Mild cleanups

fitnesstrax/app/Cargo.toml

@@ -7,6 +7,7 @@ edition = "2021"
 
 [dependencies]
 adw             = { version = "0.5", package = "libadwaita", features = [ "v1_2" ] }
+async-channel   = { version = "2.1" }
 emseries        = { path = "../../emseries" }
 ft-core         = { path = "../core" }
 gio             = { version = "0.18" }

fitnesstrax/app/src/main.rs

@@ -17,6 +17,7 @@ You should have received a copy of the GNU General Public License along with Fit
 mod ui;
 
 use adw::prelude::*;
+use async_channel::{Receiver, Sender};
 use emseries::{EmseriesReadError, Series};
 use ft_core::TraxRecord;
 use gio::resources_lookup_data;
@@ -36,43 +37,77 @@ const APP_ID_PROD: &str = "com.luminescent-dreams.fitnesstrax";
 
 const RESOURCE_BASE_PATH: &str = "/com/luminescent-dreams/fitnesstrax/";
 
-/// A set of events that can occur at the global application level. These events should represent
+/// Invocations are how parts of the application, primarily the UI, will send requests to the core.
-/// significant state changes that should go through a central dispatcher.
+#[derive(Debug)]
-enum Events {
+enum AppInvocation {
-    DatabaseChanged(Series<TraxRecord>),
+    /// Tell the core to try to open a database.
+    OpenDatabase(PathBuf),
+
+    /// Request a set of records from the core.
+    // Note: this will require a time range, but doesn't yet.
+    RequestRecords,
 }
+
+/// Responses are messages that the core sends to the UI. Though they are called responses, the
+/// could actually be pre-emptively sent, such as notifications. The UI will need to be able to
+/// process those any time they arrive.
+///
+/// A typical use would be for the UI to send an [AppInvocation::RequestRecords] request and
+/// receive [AppResponse::Records].
+#[derive(Debug)]
+enum AppResponse {
+    /// No database is available. The UI should typically display a placeholder, such as the
+    /// welcome view.
+    NoDatabase,
+
+    /// The database is open and here is a set of records. Typically, the set of records will be
+    /// all of the records within a time frame, but this can actually be any set of records.
+    Records,
+
+    /// The database has been changed. This message is useful for telling the UI that a significant
+    /// change has happened. Further, the UI needs to save PathBuf to settings, because the
+    /// gio::Settings system can't be run in the fully async background.
+    DatabaseChanged(PathBuf),
+}
+
 // Note that I have not yet figured out the communication channel or how the central dispatcher
 // should work. There's a dance between the App and the AppWindow that I haven't figured out yet.
 
 /// The real, headless application. This is where all of the logic will reside.
 #[derive(Clone)]
 struct App {
-    settings: gio::Settings,
     database: Arc<RwLock<Option<Series<TraxRecord>>>>,
 }
 
 impl App {
-    pub fn new(settings: gio::Settings) -> Self {
+    pub fn new(db_path: Option<PathBuf>) -> Self {
+        let database = db_path.map(|path| Series::open(path).unwrap());
         let s = Self {
-            settings,
+            database: Arc::new(RwLock::new(database)),
-            database: Arc::new(RwLock::new(None)),
         };
 
-        if !s.settings.string("series-path").is_empty() {
-            let path = PathBuf::from(s.settings.string("series-path"));
-            let db = Series::open(path).unwrap();
-            *s.database.write().unwrap() = Some(db);
-        }
-
         s
     }
 
+    pub async fn process_invocation(&self, invocation: AppInvocation) -> AppResponse {
+        match invocation {
+            AppInvocation::OpenDatabase(db_path) => {
+                self.open_db(&db_path);
+                AppResponse::DatabaseChanged(db_path)
+            }
+            AppInvocation::RequestRecords => {
+                if self.database.read().unwrap().is_none() {
+                    AppResponse::NoDatabase
+                } else {
+                    AppResponse::Records
+                }
+            }
+        }
+    }
+
     pub fn open_db(&self, path: &Path) {
         let db = Series::open(path).unwrap();
         *self.database.write().unwrap() = Some(db);
-        self.settings
-            .set_string("series-path", path.to_str().unwrap())
-            .unwrap();
     }
 }
 
