//! lesavka-server - **auto-cycle disabled**
// server/src/main.rs
#![forbid(unsafe_code)]

use std::{panic, backtrace::Backtrace, pin::Pin, sync::Arc, time::Duration};
use std::sync::atomic::AtomicBool;
use anyhow::Context as _;
use futures_util::{Stream, StreamExt};
use tokio::{
    fs::{OpenOptions},
    io::AsyncWriteExt,
    sync::Mutex,
};
use tokio_stream::wrappers::ReceiverStream;
use tonic::{Request, Response, Status};
use tonic::transport::Server;
use tonic_reflection::server::{Builder as ReflBuilder};
use tracing::{info, warn, error, trace};
use tracing_subscriber::{filter::EnvFilter, fmt, prelude::*};
use tracing_appender::non_blocking::WorkerGuard;

use lesavka_common::lesavka::{
    ResetUsbRequest, ResetUsbReply,
    relay_server::{Relay, RelayServer},
    KeyboardReport, MouseReport, MonitorRequest, VideoPacket,
};

use lesavka_server::{usb_gadget::UsbGadget, video};

/*──────────────── constants ────────────────*/
/// **false** = never reset automatically.  
const AUTO_CYCLE: bool = false;

/*──────────────── logging ───────────────────*/
fn init_tracing() -> anyhow::Result<WorkerGuard> {
    let file = std::fs::OpenOptions::new()
        .create(true).truncate(true).write(true)
        .open("/tmp/lesavka-server.log")?;
    let (file_writer, guard) = tracing_appender::non_blocking(file);

    let env_filter = EnvFilter::try_from_default_env().unwrap_or_else(|_| {
        EnvFilter::new("lesavka_server=info,lesavka_server::video=warn")
    });
    let filter_str = env_filter.to_string();

    tracing_subscriber::registry()
        .with(env_filter)
        .with(
            fmt::layer()
                .with_target(true)
                .with_thread_ids(true),
        )
        .with(
            fmt::layer()
                .with_writer(file_writer)
                .with_ansi(false)
                .with_target(true)
                .with_level(true),
        )
        .init();
    tracing::info!("📜 effective RUST_LOG = \"{}\"", filter_str);
    Ok(guard)
}

/*──────────────── helpers ───────────────────*/
async fn open_with_retry(path: &str) -> anyhow::Result<tokio::fs::File> {
    for attempt in 1..=200 {                       // ≈10 s
        match OpenOptions::new()
            .write(true).custom_flags(libc::O_NONBLOCK).open(path).await
        {
            Ok(f) => {
                info!("✅ {path} opened on attempt #{attempt}");
                return Ok(f);
            }
            Err(e) if e.raw_os_error() == Some(libc::EBUSY) => {
                trace!("⏳ {path} busy… retry #{attempt}");
                tokio::time::sleep(Duration::from_millis(50)).await;
            }
            Err(e) => return Err(e).with_context(|| format!("opening {path}")),
        }
    }
    Err(anyhow::anyhow!("timeout waiting for {path}"))
}

/*──────────────── Handler ───────────────────*/
struct Handler {
    kb: Arc<Mutex<tokio::fs::File>>,
    ms: Arc<Mutex<tokio::fs::File>>,
    gadget: UsbGadget,
    did_cycle: AtomicBool,
}

impl Handler {
    async fn new(gadget: UsbGadget) -> anyhow::Result<Self> {
        if AUTO_CYCLE {
            info!("🛠️  Initial USB reset…");
            let _ = gadget.cycle();        // ignore failure - may boot without host
        } else {
            info!("🛠️  AUTO_CYCLE disabled - no initial reset");
        }

        info!("🛠️  opening HID endpoints …");
        let kb = open_with_retry("/dev/hidg0").await?;
        let ms = open_with_retry("/dev/hidg1").await?;
        info!("✅ HID endpoints ready");

