//! navka-server — receive HidReport and write to /dev/hidg0
// main.rs
#![forbid(unsafe_code)]

use std::{pin::Pin, sync::Arc};
use tokio::{fs::{File, OpenOptions}, io::AsyncWriteExt, sync::Mutex};
use tokio_stream::{wrappers::ReceiverStream, Stream, StreamExt};
use tonic::{transport::Server, Request, Response, Status};
use tracing::{error, info, trace};
use tracing_subscriber::{fmt, EnvFilter};

use navka_common::navka::{
    relay_server::{Relay, RelayServer},
    hid_report,
    HidReport,
};

struct Handler {
    kb: Arc<Mutex<File>>,
    ms: Arc<Mutex<File>>,
}

#[tonic::async_trait]
impl Relay for Handler {
    type StreamStream =
        Pin<Box<dyn Stream<Item = Result<HidReport, Status>> + Send + 'static>>;

    async fn stream(
        &self,
        request: Request<tonic::Streaming<HidReport>>,
    ) -> Result<Response<Self::StreamStream>, Status> {
        info!("▶️  new client stream from {:?}", request.remote_addr());
        let mut in_stream = request.into_inner();
        let kb = self.kb.clone();
        let ms = self.ms.clone();
        let (tx, rx) = tokio::sync::mpsc::channel(32);

        tokio::spawn(async move {
            while let Some(msg) = in_stream.next().await.transpose()? {
                match msg.kind {
                    /* ───── KEYBOARD ───── */
                    Some(hid_report::Kind::KeyboardReport(ref v)) if v.len() == 8 => {
                        match kb.lock().await.write_all(v).await {
                            Ok(_) => info!("⌨️  → /dev/hidg0  (8 B)"),
                            Err(e) if e.kind() == std::io::ErrorKind::WouldBlock => {
                                trace!("⌨️  /dev/hidg0 busy, dropped packet");
                                continue;
                            }
                            Err(e) => {
                                error!("⌨️  write error: {e}");
                                continue;
                            }
                        }
                    }

                    /* ─────  MOUSE  ───── */
                    Some(hid_report::Kind::MouseReport(ref v)) if v.len() == 4 => {
                        match ms.lock().await.write_all(v).await {
                            Ok(_) => info!("🖱️  → /dev/hidg1  (4 B)"),
                            Err(e) if e.kind() == std::io::ErrorKind::WouldBlock => {
                                trace!("🖱️  /dev/hidg1 busy, dropped packet");
                                continue;
                            }
                            Err(e) => {
                                error!("🖱️  write error: {e}");
                                continue;
                            }
                        }
                    }

                    /* ───── bad / unknown ───── */
                    _ => {
                        error!(?msg.kind, "⚠️  malformed packet");
                        continue;
                    }
                }

                // echo back so the client knows we’re alive
                let _ = tx.send(Ok(msg)).await;
            }
            info!("🔚 client stream closed");
            Ok::<_, Status>(())
        });

        Ok(Response::new(Box::pin(ReceiverStream::new(rx))))
    }
}

#[tokio::main]
async fn main() -> anyhow::Result<()> {
    fmt().with_env_filter(
        // honour RUST_LOG but fall back to very chatty defaults
        EnvFilter::try_from_default_env().unwrap_or_else(|_| {
            EnvFilter::new(
                "navka_client=trace,\
                 navka_server=trace,\
                 tonic=debug,\
                 h2=debug,\
                 tower=debug",
            )
        }),
    )
    .with_target(true)
    .with_thread_ids(true)
    .with_file(true)
    .init();

    let kb = OpenOptions::new()
        .write(true)
        .read(true)
        .custom_flags(libc::O_NONBLOCK)
        .open("/dev/hidg0")
        .await?;

    let ms = OpenOptions::new()
        .write(true)
        .read(true)
        .custom_flags(libc::O_NONBLOCK)
        .open("/dev/hidg1")
        .await?;

    let handler = Handler {
        kb: Arc::new(Mutex::new(kb)),
        ms: Arc::new(Mutex::new(ms)),
    };

    println!("🌐 navka-server listening on 0.0.0.0:50051");
    Server::builder()
        .add_service(RelayServer::new(handler))
        .serve(([0, 0, 0, 0], 50051).into())
        .await?;
    Ok(())
}