use anyhow::Result;
use crate::digest_engine::DigestEngine;
use std::io::{Read, Write};
use std::io;

#[derive(Debug, Eq, PartialEq, Clone, Default)]
pub struct DigestEngineNone {}

impl DigestEngineNone {
    pub fn new() -> DigestEngineNone {
        DigestEngineNone {}
    }
}

impl DigestEngine for DigestEngineNone {
    fn create(&self) -> Result<Box<dyn Write>> {
        Ok(Box::new(DummyWriter::new()))
    }
    
    fn finalize(&mut self) -> io::Result<String> {
        Ok("none".to_string())
    }
    
    fn update(&mut self, _data: &[u8]) {}
}

// Dummy writer that implements Write for the none digest engine
struct DummyWriter;

impl DummyWriter {
    fn new() -> Self {
        DummyWriter
    }
}

impl Write for DummyWriter {
    fn write(&mut self, _buf: &[u8]) -> io::Result<usize> {
        Ok(0)
    }

    fn flush(&mut self) -> io::Result<()> {
        Ok(())
    }
}