Proof of principle working

src/main.rs

@@ -79,18 +79,19 @@ fn with<Database: IDatabase + 'static, Library: ILibrary + 'static>(
     let backend = CrosstermBackend::new(io::stdout());
     let terminal = Terminal::new(backend).expect("failed to initialise terminal");
 
-    let channel = EventChannel::new();
-    let listener = EventListener::new(channel.sender());
-    let handler = EventHandler::new(channel.receiver());
-
     let http =
         MusicBrainzHttp::new(MUSICHOARD_HTTP_USER_AGENT).expect("failed to initialise HTTP client");
     let client = MusicBrainzClient::new(http);
     let musicbrainz = MusicBrainz::new(client);
 
-    let app = App::new(music_hoard, musicbrainz);
+    let channel = EventChannel::new();
+    let listener = EventListener::new(channel.sender());
+
+    let app = App::new(music_hoard, musicbrainz, channel.sender());
     let ui = Ui;
 
+    let handler = EventHandler::new(channel.receiver());
+
     // Run the TUI application.
     Tui::run(terminal, app, ui, handler, listener).expect("failed to run tui");
 }

src/tui/app/machine/error.rs

@@ -39,6 +39,10 @@ impl IAppInteractError for AppMachine<AppError> {
     fn dismiss_error(self) -> Self::APP {
         AppMachine::browse(self.inner).into()
     }
+
+    fn no_op(self) -> Self::APP {
+        self.into()
+    }
 }
 
 #[cfg(test)]

src/tui/app/machine/fetch.rs

@@ -1,5 +1,8 @@
 use std::{
-    sync::{mpsc, Arc, Mutex},
+    sync::{
+        mpsc::{self, TryRecvError},
+        Arc, Mutex,
+    },
     thread, time,
 };
 
@@ -11,10 +14,8 @@ use musichoard::collection::{
 
 use crate::tui::{
     app::{
-        machine::{App, AppInner, AppMachine},
-        AppMatchesInfo, AppPublic, AppState, IAppInteractFetch,
-    },
-    lib::interface::musicbrainz::{Error as MbError, IMusicBrainz},
+        machine::{App, AppInner, AppMachine}, AppMatchesInfo, AppPublic, AppState, IAppEventFetch, IAppInteractFetch
+    }, event::{Event, EventSender}, lib::interface::musicbrainz::{Error as MbError, IMusicBrainz}
 };
 
 use super::matches::AppMatches;
@@ -24,6 +25,10 @@ pub struct AppFetch {
 }
 
 impl AppMachine<AppFetch> {
+    fn fetch(inner: AppInner, state: AppFetch) -> Self {
+        AppMachine { inner, state }
+    }
+
     pub fn app_fetch_new(inner: AppInner) -> App {
         let coll = inner.music_hoard.get_collection();
         let artist = match inner.selection.state_artist(coll) {
@@ -36,14 +41,16 @@ impl AppMachine<AppFetch> {
         match artist.meta.musicbrainz {
             Some(ref arid) => {
                 let musicbrainz = Arc::clone(&inner.musicbrainz);
+                let events = inner.events.clone();
                 let arid = arid.mbid().clone();
                 let albums = artist.albums.iter().map(|a| &a.meta).cloned().collect();
-                thread::spawn(|| Self::fetch_albums(musicbrainz, fetch_tx, arid, albums));
+                thread::spawn(|| Self::fetch_albums(musicbrainz, fetch_tx, events, arid, albums));
             }
             None => {
                 let musicbrainz = Arc::clone(&inner.musicbrainz);
+                let events = inner.events.clone();
                 let artist = artist.meta.clone();
-                thread::spawn(|| Self::fetch_artist(musicbrainz, fetch_tx, artist));
+                thread::spawn(|| Self::fetch_artist(musicbrainz, fetch_tx, events, artist));
             }
         };
 
