Clean up tui implementation

src/collection/mod.rs

@@ -1,3 +1,5 @@
+//! Module for managing the music collection, i.e. "The Music Hoard".
+
 use std::fmt;
 
 use crate::{
@@ -41,6 +43,8 @@ impl From<database::Error> for Error {
     }
 }
 
+/// The collection manager. It is responsible for pulling information from both the library and the
+/// database, ensuring its consistent and writing back any changes.
 pub struct CollectionManager {
     library: Box<dyn Library + Send + Sync>,
     database: Box<dyn Database + Send + Sync>,
@@ -48,6 +52,7 @@ pub struct CollectionManager {
 }
 
 impl CollectionManager {
+    /// Create a new [`CollectionManager`] with the provided [`Library`] and [`Database`].
     pub fn new(
         library: Box<dyn Library + Send + Sync>,
         database: Box<dyn Database + Send + Sync>,
@@ -59,16 +64,19 @@ impl CollectionManager {
         }
     }
 
+    /// Rescan the library and integrate any updates into the collection.
     pub fn rescan_library(&mut self) -> Result<(), Error> {
         self.collection = self.library.list(&Query::default())?;
         Ok(())
     }
 
+    /// Save the collection state to the database.
     pub fn save_to_database(&mut self) -> Result<(), Error> {
         self.database.write(&self.collection)?;
         Ok(())
     }
 
+    /// Get the current collection.
     pub fn get_collection(&self) -> &Collection {
         &self.collection
     }

src/library/mod.rs

@@ -115,10 +115,10 @@ impl fmt::Display for Error {
     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
         match *self {
             Self::CmdExecError(ref s) => write!(f, "the library failed to execute a command: {s}"),
-            Self::InvalidData(ref s) => write!(f, "the library returned invalid data: {s}"),
+            Self::InvalidData(ref s) => write!(f, "the library received invalid data: {s}"),
             Self::IoError(ref s) => write!(f, "the library experienced an I/O error: {s}"),
-            Self::ParseIntError(ref s) => write!(f, "the library returned an invalid integer: {s}"),
-            Self::Utf8Error(ref s) => write!(f, "the library returned invalid UTF-8: {s}"),
+            Self::ParseIntError(ref s) => write!(f, "the library received an invalid integer: {s}"),
+            Self::Utf8Error(ref s) => write!(f, "the library received invalid UTF-8: {s}"),
         }
     }
 }

src/main.rs

@@ -6,21 +6,17 @@ use std::path::PathBuf;
 use structopt::StructOpt;
 
 use musichoard::{
-    database::{
-        json::{JsonDatabase, JsonDatabaseFileBackend},
-        DatabaseWrite,
-    },
-    library::{
-        beets::{BeetsLibrary, BeetsLibraryCommandExecutor},
-        Library, Query,
-    }, collection::CollectionManager,
+    collection::CollectionManager,
+    database::json::{JsonDatabase, JsonDatabaseFileBackend},
+    library::beets::{BeetsLibrary, BeetsLibraryCommandExecutor},
 };
 
 mod tui;
 use tui::{
     app::App,
-    event::{Event, EventHandler},
-    handler::handle_key_events,
+    event::{EventChannel, EventListener},
+    handler::EventHandler,
+    ui::Ui,
     Tui,
 };
 
@@ -28,7 +24,7 @@ use tui::{
 struct Opt {
     #[structopt(
         short = "b",
-        long = "beets-config",
+        long = "beets",
         name = "beets config file path",
         parse(from_os_str)
     )]
@@ -58,25 +54,16 @@ fn main() {
 
     let collection_manager = CollectionManager::new(Box::new(beets), Box::new(database));
 
-    let mut app = App::new(collection_manager).expect("failed to initialise app");
-
     // Initialize the terminal user interface.
     let backend = CrosstermBackend::new(io::stdout());
     let terminal = Terminal::new(backend).expect("failed to initialise terminal");
-    let events = EventHandler::new();
-    let mut tui = Tui::new(terminal, events);
-    tui.init();
+    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);
 
