introduce proper error boundary

src/error.rs

@@ -0,0 +1,50 @@
+use futures::Future;
+use glib::subclass::prelude::*;
+use gtk::prelude::*;
+use gtk::{self, glib};
+
+use crate::widgets::NotifyWindow;
+
+pub type Error = anyhow::Error;
+
+pub trait ErrorBoundaryProvider {
+    fn error_boundary(&self) -> ErrorBoundary;
+}
+
+impl<W: IsA<gtk::Widget>> ErrorBoundaryProvider for W {
+    fn error_boundary(&self) -> ErrorBoundary {
+        let direct_ancestor: Option<adw::ToastOverlay> = self
+            .ancestor(adw::ToastOverlay::static_type())
+            .and_downcast();
+        let win: Option<adw::ToastOverlay> = self
+            .ancestor(NotifyWindow::static_type())
+            .and_downcast()
+            .map(|win: NotifyWindow| win.imp().toast_overlay.clone());
+        let toast_overlay = direct_ancestor.or(win);
+        ErrorBoundary {
+            source: self.clone().into(),
+            boundary: toast_overlay,
+        }
+    }
+}
+
+pub struct ErrorBoundary {
+    source: gtk::Widget,
+    boundary: Option<adw::ToastOverlay>,
+}
+
+impl ErrorBoundary {
+    pub fn spawn<T>(self, f: impl Future<Output = Result<T, Error>> + 'static) {
+        glib::MainContext::ref_thread_default().spawn_local_with_priority(
+            glib::Priority::DEFAULT_IDLE,
+            async move {
+                if let Err(e) = f.await {
+                    if let Some(boundary) = self.boundary {
+                        boundary.add_toast(adw::Toast::builder().title(&e.to_string()).build());
+                    }
+                    tracing::error!(source=?self.source.type_().name(), error=?e);
+                }
+            },
+        );
+    }
+}