use std::future::Future;
use std::net::SocketAddr;

use axum::{Router, serve};
use database::db::ServerPostgres;
use eyre::{Context, Result};

pub(crate) mod database;
mod handlers;
mod metrics;
mod router;

pub(crate) use settings::Settings;

pub(crate) mod settings;

use tokio::net::TcpListener;
use tokio::signal;

#[cfg(target_family = "unix")]
async fn shutdown_signal() {
    let mut term = signal::unix::signal(signal::unix::SignalKind::terminate())
        .expect("failed to register signal handler");
    let mut interrupt = signal::unix::signal(signal::unix::SignalKind::interrupt())
        .expect("failed to register signal handler");

    tokio::select! {
        _ = term.recv() => {},
        _ = interrupt.recv() => {},
    };
    eprintln!("Shutting down gracefully...");
}

pub(crate) async fn launch(settings: Settings, addr: SocketAddr) -> Result<()> {
    launch_with_tcp_listener(
        settings,
        TcpListener::bind(addr)
            .await
            .context("could not connect to socket")?,
        shutdown_signal(),
    )
    .await
}

pub(crate) async fn launch_with_tcp_listener(
    settings: Settings,
    listener: TcpListener,
    shutdown: impl Future<Output = ()> + Send + 'static,
) -> Result<()> {
    let r = make_router(settings).await?;

    serve(listener, r.into_make_service())
        .with_graceful_shutdown(shutdown)
        .await?;

    Ok(())
}

// The separate listener means it's much easier to ensure metrics are not accidentally exposed to
// the public.
pub(crate) async fn launch_metrics_server(host: String, port: u16) -> Result<()> {
    let listener = TcpListener::bind((host, port))
        .await
        .context("failed to bind metrics tcp")?;

    let recorder_handle = metrics::setup_metrics_recorder();

    let router = Router::new().route(
        "/metrics",
        axum::routing::get(move || std::future::ready(recorder_handle.render())),
    );

    serve(listener, router.into_make_service())
        .with_graceful_shutdown(shutdown_signal())
        .await?;

    Ok(())
}

async fn make_router(settings: Settings) -> Result<Router, eyre::Error> {
    let db = ServerPostgres::new(&settings.db_settings)
        .await
        .wrap_err_with(|| format!("failed to connect to db: {:?}", settings.db_settings))?;
    let r = router::router(db, settings);
    Ok(r)
}