-    // Main loop.
-    while app.is_running() {
-        tui.draw(&mut app);
-        match tui.events.next_event() {
-            Event::Key(key_event) => handle_key_events(key_event, &mut app),
-            Event::Mouse(_) => {}
-            Event::Resize(_, _) => {}
-        }
-    }
-
-    // Exit the user interface.
-    tui.exit();
+    // Run the TUI application.
+    tui.run();
 }

src/tui/app.rs

@@ -2,7 +2,7 @@ use musichoard::{collection::CollectionManager, Album, AlbumId, Artist, ArtistId
 
 use super::Error;
 
-#[derive(Copy, Clone)]
+#[derive(Copy, Clone, PartialEq, Eq)]
 pub enum Category {
     Artist,
     Album,
@@ -16,17 +16,6 @@ pub struct Selection {
     track: u16,
 }
 
-impl Default for Selection {
-    fn default() -> Self {
-        Selection {
-            active: Category::Artist,
-            artist: 0,
-            album: 0,
-            track: 0,
-        }
-    }
-}
-
 pub struct App {
     collection_manager: CollectionManager,
     selection: Selection,
@@ -38,7 +27,12 @@ impl App {
         collection_manager.rescan_library()?;
         Ok(App {
             collection_manager,
-            selection: Selection::default(),
+            selection: Selection {
+                active: Category::Artist,
+                artist: 0,
+                album: 0,
+                track: 0,
+            },
             running: true,
         })
     }
@@ -117,10 +111,10 @@ impl App {
     }
 
     fn increment_track_selection(&mut self) {
-        let artists: &Vec<Artist> = self.collection_manager.get_collection();
-        let albums: &Vec<Album> = &artists[self.selection.artist as usize].albums;
-        let tracks: &Vec<Track> = &albums[self.selection.album as usize].tracks;
         if let Some(result) = self.selection.track.checked_add(1) {
+            let artists: &Vec<Artist> = self.collection_manager.get_collection();
+            let albums: &Vec<Album> = &artists[self.selection.artist as usize].albums;
+            let tracks: &Vec<Track> = &albums[self.selection.album as usize].tracks;
             if (result as usize) < tracks.len() {
                 self.selection.track = result;
             }

src/tui/event.rs

@@ -2,59 +2,85 @@ use crossterm::event::{self, Event as CrosstermEvent, KeyEvent, MouseEvent};
 use std::sync::mpsc;
 use std::thread;
 
-/// Terminal events.
-#[derive(Clone, Copy, Debug)]
+#[derive(Clone, Copy)]
 pub enum Event {
-    /// Key press.
     Key(KeyEvent),
-    /// Mouse click/scroll.
     Mouse(MouseEvent),
-    /// Terminal resize.
     Resize(u16, u16),
 }
 
-/// Terminal event handler.
-#[derive(Debug)]
-pub struct EventHandler {
-    /// Event sender channel.
+pub struct EventChannel {
     sender: mpsc::Sender<Event>,
-    /// Event receiver channel.
     receiver: mpsc::Receiver<Event>,
-    /// Event handler thread.
-    handler: thread::JoinHandle<()>,
 }
 
-impl EventHandler {
-    /// Constructs a new instance of [`EventHandler`].
+#[derive(Clone)]
+pub struct EventSender {
+    sender: mpsc::Sender<Event>,
+}
+
+pub struct EventReceiver {
+    receiver: mpsc::Receiver<Event>,
+}
+
+impl EventChannel {
     pub fn new() -> Self {
         let (sender, receiver) = mpsc::channel();
-        let handler = {
-            let sender = sender.clone();
-            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)),
-                    _ => unimplemented!(),
-                }
-                .expect("failed to send terminal event")
-            })
-        };
-        Self {
-            sender,
-            receiver,
-            handler,
+        EventChannel { sender, receiver }
+    }
+
+    pub fn sender(&self) -> EventSender {
+        EventSender {
+            sender: self.sender.clone(),
         }
     }
 
