fix: signal_for must indicate when the action was not emitted

Also refactor some code.

src/app/state/action.rs

@@ -15,23 +15,18 @@ pub enum Action {
 impl Action {
     /// Return a [Signal] containing only the given [Action]
     ///
-    /// The signal value will be the [Action]'s index in the original signal.
-    pub fn signal_for<F>(cx: Scope, sig: Signal<(usize, Action)>, f: F) -> Signal<usize>
+    /// The signal value will be the [Action]'s index in the original signal, which index is [None] if the action was never emitted..
+    pub fn signal_for<F>(cx: Scope, sig: Signal<(usize, Action)>, f: F) -> Signal<Option<usize>>
     where
         F: Fn(Action) -> bool + 'static,
     {
-        signal_filter_map(
-            cx,
-            sig,
-            0,
-            move |(idx, action)| {
-                if f(action) {
-                    Some(idx)
-                } else {
-                    None
-                }
-            },
-        )
+        signal_filter_map(cx, sig, None, move |(idx, action)| {
+            if f(action) {
+                Some(Some(idx))
+            } else {
+                None
+            }
+        })
     }
 }
 

src/app/state/datum.rs

@@ -36,7 +36,7 @@ impl<T> Datum<T> {
     /// Refresh the datum [Signal] using the given function
     ///
     /// If a previous refresh is still running, it will be cancelled.
-    pub async fn refresh_with<F>(signal: Signal<Self>, f: F)
+    pub async fn refresh_with<F>(signal: Signal<Datum<T>>, f: F)
     where
         F: Future<Output = T> + Send + 'static,
         T: Send + 'static,

src/app/state/mod.rs

@@ -39,7 +39,7 @@ pub struct AppState {
 
 impl AppState {
     fn new(cx: Scope) -> Self {
-        tracing::debug!("🔨 Creating AppState default value");
+        tracing::debug!("🔨 Creating new AppState");
         let recent_flakes =
             new_storage::<LocalStorage, _>(cx, "recent_flakes".to_string(), FlakeUrl::suggestions);
         AppState {
@@ -94,21 +94,22 @@ impl AppState {
         // Build `state.flake` signal when `state.flake_url` changes or the
         // RefreshFlake action is triggered
         {
-            let flake_url = self.flake_url.read().clone();
-            let refresh_action =
-                Action::signal_for(cx, self.action, |act| act == Action::RefreshFlake);
-            let idx = *refresh_action.read();
-            use_future(cx, (&flake_url, &idx), |(flake_url, idx)| async move {
+            let refresh_flake = |(flake_url, idx): (Option<FlakeUrl>, Option<usize>)| async move {
                 if let Some(flake_url) = flake_url {
-                    tracing::info!("Updating flake [{}] {} ...", flake_url, idx);
+                    tracing::info!("Updating flake [{}] {:?} ...", flake_url, idx);
                     Datum::refresh_with(self.flake, async move {
                         Flake::from_nix(&nix_rs::command::NixCmd::default(), flake_url.clone())
                             .await
                             .map_err(|e| Into::<SystemError>::into(e.to_string()))
                     })
                     .await
                 }
-            });
+            };
+            let flake_url = self.flake_url.read().clone();
+            let refresh_action =
+                Action::signal_for(cx, self.action, |act| act == Action::RefreshFlake);
+            let idx = *refresh_action.read();
+            use_future(cx, (&flake_url, &idx), refresh_flake);
         }
 
         // Update recent_flakes
@@ -147,7 +148,7 @@ impl AppState {
                 Action::signal_for(cx, self.action, |act| act == Action::GetNixInfo);
             let idx = *get_nix_info_action.read();
             use_future(cx, (&idx,), |(idx,)| async move {
-                tracing::info!("Updating nix info [{}] ...", idx);
+                tracing::info!("Updating nix info [{:?}] ...", idx);
                 Datum::refresh_with(self.nix_info, async {
                     NixInfo::from_nix(&nix_rs::command::NixCmd::default())
                         .await