use tokio::io::{AsyncRead, AsyncReadExt};

pub struct StreamCodec<S> {
	stream: S,
}

impl<S: AsyncRead + Unpin> StreamCodec<S> {
	pub fn new(stream: S) -> Self {
		Self { stream }
	}

	pub async fn next(&mut self) -> Result<Vec<u8>, std::io::Error> {
		let mut buf = vec![0; 8];
		self.stream.read_exact(&mut buf).await?;
		let expected_len = u32::from_be_bytes(buf[0..4].try_into().unwrap()) as usize;
		if expected_len < 8 || expected_len > 8 * 1024 * 1024 {
			return Err(std::io::ErrorKind::InvalidData.into());
		}
		buf.resize(expected_len, 0);
		self.stream.read_exact(&mut buf[8..expected_len]).await?;
		Ok(buf)
	}

	pub fn get_mut(&mut self) -> &mut S {
		&mut self.stream
	}
}

/*#[cfg(test)]
mod test {
	use super::*;

	use tokio_util::{bytes::BytesMut, codec::Framed};

	#[test]
	fn test_decode() {
		let stream = futures_util::stream::iter([BytesMut::fr&[0u8]]);
		let stream = Framed::new(stream, CustomCodec::new());
	}
}*/