap();
///         let element = document.get_element_by_id("my_element").unwrap();
///         element.scroll_into_view();
///         original_scroll_position.set(window.scroll_y().unwrap());
///     });
///
///     use_drop(move || {
///         /// restore scroll to the top of the page
///         let window = web_sys::window().unwrap();
///         window.scroll_with_x_and_y(*original_scroll_position.current(), 0.0);
///     });
///
///     rsx!{
///         div {
///             id: "my_element",
///             "hello"
///         }
///     }
/// }
/// ```
pub fn use_drop<D: FnOnce() + 'static>(destroy: D) {
    struct LifeCycle<D: FnOnce()> {
        /// Wrap the closure in an option so that we can take it out on drop.
        ondestroy: Option<D>,
    }

    /// On drop, we want to run the closure.
    impl<D: FnOnce()> Drop for LifeCycle<D> {
        fn drop(&mut self) {
            if let Some(f) = self.ondestroy.take() {
                f();
            }
        }
    }

    // We need to impl clone for the lifecycle, but we don't want the drop handler for the closure to be called twice.
    impl<D: FnOnce()> Clone for LifeCycle<D> {
        fn clone(&self) -> Self {
            Self { ondestroy: None }
        }
    }

    use_hook(|| LifeCycle {
        ondestroy: Some(destroy),
    });
}

/// A hook that allows you to insert a "before render" function.
///
/// This function will always be called before dioxus tries to render your component. This should be used for safely handling
/// early returns
pub fn use_before_render(f: impl FnMut() + 'static) {
    use_hook(|| before_render(f));
}

/// Push this function to be run after the next render
///
/// This function will always be called before dioxus tries to render your component. This should be used for safely handling
/// early returns
pub fn use_after_render(f: impl FnMut() + 'static) {
    use_hook(|| after_render(f));
}

/// Push a function to be run before the next render
/// This is a hook and will always run, so you can't unschedule it
/// Will run for every progression of suspense, though this might change in the future
pub fn before_render(f: impl FnMut() + 'static) {
    Runtime::with_current_scope(|cx| cx.push_before_render(f));
}

/// Push a function to be run after the render is complete, even if it didn't complete successfully
pub fn after_render(f: impl FnMut() + 'static) {
    Runtime::with_current_scope(|cx| cx.push_after_render(f));
}

/// Wait for the next render to complete
///
/// This is useful if you've just triggered an update and want to wait for it to finish before proceeding with valid
/// DOM nodes.
///
/// Effects rely on this to ensure that they only run effects after the DOM has been updated. Without wait_for_next_render effects
/// are run immediately before diffing the DOM, which causes all sorts of out-of-sync weirdness.
pub async fn wait_for_next_render() {
    // Wait for the flush lock to be available
    // We release it immediately, so it's impossible for the lock to be held longer than this function
    Runtime::with(|rt| rt.render_signal.subscribe())
        .unwrap()
        .await;
}

/// Use a hook with a cleanup function
pub fn use_hook_with_cleanup<T: Clone + 'static>(
    hook: impl FnOnce() -> T,
    cleanup: impl FnOnce(T) + 'static,
) -> T {
    let value = use_hook(hook);
    let _value = value.clone();
    use_drop(move || cleanup(_value));
    value
}