add basic backend

backend/src/main.rs

@@ -1,3 +1,79 @@
-fn main() {
-    println!("Hello, world!");
+use std::sync::mpsc;
+
+use clap::Parser;
+use nuchat::app;
+use tokio::net::TcpListener;
+use tokio::signal;
+use tracing::info;
+use tracing_subscriber::{layer::SubscriberExt, util::SubscriberInitExt};
+
+#[derive(Parser, Debug)]
+#[command(version, about, long_about = None)]
+struct Args {
+    /// Port to run server on
+    #[arg(long, default_value_t = 7000)]
+    port: u32,
+
+    /// Host to run server on
+    #[arg(long, default_value = "127.0.0.1")]
+    host: String,
+}
+
+#[tokio::main]
+async fn main() {
+    let args = Args::parse();
+    tracing_subscriber::registry()
+        .with(
+            tracing_subscriber::EnvFilter::try_from_default_env().unwrap_or_else(|_| {
+                format!("{}=debug,tower_http=debug", env!("CARGO_CRATE_NAME")).into()
+            }),
+        )
+        .with(tracing_subscriber::fmt::layer().with_target(false))
+        .init();
+
+    let listener = TcpListener::bind(format!("{}:{}", args.host, args.port))
+        .await
+        .unwrap();
+    tracing::debug!("listening on {}", listener.local_addr().unwrap());
+
+    let (app, rx) = app();
+    axum::serve(listener, app)
+        .with_graceful_shutdown(shutdown_signal(rx))
+        .await
+        .unwrap();
+    info!("Server stopped");
+}
+
+#[allow(clippy::unused_async)]
+#[allow(clippy::unused)]
+async fn await_shutdown(rx: mpsc::Receiver<bool>) -> Result<bool, mpsc::RecvError> {
+    rx.recv()
+}
+
+async fn shutdown_signal(rx: mpsc::Receiver<bool>) {
+    let endpoint = tokio::spawn(async move { rx.recv() }).into_future();
+
+    let ctrl_c = async {
+        signal::ctrl_c()
+            .await
+            .expect("failed to install Ctrl+C handler");
+    };
+
+    #[cfg(unix)]
+    let terminate = async {
+        signal::unix::signal(signal::unix::SignalKind::terminate())
+            .expect("failed to install signal handler")
+            .recv()
+            .await;
+    };
+
+    #[cfg(not(unix))]
+    let terminate = std::future::pending::<()>();
+
+    tokio::select! {
+        _ = ctrl_c => {},
+        _ = terminate => {},
+        _ = endpoint => {},
+    }
+    info!("Shutting server down gracefully...");
 }