use tokio::fs;
use tokio::io::{AsyncReadExt, AsyncWriteExt, Result};

/// Checks if a block device is uninitialized.
/// It assumed that a initialized device always has a non-zero byte in the first 8kiB.
pub async fn is_uninitialized(dev_path: &str) -> Result<bool> {
    let mut dev = fs::File::open(dev_path).await?;

    let mut buf = [0u8; 8 << 10];
    dev.read_exact(&mut buf).await?;

    Ok(buf.into_iter().all(|b| b == 0))
}

/// zeroes the first 8kiB of the device so it looks uninitialized again.
pub async fn uninitialize(dev_path: &str) -> Result<()> {
    let mut dev = fs::File::options().write(true).open(dev_path).await?;

    let buf = [0u8; 8 << 10];
    dev.write_all(&buf).await
}