InAppNotif: Refactor to infer the undo state

If we use an Optional instead of passing empty closures, we
can infer if the Undo button needs to be shown.

podcasts-gtk/resources/gtk/inapp_notif.ui

@@ -100,7 +100,6 @@ Tobias Bernard
             <child>
               <object class="GtkButton" id="undo">
                 <property name="label" translatable="yes">Undo</property>
-                <property name="visible">True</property>
                 <property name="can_focus">True</property>
                 <property name="receives_default">True</property>
                 <property name="halign">center</property>

podcasts-gtk/src/app.rs

@@ -17,7 +17,7 @@ use settings::{self, WindowGeometry};
 use stacks::{Content, PopulatedState};
 use utils;
 use widgets::about_dialog;
-use widgets::appnotif::{InAppNotification, UndoState};
+use widgets::appnotif::InAppNotification;
 use widgets::player;
 use widgets::show_menu::{mark_all_notif, remove_show_notif, ShowMenu};
 
@@ -306,7 +306,8 @@ impl App {
                 Action::ErrorNotification(err) => {
                     error!("An error notification was triggered: {}", err);
                     let callback = || glib::Continue(false);
-                    let notif = InAppNotification::new(&err, callback, || {}, UndoState::Hidden);
+                    let undo_cb: Option<fn()> = None;
+                    let notif = InAppNotification::new(&err, callback, undo_cb);
                     notif.show(&self.overlay);
                 }
                 Action::InitEpisode(rowid) => {

podcasts-gtk/src/widgets/appnotif.rs

@@ -6,6 +6,7 @@ use std::cell::RefCell;
 use std::rc::Rc;
 
 #[derive(Debug, Clone, Copy)]
+#[allow(dead_code)]
 pub(crate) enum UndoState {
     Shown,
     Hidden,
@@ -38,12 +39,7 @@ impl Default for InAppNotification {
 }
 
 impl InAppNotification {
-    pub(crate) fn new<F, U>(
-        text: &str,
-        mut callback: F,
-        undo_callback: U,
-        show_undo: UndoState,
-    ) -> Self
+    pub(crate) fn new<F, U>(text: &str, mut callback: F, undo_callback: Option<U>) -> Self
     where
         F: FnMut() -> glib::Continue + 'static,
         U: Fn() + 'static,
@@ -58,6 +54,10 @@ impl InAppNotification {
         });
         let id = Rc::new(RefCell::new(Some(id)));
 
+        if undo_callback.is_some() {
+            notif.set_undo_state(UndoState::Shown)
+        };
+
         // Cancel the callback
         let revealer = notif.revealer.clone();
         notif.undo.connect_clicked(move |_| {
@@ -66,7 +66,9 @@ impl InAppNotification {
                 glib::source::source_remove(id);
             }
 
-            undo_callback();
+            if let Some(ref f) = undo_callback {
+                f();
+            }
 
             // Hide the notification
             revealer.set_reveal_child(false);
@@ -78,11 +80,6 @@ impl InAppNotification {
             revealer.set_reveal_child(false);
         });
 
-        match show_undo {
-            UndoState::Shown => (),
-            UndoState::Hidden => notif.undo.hide(),
-        }
-
         notif
     }
 
@@ -96,4 +93,11 @@ impl InAppNotification {
         // so there will be a nice animation.
         self.revealer.set_reveal_child(true);
     }
+
+    pub(crate) fn set_undo_state(&self, state: UndoState) {
+        match state {
+            UndoState::Shown => self.undo.show(),
+            UndoState::Hidden => self.undo.hide(),
+        }
+    }
 }

podcasts-gtk/src/widgets/show_menu.rs

@@ -13,7 +13,7 @@ use podcasts_data::Show;
 
 use app::Action;
 use utils;
-use widgets::appnotif::{InAppNotification, UndoState};
+use widgets::appnotif::InAppNotification;
 
 use std::sync::Arc;
 
@@ -145,7 +145,7 @@ pub(crate) fn mark_all_notif(pd: Arc<Show>, sender: &Sender<Action>) -> InAppNot
 
     let undo_callback = clone!(sender => move || sender.send(Action::RefreshWidgetIfSame(id)));
     let text = i18n("Marked all episodes as listened");
-    InAppNotification::new(&text, callback, undo_callback, UndoState::Shown)
+    InAppNotification::new(&text, callback, Some(undo_callback))
 }
 
 pub(crate) fn remove_show_notif(pd: Arc<Show>, sender: Sender<Action>) -> InAppNotification {
@@ -177,5 +177,5 @@ pub(crate) fn remove_show_notif(pd: Arc<Show>, sender: Sender<Action>) -> InAppN
         sender.send(Action::RefreshEpisodesView);
     };
 
-    InAppNotification::new(&text, callback, undo_callback, UndoState::Shown)
+    InAppNotification::new(&text, callback, Some(undo_callback))
 }