#![feature(never_type)]

pub mod config;

use anyhow::bail;
use azalea_protocol::{
    packets::{
        handshaking::{client_intention_packet::ClientIntentionPacket, ServerboundHandshakePacket},
        login::ServerboundLoginPacket,
        ConnectionProtocol,
    },
    read::read_packet,
    write::write_packet,
};
// use azalea_protocol::{
//     packets::{
//         handshake::{client_intention_packet::ClientIntentionPacket, ServerboundHandshakePacket},
//         login::ServerboundLoginPacket,
//         ConnectionProtocol,
//     },
//     read::read_packet,
//     write::write_packet,
// };
use bytes::BytesMut;
use config::Config;
use log::{error, info, warn};
use std::{
    fs::read_to_string,
    sync::{Arc, RwLock},
};
use tokio::{
    io::{AsyncReadExt, AsyncWriteExt},
    net::{
        tcp::{OwnedReadHalf, OwnedWriteHalf},
        TcpListener, TcpStream,
    },
};

fn main() {
    env_logger::builder()
        .filter_level(log::LevelFilter::Info)
        .parse_env("LOG")
        .init();
    tokio::runtime::Builder::new_multi_thread()
        .enable_all()
        .build()
        .unwrap()
        .block_on(async move {
            match run().await {
                Ok(_) => {}
                Err(err) => error!("fatal error: {err}"),
            }
        });
}

async fn run() -> anyhow::Result<!> {
    let config = Arc::new(RwLock::new(Arc::new(serde_yaml::from_str::<Config>(
        &read_to_string(std::env::args().nth(1).unwrap_or("proxy.yaml".to_string()))?,
    )?)));
    config::watch(config.clone());

    let listener = TcpListener::bind(config.read().unwrap().bind).await?;
    info!("listening");
    loop {
        match listener.accept().await {
            Ok((sock, addr)) => {
                info!("connected: {addr}");
                let config = config.read().unwrap().clone();
                tokio::spawn(async move {
                    match handle_client(config, sock).await {
                        Ok(()) => info!("disconnected: {addr}"),
                        Err(err) => warn!("error: ({addr}) {err}"),
                    }
                });
            }
            Err(e) => error!("{}", e),
        }
    }
}

async fn handle_client(config: Arc<Config>, sock: TcpStream) -> Result<(), anyhow::Error> {
    let mut buf = BytesMut::new();
    sock.set_nodelay(true)?;
    let (mut downstream_reader, downstream_writer) = sock.into_split();

    let handshake = read_packet::<ServerboundHandshakePacket, _>(
        &mut downstream_reader,
        &mut buf,
        None,
        &mut None,
    )
    .await?;

    let upstream_handshake = match handshake {
        ServerboundHandshakePacket::ClientIntention(p) => {
            info!(
                "new client (version={}, intent={:?})",
                p.protocol_version, p.intention
            );
            if p.protocol_version != config.protocol {
                bail!("protocol version unsupported")
            }
            match p.intention {
                ConnectionProtocol::Status => {
                    handle_status_intent(config, downstream_writer, downstream_reader).await?;
                    return Ok(());
                }
                ConnectionProtocol::Login => {}
                _ => bail!("unsupported intent"),
            }
            p
        }
    };

    let login =
        read_packet::<ServerboundLoginPacket, _>(&mut downstream_reader, &mut buf, None, &mut None)
            .await?;
    let upstream_login = match login {
        ServerboundLoginPacket::Hello(mut p) => {
            info!("client hello (username={:?})", p.name);

            let profile = config
                .whitelist
                .iter()
                .find(|e| e.token.as_ref().map_or(false, |e| e == &p.name));

            match profile {
                Some(profile) => {
                    info!("login as {:?}", profile.username);
                    p.name = profile.username.clone();
                }
                None => bail!("no profile found, disconnecting client"),
            }
            p
        }
        ServerboundLoginPacket::LoginAcknowledged(_) => bail!("wtf?"),
        ServerboundLoginPacket::Key(_) => bail!("key not supported"),
        ServerboundLoginPacket::CustomQueryAnswer(_) => bail!("custom query not supported"),
    };

    let upstream = TcpStream::connect(config.backend).await?;
    let (upstream_reader, mut upstream_writer) = upstream.into_split();

    write_packet(
        &ServerboundHandshakePacket::ClientIntention(upstream_handshake),
        &mut upstream_writer,
        None,
        &mut None,
    )
    .await?;

    write_packet::<ServerboundLoginPacket, _>(
        &ServerboundLoginPacket::Hello(upstream_login),
        &mut upstream_writer,
        None,
        &mut None,
    )
    .await?;

    let task_res = tokio::spawn(async move { connect(downstream_writer, upstream_reader).await });
    let res = connect(upstream_writer, downstream_reader).await;
    task_res.abort();
    res?;
    if let Ok(r) = task_res.await {
        r?;
    }