@@ -218,14 +253,38 @@ impl HistoricalView {
     }
 }
 
+#[derive(Clone, Debug, PartialEq)]
+enum ViewName {
+    Placeholder,
+    Welcome,
+    Historical,
+}
+
+enum View {
+    Placeholder(gtk::Widget),
+    Welcome(gtk::Widget),
+    Historical(gtk::Widget),
+}
+
+impl View {
+    fn widget<'a>(&'a self) -> &'a gtk::Widget {
+        match self {
+            View::Placeholder(widget) => widget,
+            View::Welcome(widget) => widget,
+            View::Historical(widget) => widget,
+        }
+    }
+}
+
 /// The application window, or the main window, is the main user interface for the app. Almost
 /// everything occurs here.
 #[derive(Clone)]
 struct AppWindow {
-    app: App,
+    app_tx: Sender<AppInvocation>,
     window: adw::ApplicationWindow,
     layout: gtk::Box,
-    current_view: Rc<RefCell<gtk::Widget>>,
+    current_view: Rc<RefCell<View>>,
+    settings: gio::Settings,
 }
 
 impl AppWindow {
@@ -235,7 +294,7 @@ impl AppWindow {
     /// otherwise we don't use this.
     ///
     /// app is a core [App] object which encapsulates all of the basic logic.
-    fn new(adw_app: &adw::Application, app: App) -> AppWindow {
+    fn new(app_id: &str, adw_app: &adw::Application, app_tx: Sender<AppInvocation>) -> AppWindow {
         let window = adw::ApplicationWindow::builder()
             .application(adw_app)
             .width_request(800)
@@ -266,59 +325,74 @@ impl AppWindow {
             .orientation(gtk::Orientation::Vertical)
             .build();
 
-        let initial_view = PlaceholderView::new();
+        let initial_view = View::Placeholder(PlaceholderView::new().upcast());
 
         layout.append(&header);
-        layout.append(&initial_view);
+        layout.append(initial_view.widget());
 
         window.set_content(Some(&layout));
         window.present();
 
         let s = Self {
-            app: app.clone(),
+            app_tx,
             window,
             layout,
-            current_view: Rc::new(RefCell::new(initial_view.upcast())),
+            current_view: Rc::new(RefCell::new(initial_view)),
+            settings: gio::Settings::new(app_id),
         };
 
-        let initial_view = if app.database.read().unwrap().is_none() {
-            WelcomeView::new({
-                let app = app.clone();
-                let s = s.clone();
-                Box::new(move |path: PathBuf| {
-                    // The user has selected a path. Perhaps the path is new, perhaps it already
-                    // exists.
-                    //
-                    // If the file exists already, attempt to read it. Fail if that doesn't work.
-                    // A should show to the user something that indicates that the file exists but is
-                    // not already a database.
-                    //
-                    // If the file does not exist, create a new one. Again, show the user an error if
-                    // some kind of error occurs.
-                    app.open_db(&path);
-                    s.change_view(HistoricalView::new().upcast());
-                })
-            })
-            .upcast()
-        } else {
-            HistoricalView::new().upcast()
-        };
-
-        s.change_view(initial_view);
-
         s
     }
 
