use crate::StoreBackend;
use core::fmt;

/// expect this for any write operation to `NoFlash`
#[derive(Debug, Clone, Copy, PartialEq, Eq)]
pub struct NoFlashError;

impl fmt::Display for NoFlashError {
    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
        write!(f, "no flash")
    }
}

/// a valid `StoreBackend` that can be used for configurations lacking a flash
#[derive(Debug, Clone, Copy)]
pub struct NoFlash;

impl StoreBackend for NoFlash {
    type Data = [u8; 0];

    fn data(&self) -> &Self::Data {
        &[]
    }

    type Error = NoFlashError;
    fn erase(&mut self) -> Result<(), Self::Error> {
        Err(NoFlashError)
    }

    fn program(&mut self, _: usize, _: &[u8]) -> Result<(), Self::Error> {
        Err(NoFlashError)
    }

    fn backup_space(&self) -> &'static mut [u8] {
        &mut []
    }
}