tess-cli 0.18.5

use std::io;
use std::sync::Arc;
use std::sync::atomic::AtomicBool;

use crossterm::cursor::{Hide, Show};
use crossterm::terminal::{disable_raw_mode, enable_raw_mode, EnterAlternateScreen, LeaveAlternateScreen};

/// RAII guard that enables raw mode + alt screen on construction and restores
/// the terminal on drop (including during panic unwind).
pub struct TerminalGuard;

impl TerminalGuard {
    pub fn enter() -> io::Result<Self> {
        enable_raw_mode()?;
        crossterm::execute!(io::stdout(), EnterAlternateScreen, Hide)?;
        Ok(TerminalGuard)
    }
}

impl Drop for TerminalGuard {
    fn drop(&mut self) {
        let _ = crossterm::execute!(io::stdout(), Show, LeaveAlternateScreen);
        let _ = disable_raw_mode();
    }
}

/// Restore terminal manually (for panic hook). Idempotent and best-effort.
pub fn restore_terminal_best_effort() {
    let _ = crossterm::execute!(io::stdout(), Show, LeaveAlternateScreen);
    let _ = disable_raw_mode();
}

pub fn install_panic_hook() {
    let prev = std::panic::take_hook();
    std::panic::set_hook(Box::new(move |info| {
        restore_terminal_best_effort();
        prev(info);
    }));
}

/// Returns a flag that becomes `true` on SIGTERM or SIGHUP.
pub fn install_signal_flag() -> Arc<AtomicBool> {
    let flag = Arc::new(AtomicBool::new(false));
    let _ = signal_hook::flag::register(signal_hook::consts::SIGTERM, Arc::clone(&flag));
    let _ = signal_hook::flag::register(signal_hook::consts::SIGHUP, Arc::clone(&flag));
    flag
}

#[cfg(test)]
mod tests {
    use super::*;
    use std::sync::atomic::Ordering;

    #[test]
    fn signal_flag_starts_false() {
        let f = install_signal_flag();
        assert!(!f.load(Ordering::SeqCst));
    }

    #[test]
    fn restore_is_idempotent() {
        // Should not panic when raw mode was never enabled.
        restore_terminal_best_effort();
        restore_terminal_best_effort();
    }
}