apple-quant-algorithmic 0.3.0

use std::{
	sync::{
		atomic::{self, AtomicBool, AtomicU64, AtomicU8},
		Arc,
	},
	time::{Duration, Instant},
};

use apple_quant_core::{
	log::{error, info, warn},
	AddUnchecked, SubChecked,
};

use bitflag::bitflag;
use smallvec::SmallVec;
use thingbuf::recycling::DefaultRecycle;
use tokio::task::yield_now;
use tokio_stream::StreamExt;
use tokio_util::time::DelayQueue;

use crate::{
	backend::{
		DataBackend, MarketDataDecoder, MarketDataDecoderProvider, OrdersBackend,
		OrdersBackendUpdate, OrdersBackendUpdateRecycle, RemoteOrderId,
	},
	order::{
		DesiredVolumeOrder, MatchableOrder, NewCanceledState, NewPartialFillState,
		NewWorkingState, OrderStateUpdate, OrderStateUpdateListInline, PartialOrderFill,
		RemoteOrder,
	},
	timestamp::{Timestamp, Timestamped, UtcNs},
	volume::{DirectionlessVolume, Zeroable, ZeroableExt, ZeroableVolume},
	aggregation::TradeTradeTimestamp, instrument::InstrumentSpec,
	liquidity::LiquidityEstimation, order_manager::OrdersCapacitySpec, strategy::Strategy,
};

use super::{specs, MarketDataStream, OrderInWorking, RemoteRequest};

pub(super) async fn remote_link<
	IS: InstrumentSpec,
	MDD: MarketDataDecoder<IS>,
	CapacitySpec: specs::CapacitySpec,
>(
	mut link_request_receiver: thingbuf::mpsc::Receiver<RemoteRequest<IS>>,
	link_orders_backend_update_sender: thingbuf::mpsc::Sender<
		OrdersBackendUpdate<IS>,
		OrdersBackendUpdateRecycle,
	>,
	market_data_stream: MarketDataStream<IS, MDD>,
) {
	let (
		remote_request_sender,
		remote_request_receiver,
	) = thingbuf::mpsc::channel(64);

	let (
		orders_backend_update_sender,
		mut orders_backend_update_receiver,
	) = thingbuf::mpsc::with_recycle(1, OrdersBackendUpdateRecycle);

	let (
		timestamp_sender,
		mut timestamp_receiver,
	) = thingbuf::mpsc::channel(1);

	let _remote_join_handle = tokio::spawn(async move {
		remote::<IS, MDD, CapacitySpec>(
			remote_request_receiver,
			orders_backend_update_sender,
			market_data_stream,
			timestamp_sender,
		).await;
	});

	let mut request_delay_queue = Vec::with_capacity(64);
	let mut response_delay_queue = Vec::with_capacity(64);
	let mut newest_timestamp: Option<Timestamp> = None;

	'remote_link: loop {
		yield_now().await;

		let recv_ref = match timestamp_receiver.try_recv_ref() {
			Ok(
				recv_ref,
			) => recv_ref,
			Err(thingbuf::mpsc::errors::TryRecvError::Empty) => continue,
			Err(thingbuf::mpsc::errors::TryRecvError::Closed) => {
				warn!("Channel closed; remote link exiting.");
				return;
			},
			_ => {
				error!("Exiting; unkown error.");
				return;
			},
		};

		newest_timestamp = *recv_ref;

		//
		// LINK REQUEST RECEIVE
		//
		// Exit condition continues and breaks 'remote_loop.
		#[allow(irrefutable_let_patterns)]
		'receiver: while let remote_request = match link_request_receiver.try_recv() {
			Ok(
				remote_request,
			) => remote_request,
			Err(thingbuf::mpsc::errors::TryRecvError::Empty) => break 'receiver,
			Err(thingbuf::mpsc::errors::TryRecvError::Closed) => {
				warn!("Channel closed; remote link exiting.");
				return;
			},
			_ => {
				error!("Exiting; unkown error.");
				return;
			},
		} {
			request_delay_queue.push((newest_timestamp, remote_request));
		}