-    /// Receive the next event from the handler thread.
-    ///
-    /// This function will always block the current thread if
-    /// there is no data available and it's possible for more data to be sent.
-    pub fn next_event(&self) -> Event {
-        self.receiver.recv().expect("failed to receive terminal event")
+    pub fn receiver(self) -> EventReceiver {
+        EventReceiver {
+            receiver: self.receiver,
+        }
+    }
+}
+
+impl EventSender {
+    pub fn send(&self, event: Event) {
+        self.sender
+            .send(event)
+            .expect("failed to send terminal event");
+    }
+}
+
+impl EventReceiver {
+    pub fn recv(&self) -> Event {
+        self.receiver
+            .recv()
+            .expect("failed to receive terminal event")
+    }
+}
+
+pub struct EventListener {
+    events: Option<EventSender>,
+}
+
+impl EventListener {
+    pub fn new(events: EventSender) -> EventListener {
+        EventListener {
+            events: Some(events),
+        }
+    }
+
+    pub fn spawn(&mut self) {
+        let sender = self.events.take().unwrap();
+        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)),
+                _ => unimplemented!(),
+            }
+        });
     }
 }

src/tui/handler.rs

@@ -1,35 +1,52 @@
 use crossterm::event::{KeyCode, KeyEvent, KeyModifiers};
 
-use super::app::App;
+use super::{app::App, event::{Event, EventReceiver}};
 
-/// Handles the key events and updates the state of [`App`].
-pub fn handle_key_events(key_event: KeyEvent, app: &mut App) {
-    match key_event.code {
-        // Exit application on `ESC` or `q`.
-        KeyCode::Esc | KeyCode::Char('q') => {
-            app.quit();
+pub struct EventHandler {
+    events: EventReceiver,
+}
+
+impl EventHandler {
+    pub fn new(events: EventReceiver) -> Self {
+        EventHandler { events }
+    }
+
+    pub fn handle_next_event(&mut self, app: &mut App) {
+        match self.events.recv() {
+            Event::Key(key_event) => Self::handle_key_event(app, key_event),
+            Event::Mouse(_) => {}
+            Event::Resize(_, _) => {}
         }
-        // Exit application on `Ctrl-C`.
-        KeyCode::Char('c') | KeyCode::Char('C') => {
-            if key_event.modifiers == KeyModifiers::CONTROL {
+    }
+
+    fn handle_key_event(app: &mut App, key_event: KeyEvent) {
+        match key_event.code {
+            // Exit application on `ESC` or `q`.
+            KeyCode::Esc | KeyCode::Char('q') => {
                 app.quit();
             }
+            // Exit application on `Ctrl-C`.
+            KeyCode::Char('c') | KeyCode::Char('C') => {
+                if key_event.modifiers == KeyModifiers::CONTROL {
+                    app.quit();
+                }
+            }
+            // Category change.
+            KeyCode::Left => {
+                app.decrement_category();
+            }
+            KeyCode::Right => {
+                app.increment_category();
+            }
+            // Selection change.
+            KeyCode::Up => {
+                app.decrement_selection();
+            }
+            KeyCode::Down => {
+                app.increment_selection();
+            }
+            // Other keys.
+            _ => {}
         }
-        // Category change.
-        KeyCode::Left => {
-            app.decrement_category();
-        }
-        KeyCode::Right => {
-            app.increment_category();
-        }
-        // Selection change.
-        KeyCode::Up => {
-            app.decrement_selection();
-        }
-        KeyCode::Down => {
-            app.increment_selection();
-        }
-        // Other handlers you could add here.
-        _ => {}
     }
 }

src/tui/mod.rs

@@ -8,17 +8,15 @@ use std::io;
 pub mod app;
 pub mod event;
 pub mod handler;
-
-mod ui;
-
-use event::EventHandler;
+pub mod ui;
 
 use self::app::App;
+use self::event::EventListener;
+use self::handler::EventHandler;
+use self::ui::Ui;
 
-/// Error type for the TUI.
 #[derive(Debug)]
 pub enum Error {
-    /// The collection manager failed.
     CollectionError(String),
 }
 
