use async_ringbuf::{AsyncHeapCons, AsyncHeapProd, AsyncHeapRb, traits::*};
use crossbeam::atomic::AtomicCell;
use std::{
    collections::HashMap,
    fmt::Debug,
    sync::Arc,
    task::{Poll, ready},
};

use async_trait::async_trait;
use futures::{Sink, SinkExt, Stream, StreamExt};
use once_cell::sync::Lazy;

use tokio::sync::mpsc::{UnboundedReceiver, UnboundedSender, unbounded_channel};

use uuid::Uuid;

use crate::tunnel::{FromUrl, IpVersion, SinkError, SinkItem};

use super::{
    StreamItem, Tunnel, TunnelConnector, TunnelError, TunnelInfo, TunnelListener,
    build_url_from_socket_addr, common::TunnelWrapper,
};

pub static RING_TUNNEL_CAP: usize = 128;
static RING_TUNNEL_RESERVED_CAP: usize = 4;

type RingLock = parking_lot::Mutex<()>;

type RingItem = SinkItem;

pub struct RingTunnel {
    id: Uuid,

    ring_cons_impl: AtomicCell<Option<AsyncHeapCons<RingItem>>>,
    ring_prod_impl: AtomicCell<Option<AsyncHeapProd<RingItem>>>,
}

impl RingTunnel {
    fn id(&self) -> &Uuid {
        &self.id
    }

    pub fn new(cap: usize) -> Self {
        let id = Uuid::new_v4();
        let ring_impl = AsyncHeapRb::new(std::cmp::max(RING_TUNNEL_RESERVED_CAP * 2, cap));
        let (ring_prod_impl, ring_cons_impl) = ring_impl.split();
        Self {
            id,
            ring_cons_impl: AtomicCell::new(Some(ring_cons_impl)),
            ring_prod_impl: AtomicCell::new(Some(ring_prod_impl)),
        }
    }

    pub fn new_with_id(id: Uuid, cap: usize) -> Self {
        let mut ret = Self::new(cap);
        ret.id = id;
        ret
    }
}

impl Debug for RingTunnel {
    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
        f.debug_struct("RingTunnel").field("id", &self.id).finish()
    }
}

pub struct RingStream {
    id: Uuid,
    ring_cons_impl: AsyncHeapCons<RingItem>,
}

impl RingStream {
    pub fn new(tunnel: Arc<RingTunnel>) -> Self {
        Self {
            id: tunnel.id,
            ring_cons_impl: tunnel.ring_cons_impl.take().unwrap(),
        }
    }
}

impl Stream for RingStream {
    type Item = StreamItem;

    fn poll_next(
        self: std::pin::Pin<&mut Self>,
        cx: &mut std::task::Context<'_>,
    ) -> Poll<Option<Self::Item>> {
        let ret = ready!(self.get_mut().ring_cons_impl.poll_next_unpin(cx));
        match ret {
            Some(item) => Poll::Ready(Some(Ok(item))),
            None => Poll::Ready(None),
        }
    }
}

impl Debug for RingStream {
    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
        f.debug_struct("RingStream")
            .field("id", &self.id)
            .field("len", &self.ring_cons_impl.base().occupied_len())
            .field("cap", &self.ring_cons_impl.base().capacity())
            .finish()
    }
}

pub struct RingSink {
    id: Uuid,
    ring_prod_impl: AsyncHeapProd<RingItem>,
}

impl RingSink {
    pub fn new(tunnel: Arc<RingTunnel>) -> Self {
        Self {
            id: tunnel.id,
            ring_prod_impl: tunnel.ring_prod_impl.take().unwrap(),
        }
    }

    pub fn try_send(&mut self, item: RingItem) -> Result<(), RingItem> {
        let base = self.ring_prod_impl.base();
        if base.occupied_len() >= base.capacity().get() - RING_TUNNEL_RESERVED_CAP {
            return Err(item);
        }
        self.ring_prod_impl.try_push(item)
    }

    pub fn force_send(&mut self, item: RingItem) -> Result<(), RingItem> {
        self.ring_prod_impl.try_push(item)
    }
}

impl Sink<SinkItem> for RingSink {
    type Error = SinkError;

    fn poll_ready(
        self: std::pin::Pin<&mut Self>,
        cx: &mut std::task::Context<'_>,
    ) -> std::task::Poll<Result<(), Self::Error>> {
        let ret = ready!(self.get_mut().ring_prod_impl.poll_ready_unpin(cx));
        Poll::Ready(ret.map_err(|_| TunnelError::Shutdown))
    }

