use iced::futures::channel::oneshot;

/// Run a blocking closure on a thread pool thread and await its result.
/// Used to offload blocking work (HTTP, disk, process spawning) without
/// stalling the iced event loop.
pub async fn async_blocking<T, F>(f: F) -> T
where
    T: Send + 'static,
    F: FnOnce() -> T + Send + 'static,
{
    let (tx, rx) = oneshot::channel();
    std::thread::spawn(move || {
        let _ = tx.send(f());
    });
    rx.await.expect("blocking task panicked")
}

/// Open a native folder picker dialog and return the chosen path, or None if
/// the user cancelled. Tries zenity (GNOME/GTK) then kdialog (KDE) in order.
pub fn pick_folder(title: &str) -> Option<String> {
    for (cmd, args) in [
        ("zenity", vec!["--file-selection", "--directory", "--title", title]),
        ("kdialog", vec!["--getexistingdirectory", "/home", "--title", title]),
    ] {
        let Ok(out) = std::process::Command::new(cmd).args(&args).output() else {
            continue;
        };
        if out.status.success() {
            let s = String::from_utf8_lossy(&out.stdout).trim().to_string();
            if !s.is_empty() {
                return Some(s);
            }
        }
    }
    None
}

/// Open a native file picker dialog starting in `start_dir`, or None if
/// the user cancelled. Tries zenity then kdialog.
pub fn pick_file(title: &str, start_dir: &str) -> Option<String> {
    // zenity uses --filename with a trailing slash to open a directory
    let start_slash = format!("{}/", start_dir.trim_end_matches('/'));
    let zenity_args = vec![
        "--file-selection",
        "--title",
        title,
        "--filename",
        &start_slash,
    ];
    let kdialog_args = vec!["--getopenfilename", start_dir, "--title", title];
    for (cmd, args) in [("zenity", zenity_args.as_slice()), ("kdialog", kdialog_args.as_slice())] {
        let Ok(out) = std::process::Command::new(cmd).args(args).output() else {
            continue;
        };
        if out.status.success() {
            let s = String::from_utf8_lossy(&out.stdout).trim().to_string();
            if !s.is_empty() {
                return Some(s);
            }
        }
    }
    None
}