Add connection status indicator

gui/src/io.rs

@@ -0,0 +1,67 @@
+use std::sync::Arc;
+
+use slint::ComponentHandle;
+use tokio::sync::mpsc;
+
+use crate::{runtime::spawn, ui};
+
+/// A thing for spawning I/O-tasks and updating the GUI `ConnectionStatus` with the result.
+#[derive(Clone)]
+pub struct Io {
+    state: Arc<State>,
+}
+
+struct State {
+    status: mpsc::Sender<ui::ConnectionStatus>,
+}
+
+impl Io {
+    pub fn new(app: &ui::App) -> Self {
+        let (tx, mut rx) = mpsc::channel(10);
+        let app_weak = app.as_weak();
+
+        spawn(async move {
+            loop {
+                let Some(status) = rx.recv().await else {
+                    return;
+                };
+
+                let _ = app_weak.upgrade_in_event_loop(move |app| {
+                    app.global::<ui::State>().set_connection_status(status);
+                });
+            }
+        });
+
+        Io {
+            state: Arc::new(State { status: tx }),
+        }
+    }
+
+    /// Spawn a fallible async function.
+    ///
+    /// Update the `ConnectionStatus` in the GUI depending on whether the result is an error.
+    pub fn spawn<Fut>(&self, f: impl FnOnce() -> Fut + Send + 'static)
+    where
+        Fut: Future<Output = anyhow::Result<()>>,
+        Fut: Send + 'static,
+    {
+        let io = self.clone();
+        spawn(async move {
+            let _ = io.state.status.send(ui::ConnectionStatus::Syncing).await;
+            let result = f().await;
+            let was_error = result.is_err();
+            if let Err(e) = result {
+                eprintln!("{e:?}");
+            }
+            let _ = io
+                .state
+                .status
+                .send(if was_error {
+                    ui::ConnectionStatus::Error
+                } else {
+                    ui::ConnectionStatus::Idle
+                })
+                .await;
+        });
+    }
+}