use std::collections::HashMap;
use std::net::SocketAddr;
use std::sync::atomic::{self, AtomicU16};
use std::sync::Arc;

use async_trait::async_trait;
use bytes::Bytes;
use log::{debug, trace};

use sodiumoxide::crypto::sign::ed25519;
use tokio::io::split;
use tokio::net::TcpStream;
use tokio::sync::{mpsc, oneshot, watch};

use kuska_handshake::async_std::{
	handshake_client, handshake_server, BoxStream, TokioCompatExt, TokioCompatExtRead,
	TokioCompatExtWrite,
};

use crate::error::*;
use crate::message::*;
use crate::netapp::*;
use crate::proto::*;
use crate::util::*;

pub struct ServerConn {
	netapp: Arc<NetApp>,
	pub remote_addr: SocketAddr,
	pub peer_pk: ed25519::PublicKey,
	resp_send: mpsc::UnboundedSender<(RequestID, RequestPriority, Vec<u8>)>,
	close_send: watch::Sender<bool>,
}

impl ServerConn {
	pub(crate) async fn run(netapp: Arc<NetApp>, socket: TcpStream) -> Result<(), Error> {
		let mut asyncstd_socket = TokioCompatExt::wrap(socket);
		let handshake = handshake_server(
			&mut asyncstd_socket,
			netapp.netid.clone(),
			netapp.pubkey.clone(),
			netapp.privkey.clone(),
		)
		.await?;
		let peer_pk = handshake.peer_pk.clone();

		let tokio_socket = asyncstd_socket.into_inner();
		let remote_addr = tokio_socket.peer_addr().unwrap();

		debug!(
			"Handshake complete (server) with {}@{}",
			hex::encode(&peer_pk),
			remote_addr
		);

		let (read, write) = split(tokio_socket);

		let read = TokioCompatExtRead::wrap(read);
		let write = TokioCompatExtWrite::wrap(write);

		let (box_stream_read, box_stream_write) =
			BoxStream::from_handshake(read, write, handshake, 0x8000).split_read_write();

		let (resp_send, resp_recv) = mpsc::unbounded_channel();

		let (close_send, close_recv) = watch::channel(false);

		let conn = Arc::new(ServerConn {
			netapp: netapp.clone(),
			remote_addr,
			peer_pk: peer_pk.clone(),
			resp_send,
			close_send,
		});

		netapp.connected_as_server(peer_pk.clone(), conn.clone());

		let conn2 = conn.clone();
		let conn3 = conn.clone();
		tokio::try_join!(
			conn2.recv_loop(box_stream_read, close_recv.clone()),
			conn3.send_loop(resp_recv, box_stream_write, close_recv.clone()),
		)
		.map(|_| ())
		.log_err("ServerConn recv_loop/send_loop");

		netapp.disconnected_as_server(&peer_pk, conn);

		Ok(())
	}

	pub fn close(&self) {
		self.close_send.broadcast(true).unwrap();
	}
}

impl SendLoop for ServerConn {}

#[async_trait]
impl RecvLoop for ServerConn {
	async fn recv_handler(self: Arc<Self>, id: u16, bytes: Vec<u8>) {
		let bytes: Bytes = bytes.into();

		let prio = bytes[0];

		let mut kind_bytes = [0u8; 4];
		kind_bytes.copy_from_slice(&bytes[1..5]);
		let kind = u32::from_be_bytes(kind_bytes);

		if let Some(handler) = self.netapp.msg_handlers.load().get(&kind) {
			let resp = handler(self.peer_pk.clone(), bytes.slice(5..)).await;
			self.resp_send
				.send((id, prio, resp))
				.log_err("ServerConn recv_handler send resp");
		}
	}
}
pub struct ClientConn {
	pub netapp: Arc<NetApp>,
	pub remote_addr: SocketAddr,
	pub peer_pk: ed25519::PublicKey,
	query_send: mpsc::UnboundedSender<(RequestID, RequestPriority, Vec<u8>)>,
	next_query_number: AtomicU16,
	resp_send: mpsc::UnboundedSender<(RequestID, Vec<u8>)>,
	resp_notify_send: mpsc::UnboundedSender<(RequestID, oneshot::Sender<Vec<u8>>)>,
	close_send: watch::Sender<bool>,
}

impl ClientConn {
	pub(crate) async fn init(
		netapp: Arc<NetApp>,
		socket: TcpStream,
		remote_pk: ed25519::PublicKey,
	) -> Result<(), Error> {
		let mut asyncstd_socket = TokioCompatExt::wrap(socket);

		let handshake = handshake_client(
			&mut asyncstd_socket,
			netapp.netid.clone(),
			netapp.pubkey.clone(),
			netapp.privkey.clone(),
			remote_pk.clone(),
		)
		.await?;