    fn start_send(self: std::pin::Pin<&mut Self>, item: SinkItem) -> Result<(), Self::Error> {
        self.get_mut()
            .ring_prod_impl
            .start_send_unpin(item)
            .map_err(|_| TunnelError::Shutdown)
    }

    fn poll_flush(
        self: std::pin::Pin<&mut Self>,
        cx: &mut std::task::Context<'_>,
    ) -> std::task::Poll<Result<(), Self::Error>> {
        let ret = ready!(self.get_mut().ring_prod_impl.poll_flush_unpin(cx));
        Poll::Ready(ret.map_err(|_| TunnelError::Shutdown))
    }

    fn poll_close(
        self: std::pin::Pin<&mut Self>,
        cx: &mut std::task::Context<'_>,
    ) -> std::task::Poll<Result<(), Self::Error>> {
        let ret = ready!(self.get_mut().ring_prod_impl.poll_close_unpin(cx));
        Poll::Ready(ret.map_err(|_| TunnelError::Shutdown))
    }
}

impl Debug for RingSink {
    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
        f.debug_struct("RingSink")
            .field("id", &self.id)
            .field("len", &self.ring_prod_impl.base().occupied_len())
            .field("cap", &self.ring_prod_impl.base().capacity())
            .finish()
    }
}

struct Connection {
    client: Arc<RingTunnel>,
    server: Arc<RingTunnel>,
}

type ConnectionMap = HashMap<uuid::Uuid, UnboundedSender<Arc<Connection>>>;

static CONNECTION_MAP: Lazy<Arc<std::sync::Mutex<ConnectionMap>>> =
    Lazy::new(|| Arc::new(std::sync::Mutex::new(HashMap::new())));

#[derive(Debug)]
pub struct RingTunnelListener {
    listener_addr: url::Url,
    conn_sender: UnboundedSender<Arc<Connection>>,
    conn_receiver: UnboundedReceiver<Arc<Connection>>,

    key_in_conn_map: Option<uuid::Uuid>,
}

impl RingTunnelListener {
    pub fn new(key: url::Url) -> Self {
        let (conn_sender, conn_receiver) = unbounded_channel();
        RingTunnelListener {
            listener_addr: key,
            conn_sender,
            conn_receiver,
            key_in_conn_map: None,
        }
    }
}

fn get_tunnel_for_client(conn: Arc<Connection>) -> impl Tunnel {
    TunnelWrapper::new(
        RingStream::new(conn.client.clone()),
        RingSink::new(conn.server.clone()),
        Some(TunnelInfo {
            tunnel_type: "ring".to_owned(),
            local_addr: Some(build_url_from_socket_addr(&conn.client.id.into(), "ring").into()),
            remote_addr: Some(build_url_from_socket_addr(&conn.server.id.into(), "ring").into()),
            resolved_remote_addr: Some(
                build_url_from_socket_addr(&conn.server.id.into(), "ring").into(),
            ),
        }),
    )
}

fn get_tunnel_for_server(conn: Arc<Connection>) -> impl Tunnel {
    TunnelWrapper::new(
        RingStream::new(conn.server.clone()),
        RingSink::new(conn.client.clone()),
        Some(TunnelInfo {
            tunnel_type: "ring".to_owned(),
            local_addr: Some(build_url_from_socket_addr(&conn.server.id.into(), "ring").into()),
            remote_addr: Some(build_url_from_socket_addr(&conn.client.id.into(), "ring").into()),
            resolved_remote_addr: Some(
                build_url_from_socket_addr(&conn.client.id.into(), "ring").into(),
            ),
        }),
    )
}

impl RingTunnelListener {
    async fn get_addr(&self) -> Result<Uuid, TunnelError> {
        Uuid::from_url(self.listener_addr.clone(), IpVersion::Both).await
    }
}

