use std::path::Path;
use std::sync::Arc;
use std::time::Duration;

use anyhow::Result;
use async_trait::async_trait;
use russh::keys::*;
use russh::*;
use tokio::net::ToSocketAddrs;
use std::io::stdout;
use std::io::Write;

pub struct Client {}

// More SSH event handlers
// can be defined in this trait
// In this example, we're only using Channel, so these aren't needed.
#[async_trait]
impl client::Handler for Client {
    type Error = russh::Error;

    async fn check_server_key(
        &mut self,
        _server_public_key: &key::PublicKey,
    ) -> Result<bool, Self::Error> {
        Ok(true)
    }
}

pub struct Session {
    session: client::Handle<Client>,
}

impl Session {
    pub async fn connect<P: AsRef<Path>, A: ToSocketAddrs>(
        key_path: P,
        user: impl Into<String>,
        addrs: A,
    ) -> Result<Self> {
        let key_pair = load_secret_key(key_path, None)?;
        let config = client::Config {
            inactivity_timeout: Some(Duration::from_secs(5)),
            ..<_>::default()
        };

        let config = Arc::new(config);
        let sh = Client {};

        let mut session = client::connect(config, addrs, sh).await?;
        let auth_res = session
            .authenticate_publickey(user, Arc::new(key_pair))
            .await?;

        if !auth_res {
            anyhow::bail!("Authentication failed");
        }

        Ok(Self { session })
    }

    pub async fn call(&mut self, command: &str) -> Result<u32> {
        let mut channel = self.session.channel_open_session().await?;
        channel.exec(true, command).await?;

        let mut code = None;
        let mut stdout = stdout();

        loop {
            // There's an event available on the session channel
            let Some(msg) = channel.wait().await else {
                break;
            };
            match msg {
                // Write data to the terminal
                ChannelMsg::Data { ref data } => {
                    stdout.write_all(data)?;
                    stdout.flush()?;
                }
                // The command has returned an exit code
                ChannelMsg::ExitStatus { exit_status } => {
                    code = Some(exit_status);
                    // cannot leave the loop immediately, there might still be more data to receive
                }
                _ => {}
            }
        }
        Ok(code.expect("program did not exit cleanly"))
    }

    pub async fn close(&mut self) -> Result<()> {
        self.session
            .disconnect(Disconnect::ByApplication, "", "English")
            .await?;
        Ok(())
    }
}


