//! Safe frontend SIGINT subscription for the synchronous worker lifecycle.

use std::{
    io,
    sync::{
        Arc,
        atomic::{AtomicU32, Ordering},
    },
    thread,
};

use signal_hook::{consts::signal::SIGINT, iterator::Signals};

use super::Cancellation;

/// Process-wide interrupt count observed by the production CLI frontend.
#[derive(Clone, Debug)]
pub struct InterruptCounter {
    count: Arc<AtomicU32>,
}

impl InterruptCounter {
    /// Installs a safe SIGINT iterator and detached counter thread.
    pub fn install() -> io::Result<Self> {
        let mut signals = Signals::new([SIGINT])?;
        let count = Arc::new(AtomicU32::new(0));
        let thread_count = Arc::clone(&count);
        thread::Builder::new()
            .name("ghidr-sigint".to_owned())
            .spawn(move || {
                for _signal in signals.forever() {
                    let _previous =
                        thread_count.fetch_update(Ordering::SeqCst, Ordering::SeqCst, |value| {
                            Some(value.saturating_add(1))
                        });
                }
            })?;
        Ok(Self { count })
    }
}

impl Cancellation for InterruptCounter {
    fn interrupt_count(&self) -> u32 {
        self.count.load(Ordering::SeqCst)
    }
}