		//
		// ORDERS BACKEND UPDATE RECEIVE
		//
		#[allow(irrefutable_let_patterns)]
		'receiver: while let orders_backend_update = match orders_backend_update_receiver.try_recv() {
			Ok(
				orders_backend_update,
			) => orders_backend_update,
			Err(thingbuf::mpsc::errors::TryRecvError::Empty) => break 'receiver,
			Err(thingbuf::mpsc::errors::TryRecvError::Closed) => {
				warn!("Channel closed; remote link exiting.");
				return;
			},
			_ => {
				error!("Exiting; unkown error.");
				return;
			},
		} {
			response_delay_queue.push((newest_timestamp, orders_backend_update));
		}

		//
		// ORDERS BACKEND UPDATE SEND
		//
		let process_remote_requests = request_delay_queue
			.extract_if(.., |(
				timestamp,
				remote_request,
			)| {
				if let Some(
					timestamp,
				) = timestamp && newest_timestamp.unwrap() < *timestamp {
					return false;
				}

				true
			})
			.map(|(
				_,
				remote_request,
			)| remote_request);

		for remote_request in process_remote_requests {
			if let Err(
				_,
			) = remote_request_sender.send(
				remote_request,
			).await {
				warn!("Channel closed; remote link exiting.");
				return;
			}
		}

		//
		// LINK RESPONSE SEND
		//
		let process_response_responses = response_delay_queue
			.extract_if(.., |(
				timestamp,
				remote_response,
			)| {
				if let Some(
					timestamp,
				) = timestamp && newest_timestamp.unwrap() < *timestamp {
					return false;
				}

				true
			})
			.map(|(
				_,
				remote_response,
			)| remote_response);

		for orders_backend_update in process_response_responses {
			if let Err(
				_,
			) = link_orders_backend_update_sender.send(
				orders_backend_update,
			).await {
				warn!("Channel closed; remote link exiting.");
				return;
			}
		}
		// `recv_ref` dropped here, releasing block.
	}
}

async fn remote<
	IS: InstrumentSpec,
	MDD: MarketDataDecoder<IS>,
	CapacitySpec: specs::CapacitySpec,
>(
	mut request_receiver: thingbuf::mpsc::Receiver<RemoteRequest<IS>>,
	orders_backend_update_sender: thingbuf::mpsc::Sender<
		OrdersBackendUpdate<IS>,
		OrdersBackendUpdateRecycle,
	>,
	mut market_data_stream: MarketDataStream<IS, MDD>,
	timestamp_sender: thingbuf::mpsc::Sender<Option<Timestamp>>,
) {
	let mut orders_in_working: SmallVec<[OrderInWorking<IS>; CapacitySpec::WORKING]> = SmallVec::default();

	let mut remote_order_id_counter = 0;

	loop {
		yield_now().await;
		let mut remote_requests: SmallVec<[RemoteRequest<IS>; 8]> = SmallVec::default();

		loop {
			let remote_request = match request_receiver.try_recv() {
				Ok(
					remote_request,
				) => remote_request,
				Err(thingbuf::mpsc::errors::TryRecvError::Empty) => break,
				Err(thingbuf::mpsc::errors::TryRecvError::Closed) => {
					warn!("Channel closed; remote exiting.");
					return;
				},
				_ => {
					error!("Exiting; unkown error.");
					return;
				},
			};

			remote_requests.push(remote_request);
		}

		let mut order_state_updates = OrderStateUpdateListInline::default();

		for remote_request in remote_requests {
			match remote_request {
				RemoteRequest::SubmitOrder {
					local_order_id,
					remote_order,
				} => {
					remote_order_id_counter += 1;

					let remote_order_id = RemoteOrderId::new_from_u64(
						remote_order_id_counter,
					);

					let order_in_working = OrderInWorking {
						remote_order_id,
						remote_order,
						liquidity_estimation: LiquidityEstimation::default(),
						partial_order_fills: SmallVec::default(),
					};

					orders_in_working.push(order_in_working);

					let order_state_update = OrderStateUpdate::NewWorkingState(NewWorkingState {
						local_order_id,
						remote_order_id,
						booking_timestamp: Timestamp::now(),
					});

