use crate::messages::{ClientMessage, ServerMessage};
use async_std::sync::Arc;
use async_std::sync::Mutex;
use std::collections::HashMap;

use async_std::net::{SocketAddr, TcpListener, TcpStream};
use async_std::sync::{Receiver, Sender};
use async_std::task;
use async_tungstenite::{accept_async, WebSocketStream};
use futures_util::{stream::SplitSink, stream::SplitStream, SinkExt, StreamExt};

#[derive(Debug)]
pub struct NetworkMessage<T> {
	pub conn_id: usize,
	pub data: NetworkPayload<T>,
}

#[derive(Debug)]
pub enum NetworkPayload<T> {
	Connected,
	Disconnected,
	Message(T),
	InvalidFormat(String),
}

struct Connection {
	stream: SplitSink<WebSocketStream<TcpStream>, tungstenite::Message>,
	address: SocketAddr,
	conn_id: usize,
}

pub struct NetworkManager {
	connections: HashMap<usize, Connection>,
}

impl NetworkManager {
	pub fn new() -> Self {
		NetworkManager {
			connections: HashMap::new(),
		}
	}

	fn register(&mut self, conn: Connection) {
		self.connections.insert(conn.conn_id, conn);
	}

	async fn send(&mut self, message: NetworkMessage<ServerMessage>) {
		let conn = self
			.connections
			.get_mut(&message.conn_id)
			.expect("cant send message to an unregistered connection");
		if let NetworkPayload::Message(msg) = message.data {
			let res = conn.stream.send(msg.into()).await;
			if let Err(err) = res {
				log::error!("Error sending message over to game instance: {:?}", err)
			}
		}
	}
}

pub async fn listen(
	bind: String,
	incoming: Sender<NetworkMessage<ClientMessage>>,
	outgoing: Receiver<NetworkMessage<ServerMessage>>,
) {
	let network = Arc::new(Mutex::new(NetworkManager::new()));
	let listener = TcpListener::bind(&bind).await.expect("Can't listen");
	log::info!("Listening on: {}", bind);
	task::spawn(write_loop(network.clone(), outgoing));
	while let Ok((stream, _)) = listener.accept().await {
		let peer = stream
			.peer_addr()
			.expect("connected streams should have a peer address");
		log::info!("Peer address: {}", peer);
		match accept_connection(peer, stream, incoming.clone()).await {
			Ok(conn) => {
				network.lock().await.register(conn);
			}
			Err(err) => log::warn!("failed connection from {:?}: {:?}", peer, err),
		}
	}
}

async fn accept_connection(
	peer: SocketAddr,
	stream: TcpStream,
	incoming: Sender<NetworkMessage<ClientMessage>>,
) -> Result<Connection, tungstenite::Error> {
	// Generate random connection id
	let conn_id = rand::random();

	// Get streams
	let ws_stream = accept_async(stream).await?;
	let (ws_sender, ws_receiver) = ws_stream.split();

	// Send event to game instance
	incoming
		.send(NetworkMessage {
			conn_id,
			data: NetworkPayload::Connected,
		})
		.await;
	// Start read loop
	task::spawn(read_loop(ws_receiver, incoming, conn_id));

	// Return connection instance for network manager
	Ok(Connection {
		stream: ws_sender,
		address: peer,
		conn_id,
	})
}

async fn read_loop(
	mut stream: SplitStream<WebSocketStream<TcpStream>>,
	ch: Sender<NetworkMessage<ClientMessage>>,
	conn_id: usize,
) {
	loop {
		let recv = stream.next().await;
		match recv {
			// Handle close
			Some(Ok(tungstenite::Message::Close(reason))) => {
				ch.send(NetworkMessage {
					conn_id,
					data: NetworkPayload::Disconnected,
				})
				.await;
				log::info!("{:?} left for: {:?}", conn_id, reason);
				break;
			}
			// Message received
			Some(Ok(message)) => match ClientMessage::try_read(message) {
				Ok(msg) => {
					ch.send(NetworkMessage {
						conn_id,
						data: NetworkPayload::Message(msg),
					})
					.await;
				}
				Err(err) => {
					log::warn!("[{:?}] invalid message received: {:?}", conn_id, err);
					// Ask server to notify client about them fucking up
					ch.send(NetworkMessage {
						conn_id,
						data: NetworkPayload::InvalidFormat(err.to_string()),
					})
					.await;
				}
			},
			// Errors
			Some(Err(err)) => {
				log::warn!("error received in read loop: {:?}", err);
				break;
			}
			None => break,
		}
	}
	log::info!("stopped read loop for {:?}", conn_id);
}

async fn write_loop(net: Arc<Mutex<NetworkManager>>, ch: Receiver<NetworkMessage<ServerMessage>>) {
	loop {
		match ch.recv().await {
			Ok(msg) => {
				net.lock().await.send(msg).await;
			}
			Err(err) => {
				log::warn!("write loop received error: {:?}", err);
				break;
			}
		}
	}
}