#[async_trait]
impl TunnelListener for RingTunnelListener {
    async fn listen(&mut self) -> Result<(), TunnelError> {
        tracing::info!("listen new conn of key: {}", self.listener_addr);
        let addr = self.get_addr().await?;
        CONNECTION_MAP
            .lock()
            .unwrap()
            .insert(addr, self.conn_sender.clone());
        self.key_in_conn_map = Some(addr);
        Ok(())
    }

    async fn accept(&mut self) -> Result<Box<dyn Tunnel>, TunnelError> {
        tracing::info!("waiting accept new conn of key: {}", self.listener_addr);
        let my_addr = self.get_addr().await?;
        if let Some(conn) = self.conn_receiver.recv().await {
            if conn.server.id == my_addr {
                tracing::info!("accept new conn of key: {}", self.listener_addr);
                return Ok(Box::new(get_tunnel_for_server(conn)));
            } else {
                tracing::error!(?conn.server.id, ?my_addr, "got new conn with wrong id");
                return Err(TunnelError::InternalError(
                    "accept got wrong ring server id".to_owned(),
                ));
            }
        }

        return Err(TunnelError::InternalError(
            "conn receiver stopped".to_owned(),
        ));
    }

    fn local_url(&self) -> url::Url {
        self.listener_addr.clone()
    }
}

impl Drop for RingTunnelListener {
    fn drop(&mut self) {
        if let Some(addr) = self.key_in_conn_map {
            CONNECTION_MAP.lock().unwrap().remove(&addr);
        }
    }
}

pub struct RingTunnelConnector {
    remote_addr: url::Url,
}

impl RingTunnelConnector {
    pub fn new(remote_addr: url::Url) -> Self {
        RingTunnelConnector { remote_addr }
    }
}

#[async_trait]
impl TunnelConnector for RingTunnelConnector {
    async fn connect(&mut self) -> Result<Box<dyn Tunnel>, super::TunnelError> {
        let remote_addr = Uuid::from_url(self.remote_addr.clone(), IpVersion::Both).await?;
        let entry = CONNECTION_MAP
            .lock()
            .unwrap()
            .get(&remote_addr)
            .unwrap()
            .clone();
        tracing::info!("connecting");
        let conn = Arc::new(Connection {
            client: Arc::new(RingTunnel::new(RING_TUNNEL_CAP)),
            server: Arc::new(RingTunnel::new_with_id(remote_addr, RING_TUNNEL_CAP)),
        });
        entry
            .send(conn.clone())
            .map_err(|_| TunnelError::InternalError("send conn to listner failed".to_owned()))?;
        Ok(Box::new(get_tunnel_for_client(conn)))
    }

    fn remote_url(&self) -> url::Url {
        self.remote_addr.clone()
    }
}

pub fn create_ring_tunnel_pair() -> (Box<dyn Tunnel>, Box<dyn Tunnel>) {
    let conn = Arc::new(Connection {
        client: Arc::new(RingTunnel::new(RING_TUNNEL_CAP)),
        server: Arc::new(RingTunnel::new(RING_TUNNEL_CAP)),
    });
    (
        Box::new(get_tunnel_for_server(conn.clone())),
        Box::new(get_tunnel_for_client(conn)),
    )
}

#[cfg(test)]
mod tests {
    use futures::StreamExt;
    use tokio::time::timeout;

    use crate::tunnel::common::tests::{_tunnel_bench, _tunnel_pingpong};

    use super::*;

    #[tokio::test]
    async fn ring_pingpong() {
        let id: url::Url = format!("ring://{}", Uuid::new_v4()).parse().unwrap();
        let listener = RingTunnelListener::new(id.clone());
        let connector = RingTunnelConnector::new(id.clone());
        _tunnel_pingpong(listener, connector).await
    }

    #[tokio::test]
    async fn ring_bench() {
        let id: url::Url = format!("ring://{}", Uuid::new_v4()).parse().unwrap();
        let listener = RingTunnelListener::new(id.clone());
        let connector = RingTunnelConnector::new(id);
        _tunnel_bench(listener, connector).await
    }

    #[tokio::test]
    async fn ring_close() {
        let (stunnel, ctunnel) = create_ring_tunnel_pair();
        drop(stunnel);

        let mut stream = ctunnel.split().0;
        let ret = stream.next().await;
        assert!(ret.as_ref().is_none(), "expect none, got {:?}", ret);
    }

    #[tokio::test]
    async fn abort_ring_stream() {
        let (_stunnel, ctunnel) = create_ring_tunnel_pair();
        let mut stream = ctunnel.split().0;
        let task = tokio::spawn(async move {
            let _ = stream.next().await;
        });
        tokio::time::sleep(tokio::time::Duration::from_secs(1)).await;
        task.abort();
        let _ = tokio::join!(task);
    }

    #[tokio::test]
    async fn ring_stream_recv_timeout() {
        let (_stunnel, ctunnel) = create_ring_tunnel_pair();
        let mut stream = ctunnel.split().0;
        let _ = timeout(tokio::time::Duration::from_millis(10), stream.next()).await;
    }
}