copy implementation over from teleterm

2 files changed, 75 insertions, 7 deletions

diff --git a/Cargo.toml b/Cargo.toml
index 9f5eb1c..a1d2b8e 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -4,6 +4,9 @@ version = "0.1.0"
 authors = ["Jesse Luehrs <doy@tozt.net>"]
 edition = "2018"
 
-# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
-
 [dependencies]
+futures = "0.1.29"
+snafu = { version = "0.5", features = ["futures-01"] }
+term_size = "0.3"
+tokio = "0.1.22"
+tokio-signal = "0.2"
diff --git a/src/lib.rs b/src/lib.rs
index 31e1bb2..218010e 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -1,7 +1,72 @@
-#[cfg(test)]
-mod tests {
-    #[test]
-    fn it_works() {
-        assert_eq!(2 + 2, 4);
+use futures::future::Future as _;
+use futures::stream::Stream as _;
+use snafu::futures01::StreamExt as _;
+use snafu::ResultExt as _;
+use std::convert::TryInto as _;
+
+#[derive(Debug, snafu::Snafu)]
+pub enum Error {
+    #[snafu(display("failed to get terminal size"))]
+    GetTerminalSize,
+
+    #[snafu(display("invalid terminal size found: {}", source))]
+    InvalidTerminalSize { source: std::num::TryFromIntError },
+
+    #[snafu(display("SIGWINCH handler failed: {}", source))]
+    SigWinchHandler { source: std::io::Error },
+}
+
+pub type Result<T> = std::result::Result<T, Error>;
+
+pub struct Resizer {
+    winches:
+        Box<dyn futures::stream::Stream<Item = (), Error = Error> + Send>,
+    sent_initial_size: bool,
+}
+
+impl Resizer {
+    pub fn new() -> Self {
+        Self::default()
+    }
+}
+
+impl Default for Resizer {
+    fn default() -> Self {
+        let winches = tokio_signal::unix::Signal::new(
+            tokio_signal::unix::libc::SIGWINCH,
+        )
+        .flatten_stream()
+        .map(|_| ())
+        .context(SigWinchHandler);
+        Self {
+            winches: Box::new(winches),
+            sent_initial_size: false,
+        }
+    }
+}
+
+#[must_use = "streams do nothing unless polled"]
+impl futures::stream::Stream for Resizer {
+    type Item = (u16, u16);
+    type Error = Error;
+
+    fn poll(&mut self) -> futures::Poll<Option<Self::Item>, Self::Error> {
+        if !self.sent_initial_size {
+            self.sent_initial_size = true;
+            return Ok(futures::Async::Ready(Some(term_size()?)));
+        }
+        let _ = futures::try_ready!(self.winches.poll());
+        Ok(futures::Async::Ready(Some(term_size()?)))
+    }
+}
+
+fn term_size() -> Result<(u16, u16)> {
+    if let Some((cols, rows)) = term_size::dimensions() {
+        Ok((
+            rows.try_into().context(InvalidTerminalSize)?,
+            cols.try_into().context(InvalidTerminalSize)?,
+        ))
+    } else {
+        Err(Error::GetTerminalSize)
     }
 }