use {
    crate::{
        copy_device::{CopyDevice, CopyDeviceRegistry},
        utils::errorfmt::ErrorFmt,
    },
    std::{
        cell::OnceCell,
        fmt::{Debug, Formatter},
        rc::Rc,
    },
    uapi::c::dev_t,
};

pub struct CopyDeviceHolder {
    pub registry: Rc<CopyDeviceRegistry>,
    pub devnum: dev_t,
    pub dev: OnceCell<Option<Rc<CopyDevice>>>,
}

impl Debug for CopyDeviceHolder {
    fn fmt(&self, f: &mut Formatter<'_>) -> std::fmt::Result {
        f.debug_struct("CopyDeviceHolder").finish_non_exhaustive()
    }
}

impl CopyDeviceHolder {
    pub fn get(&self) -> Option<Rc<CopyDevice>> {
        self.dev
            .get_or_init(
                || match self.registry.get(self.devnum)?.create_device().map(Some) {
                    Ok(d) => d,
                    Err(e) => {
                        log::error!(
                            "Could not get copy device for {}: {}",
                            self.devnum,
                            ErrorFmt(e),
                        );
                        None
                    }
                },
            )
            .clone()
    }
}