		let tokio_socket = asyncstd_socket.into_inner();
		let remote_addr = tokio_socket.peer_addr().unwrap();

		debug!(
			"Handshake complete (client) with {}@{}",
			hex::encode(&remote_pk),
			remote_addr
		);

		let (read, write) = split(tokio_socket);

		let read = TokioCompatExtRead::wrap(read);
		let write = TokioCompatExtWrite::wrap(write);

		let (box_stream_read, box_stream_write) =
			BoxStream::from_handshake(read, write, handshake, 0x8000).split_read_write();

		let (query_send, query_recv) = mpsc::unbounded_channel();
		let (resp_send, resp_recv) = mpsc::unbounded_channel();
		let (resp_notify_send, resp_notify_recv) = mpsc::unbounded_channel();

		let (close_send, close_recv) = watch::channel(false);

		let conn = Arc::new(ClientConn {
			netapp: netapp.clone(),
			remote_addr,
			peer_pk: remote_pk.clone(),
			next_query_number: AtomicU16::from(0u16),
			query_send,
			resp_send,
			resp_notify_send,
			close_send,
		});

		netapp.connected_as_client(remote_pk.clone(), conn.clone());

		tokio::spawn(async move {
			let conn2 = conn.clone();
			let conn3 = conn.clone();
			let conn4 = conn.clone();
			tokio::try_join!(
				conn2.send_loop(query_recv, box_stream_write, close_recv.clone()),
				conn3.recv_loop(box_stream_read, close_recv.clone()),
				conn4.dispatch_resp(resp_recv, resp_notify_recv, close_recv.clone()),
			)
			.map(|_| ())
			.log_err("ClientConn send_loop/recv_loop/dispatch_loop");

			netapp.disconnected_as_client(&remote_pk, conn);
		});

		Ok(())
	}

	pub fn close(&self) {
		self.close_send.broadcast(true).unwrap();
	}

	async fn dispatch_resp(
		self: Arc<Self>,
		mut resp_recv: mpsc::UnboundedReceiver<(RequestID, Vec<u8>)>,
		mut resp_notify_recv: mpsc::UnboundedReceiver<(RequestID, oneshot::Sender<Vec<u8>>)>,
		mut must_exit: watch::Receiver<bool>,
	) -> Result<(), Error> {
		let mut resps: HashMap<RequestID, Vec<u8>> = HashMap::new();
		let mut resp_notify: HashMap<RequestID, oneshot::Sender<Vec<u8>>> = HashMap::new();
		while !*must_exit.borrow() {
			tokio::select! {
				resp = resp_recv.recv() => {
					if let Some((id, resp)) = resp {
						trace!("dispatch_resp: got resp to {}, {} bytes", id, resp.len());
						if let Some(ch) = resp_notify.remove(&id) {
							ch.send(resp).map_err(|_| Error::Message("Could not dispatch reply".to_string()))?;
						} else {
							resps.insert(id, resp);
						}
					}
				}
				resp_ch = resp_notify_recv.recv() => {
					if let Some((id, resp_ch)) = resp_ch {
						trace!("dispatch_resp: got resp_ch {}", id);
						if let Some(rs) = resps.remove(&id) {
							resp_ch.send(rs).map_err(|_| Error::Message("Could not dispatch reply".to_string()))?;
						} else {
							resp_notify.insert(id, resp_ch);
						}
					}
				}
				exit = must_exit.recv() => {
					if exit == Some(true) {
						break;
					}
				}
			}
		}
		Ok(())
	}

	pub async fn request<T>(
		self: Arc<Self>,
		rq: T,
		prio: RequestPriority,
	) -> Result<<T as Message>::Response, Error>
	where
		T: Message,
	{
		let id = self
			.next_query_number
			.fetch_add(1u16, atomic::Ordering::Relaxed);
		let mut bytes = vec![prio];
		bytes.extend_from_slice(&u32::to_be_bytes(T::KIND)[..]);
		bytes.extend_from_slice(&rmp_to_vec_all_named(&rq)?[..]);

		let (resp_send, resp_recv) = oneshot::channel();
		self.resp_notify_send.send((id, resp_send))?;

		trace!("request: query_send {}, {} bytes", id, bytes.len());
		self.query_send.send((id, prio, bytes))?;

		let resp = resp_recv.await?;

		rmp_serde::decode::from_read_ref::<_, Result<<T as Message>::Response, String>>(&resp[..])?
			.map_err(Error::Remote)
	}
}

impl SendLoop for ClientConn {}

#[async_trait]
impl RecvLoop for ClientConn {
	async fn recv_handler(self: Arc<Self>, id: RequestID, msg: Vec<u8>) {
		self.resp_send
			.send((id, msg))
			.log_err("ClientConn::recv_handler");
	}
}