Handle results

src/main.rs

@@ -57,13 +57,17 @@ fn main() {
     // Initialize the terminal user interface.
     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 ui = Ui::new();
+
     let app = App::new(collection_manager).expect("failed to initialise app");
-    let mut tui = Tui::new(terminal, listener, handler, ui, app);
+
+    let tui = Tui::new(terminal, listener, handler, ui, app);
 
     // Run the TUI application.
-    tui.run();
+    tui.run().expect("failed to run tui");
 }

src/tui/event.rs

@@ -1,8 +1,39 @@
 use crossterm::event::{self, Event as CrosstermEvent, KeyEvent, MouseEvent};
 use std::sync::mpsc;
-use std::thread;
+use std::{fmt, thread};
 
-#[derive(Clone, Copy)]
+#[derive(Debug)]
+pub enum EventError {
+    SendError(Event),
+    RecvError,
+    IoError(std::io::Error),
+}
+
+impl fmt::Display for EventError {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        match *self {
+            Self::SendError(ref e) => write!(f, "failed to send event: {e:?}"),
+            Self::RecvError => write!(f, "receive event call failed"),
+            Self::IoError(ref e) => {
+                write!(f, "an I/O error was triggered during event handling: {e}")
+            }
+        }
+    }
+}
+
+impl From<mpsc::SendError<Event>> for EventError {
+    fn from(err: mpsc::SendError<Event>) -> EventError {
+        EventError::SendError(err.0)
+    }
+}
+
+impl From<mpsc::RecvError> for EventError {
+    fn from(_: mpsc::RecvError) -> EventError {
+        EventError::RecvError
+    }
+}
+
+#[derive(Clone, Copy, Debug)]
 pub enum Event {
     Key(KeyEvent),
     Mouse(MouseEvent),
@@ -43,44 +74,46 @@ impl EventChannel {
 }
 
 impl EventSender {
-    pub fn send(&self, event: Event) {
-        self.sender
-            .send(event)
-            .expect("failed to send terminal event");
+    pub fn send(&self, event: Event) -> Result<(), EventError> {
+        Ok(self.sender.send(event)?)
     }
 }
 
 impl EventReceiver {
-    pub fn recv(&self) -> Event {
-        self.receiver
-            .recv()
-            .expect("failed to receive terminal event")
+    pub fn recv(&self) -> Result<Event, EventError> {
+        Ok(self.receiver.recv()?)
     }
 }
 
 pub struct EventListener {
-    events: Option<EventSender>,
+    events: EventSender,
 }
 
 impl EventListener {
     pub fn new(events: EventSender) -> EventListener {
-        EventListener {
-            events: Some(events),
-        }
+        EventListener { events }
     }
 
-    pub fn spawn(&mut self) {
-        let sender = self.events.take().unwrap();
-        thread::spawn(move || loop {
+    pub fn spawn(self) -> thread::JoinHandle<EventError> {
+        thread::spawn(move || {
+            loop {
                 // Put this inside an if event::poll {...} if the display needs to be refreshed on a
                 // periodic basis. See
                 // https://github.com/tui-rs-revival/rust-tui-template/blob/master/src/event.rs.
-            match event::read().expect("unable to read event") {
-                CrosstermEvent::Key(e) => sender.send(Event::Key(e)),
-                CrosstermEvent::Mouse(e) => sender.send(Event::Mouse(e)),
-                CrosstermEvent::Resize(w, h) => sender.send(Event::Resize(w, h)),
+                match event::read() {
+                    Ok(event) => {
+                        if let Err(err) = match event {
+                            CrosstermEvent::Key(e) => self.events.send(Event::Key(e)),
+                            CrosstermEvent::Mouse(e) => self.events.send(Event::Mouse(e)),
+                            CrosstermEvent::Resize(w, h) => self.events.send(Event::Resize(w, h)),
                             _ => unimplemented!(),
-            }
-        });
+                        } {
+                            return err;
+                        }
+                    }
+                    Err(err) => return EventError::IoError(err),
+                };
+            }
+        })
     }
 }

src/tui/handler.rs

@@ -1,6 +1,6 @@
 use crossterm::event::{KeyCode, KeyEvent, KeyModifiers};
 
-use super::{app::App, event::{Event, EventReceiver}};
+use super::{app::App, event::{Event, EventReceiver, EventError}};
 
 pub struct EventHandler {
     events: EventReceiver,
@@ -11,12 +11,13 @@ impl EventHandler {
         EventHandler { events }
     }
 
