use std::net::SocketAddr;
use std::sync::Arc;

use gateway::observability;
use gateway::routing;
use gateway::storage;
use gateway::AppState;

#[tokio::main]
async fn main() -> anyhow::Result<()> {
    observability::init_tracing();
    let metrics = observability::init_metrics();
    let authn = gateway::authn::AuthnConfig::from_env();

    let build_version = option_env!("GATEWAY_BUILD_VERSION").unwrap_or("dev");
    let build_sha = option_env!("GATEWAY_BUILD_SHA").unwrap_or("unknown");
    tracing::info!(build_version, build_sha, "gateway starting");

    let addr: SocketAddr = std::env::var("GATEWAY_ADDR")
        .unwrap_or_else(|_| "0.0.0.0:8080".to_string())
        .parse()?;

    let storage_path =
        std::env::var("GATEWAY_STORAGE_PATH").unwrap_or_else(|_| "./data/gateway.mdbx".to_string());
    if let Some(parent) = std::path::Path::new(&storage_path).parent() {
        let _ = std::fs::create_dir_all(parent);
    }
    let storage = storage::GatewayStorage::open_edge_storage(storage_path, "gateway")
        .unwrap_or_else(|_| storage::GatewayStorage::new_in_memory());

    let routing_source: Arc<dyn routing::RoutingSource> =
        if let Ok(path) = std::env::var("GATEWAY_ROUTING_FILE") {
            Arc::new(routing::StaticFileSource::new(path))
        } else if let (Ok(nats_url), Ok(bucket), Ok(key)) = (
            std::env::var("GATEWAY_ROUTING_NATS_URL"),
            std::env::var("GATEWAY_ROUTING_NATS_BUCKET"),
            std::env::var("GATEWAY_ROUTING_NATS_KEY"),
        ) {
            Arc::new(routing::NatsKvSource::connect(nats_url, bucket, key).await?)
        } else {
            Arc::new(routing::FixedSource::new(routing::RoutingConfig::empty()))
        };

    let routing = routing::RouterState::new(routing_source).await?;
    let _routing_watcher = routing.start_watcher();

    let grpc_addr: SocketAddr = std::env::var("GATEWAY_GRPC_ADDR")
        .unwrap_or_else(|_| "0.0.0.0:8081".to_string())
        .parse()?;

    let state = AppState {
        metrics,
        routing,
        storage,
        authn,
    };

    let app = gateway::app(state.clone());

    let listener = tokio::net::TcpListener::bind(addr).await?;
    tracing::info!(%addr, "gateway listening");

    tracing::info!(%grpc_addr, "gateway grpc listening");

    let (shutdown_tx, _shutdown_rx) = tokio::sync::broadcast::channel::<()>(2);
    let shutdown_task = {
        let shutdown_tx = shutdown_tx.clone();
        tokio::spawn(async move {
            shutdown_signal().await;
            let _ = shutdown_tx.send(());
        })
    };

    let http_task = {
        let mut shutdown_rx = shutdown_tx.subscribe();
        tokio::spawn(async move {
            axum::serve(listener, app)
                .with_graceful_shutdown(async move {
                    let _ = shutdown_rx.recv().await;
                })
                .await
                .unwrap();
        })
    };

    let grpc_task = {
        let mut shutdown_rx = shutdown_tx.subscribe();
        let svc = gateway::grpc::GatewayCommandService::new(state.routing.clone());
        tokio::spawn(async move {
            tonic::transport::Server::builder()
                .add_service(
                    gateway::grpc::proto::command_service_server::CommandServiceServer::new(svc),
                )
                .serve_with_shutdown(grpc_addr, async move {
                    let _ = shutdown_rx.recv().await;
                })
                .await
                .unwrap();
        })
    };

    tokio::select! {
        _ = http_task => {},
        _ = grpc_task => {},
    }
    let _ = shutdown_task.await;

    Ok(())
}

async fn shutdown_signal() {
    let ctrl_c = async {
        let _ = tokio::signal::ctrl_c().await;
    };

    #[cfg(unix)]
    let terminate = async {
        let mut sigterm = tokio::signal::unix::signal(tokio::signal::unix::SignalKind::terminate())
            .expect("failed to register SIGTERM handler");
        sigterm.recv().await;
    };

    #[cfg(not(unix))]
    let terminate = std::future::pending::<()>();

    tokio::select! {
        _ = ctrl_c => {},
        _ = terminate => {},
    }
}