use crate::{Node, WasmNotSend};
use core::future::Future;
use core::ops::Deref;
use std::sync::Mutex;

#[cfg(feature = "alloc")]
use alloc::sync::Arc;
use dyn_any::DynFuture;

/// Caches the output of a given Node and acts as a proxy
#[derive(Default)]
pub struct MemoNode<T, CachedNode> {
	cache: Arc<Mutex<Option<T>>>,
	node: CachedNode,
}
impl<'i, 'o: 'i, T: 'i + Clone + 'o + WasmNotSend, CachedNode: 'i> Node<'i, ()> for MemoNode<T, CachedNode>
where
	CachedNode: for<'any_input> Node<'any_input, ()>,
	for<'a> <CachedNode as Node<'a, ()>>::Output: core::future::Future<Output = T> + WasmNotSend,
{
	// TODO: This should return a reference to the cached cached_value
	// but that requires a lot of lifetime magic <- This was suggested by copilot but is pretty accurate xD
	type Output = DynFuture<'i, T>;
	fn eval(&'i self, input: ()) -> Self::Output {
		if let Some(cached_value) = self.cache.lock().as_ref().unwrap().deref() {
			let data = cached_value.clone();
			Box::pin(async move { data })
		} else {
			let fut = self.node.eval(input);
			let cache = self.cache.clone();
			Box::pin(async move {
				let value = fut.await;
				*cache.lock().unwrap() = Some(value.clone());
				value
			})
		}
	}

	fn reset(&self) {
		self.cache.lock().unwrap().take();
	}
}

impl<T, CachedNode> MemoNode<T, CachedNode> {
	pub fn new(node: CachedNode) -> MemoNode<T, CachedNode> {
		MemoNode { cache: Default::default(), node }
	}
}

/// Caches the output of a given Node and acts as a proxy.
/// In contrast to the regular `MemoNode`. This node ignores all input.
/// Using this node might result in the document not updating properly,
/// use with caution.
#[derive(Default)]
pub struct ImpureMemoNode<I, T, CachedNode> {
	cache: Arc<Mutex<Option<T>>>,
	node: CachedNode,
	_phantom: std::marker::PhantomData<I>,
}

impl<'i, 'o: 'i, I: 'i, T: 'i + Clone + 'o + WasmNotSend, CachedNode: 'i> Node<'i, I> for ImpureMemoNode<I, T, CachedNode>
where
	CachedNode: for<'any_input> Node<'any_input, I>,
	for<'a> <CachedNode as Node<'a, I>>::Output: core::future::Future<Output = T> + WasmNotSend,
{
	// TODO: This should return a reference to the cached cached_value
	// but that requires a lot of lifetime magic <- This was suggested by copilot but is pretty accurate xD
	type Output = DynFuture<'i, T>;
	fn eval(&'i self, input: I) -> Self::Output {
		if let Some(cached_value) = self.cache.lock().as_ref().unwrap().deref() {
			let data = cached_value.clone();
			Box::pin(async move { data })
		} else {
			let fut = self.node.eval(input);
			let cache = self.cache.clone();
			Box::pin(async move {
				let value = fut.await;
				*cache.lock().unwrap() = Some(value.clone());
				value
			})
		}
	}

	fn reset(&self) {
		self.cache.lock().unwrap().take();
	}
}

impl<T, I, CachedNode> ImpureMemoNode<I, T, CachedNode> {
	pub fn new(node: CachedNode) -> ImpureMemoNode<I, T, CachedNode> {
		ImpureMemoNode {
			cache: Default::default(),
			node,
			_phantom: core::marker::PhantomData,
		}
	}
}

/// Stores both what a node was called with and what it returned.
#[derive(Clone, Debug)]
pub struct IORecord<I, O> {
	pub input: I,
	pub output: O,
}

#[cfg(feature = "alloc")]
/// Caches the output of the last graph evaluation for introspection
#[derive(Default)]
pub struct MonitorNode<I, T, N> {
	#[allow(clippy::type_complexity)]
	io: Arc<Mutex<Option<Arc<IORecord<I, T>>>>>,
	node: N,
}

#[cfg(feature = "alloc")]
impl<'i, T, I, N> Node<'i, I> for MonitorNode<I, T, N>
where
	I: Clone + 'static + Send + Sync,
	T: Clone + 'static + Send + Sync,
	for<'a> N: Node<'a, I, Output: Future<Output = T> + WasmNotSend> + 'i,
{
	type Output = DynFuture<'i, T>;
	fn eval(&'i self, input: I) -> Self::Output {
		let io = self.io.clone();
		let output_fut = self.node.eval(input.clone());
		Box::pin(async move {
			let output = output_fut.await;
			*io.lock().unwrap() = Some(Arc::new(IORecord { input, output: output.clone() }));
			output
		})
	}

	fn serialize(&self) -> Option<Arc<dyn core::any::Any>> {
		let io = self.io.lock().unwrap();
		(io).as_ref().map(|output| output.clone() as Arc<dyn core::any::Any>)
	}
}

#[cfg(feature = "alloc")]
impl<I, T, N> MonitorNode<I, T, N> {
	pub fn new(node: N) -> MonitorNode<I, T, N> {
		MonitorNode { io: Arc::new(Mutex::new(None)), node }
	}
}