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use std::{collections::BTreeSet, sync::Mutex, thread};

use conquer_once::Lazy;
use signal_hook::{
    consts::{SIGINT, SIGQUIT, SIGTERM},
    iterator::Signals,
};

use crate::core::client::Client;

static WATCHDOG: Lazy<Mutex<Watchdog>> = Lazy::new(|| {
    thread::spawn(move || {
        let runtime = tokio::runtime::Builder::new_current_thread()
            .enable_all()
            .build()
            .expect("failed to start watchdog runtime in background");

        runtime.block_on(async {
            let signal_docker = Client::lazy_client().await;
            let mut signals = Signals::new([SIGTERM, SIGINT, SIGQUIT])
                .expect("failed to register signal handler");

            for signal in &mut signals {
                for container_id in WATCHDOG
                    .lock()
                    .map(|s| s.containers.clone())
                    .unwrap_or_default()
                {
                    signal_docker.stop(&container_id).await;
                    signal_docker.rm(&container_id).await;
                }

                let _ = signal_hook::low_level::emulate_default_handler(signal);
            }
        });
    });

    Mutex::new(Watchdog::default())
});

#[derive(Default)]
pub(crate) struct Watchdog {
    containers: BTreeSet<String>,
}

/// Register a container for observation
pub(crate) fn register(container_id: String) {
    WATCHDOG
        .lock()
        .expect("failed to access watchdog")
        .containers
        .insert(container_id);
}
/// Unregisters a container for observation
pub(crate) fn unregister(container_id: &str) {
    WATCHDOG
        .lock()
        .expect("failed to access watchdog")
        .containers
        .remove(container_id);
}