//! Run with
//!
//! ```not_rust
//! cargo run -p example-websockets-http2
//! ```

use axum::{
    extract::{
        ws::{self, WebSocketUpgrade},
        State,
    },
    http::Version,
    routing::any,
    Router,
};
use axum_server::tls_rustls::RustlsConfig;
use std::{net::SocketAddr, path::PathBuf};
use tokio::sync::broadcast;
use tower_http::services::ServeDir;
use tracing_subscriber::{layer::SubscriberExt, util::SubscriberInitExt};

#[tokio::main]
async fn main() {
    tracing_subscriber::registry()
        .with(
            tracing_subscriber::EnvFilter::try_from_default_env()
                .unwrap_or_else(|_| format!("{}=debug", env!("CARGO_CRATE_NAME")).into()),
        )
        .with(tracing_subscriber::fmt::layer())
        .init();

    let assets_dir = PathBuf::from(env!("CARGO_MANIFEST_DIR")).join("assets");

    // configure certificate and private key used by https
    let config = RustlsConfig::from_pem_file(
        PathBuf::from(env!("CARGO_MANIFEST_DIR"))
            .join("self_signed_certs")
            .join("cert.pem"),
        PathBuf::from(env!("CARGO_MANIFEST_DIR"))
            .join("self_signed_certs")
            .join("key.pem"),
    )
    .await
    .unwrap();

    // build our application with some routes and a broadcast channel
    let app = Router::new()
        .fallback_service(ServeDir::new(assets_dir).append_index_html_on_directories(true))
        .route("/ws", any(ws_handler))
        .with_state(broadcast::channel::<String>(16).0);

    let addr = SocketAddr::from(([127, 0, 0, 1], 3000));
    tracing::debug!("listening on {}", addr);

    let mut server = axum_server::bind_rustls(addr, config);

    // IMPORTANT: This is required to advertise our support for HTTP/2 websockets to the client.
    // If you use axum::serve, it is enabled by default.
    server.http_builder().http2().enable_connect_protocol();

    server.serve(app.into_make_service()).await.unwrap();
}

async fn ws_handler(
    ws: WebSocketUpgrade,
    version: Version,
    State(sender): State<broadcast::Sender<String>>,
) -> axum::response::Response {
    tracing::debug!("accepted a WebSocket using {version:?}");
    let mut receiver = sender.subscribe();
    ws.on_upgrade(|mut ws| async move {
        loop {
            tokio::select! {
                // Since `ws` is a `Stream`, it is by nature cancel-safe.
                res = ws.recv() => {
                    match res {
                        Some(Ok(ws::Message::Text(s))) => {
                            let _ = sender.send(s);
                        }
                        Some(Ok(_)) => {}
                        Some(Err(e)) => tracing::debug!("client disconnected abruptly: {e}"),
                        None => break,
                    }
                }
                // Tokio guarantees that `broadcast::Receiver::recv` is cancel-safe.
                res = receiver.recv() => {
                    match res {
                        Ok(msg) => if let Err(e) = ws.send(ws::Message::Text(msg)).await {
                            tracing::debug!("client disconnected abruptly: {e}");
                        }
                        Err(_) => continue,
                    }
                }
            }
        }
    })
}