@@ -28,46 +26,53 @@ impl From<collection::Error> for Error {
     }
 }
 
-/// Representation of a terminal user interface.
-///
-/// It is responsible for setting up the terminal,
-/// initializing the interface and handling the draw events.
-#[derive(Debug)]
 pub struct Tui<B: Backend> {
-    /// Interface to the Terminal.
     terminal: Terminal<B>,
-    /// Terminal event handler.
-    pub events: EventHandler,
+    listener: EventListener,
+    handler: EventHandler,
+    ui: Ui,
+    app: App,
 }
 
 impl<B: Backend> Tui<B> {
-    /// Constructs a new instance of [`Tui`].
-    pub fn new(terminal: Terminal<B>, events: EventHandler) -> Self {
-        Self { terminal, events }
+    pub fn new(
+        terminal: Terminal<B>,
+        listener: EventListener,
+        handler: EventHandler,
+        ui: Ui,
+        app: App,
+    ) -> Self {
+        Self {
+            terminal,
+            listener,
+            handler,
+            ui,
+            app,
+        }
     }
 
-    /// Initializes the terminal interface.
-    ///
-    /// It enables the raw mode and sets terminal properties.
-    pub fn init(&mut self) {
+    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();
     }
 
-    /// [`Draw`] the terminal interface by [`rendering`] the widgets.
-    ///
-    /// [`Draw`]: tui::Terminal::draw
-    /// [`rendering`]: crate::ui:render
-    pub fn draw(&mut self, app: &mut App) {
-        self.terminal.draw(|frame| ui::render(app, frame)).unwrap();
+    pub fn run(&mut self) {
+        self.init();
+
+        self.listener.spawn();
+        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);
+        }
+
+        self.exit();
     }
 
-    /// Exits the terminal interface.
-    ///
-    /// It disables the raw mode and reverts back the terminal properties.
-    pub fn exit(&mut self) {
+    fn exit(&mut self) {
         terminal::disable_raw_mode().unwrap();
         crossterm::execute!(io::stdout(), LeaveAlternateScreen, DisableMouseCapture).unwrap();
         self.terminal.show_cursor().unwrap();

src/tui/ui.rs

@@ -1,176 +1,204 @@
-use musichoard::{collection::Collection, TrackFormat};
+use musichoard::TrackFormat;
 use ratatui::{
     backend::Backend,
     layout::{Alignment, Rect},
-    style::{Color, Modifier, Style},
+    style::{Color, Style},
     widgets::{Block, BorderType, Borders, List, ListItem, ListState, Paragraph},
     Frame,
 };
 
 use super::app::{App, Category};
 
-/// Renders the user interface widgets.
-pub fn render<B: Backend>(app: &mut App, frame: &mut Frame<'_, B>) {
-    // This is where you add new widgets.
-    // See the following resources:
-    // - https://docs.rs/ratatui/latest/ratatui/widgets/index.html
-    // - https://github.com/tui-rs-revival/ratatui/tree/master/examples
+struct ArtistArea {
+    list: Rect,
+}
 
-    let artists: Vec<ListItem> = app
-        .get_artists()
-        .iter()
-        .map(|id| ListItem::new(id.name.as_str()))
-        .collect();
+struct AlbumArea {
+    list: Rect,
+    info: Rect,
+}
 
-    let frame_rect = frame.size();
-    let width_over_three = frame_rect.width / 3;
-    let height_over_three = frame_rect.height / 3;
+struct TrackArea {
+    list: Rect,
+    info: Rect,
+}
 
-    let artists_rect = Rect {
-        x: frame_rect.x,
-        y: frame_rect.y,
-        width: width_over_three,
-        height: frame_rect.height,
-    };
+struct FrameAreas {
+    artists: ArtistArea,
+    albums: AlbumArea,
+    tracks: TrackArea,
+}
 
-    let mut artists_state = ListState::default();
-    artists_state.select(Some(app.selected_artist()));
+struct SelectionList<'a> {
+    list: List<'a>,
+    state: ListState,
+    active: bool,
+}
 