    Ok(())
}

async fn connect(mut writer: OwnedWriteHalf, mut reader: OwnedReadHalf) -> anyhow::Result<()> {
    let mut buf = [0; 1024];
    loop {
        let size = reader.read(&mut buf).await?;
        if size == 0 {
            break Ok(());
        }
        writer.write_all(&buf[..size]).await?;
    }
}

async fn handle_status_intent(
    config: Arc<Config>,
    writer: OwnedWriteHalf,
    reader: OwnedReadHalf,
) -> anyhow::Result<()> {
    // let mut buf = BytesMut::new();
    let upstream = TcpStream::connect(config.backend).await?;
    upstream.set_nodelay(true)?;
    let (upstream_reader, mut upstream_writer) = upstream.into_split();

    write_packet(
        &ServerboundHandshakePacket::ClientIntention(ClientIntentionPacket {
            protocol_version: config.protocol,
            hostname: config.backend.ip().to_string(),
            port: config.backend.port(),
            intention: ConnectionProtocol::Status,
        }),
        &mut upstream_writer,
        None,
        &mut None,
    )
    .await?;

    let task_res = tokio::spawn(async move { connect(writer, upstream_reader).await });
    let res = connect(upstream_writer, reader).await;
    task_res.abort();
    res?;
    if let Ok(r) = task_res.await {
        r?;
    }

    return Ok(());
}

// loop {
//     let req = read_packet::<ServerboundStatusPacket, _>(&mut reader, &mut buf, None, &mut None)
//         .await?;
//     info!("{req:?}");
//     match req {
//         ServerboundStatusPacket::StatusRequest(..) => {
//             write_packet(
//                 &ClientboundStatusPacket::StatusResponse(ClientboundStatusResponsePacket {
//                     description: azalea_chat::component::Component::Text(
//                         legacy_color_code_to_text_component("blub"),
//                     ),
//                     favicon: None,
//                     players: Players {
//                         max: 10,
//                         online: 0,
//                         sample: vec![],
//                     },
//                     version: Version {
//                         name: azalea_chat::component::Component::Text(
//                             legacy_color_code_to_text_component("blub"),
//                         ),
//                         protocol: 760,
//                     },
//                 }),
//                 &mut writer,
//                 None,
//                 &mut None,
//             )
//             .await?;
//         }
//         ServerboundStatusPacket::PingRequest(p) => {
//             write_packet(
//                 &ClientboundStatusPacket::PongResponse(ClientboundPongResponsePacket {
//                     time: p.time,
//                 }),
//                 &mut writer,
//                 None,
//                 &mut None,
//             )
//             .await?;
//         }
//     }
// }
// Ok(())

// for _ in 0..3 {
//     let a = read_packet::<ClientboundLoginPacket, _>(
//         &mut upstream_reader,
//         &mut buf,
//         None,
//         &mut None,
//     )
//     .await?;
//     debug!("login {a:?}");
//     write_packet(&a, &mut downstream_writer, None, &mut None).await?;
// }

// tokio::spawn(async move {
//     let mut buf = BytesMut::new();
//     loop {
//         let a = read_packet::<ClientboundGamePacket, _>(
//             &mut upstream_reader,
//             &mut buf,
//             None,
//             &mut None,
//         )
//         .await
//         .unwrap();
//         debug!("downstream {a:?}");
//         write_packet(&a, &mut downstream_writer, None, &mut None)
//             .await
//             .unwrap();
//     }
// });

// loop {
//     let a = read_packet::<ClientboundGamePacket, _>(
//         &mut downstream_reader,
//         &mut buf,
//         None,
//         &mut None,
//     )
//     .await?;
//     debug!("upstream {a:?}");
//     write_packet(&a, &mut upstream_writer, None, &mut None).await?;
// }