@@ -52,23 +59,27 @@ impl AppMachine<AppFetch> {
     }
 
     pub fn app_fetch_next(inner: AppInner, fetch: AppFetch, first: bool) -> App {
-        match fetch.fetch_rx.recv() {
+        match fetch.fetch_rx.try_recv() {
             Ok(fetch_result) => match fetch_result {
                 Ok(mut next_match) => {
                     next_match.push_cannot_have_mbid();
                     let current = Some(next_match);
                     AppMachine::matches(inner, AppMatches::new(current, fetch)).into()
                 }
-                Err(err) => AppMachine::error(inner, format!("fetch failed: {err}")).into(),
+                Err(fetch_err) => {
+                    AppMachine::error(inner, format!("fetch failed: {fetch_err}")).into()
+                }
             },
-            // only happens when the sender disconnects which means it finished its job
-            Err(_) => {
+            Err(try_recv_err) => match try_recv_err {
+                TryRecvError::Disconnected => {
                     if first {
                         AppMachine::matches(inner, AppMatches::empty(fetch)).into()
                     } else {
                         AppMachine::browse(inner).into()
                     }
                 }
+                TryRecvError::Empty => AppMachine::fetch(inner, fetch).into(),
+            },
         }
     }
 }
@@ -104,6 +115,14 @@ impl IAppInteractFetch for AppMachine<AppFetch> {
     }
 }
 
+impl IAppEventFetch for AppMachine<AppFetch> {
+    type APP = App;
+
+    fn fetch_result_ready(self) -> Self::APP {
+        Self::app_fetch_next(self.inner, self.state, false)
+    }
+}
+
 type FetchError = MbError;
 type FetchResult = Result<AppMatchesInfo, FetchError>;
 type FetchSender = mpsc::Sender<FetchResult>;
@@ -113,11 +132,13 @@ trait IAppInteractFetchPrivate {
     fn fetch_artist(
         musicbrainz: Arc<Mutex<dyn IMusicBrainz + Send>>,
         fetch_tx: FetchSender,
+        events: EventSender,
         artist: ArtistMeta,
     );
     fn fetch_albums(
         musicbrainz: Arc<Mutex<dyn IMusicBrainz + Send>>,
         fetch_tx: FetchSender,
+        events: EventSender,
         arid: Mbid,
         albums: Vec<AlbumMeta>,
     );
@@ -127,16 +148,22 @@ impl IAppInteractFetchPrivate for AppMachine<AppFetch> {
     fn fetch_artist(
         musicbrainz: Arc<Mutex<dyn IMusicBrainz + Send>>,
         fetch_tx: FetchSender,
+        events: EventSender,
         artist: ArtistMeta,
     ) {
         let result = musicbrainz.lock().unwrap().search_artist(&artist);
         let result = result.map(|list| AppMatchesInfo::artist(artist, list));
-        fetch_tx.send(result).ok();
+        if fetch_tx.send(result).is_ok() {
+            // If this send fails the event listener is dead. Don't panic as this function runs
+            // in a detached thread so this might be happening during normal shut down.
+            events.send(Event::FetchResultReady).ok();
+        }
     }
 
     fn fetch_albums(
         musicbrainz: Arc<Mutex<dyn IMusicBrainz + Send>>,
         fetch_tx: FetchSender,
+        events: EventSender,
         arid: Mbid,
         albums: Vec<AlbumMeta>,
     ) {
@@ -154,6 +181,12 @@ impl IAppInteractFetchPrivate for AppMachine<AppFetch> {
                 return;
             }
 
+            if events.send(Event::FetchResultReady).is_err() {
+                // If this send fails the event listener is dead. Don't panic as this function runs
+                // in a detached thread so this might be happening during normal shut down.
+                return;
+            }
+
             if album_iter.peek().is_some() {
                 thread::sleep(time::Duration::from_secs(1));
             }

src/tui/app/machine/mod.rs

@@ -11,6 +11,7 @@ use std::sync::{Arc, Mutex};
 
 use crate::tui::{
     app::{selection::Selection, AppPublic, AppPublicInner, AppState, IAppAccess, IAppInteract},
+    event::EventSender,
     lib::{interface::musicbrainz::IMusicBrainz, IMusicHoard},
 };
 
@@ -44,15 +45,17 @@ pub struct AppInner {
     music_hoard: Box<dyn IMusicHoard>,
     musicbrainz: Arc<Mutex<dyn IMusicBrainz + Send>>,
     selection: Selection,
+    events: EventSender,
 }
 
 impl App {
     pub fn new<MH: IMusicHoard + 'static, MB: IMusicBrainz + Send + 'static>(
         mut music_hoard: MH,
         musicbrainz: MB,
+        events: EventSender,
     ) -> Self {
         let init_result = Self::init(&mut music_hoard);
-        let inner = AppInner::new(music_hoard, musicbrainz);
+        let inner = AppInner::new(music_hoard, musicbrainz, events);
         match init_result {
             Ok(()) => AppMachine::browse(inner).into(),
             Err(err) => AppMachine::critical(inner, err.to_string()).into(),
@@ -137,6 +140,7 @@ impl AppInner {
     pub fn new<MH: IMusicHoard + 'static, MB: IMusicBrainz + Send + 'static>(
         music_hoard: MH,
         musicbrainz: MB,
+        events: EventSender,
     ) -> Self {
         let selection = Selection::new(music_hoard.get_collection());
         AppInner {
@@ -144,6 +148,7 @@ impl AppInner {
             music_hoard: Box::new(music_hoard),
             musicbrainz: Arc::new(Mutex::new(musicbrainz)),
             selection,
+            events,
         }
     }
 }
@@ -165,7 +170,7 @@ mod tests {
 