-    frame.render_stateful_widget(
-        List::new(artists)
-            .highlight_style(Style::default().bg(
-                if let Category::Artist = app.get_active_category() {
-                    Color::DarkGray
-                } else {
-                    Color::Black
-                },
-            ))
-            .highlight_symbol(">> ")
-            .style(Style::default().fg(Color::White).bg(Color::Black))
-            .block(
-                Block::default()
-                    .title(" Artists ")
-                    .title_alignment(Alignment::Center)
-                    .borders(Borders::ALL)
-                    .border_type(BorderType::Rounded),
-            ),
-        artists_rect,
-        &mut artists_state,
-    );
+struct ArtistState<'a> {
+    list: SelectionList<'a>,
+}
 
-    let albums: Vec<ListItem> = app
-        .get_albums()
-        .iter()
-        .map(|id| ListItem::new(id.title.as_str()))
-        .collect();
+struct AlbumState<'a> {
+    list: SelectionList<'a>,
+    info: Paragraph<'a>,
+}
 
-    let albums_rect = Rect {
-        x: artists_rect.x + artists_rect.width,
-        y: frame_rect.y,
-        width: width_over_three,
-        height: frame_rect.height - height_over_three,
-    };
+struct TrackState<'a> {
+    list: SelectionList<'a>,
+    info: Paragraph<'a>,
+}
 
-    let mut albums_state = ListState::default();
-    albums_state.select(Some(app.selected_album()));
+struct AppState<'a> {
+    artists: ArtistState<'a>,
+    albums: AlbumState<'a>,
+    tracks: TrackState<'a>,
+}
 
-    frame.render_stateful_widget(
-        List::new(albums)
-            .highlight_style(Style::default().bg(
-                if let Category::Album = app.get_active_category() {
-                    Color::DarkGray
-                } else {
-                    Color::Black
-                },
-            ))
-            .highlight_symbol(">> ")
-            .style(Style::default().fg(Color::White).bg(Color::Black))
-            .block(
-                Block::default()
-                    .title(" Albums ")
-                    .title_alignment(Alignment::Center)
-                    .borders(Borders::ALL)
-                    .border_type(BorderType::Rounded),
-            ),
-        albums_rect,
-        &mut albums_state,
-    );
+pub struct Ui {}
 
-    let album = app.get_albums()[app.selected_album()];
+impl Ui {
+    const COLOR_FG: Color = Color::White;
+    const COLOR_BG: Color = Color::Black;
+    const COLOR_HL: Color = Color::DarkGray;
 
-    let albums_info_rect = Rect {
-        x: albums_rect.x,
-        y: albums_rect.y + albums_rect.height,
-        width: albums_rect.width,
-        height: height_over_three,
-    };
+    pub fn new() -> Self {
+        Ui {}
+    }
 
