use std::sync::mpsc;

use clap::Parser;
use nuchat::Config;
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,

    /// Admin secret to use, leave blank to disable
    #[arg(long)]
    admin_secret: Option<String>,
}

#[tokio::main]
async fn main() {
    let args = Args::parse();
    let config = BinConfig::from_args(args);
    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!("{}:{}", config.0.host, config.0.port))
        .await
        .unwrap();
    tracing::debug!("listening on {}", listener.local_addr().unwrap());

    let (app, rx) = app(&config.0);
    axum::serve(listener, app)
        .with_graceful_shutdown(shutdown_signal(rx))
        .await
        .unwrap();
    info!("Server stopped");
}

#[allow(clippy::unused_async)]
#[allow(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...");
}

struct BinConfig(Config);
impl BinConfig {
    fn from_args(args: Args) -> Self {
        Self(Config {
            port: args.port,
            host: args.host,
            admin_secret: args.admin_secret,
        })
    }
}