+    pub fn change_view(&self, view: ViewName) {
+        self.swap_main(self.construct_view(view));
+    }
+
+    pub fn process_response(&self, response: AppResponse) {
+        match response {
+            AppResponse::DatabaseChanged(db_path) => {
+                self.settings
+                    .set_string("series-path", db_path.to_str().unwrap())
+                    .unwrap();
+                self.change_view(ViewName::Historical);
+            }
+            AppResponse::NoDatabase => {
+                self.change_view(ViewName::Welcome);
+            }
+            AppResponse::Records => {
+                self.change_view(ViewName::Historical);
+            }
+        }
+    }
+
     // Switch views.
     //
     // This function only replaces the old view with the one which matches the current view state.
     // It is responsible for ensuring that the new view goes into the layout in the correct
     // position.
-    fn change_view(&self, view: gtk::Widget) {
+    fn swap_main(&self, view: View) {
-        let mut current_view = self.current_view.borrow_mut();
+        let mut current_widget = self.current_view.borrow_mut();
-        self.layout.remove(&*current_view);
+        self.layout.remove(&*current_widget.widget());
-        *current_view = view;
+        *current_widget = view;
-        self.layout.append(&*current_view);
+        self.layout.append(&*current_widget.widget());
+    }
+
+    fn construct_view(&self, view: ViewName) -> View {
+        match view {
+            ViewName::Placeholder => View::Placeholder(PlaceholderView::new().upcast()),
+            ViewName::Welcome => View::Welcome(
+                WelcomeView::new({
+                    let s = self.clone();
+                    Box::new(move |path: PathBuf| {
+                        s.app_tx
+                            .send_blocking(AppInvocation::OpenDatabase(path))
+                            .unwrap();
+                    })
+                })
+                .upcast(),
+            ),
+            ViewName::Historical => View::Historical(HistoricalView::new().upcast()),
+        }
     }
 }
 
@@ -337,25 +411,68 @@ fn main() {
     };
 
     let settings = gio::Settings::new(app_id);
-
+    let app = App::new({
-    println!("database path: {}", settings.string("series-path"));
+        let path = settings.string("series-path");
-
+        if path.is_empty() {
-    let app = App::new(settings);
+            None
-
+        } else {
-    /*
+            Some(PathBuf::from(path))
-    let runtime = tokio::runtime::Builder::new_multi_thread()
+        }
-        .enable_all()
+    });
-        .build()
-        .unwrap();
-        */
 
     let adw_app = adw::Application::builder()
         .application_id(app_id)
         .resource_base_path(RESOURCE_BASE_PATH)
         .build();
 
+    let runtime = tokio::runtime::Builder::new_multi_thread()
+        .enable_all()
+        .build()
+        .unwrap();
+
     adw_app.connect_activate(move |adw_app| {
-        AppWindow::new(adw_app, app.clone());
+        // These channels are used to send messages to the UI. Anything that needs to send a
+        // message to the UI will send it via `ui_tx`. We will have one single process that owns
+        // `ui_rx`. That process will read messages coming in and send them to AppWindow for proper
+        // processing.
+        //
+        // The core app will usually only send messages in response to a request, but this channel
+        // can also be used to tell the UI that something happened in the background, such as
+        // detecting a watch, detecting new tracks to import, and so forth.
+        let (ui_tx, ui_rx) = async_channel::unbounded::<AppResponse>();
+
+        // These channels are used for communicating with the app. Already I can see that a lot of
+        // different event handlers will need copies of app_tx in order to send requests into the
+        // UI.
+        let (app_tx, app_rx) = async_channel::unbounded::<AppInvocation>();
+
+        let window = AppWindow::new(app_id, adw_app, app_tx.clone());
+
+        // Spawn a future where the UI will receive messages for the app window. Previously, this
+        // would have been done by creating a glib::MainContext::channel(), but that has been
+        // deprecated since gtk 4.10 in favor of using `async_channel`.
+        glib::spawn_future_local(async move {
+            // The app requests data to start with. This kicks everything off. The response from
+            // the app will cause the window to be updated shortly.
+            let _ = app_tx.send(AppInvocation::RequestRecords).await;
+
+            while let Ok(response) = ui_rx.recv().await {
+                window.process_response(response);
+            }
+        });
+
+        // The tokio runtime starts up here and will handle all of the asynchronous operations that
+        // the application needs to do. Messages arrive on `app_rx` and responses will be sent via
+        // `ui_tx`.
+        runtime.spawn({
+            let app = app.clone();
+            async move {
+                while let Ok(invocation) = app_rx.recv().await {
+                    let response = app.process_invocation(invocation).await;
+                    let _ = ui_tx.send(response).await;
+                }
+            }
+        });
     });
 
     let args: Vec<String> = env::args().collect();