					// Pending order is always guaranteed because it ties the [`LocalOrderId`] and [`RemoteOrderId`] together.
					order_state_updates.push(order_state_update);
				},
				RemoteRequest::ModifyVolume {
					remote_order_id,
					volume,
				} => {
					let Some((
						order_in_working_idx,
						order_in_working,
					)) = orders_in_working.iter_mut().enumerate().find(|(
						_,
						order_in_working,
					)| order_in_working.remote_order_id == remote_order_id) else {
						warn!("Could not find {:?} in working orders.", remote_order_id);
						continue;
					};

					let RemoteOrder::Limit(
						limit_order,
					) = &mut order_in_working.remote_order else {
						continue;
					};

					let mut filled_volume: Zeroable<DirectionlessVolume<IS>> = Zeroable::ZERO;

					for partial_order_fill in order_in_working.partial_order_fills.iter() {
						filled_volume = filled_volume.add_unchecked(
							partial_order_fill.directional_intent_volume.directionless_volume.as_zeroable(),
						);
					}

					let Some(
						filled_volume,
					) = filled_volume.as_optional_nonzero_ref() else {
						limit_order.resting_volume.directionless_volume = volume;
						continue;
					};

					let will_have_resting_volume = volume.sub_checked(filled_volume).is_ok();

					if !will_have_resting_volume {
						orders_in_working.swap_remove(order_in_working_idx);

						let order_state_update = OrderStateUpdate::NewCanceledState(NewCanceledState {
							remote_order_id,
						});

						order_state_updates.push(order_state_update);
						continue;
					}

					limit_order.resting_volume.directionless_volume = volume;
				},
				RemoteRequest::CancelOrder(
					remote_order_id,
				) => {
					let Some(
						orders_in_working_idx,
					) = orders_in_working.iter().position(|
						order_in_working,
					| order_in_working.remote_order_id == remote_order_id) else {
						warn!("Could not find {:?} in working orders.", remote_order_id);
						continue;
					};

					let _ = orders_in_working.swap_remove(orders_in_working_idx);

					let order_state_update = OrderStateUpdate::NewCanceledState(NewCanceledState {
						remote_order_id,
					});

					order_state_updates.push(order_state_update);
				},
				RemoteRequest::CancelAll | RemoteRequest::CancelFlattenAll => {
					for remote_order_id in orders_in_working
						.drain(..)
						.map(|
							order_in_working,
						| order_in_working.remote_order_id)
					{
						let order_state_update = OrderStateUpdate::NewCanceledState(NewCanceledState {
							remote_order_id,
						});

						order_state_updates.push(order_state_update);
					}
				},
				_ => { warn!("Remote request nop triggered."); },
			}
		}

		let Ok(
			decoded_tick,
		) = market_data_stream.decode_tick().await else {
			warn!("Channel closed; remote exiting.");
			return;
		};

		let Some((
			trades,
			newest_trade_timestamp,
		)) = decoded_tick else {
			continue;
		};

		for order_in_working in orders_in_working.iter_mut() {
			order_in_working.liquidity_estimation.walk_trades(trades.iter());
		}

		let mut orders_backend_update = OrdersBackendUpdate {
			order_state_updates,
			trades,
		};

		orders_in_working.drain_filter(|
			order_in_working,
		| {
			let Some(
				price,
			) = order_in_working.remote_order.is_liquidable(
				&order_in_working.liquidity_estimation,
			) else {
				return false;
			};

			let directional_intent_volume = match order_in_working.remote_order.desired_directional_intent_volume() {
				Ok(
					directional_intent_volume,
				) => directional_intent_volume,
				Err(
					error,
				) => {
					error!("{error:?}");
					return true;
				},
			};

			let partial_order_fill = PartialOrderFill {
				price,
				directional_intent_volume,
				timestamp: newest_trade_timestamp,
			};

			let order_state_update = OrderStateUpdate::NewPartialFillState(NewPartialFillState {
				remote_order_id: order_in_working.remote_order_id,
				partial_order_fill,
			});

			orders_backend_update.order_state_updates.push(order_state_update);
			true
		}).for_each(drop);

		// Expected to block.
		if let Err(
			_,
		) = orders_backend_update_sender.send(
			orders_backend_update,
		).await {
			warn!("Channel closed; remote exiting.");
			return;
		}

		// Expected to block.
		if let Err(
			_,
		) = timestamp_sender.send(
			Some(newest_trade_timestamp.timestamp()),
		).await {
			warn!("Channel closed; remote exiting.");
			return;
		}
	}
}