     use crate::tui::{
         app::{AppState, IAppInteract, IAppInteractBrowse},
-        lib::{interface::musicbrainz::MockIMusicBrainz, MockIMusicHoard},
+        lib::{interface::musicbrainz::MockIMusicBrainz, MockIMusicHoard}, EventChannel,
     };
 
     use super::*;
@@ -250,17 +255,21 @@ mod tests {
         MockIMusicBrainz::new()
     }
 
+    fn events() -> EventSender {
+        EventChannel::new().sender()
+    }
+
     pub fn inner(music_hoard: MockIMusicHoard) -> AppInner {
-        AppInner::new(music_hoard, mb_api())
+        AppInner::new(music_hoard, mb_api(), events())
     }
 
     pub fn inner_with_mb(music_hoard: MockIMusicHoard, mb_api: MockIMusicBrainz) -> AppInner {
-        AppInner::new(music_hoard, mb_api)
+        AppInner::new(music_hoard, mb_api, events())
     }
 
     #[test]
     fn state_browse() {
-        let mut app = App::new(music_hoard_init(vec![]), mb_api());
+        let mut app = App::new(music_hoard_init(vec![]), mb_api(), events());
         assert!(app.is_running());
 
         let state = app.state();
@@ -276,7 +285,7 @@ mod tests {
 
     #[test]
     fn state_info() {
-        let mut app = App::new(music_hoard_init(vec![]), mb_api());
+        let mut app = App::new(music_hoard_init(vec![]), mb_api(), events());
         assert!(app.is_running());
 
         app = app.unwrap_browse().show_info_overlay();
@@ -294,7 +303,7 @@ mod tests {
 
     #[test]
     fn state_reload() {
-        let mut app = App::new(music_hoard_init(vec![]), mb_api());
+        let mut app = App::new(music_hoard_init(vec![]), mb_api(), events());
         assert!(app.is_running());
 
         app = app.unwrap_browse().show_reload_menu();
@@ -312,7 +321,7 @@ mod tests {
 
     #[test]
     fn state_search() {
-        let mut app = App::new(music_hoard_init(vec![]), mb_api());
+        let mut app = App::new(music_hoard_init(vec![]), mb_api(), events());
         assert!(app.is_running());
 
         app = app.unwrap_browse().begin_search();
@@ -349,7 +358,7 @@ mod tests {
 
     #[test]
     fn state_error() {
-        let mut app = App::new(music_hoard_init(vec![]), mb_api());
+        let mut app = App::new(music_hoard_init(vec![]), mb_api(), events());
         assert!(app.is_running());
 
         app = AppMachine::error(app.unwrap_browse().inner, "get rekt").into();
@@ -367,7 +376,7 @@ mod tests {
 
     #[test]
     fn state_critical() {
-        let mut app = App::new(music_hoard_init(vec![]), mb_api());
+        let mut app = App::new(music_hoard_init(vec![]), mb_api(), events());
         assert!(app.is_running());
 
         app = AppMachine::critical(app.unwrap_browse().inner, "get rekt").into();
@@ -393,7 +402,7 @@ mod tests {
             .return_once(|| Err(musichoard::Error::LibraryError(String::from("get rekt"))));
         music_hoard.expect_get_collection().return_const(vec![]);
 
-        let app = App::new(music_hoard, mb_api());
+        let app = App::new(music_hoard, mb_api(), events());
         assert!(app.is_running());
         app.unwrap_critical();
     }

src/tui/app/mod.rs

@@ -24,7 +24,7 @@ pub trait IAppInteract {
     type IS: IAppInteractInfo<APP = Self>;
     type RS: IAppInteractReload<APP = Self>;
     type SS: IAppInteractSearch<APP = Self>;
-    type FS: IAppInteractFetch<APP = Self>;
+    type FS: IAppInteractFetch<APP = Self> + IAppEventFetch<APP = Self>;
     type MS: IAppInteractMatches<APP = Self>;
     type ES: IAppInteractError<APP = Self>;
     type CS: IAppInteractCritical<APP = Self>;
@@ -98,6 +98,12 @@ pub trait IAppInteractFetch {
     fn no_op(self) -> Self::APP;
 }
 