        Ok(Self {
            kb: Arc::new(Mutex::new(kb)),
            ms: Arc::new(Mutex::new(ms)),
            gadget,
            did_cycle: AtomicBool::new(false),
        })
    }
}

/*──────────────── gRPC service ─────────────*/
#[tonic::async_trait]
impl Relay for Handler {
    /* existing streams ─ unchanged, except: no more auto-reset */
    type StreamKeyboardStream = ReceiverStream<Result<KeyboardReport, Status>>;
    type StreamMouseStream    = ReceiverStream<Result<MouseReport, Status>>;
    type CaptureVideoStream   = Pin<Box<dyn Stream<Item=Result<VideoPacket,Status>> + Send + Sync>>;

    async fn stream_keyboard(
        &self,
        req: Request<tonic::Streaming<KeyboardReport>>,
    ) -> Result<Response<Self::StreamKeyboardStream>, Status> {
        let (tx, rx) = tokio::sync::mpsc::channel(32);
        let kb = self.kb.clone();

        tokio::spawn(async move {
            let mut s = req.into_inner();
            while let Some(pkt) = s.next().await.transpose()? {
                if let Err(e) = kb.lock().await.write_all(&pkt.data).await {
                    warn!("⌨️  write failed: {e} (dropped)");
                }
                tx.send(Ok(pkt)).await.ok();
            }
            Ok::<(), Status>(())
        });

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

    async fn stream_mouse(
        &self,
        req: Request<tonic::Streaming<MouseReport>>,
    ) -> Result<Response<Self::StreamMouseStream>, Status> {
        let (tx, rx) = tokio::sync::mpsc::channel(1024);
        let ms = self.ms.clone();

        tokio::spawn(async move {
            let mut s = req.into_inner();
            while let Some(pkt) = s.next().await.transpose()? {
                if let Err(e) = ms.lock().await.write_all(&pkt.data).await {
                    warn!("🖱️  write failed: {e} (dropped)");
                }
                tx.send(Ok(pkt)).await.ok();
            }
            Ok::<(), Status>(())
        });

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

    async fn capture_video(
        &self,
        req: Request<MonitorRequest>,
    ) -> Result<Response<Self::CaptureVideoStream>, Status> {
        let id = req.into_inner().id;
        let dev = match id {
            0 => "/dev/lesavka_l_eye",
            1 => "/dev/lesavka_r_eye",
            _ => return Err(Status::invalid_argument("monitor id must be 0 or 1")),
        };
        info!("🎥 streaming {dev}");
        let s = video::eye_ball(dev, id, 6_000)
            .await
            .map_err(|e| Status::internal(format!("{e:#}")))?;
        Ok(Response::new(Box::pin(s)))
    }

    /*────────────── USB-reset RPC ───────────*/
    async fn reset_usb(
        &self,
        _req: Request<ResetUsbRequest>,
    ) -> Result<Response<ResetUsbReply>, Status> {
        info!("🔴 explicit ResetUsb() called");
        match self.gadget.cycle() {
            Ok(_)  => Ok(Response::new(ResetUsbReply { ok: true })),
            Err(e) => {
                error!("💥 cycle failed: {e:#}");
                Err(Status::internal(e.to_string()))
            }
        }
    }
}

/*──────────────── main ───────────────────────*/
#[tokio::main(worker_threads = 4)]
async fn main() -> anyhow::Result<()> {
    let _guard = init_tracing()?;

    panic::set_hook(Box::new(|p| {
        let bt = Backtrace::force_capture();
        error!("💥 panic: {p}\n{bt}");
    }));

    let gadget  = UsbGadget::new("lesavka");
    let handler = Handler::new(gadget.clone()).await?;

    info!("🌐 lesavka-server listening on 0.0.0.0:50051");
    Server::builder()
        .tcp_nodelay(true)
        .max_frame_size(Some(2*1024*1024))
        .add_service(RelayServer::new(handler))
        .add_service(ReflBuilder::configure().build_v1().unwrap())
        .serve(([0,0,0,0], 50051).into())
        .await?;
    Ok(())
}