drawbridge-hash 0.1.0

Content digest utilities.
Documentation 
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// SPDX-FileCopyrightText: 2022 Profian Inc. <opensource@profian.com>
// SPDX-License-Identifier: AGPL-3.0-only

use std::io;
use std::pin::Pin;
use std::task::{Context, Poll};

use futures::AsyncWrite;
use sha2::digest::Digest;
use sha2::{Sha224, Sha256, Sha384, Sha512};

pub(super) enum Inner {
    Sha224(Sha224),
    Sha256(Sha256),
    Sha384(Sha384),
    Sha512(Sha512),
}

pub struct Writer<T> {
    pub(super) writer: T,
    pub(super) inner: Inner,
}

impl<T: AsyncWrite + Unpin> AsyncWrite for Writer<T> {
    fn poll_write(
        mut self: Pin<&mut Self>,
        cx: &mut Context<'_>,
        buf: &[u8],
    ) -> Poll<io::Result<usize>> {
        Pin::new(&mut self.writer).poll_write(cx, buf).map_ok(|n| {
            match &mut self.inner {
                Inner::Sha224(h) => h.update(&buf[..n]),
                Inner::Sha256(h) => h.update(&buf[..n]),
                Inner::Sha384(h) => h.update(&buf[..n]),
                Inner::Sha512(h) => h.update(&buf[..n]),
            };
            n
        })
    }

    fn poll_flush(mut self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<io::Result<()>> {
        Pin::new(&mut self.writer).poll_flush(cx)
    }

    fn poll_close(mut self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<io::Result<()>> {
        Pin::new(&mut self.writer).poll_close(cx)
    }
}