use std::collections::HashMap;
use std::sync::Arc;

use async_trait::async_trait;
use rand_core::OsRng;
use russh::keys::*;
use russh::server::{Msg, Server as _, Session};
use russh::*;
use russh_keys::Certificate;
use tokio::sync::Mutex;

#[tokio::main]
async fn main() {
    env_logger::builder()
        .filter_level(log::LevelFilter::Debug)
        .init();

    let config = russh::server::Config {
        inactivity_timeout: Some(std::time::Duration::from_secs(3600)),
        auth_rejection_time: std::time::Duration::from_secs(3),
        auth_rejection_time_initial: Some(std::time::Duration::from_secs(0)),
        keys: vec![
            russh_keys::PrivateKey::random(&mut OsRng, russh_keys::Algorithm::Ed25519).unwrap(),
        ],
        preferred: Preferred {
            // key: Cow::Borrowed(&[CERT_ECDSA_SHA2_P256]),
            ..Preferred::default()
        },
        ..Default::default()
    };
    let config = Arc::new(config);
    let mut sh = Server {
        clients: Arc::new(Mutex::new(HashMap::new())),
        id: 0,
    };
    sh.run_on_address(config, ("0.0.0.0", 2222)).await.unwrap();
}

#[derive(Clone)]
struct Server {
    clients: Arc<Mutex<HashMap<(usize, ChannelId), russh::server::Handle>>>,
    id: usize,
}

impl Server {
    async fn post(&mut self, data: CryptoVec) {
        let mut clients = self.clients.lock().await;
        for ((id, channel), ref mut s) in clients.iter_mut() {
            if *id != self.id {
                let _ = s.data(*channel, data.clone()).await;
            }
        }
    }
}

impl server::Server for Server {
    type Handler = Self;
    fn new_client(&mut self, _: Option<std::net::SocketAddr>) -> Self {
        let s = self.clone();
        self.id += 1;
        s
    }
    fn handle_session_error(&mut self, _error: <Self::Handler as russh::server::Handler>::Error) {
        eprintln!("Session error: {:#?}", _error);
    }
}

#[async_trait]
impl server::Handler for Server {
    type Error = russh::Error;

    async fn channel_open_session(
        &mut self,
        channel: Channel<Msg>,
        session: &mut Session,
    ) -> Result<bool, Self::Error> {
        {
            let mut clients = self.clients.lock().await;
            clients.insert((self.id, channel.id()), session.handle());
        }
        Ok(true)
    }

    async fn auth_publickey(
        &mut self,
        _: &str,
        _key: &ssh_key::PublicKey,
    ) -> Result<server::Auth, Self::Error> {
        Ok(server::Auth::Accept)
    }

    async fn auth_openssh_certificate(
        &mut self,
        _user: &str,
        certificate: &Certificate,
    ) -> Result<server::Auth, Self::Error> {
        dbg!(certificate);
        Ok(server::Auth::Accept)
    }

    async fn data(
        &mut self,
        channel: ChannelId,
        data: &[u8],
        session: &mut Session,
    ) -> Result<(), Self::Error> {
        // Sending Ctrl+C ends the session and disconnects the client
        if data == [3] {
            return Err(russh::Error::Disconnect);
        }

        let data = CryptoVec::from(format!("Got data: {}\r\n", String::from_utf8_lossy(data)));
        self.post(data.clone()).await;
        session.data(channel, data)?;
        Ok(())
    }

    async fn tcpip_forward(
        &mut self,
        address: &str,
        port: &mut u32,
        session: &mut Session,
    ) -> Result<bool, Self::Error> {
        let handle = session.handle();
        let address = address.to_string();
        let port = *port;
        tokio::spawn(async move {
            let channel = handle
                .channel_open_forwarded_tcpip(address, port, "1.2.3.4", 1234)
                .await
                .unwrap();
            let _ = channel.data(&b"Hello from a forwarded port"[..]).await;
            let _ = channel.eof().await;
        });
        Ok(true)
    }
}