From be9f0ad6f792a9eb6ce664ed3450f93fe25bbb8d Mon Sep 17 00:00:00 2001
From: Guillaume Desmottes <guillaume.desmottes@collabora.com>
Date: Fri, 15 May 2020 14:35:39 +0200
Subject: [PATCH] wip

---
 Cargo.toml          |  1 +
 src/input_stream.rs | 51 +++++++++++++++++++++++++++++++++++++++++++++
 src/lib.rs          |  2 +-
 tests/futures.rs    | 27 ++++++++++++++++++++++++
 4 files changed, 80 insertions(+), 1 deletion(-)

diff --git a/Cargo.toml b/Cargo.toml
index faa52007..e48ccabf 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -47,6 +47,7 @@ git = "https://github.com/gtk-rs/lgpl-docs"
 libc = "0.2"
 bitflags = "1.0"
 once_cell = "1.0"
+futures = "0.3"
 futures-core = "0.3"
 futures-channel = "0.3"
 futures-util = "0.3"
diff --git a/src/input_stream.rs b/src/input_stream.rs
index 5cac8add..d7c0e517 100644
--- a/src/input_stream.rs
+++ b/src/input_stream.rs
@@ -3,6 +3,9 @@
 // Licensed under the MIT license, see the LICENSE file or <http://opensource.org/licenses/MIT>
 
 use error::to_std_io_result;
+use futures_core::task::{Context, Poll};
+use futures_io::AsyncRead;
+use futures_util::future::FutureExt;
 use gio_sys;
 use glib::object::IsA;
 use glib::translate::*;
@@ -81,6 +84,16 @@ pub trait InputStreamExtManual: Sized {
     {
         InputStreamRead(self)
     }
+
+    fn into_async_buf_read(self, buffer_size: usize) -> InputStreamAsyncBufRead<Self>
+    where
+        Self: IsA<InputStream>,
+    {
+        let mut buffer = Vec::with_capacity(buffer_size);
+        buffer.resize(buffer_size, 0);
+
+        InputStreamAsyncBufRead(self, buffer)
+    }
 }
 
 impl<O: IsA<InputStream>> InputStreamExtManual for O {
@@ -341,6 +354,44 @@ impl<T: IsA<InputStream> + IsA<Seekable>> io::Seek for InputStreamRead<T> {
     }
 }
 
+#[derive(Debug)]
+pub struct InputStreamAsyncBufRead<T: IsA<InputStream>>(T, Vec<u8>);
+
+impl<T: IsA<InputStream>> InputStreamAsyncBufRead<T> {
+    pub fn into_input_stream(self) -> T {
+        self.0
+    }
+
+    pub fn input_stream(&self) -> &T {
+        &self.0
+    }
+}
+
+impl<T: IsA<InputStream>> AsyncRead for InputStreamAsyncBufRead<T> {
+    fn poll_read(
+        self: Pin<&mut Self>,
+        cx: &mut Context,
+        buf: &mut [u8],
+    ) -> Poll<io::Result<usize>> {
+        let stream = Pin::get_ref(self.as_ref());
+        let my_buf = vec![0; 10];
+        let mut fut = stream
+            .0
+            .as_ref()
+            .read_async_future(my_buf, Priority::default());
+
+        match dbg!(fut.poll_unpin(cx)) {
+            // FIXME: copy to @buf
+            Poll::Ready(Ok((out_buf, res))) => Poll::Ready(Ok(res)),
+            Poll::Ready(Err((_, err))) => {
+                let kind = err.kind::<crate::IOErrorEnum>().unwrap();
+                Poll::Ready(Err(io::Error::new(io::ErrorKind::from(kind), err)))
+            }
+            Poll::Pending => Poll::Pending,
+        }
+    }
+}
+
 #[cfg(test)]
 mod tests {
     use crate::prelude::*;
diff --git a/src/lib.rs b/src/lib.rs
index 7b6035c7..3adc9898 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -44,7 +44,7 @@ mod inet_address;
 mod io_stream;
 pub use io_stream::IOStreamAsyncReadWrite;
 mod input_stream;
-pub use input_stream::InputStreamRead;
+pub use input_stream::{InputStreamAsyncBufRead, InputStreamRead};
 #[cfg(any(feature = "v2_44", feature = "dox"))]
 mod list_store;
 mod memory_input_stream;
diff --git a/tests/futures.rs b/tests/futures.rs
index 248886e3..7a1d8535 100644
--- a/tests/futures.rs
+++ b/tests/futures.rs
@@ -5,3 +5,30 @@
 // This target is build with edition 2018 for testing futures API.
 // TODO: merge to the test module of the corresponding source files once the crate
 // has been ported to 2018.
+
+use futures::prelude::*;
+use gio::prelude::*;
+use gio::MemoryInputStream;
+use glib::Bytes;
+use std::error::Error;
+
+#[test]
+fn async_buf_read() {
+    async fn run() -> Result<(), Box<dyn Error>> {
+        let b = Bytes::from_owned(vec![1, 2, 3]);
+        let mut read = MemoryInputStream::new_from_bytes(&b).into_async_buf_read(16);
+        let mut buf = [0u8; 10];
+
+        let ret = read.read(&mut buf).await?;
+
+        assert_eq!(ret, 3);
+        assert_eq!(buf[0], 1);
+        assert_eq!(buf[1], 2);
+        assert_eq!(buf[2], 3);
+
+        Ok(())
+    }
+
+    let main_context = glib::MainContext::default();
+    main_context.block_on(run()).unwrap();
+}