use extension_traits::extension;
use opendal::{Buffer, Error, ErrorKind, FuturesAsyncReader, Operator};

#[extension(pub trait OperatorExt)]
impl Operator {
    fn read_if_exists(
        &self,
        path: &str,
    ) -> impl Future<Output = Result<Option<Buffer>, Error>> + Send {
        async {
            match self.read(path).await {
                Ok(buffer) => Ok(Some(buffer)),
                Err(error) if matches!(error.kind(), ErrorKind::NotFound) => Ok(None),
                Err(error) => Err(error),
            }
        }
    }

    fn async_reader_if_exists(
        &self,
        path: &str,
    ) -> impl Future<Output = Result<Option<FuturesAsyncReader>, Error>> + Send {
        async {
            let reader = self.reader(path).await?;
            match reader.into_futures_async_read(..).await {
                Ok(reader) => Ok(Some(reader)),
                Err(error) if matches!(error.kind(), ErrorKind::NotFound) => Ok(None),
                Err(error) => Err(error),
            }
        }
    }
}