-    frame.render_widget(
-        Paragraph::new(format!(
+    fn construct_areas(frame: Rect) -> FrameAreas {
+        let width_one_third = frame.width / 3;
+        let height_one_third = frame.height / 3;
+
+        let panel_width = width_one_third;
+        let panel_width_last = frame.width - 2 * panel_width;
+        let panel_height_top = frame.height - height_one_third;
+        let panel_height_bottom = height_one_third;
+
+        let artist_list = Rect {
+            x: frame.x,
+            y: frame.y,
+            width: panel_width,
+            height: frame.height,
+        };
+
+        let album_list = Rect {
+            x: artist_list.x + artist_list.width,
+            y: frame.y,
+            width: panel_width,
+            height: panel_height_top,
+        };
+
+        let album_info = Rect {
+            x: album_list.x,
+            y: album_list.y + album_list.height,
+            width: album_list.width,
+            height: panel_height_bottom,
+        };
+
+        let track_list = Rect {
+            x: album_list.x + album_list.width,
+            y: frame.y,
+            width: panel_width_last,
+            height: panel_height_top,
+        };
+
+        let track_info = Rect {
+            x: track_list.x,
+            y: track_list.y + track_list.height,
+            width: track_list.width,
+            height: panel_height_bottom,
+        };
+
+        FrameAreas {
+            artists: ArtistArea { list: artist_list },
+            albums: AlbumArea {
+                list: album_list,
+                info: album_info,
+            },
+            tracks: TrackArea {
+                list: track_list,
+                info: track_info,
+            },
+        }
+    }
+
+    fn construct_artist_list(app: &App) -> ArtistState {
+        let artists = app.get_artists();
+        let list = List::new(
+            artists
+                .iter()
+                .map(|id| ListItem::new(id.name.as_str()))
+                .collect::<Vec<ListItem>>(),
+        );
+
+        let selected_artist = app.selected_artist();
+
+        let mut state = ListState::default();
+        state.select(Some(selected_artist));
+
+        let active = app.get_active_category() == Category::Artist;
+
+        ArtistState {
+            list: SelectionList {
+                list,
+                state,
+                active,
+            },
+        }
+    }
+
+    fn construct_album_list(app: &App) -> AlbumState {
+        let albums = app.get_albums();
+        let list = List::new(
+            albums
+                .iter()
+                .map(|id| ListItem::new(id.title.as_str()))
+                .collect::<Vec<ListItem>>(),
+        );
+
+        let selected_album = app.selected_album();
+
+        let mut state = ListState::default();
+        state.select(Some(selected_album));
+
+        let active = app.get_active_category() == Category::Album;
+
+        let album = albums[selected_album];
+        let info = Paragraph::new(format!(
             "Title: {}\n\
              Year: {}",
             album.title, album.year,
-        ))
-        .style(Style::default().fg(Color::White).bg(Color::Black))
-        .block(
-            Block::default()
-                .title(" Album info ")
-                .title_alignment(Alignment::Center)
-                .borders(Borders::ALL)
-                .border_type(BorderType::Rounded),
-        ),
-        albums_info_rect,
-    );
+        ));
 
-    let tracks: Vec<ListItem> = app
-        .get_tracks()
-        .iter()
-        .map(|t| ListItem::new(t.title.as_str()))
-        .collect();
+        AlbumState {
+            list: SelectionList {
+                list,
+                state,
+                active,
+            },
+            info,
+        }
+    }
 
-    let tracks_rect = Rect {
-        x: albums_rect.x + albums_rect.width,
-        y: frame_rect.y,
-        width: frame_rect.width - 2 * width_over_three,
-        height: frame_rect.height - height_over_three,
-    };
+    fn construct_track_list(app: &App) -> TrackState {
+        let tracks = app.get_tracks();
+        let list = List::new(
+            tracks
+                .iter()
+                .map(|id| ListItem::new(id.title.as_str()))
+                .collect::<Vec<ListItem>>(),
+        );
 
-    let mut tracks_state = ListState::default();
-    tracks_state.select(Some(app.selected_track()));
+        let selected_track = app.selected_track();
 
-    frame.render_stateful_widget(
-        List::new(tracks)
-            .highlight_style(Style::default().bg(
-                if let Category::Track = app.get_active_category() {
-                    Color::DarkGray
-                } else {
-                    Color::Black
-                },
-            ))
-            .highlight_symbol(">> ")
-            .style(Style::default().fg(Color::White).bg(Color::Black))
-            .block(
-                Block::default()
-                    .title(" Tracks ")
-                    .title_alignment(Alignment::Center)
-                    .borders(Borders::ALL)
-                    .border_type(BorderType::Rounded),
-            ),
-        tracks_rect,
-        &mut tracks_state,
-    );
+        let mut state = ListState::default();
+        state.select(Some(selected_track));
 
-    let track = app.get_tracks()[app.selected_track()];
+        let active = app.get_active_category() == Category::Track;
 
