1 files changed, 164 insertions, 0 deletions
diff --git a/src/state.rs b/src/state.rs
new file mode 100644
index 0000000..45ee36d
--- /dev/null
+++ b/src/state.rs
@@ -0,0 +1,164 @@
+use futures::future::Future as _;
+use futures::sink::Sink as _;
+use snafu::{OptionExt as _, ResultExt as _};
+use std::io::Write as _;
+
+#[derive(Debug, snafu::Snafu)]
+pub enum Error {
+    #[snafu(display("invalid command index: {}", idx))]
+    InvalidCommandIndex { idx: usize },
+
+    #[snafu(display("error sending message: {}", source))]
+    Send {
+        source: futures::sync::mpsc::SendError<StateEvent>,
+    },
+
+    #[snafu(display("error printing output: {}", source))]
+    PrintOutput { source: std::io::Error },
+
+    #[snafu(display("this error should not be possible"))]
+    Unreachable,
+}
+
+pub type Result<T> = std::result::Result<T, Error>;
+
+#[derive(Debug)]
+pub enum StateEvent {
+    Start(usize, String, Vec<String>),
+    Output(usize, Vec<u8>),
+    Exit(usize, std::process::ExitStatus),
+}
+
+#[derive(Debug)]
+pub struct State {
+    r: futures::sync::mpsc::Receiver<StateEvent>,
+    commands: std::collections::HashMap<usize, Command>,
+}
+
+impl State {
+    pub fn new(r: futures::sync::mpsc::Receiver<StateEvent>) -> Self {
+        Self {
+            r,
+            commands: std::collections::HashMap::new(),
+        }
+    }
+
+    pub fn command_start(
+        &mut self,
+        idx: usize,
+        cmd: &str,
+        args: &[String],
+    ) -> Result<()> {
+        snafu::ensure!(
+            !self.commands.contains_key(&idx),
+            InvalidCommandIndex { idx }
+        );
+        let command = Command::new(cmd, args);
+        self.commands.insert(idx, command.clone());
+        eprint!("running '{} {:?}'\r\n", command.cmd, command.args);
+        Ok(())
+    }
+
+    pub fn command_output(
+        &mut self,
+        idx: usize,
+        output: &[u8],
+    ) -> Result<()> {
+        let command = self
+            .commands
+            .get_mut(&idx)
+            .context(InvalidCommandIndex { idx })?;
+        command.output.append(&mut output.to_vec());
+
+        let stdout = std::io::stdout();
+        let mut stdout = stdout.lock();
+        stdout.write(output).context(PrintOutput)?;
+        stdout.flush().context(PrintOutput)?;
+
+        Ok(())
+    }
+
+    pub fn command_exit(
+        &mut self,
+        idx: usize,
+        status: std::process::ExitStatus,
+    ) -> Result<()> {
+        let command = self
+            .commands
+            .get_mut(&idx)
+            .context(InvalidCommandIndex { idx })?;
+        command.status = Some(status);
+        eprint!("command exited: {}\r\n", status);
+        Ok(())
+    }
+}
+
+impl futures::stream::Stream for State {
+    type Item = ();
+    type Error = Error;
+
+    fn poll(&mut self) -> futures::Poll<Option<Self::Item>, Self::Error> {
+        let event = futures::try_ready!(self
+            .r
+            .poll()
+            .map_err(|_| Error::Unreachable));
+        match event {
+            Some(StateEvent::Start(idx, cmd, args)) => {
+                self.command_start(idx, &cmd, &args)?;
+                Ok(futures::Async::Ready(Some(())))
+            }
+            Some(StateEvent::Output(idx, output)) => {
+                self.command_output(idx, &output)?;
+                Ok(futures::Async::Ready(Some(())))
+            }
+            Some(StateEvent::Exit(idx, status)) => {
+                self.command_exit(idx, status)?;
+                Ok(futures::Async::Ready(Some(())))
+            }
+            None => Ok(futures::Async::Ready(None)),
+        }
+    }
+}
+
+pub fn update(
+    w: futures::sync::mpsc::Sender<StateEvent>,
+    idx: usize,
+    event: &crate::eval::CommandEvent,
+) -> impl futures::future::Future<Item = (), Error = Error> {
+    match event {
+        crate::eval::CommandEvent::CommandStart(cmd, args) => {
+            w.send(crate::state::StateEvent::Start(
+                idx,
+                cmd.to_string(),
+                args.to_vec(),
+            ))
+        }
+        crate::eval::CommandEvent::Output(out) => {
+            w.send(crate::state::StateEvent::Output(idx, out.to_vec()))
+        }
+        crate::eval::CommandEvent::CommandExit(status) => {
+            w.send(crate::state::StateEvent::Exit(idx, *status))
+        }
+    }
+    .map(|_| ())
+    .map_err(|e| Error::Send { source: e })
+}
+
+#[derive(Debug, Clone)]
+struct Command {
+    cmd: String,
+    args: Vec<String>,
+    output: Vec<u8>,
+    status: Option<std::process::ExitStatus>,
+}
+
+impl Command {
+    fn new(cmd: &str, args: &[String]) -> Self {
+        Self {
+            cmd: cmd.to_string(),
+            args: args.to_vec(),
+            output: vec![],
+            status: None,
+        }
+    }
+}