-    pub fn handle_next_event(&mut self, app: &mut App) {
-        match self.events.recv() {
+    pub fn handle_next_event(&mut self, app: &mut App) -> Result<(), EventError> {
+        match self.events.recv()? {
             Event::Key(key_event) => Self::handle_key_event(app, key_event),
             Event::Mouse(_) => {}
             Event::Resize(_, _) => {}
-        }
+        };
+        Ok(())
     }
 
     fn handle_key_event(app: &mut App, key_event: KeyEvent) {

src/tui/mod.rs

@@ -11,13 +11,16 @@ pub mod handler;
 pub mod ui;
 
 use self::app::App;
-use self::event::EventListener;
+use self::event::{EventError, EventListener};
 use self::handler::EventHandler;
 use self::ui::Ui;
 
 #[derive(Debug)]
 pub enum Error {
     CollectionError(String),
+    IoError(String),
+    EventError(String),
+    ListenerPanic,
 }
 
 impl From<collection::Error> for Error {
@@ -26,9 +29,21 @@ impl From<collection::Error> for Error {
     }
 }
 
+impl From<io::Error> for Error {
+    fn from(err: io::Error) -> Error {
+        Error::IoError(err.to_string())
+    }
+}
+
+impl From<EventError> for Error {
+    fn from(err: EventError) -> Error {
+        Error::EventError(err.to_string())
+    }
+}
+
 pub struct Tui<B: Backend> {
     terminal: Terminal<B>,
-    listener: EventListener,
+    listener: Option<EventListener>,
     handler: EventHandler,
     ui: Ui,
     app: App,
@@ -44,37 +59,71 @@ impl<B: Backend> Tui<B> {
     ) -> Self {
         Self {
             terminal,
-            listener,
+            listener: Some(listener),
             handler,
             ui,
             app,
         }
     }
 
-    fn init(&mut self) {
-        terminal::enable_raw_mode().unwrap();
-        crossterm::execute!(io::stdout(), EnterAlternateScreen, EnableMouseCapture).unwrap();
-        self.terminal.hide_cursor().unwrap();
-        self.terminal.clear().unwrap();
+    fn init(&mut self) -> Result<(), Error> {
+        terminal::enable_raw_mode()?;
+        crossterm::execute!(io::stdout(), EnterAlternateScreen, EnableMouseCapture)?;
+        self.terminal.hide_cursor()?;
+        self.terminal.clear()?;
+        Ok(())
     }
 
-    pub fn run(&mut self) {
-        self.init();
-
-        self.listener.spawn();
+    fn run_loop(&mut self) -> Result<(), Error> {
         while self.app.is_running() {
             self.terminal
-                .draw(|frame| self.ui.render(&mut self.app, frame))
-                .unwrap();
-            self.handler.handle_next_event(&mut self.app);
+                .draw(|frame| self.ui.render(&mut self.app, frame))?;
+            self.handler.handle_next_event(&mut self.app)?;
         }
 
+        Ok(())
+    }
+
+    pub fn run(mut self) -> Result<(), Error> {
+        self.init()?;
+
+        let listener_handle = self.listener.take().unwrap().spawn();
+        let result = self.run_loop();
+
+        match result {
+            Ok(_) => {
+                self.exit()?;
+                Ok(())
+            }
+            Err(err) => {
+                // We want to call exit before handling the run_loop result to reset the terminal.
+                // Therefore, we suppress exit errors (if any) to not mask the original error.
+                self.exit_suppress_errors();
+
+                if listener_handle.is_finished() {
+                    match listener_handle.join() {
+                        Ok(err) => return Err(err.into()),
+                        // Calling std::panic::resume_unwind(err) as recommended by the Rust docs
+                        // will not produce an error message. The panic error message is printed at
+                        // the location of the panic which at the time is hidden by the TUI.
+                        Err(_) => return Err(Error::ListenerPanic),
+                    }
+                }
+
+                Err(err)
+            }
+        }
+    }
+
+    fn exit(&mut self) -> Result<(), Error> {
+        terminal::disable_raw_mode()?;
+        crossterm::execute!(io::stdout(), LeaveAlternateScreen, DisableMouseCapture)?;
+        self.terminal.show_cursor()?;
+        Ok(())
+    }
+
+    #[allow(unused_must_use)]
+    fn exit_suppress_errors(&mut self) {
         self.exit();
     }
-
-    fn exit(&mut self) {
-        terminal::disable_raw_mode().unwrap();
-        crossterm::execute!(io::stdout(), LeaveAlternateScreen, DisableMouseCapture).unwrap();
-        self.terminal.show_cursor().unwrap();
-    }
 }