-    let track_info_rect = Rect {
-        x: tracks_rect.x,
-        y: tracks_rect.y + tracks_rect.height,
-        width: tracks_rect.width,
-        height: height_over_three,
-    };
-
-    frame.render_widget(
-        Paragraph::new(format!(
+        let track = tracks[selected_track];
+        let info = Paragraph::new(format!(
             "Track: {}\n\
              Title: {}\n\
              Artist: {}\n\
@@ -182,15 +210,112 @@ pub fn render<B: Backend>(app: &mut App, frame: &mut Frame<'_, B>) {
                 TrackFormat::Flac => "FLAC",
                 TrackFormat::Mp3 => "MP3",
             },
-        ))
-        .style(Style::default().fg(Color::White).bg(Color::Black))
-        .block(
-            Block::default()
-                .title(" Track info ")
-                .title_alignment(Alignment::Center)
-                .borders(Borders::ALL)
-                .border_type(BorderType::Rounded),
-        ),
-        track_info_rect,
-    );
+        ));
+
+        TrackState {
+            list: SelectionList {
+                list,
+                state,
+                active,
+            },
+            info,
+        }
+    }
+
+    fn construct_app_state(app: &App) -> AppState {
+        AppState {
+            artists: Self::construct_artist_list(app),
+            albums: Self::construct_album_list(app),
+            tracks: Self::construct_track_list(app),
+        }
+    }
+
+    fn style() -> Style {
+        Style::default().fg(Self::COLOR_FG).bg(Self::COLOR_BG)
+    }
+
+    fn highlight_style(active: bool) -> Style {
+        Style::default().bg(if active {
+            Self::COLOR_HL
+        } else {
+            Self::COLOR_BG
+        })
+    }
+
+    fn block<'a>() -> Block<'a> {
+        Block::default()
+            .title_alignment(Alignment::Center)
+            .borders(Borders::ALL)
+            .border_type(BorderType::Rounded)
+    }
+
+    fn render_list_widget<B: Backend>(
+        title: &str,
+        mut list: SelectionList,
+        area: Rect,
+        frame: &mut Frame<'_, B>,
+    ) {
+        frame.render_stateful_widget(
+            list.list
+                .highlight_style(Self::highlight_style(list.active))
+                .highlight_symbol(">> ")
+                .style(Self::style())
+                .block(Self::block().title(format!(" {title} "))),
+            area,
+            &mut list.state,
+        );
+    }
+
+    fn render_info_widget<B: Backend>(
+        title: &str,
+        paragraph: Paragraph,
+        area: Rect,
+        frame: &mut Frame<'_, B>,
+    ) {
+        frame.render_widget(
+            paragraph
+                .style(Self::style())
+                .block(Self::block().title(format!(" {title} "))),
+            area,
+        );
+    }
+
+    fn render_artist_column<B: Backend>(
+        state: ArtistState,
+        area: ArtistArea,
+        frame: &mut Frame<'_, B>,
+    ) {
+        Self::render_list_widget("Artists", state.list, area.list, frame);
+    }
+
+    fn render_album_column<B: Backend>(
+        state: AlbumState,
+        area: AlbumArea,
+        frame: &mut Frame<'_, B>,
+    ) {
+        Self::render_list_widget("Albums", state.list, area.list, frame);
+        Self::render_info_widget("Album info", state.info, area.info, frame);
+    }
+
+    fn render_track_column<B: Backend>(
+        state: TrackState,
+        area: TrackArea,
+        frame: &mut Frame<'_, B>,
+    ) {
+        Self::render_list_widget("Tracks", state.list, area.list, frame);
+        Self::render_info_widget("Track info", state.info, area.info, frame);
+    }
+
+    pub fn render<B: Backend>(&mut self, app: &App, frame: &mut Frame<'_, B>) {
+        // This is where you add new widgets.
+        // See the following resources:
+        // - https://docs.rs/ratatui/latest/ratatui/widgets/index.html
+        // - https://github.com/tui-rs-revival/ratatui/tree/master/examples
+        let areas = Self::construct_areas(frame.size());
+        let app_state = Self::construct_app_state(app);
+
+        Self::render_artist_column(app_state.artists, areas.artists, frame);
+        Self::render_album_column(app_state.albums, areas.albums, frame);
+        Self::render_track_column(app_state.tracks, areas.tracks, frame);
+    }
 }