//! Map zbus errors to short, user-facing strings. The GUI surfaces these in
//! `adw::Toast` and inside the touch-prompt dialog's failure state.
//!
//! Pure logic; testable without a display server.

#[derive(Debug, Clone, Copy, PartialEq, Eq)]
#[allow(dead_code)] // wired through keys_page.rs / enroll_dialog.rs in Tasks 4-6.
pub(crate) enum ErrorKind {
    /// Daemon unreachable / bus dropped — caller should swap to disconnected banner.
    Disconnected,
    /// polkit denied. Daemon's message is usually fine to show verbatim.
    AccessDenied,
    /// Anything else — daemon returned a typed `Failed(msg)` or similar.
    Other,
}

#[allow(dead_code)] // wired through keys_page.rs / enroll_dialog.rs in Tasks 4-6.
pub(crate) fn classify(err: &zbus::Error) -> ErrorKind {
    match err {
        zbus::Error::InputOutput(_) | zbus::Error::Address(_) | zbus::Error::Handshake(_) => {
            ErrorKind::Disconnected
        }
        zbus::Error::FDO(boxed) => match boxed.as_ref() {
            zbus::fdo::Error::AccessDenied(_) => ErrorKind::AccessDenied,
            zbus::fdo::Error::ServiceUnknown(_) | zbus::fdo::Error::NameHasNoOwner(_) => {
                ErrorKind::Disconnected
            }
            _ => ErrorKind::Other,
        },
        _ => ErrorKind::Other,
    }
}

#[allow(dead_code)] // wired through keys_page.rs / enroll_dialog.rs in Tasks 4-6.
pub(crate) fn user_message(err: &zbus::Error) -> String {
    match classify(err) {
        ErrorKind::Disconnected => {
            "Couldn't reach the authentication daemon. Make sure authforge-daemon is running."
                .to_string()
        }
        ErrorKind::AccessDenied => match err {
            zbus::Error::FDO(boxed) => match boxed.as_ref() {
                zbus::fdo::Error::AccessDenied(msg) => msg.clone(),
                _ => "Access denied.".to_string(),
            },
            _ => "Access denied.".to_string(),
        },
        ErrorKind::Other => err.to_string(),
    }
}

#[cfg(test)]
mod tests {
    use super::*;

    #[test]
    fn service_unknown_classifies_as_disconnected() {
        let e = zbus::Error::FDO(Box::new(zbus::fdo::Error::ServiceUnknown(
            "no daemon".to_string(),
        )));
        assert_eq!(classify(&e), ErrorKind::Disconnected);
    }

    #[test]
    fn access_denied_classifies_as_access_denied() {
        let e = zbus::Error::FDO(Box::new(zbus::fdo::Error::AccessDenied(
            "polkit said no".to_string(),
        )));
        assert_eq!(classify(&e), ErrorKind::AccessDenied);
    }

    #[test]
    fn access_denied_user_message_is_daemon_message_verbatim() {
        let e = zbus::Error::FDO(Box::new(zbus::fdo::Error::AccessDenied(
            "polkit said no".to_string(),
        )));
        assert_eq!(user_message(&e), "polkit said no");
    }

    #[test]
    fn disconnected_user_message_mentions_authforge_daemon() {
        let e = zbus::Error::FDO(Box::new(zbus::fdo::Error::ServiceUnknown(
            "no daemon".to_string(),
        )));
        assert!(user_message(&e).contains("authforge-daemon"));
    }
}