+pub trait IAppEventFetch {
+    type APP: IAppInteract;
+
+    fn fetch_result_ready(self) -> Self::APP;
+}
+
 pub trait IAppInteractMatches {
     type APP: IAppInteract;
 
@@ -114,6 +120,8 @@ pub trait IAppInteractError {
     type APP: IAppInteract;
 
     fn dismiss_error(self) -> Self::APP;
+
+    fn no_op(self) -> Self::APP;
 }
 
 pub trait IAppInteractCritical {

src/tui/event.rs

@@ -36,6 +36,7 @@ impl From<mpsc::RecvError> for EventError {
 #[derive(Clone, Copy, Debug)]
 pub enum Event {
     Key(KeyEvent),
+    FetchResultReady,
 }
 
 pub struct EventChannel {
@@ -43,6 +44,7 @@ pub struct EventChannel {
     receiver: mpsc::Receiver<Event>,
 }
 
+#[derive(Clone)]
 pub struct EventSender {
     sender: mpsc::Sender<Event>,
 }

src/tui/handler.rs

@@ -12,6 +12,8 @@ use crate::tui::{
     event::{Event, EventError, EventReceiver},
 };
 
+use super::app::IAppEventFetch;
+
 #[cfg_attr(test, automock)]
 pub trait IEventHandler<APP: IAppInteract> {
     fn handle_next_event(&self, app: APP) -> Result<APP, EventError>;
@@ -27,6 +29,8 @@ trait IEventHandlerPrivate<APP: IAppInteract> {
     fn handle_matches_key_event(app: <APP as IAppInteract>::MS, key_event: KeyEvent) -> APP;
     fn handle_error_key_event(app: <APP as IAppInteract>::ES, key_event: KeyEvent) -> APP;
     fn handle_critical_key_event(app: <APP as IAppInteract>::CS, key_event: KeyEvent) -> APP;
+
+    fn handle_fetch_result_ready_event(app: APP) -> APP;
 }
 
 pub struct EventHandler {
@@ -41,11 +45,11 @@ impl EventHandler {
 }
 
 impl<APP: IAppInteract> IEventHandler<APP> for EventHandler {
-    fn handle_next_event(&self, mut app: APP) -> Result<APP, EventError> {
-        match self.events.recv()? {
-            Event::Key(key_event) => app = Self::handle_key_event(app, key_event),
-        };
-        Ok(app)
+    fn handle_next_event(&self, app: APP) -> Result<APP, EventError> {
+        Ok(match self.events.recv()? {
+            Event::Key(key_event) => Self::handle_key_event(app, key_event),
+            Event::FetchResultReady => Self::handle_fetch_result_ready_event(app),
+        })
     }
 }
 
@@ -87,6 +91,19 @@ impl<APP: IAppInteract> IEventHandlerPrivate<APP> for EventHandler {
         }
     }
 
+    fn handle_fetch_result_ready_event(app: APP) -> APP {
+        match app.state() {
+            AppState::Browse(browse) => browse.no_op(),
+            AppState::Info(info) => info.no_op(),
+            AppState::Reload(reload) => reload.no_op(),
+            AppState::Search(search) => search.no_op(),
+            AppState::Fetch(fetch) => fetch.fetch_result_ready(),
+            AppState::Matches(matches) => matches.no_op(),
+            AppState::Error(error) => error.no_op(),
+            AppState::Critical(critical) => critical.no_op(),
+        }
+    }
+
     fn handle_browse_key_event(app: <APP as IAppInteract>::BS, key_event: KeyEvent) -> APP {
         match key_event.code {
             // Exit application on `ESC` or `q`.

src/tui/mod.rs

@@ -174,6 +174,7 @@ mod testmod;
 mod tests {
     use std::{io, thread};
 
+    use event::EventSender;
     use lib::interface::musicbrainz::MockIMusicBrainz;
     use ratatui::{backend::TestBackend, Terminal};
 
@@ -202,8 +203,12 @@ mod tests {
         music_hoard
     }
 
+    fn events() -> EventSender {
+        EventChannel::new().sender()
+    }
+
     fn app(collection: Collection) -> App {
-        App::new(music_hoard(collection), MockIMusicBrainz::new())
+        App::new(music_hoard(collection), MockIMusicBrainz::new(), events())
     }
 
     fn listener() -> MockIEventListener {