use openworm::net::{
    ClientMsgInst, RecvHandler, RequestId, SERVER_NAME, SendResult, ServerMsg, ServerMsgInst,
    recv_uni, send_uni,
};
use quinn::{
    Connection, Endpoint, ServerConfig,
    rustls::pki_types::{CertificateDer, PrivateKeyDer, PrivatePkcs8KeyDer},
};
use std::{fs, path::Path};
use std::{
    net::{Ipv6Addr, SocketAddr, SocketAddrV6},
    sync::Arc,
};
use tokio::task::JoinHandle;
use tracing::Instrument;

pub const SERVER_HOST: Ipv6Addr = Ipv6Addr::UNSPECIFIED;

pub fn init_endpoint(port: u16, data_path: &Path) -> Endpoint {
    let cert_path = data_path.join("cert.der");
    let key_path = data_path.join("key.der");
    let (cert, key) = match fs::read(&cert_path).and_then(|x| Ok((x, fs::read(&key_path)?))) {
        Ok((cert, key)) => (
            CertificateDer::from(cert),
            PrivateKeyDer::try_from(key).unwrap(),
        ),
        Err(ref e) if e.kind() == std::io::ErrorKind::NotFound => {
            let cert = rcgen::generate_simple_self_signed([SERVER_NAME.into()]).unwrap();
            let key = PrivatePkcs8KeyDer::from(cert.signing_key.serialize_der());
            let cert = cert.cert.into();
            fs::create_dir_all(data_path).expect("failed to create certificate directory");
            fs::write(&cert_path, &cert).expect("failed to write certificate");
            fs::write(&key_path, key.secret_pkcs8_der()).expect("failed to write private key");
            (cert, key.into())
        }
        Err(e) => {
            panic!("failed to read certificate: {}", e);
        }
    };
    print!("cert hex: ");
    for x in cert.iter() {
        print!("{:02x}", x);
    }
    println!();
    let server_config = ServerConfig::with_single_cert(vec![cert], key).unwrap();
    let server_socket: SocketAddr = SocketAddr::V6(SocketAddrV6::new(SERVER_HOST, port, 0, 0));
    quinn::Endpoint::server(server_config, server_socket).unwrap()
}

#[derive(Clone)]
pub struct ClientSender {
    conn: Connection,
}

impl ClientSender {
    pub fn remote(&self) -> SocketAddr {
        self.conn.remote_address()
    }

    pub fn replier(&self, id: RequestId) -> ClientReplier {
        ClientReplier {
            conn: self.conn.clone(),
            req_id: id,
        }
    }

    pub async fn send(&self, msg: impl Into<ServerMsg>) -> SendResult {
        let msg = ServerMsgInst {
            id: None,
            msg: msg.into(),
        };
        send_uni(&self.conn, msg).await
    }
}

pub struct ClientReplier {
    conn: Connection,
    req_id: RequestId,
}

impl ClientReplier {
    pub async fn send(&self, msg: impl Into<ServerMsg>) {
        let msg = ServerMsgInst {
            id: Some(self.req_id),
            msg: msg.into(),
        };
        let _ = send_uni(&self.conn, msg).await;
    }
}

pub trait ConAccepter: Send + Sync + 'static {
    fn accept(
        &self,
        send: ClientSender,
    ) -> impl Future<Output = impl RecvHandler<ClientMsgInst>> + Send;
}

pub fn listen(
    port: u16,
    data_path: &Path,
    accepter: impl ConAccepter,
) -> (Endpoint, JoinHandle<()>) {
    let accepter = Arc::new(accepter);
    let endpoint = init_endpoint(port, data_path);
    let res = endpoint.clone();

    let handle = tokio::spawn(async move {
        println!("listening on {}", endpoint.local_addr().unwrap());
        let mut tasks = Vec::new();
        while let Some(conn) = endpoint.accept().await {
            let fut = handle_connection(conn, accepter.clone());
            tasks.push(tokio::spawn(async move {
                if let Err(e) = fut.await {
                    eprintln!("connection failed: {reason}", reason = e)
                }
            }));
        }
        for task in tasks {
            let _ = task.await;
        }
    });
    (res, handle)
}

async fn handle_connection(
    conn: quinn::Incoming,
    accepter: Arc<impl ConAccepter>,
) -> std::io::Result<()> {
    let conn = conn.await?;
    let handler = Arc::new(accepter.accept(ClientSender { conn: conn.clone() }).await);
    handler.connect().await;
    let span = tracing::info_span!(
        "connection",
        remote = %conn.remote_address(),
        protocol = %conn
            .handshake_data()
            .unwrap()
            .downcast::<quinn::crypto::rustls::HandshakeData>().unwrap()
            .protocol
            .map_or_else(|| "<none>".into(), |x| String::from_utf8_lossy(&x).into_owned())
    );
    async {
        let res = recv_uni(conn, handler.clone()).await;
        handler.disconnect(res).await;
    }
    .instrument(span)
    .await;
    Ok(())
}