Fix empty list issue

src/tui/app.rs

@@ -9,11 +9,105 @@ pub enum Category {
     Track,
 }
 
-pub struct Selection {
+struct TrackSelection {
+    index: u16,
+}
+
+impl TrackSelection {
+    fn initialise(tracks: &Vec<Track>) -> Option<TrackSelection> {
+        if !tracks.is_empty() {
+            Some(TrackSelection { index: 0 })
+        } else {
+            None
+        }
+    }
+
+    fn increment(&mut self, tracks: &Vec<Track>) {
+        if let Some(result) = self.index.checked_add(1) {
+            if (result as usize) < tracks.len() {
+                self.index = result;
+            }
+        }
+    }
+
+    fn decrement(&mut self, _tracks: &Vec<Track>) {
+        if let Some(result) = self.index.checked_sub(1) {
+            self.index = result;
+        }
+    }
+}
+
+struct AlbumSelection {
+    index: u16,
+    track: Option<TrackSelection>,
+}
+
+impl AlbumSelection {
+    fn initialise(albums: &Vec<Album>) -> Option<AlbumSelection> {
+        if !albums.is_empty() {
+            Some(AlbumSelection {
+                index: 0,
+                track: TrackSelection::initialise(&albums[0].tracks),
+            })
+        } else {
+            None
+        }
+    }
+
+    fn increment(&mut self, albums: &Vec<Album>) {
+        if let Some(result) = self.index.checked_add(1) {
+            if (result as usize) < albums.len() {
+                self.index = result;
+                self.track = TrackSelection::initialise(&albums[self.index as usize].tracks);
+            }
+        }
+    }
+
+    fn decrement(&mut self, albums: &Vec<Album>) {
+        if let Some(result) = self.index.checked_sub(1) {
+            self.index = result;
+            self.track = TrackSelection::initialise(&albums[self.index as usize].tracks);
+        }
+    }
+}
+
+struct ArtistSelection {
+    index: u16,
+    album: Option<AlbumSelection>,
+}
+
+impl ArtistSelection {
+    fn initialise(artists: &Vec<Artist>) -> Option<ArtistSelection> {
+        if !artists.is_empty() {
+            Some(ArtistSelection {
+                index: 0,
+                album: AlbumSelection::initialise(&artists[0].albums),
+            })
+        } else {
+            None
+        }
+    }
+
+    fn increment(&mut self, artists: &Vec<Artist>) {
+        if let Some(result) = self.index.checked_add(1) {
+            if (result as usize) < artists.len() {
+                self.index = result;
+                self.album = AlbumSelection::initialise(&artists[self.index as usize].albums);
+            }
+        }
+    }
+
+    fn decrement(&mut self, artists: &Vec<Artist>) {
+        if let Some(result) = self.index.checked_sub(1) {
+            self.index = result;
+            self.album = AlbumSelection::initialise(&artists[self.index as usize].albums);
+        }
+    }
+}
+
+struct Selection {
     active: Category,
-    artist: u16,
+    artist: Option<ArtistSelection>,
-    album: u16,
-    track: u16,
 }
 
 pub struct App {
@@ -25,14 +119,13 @@ pub struct App {
 impl App {
     pub fn new(mut collection_manager: CollectionManager) -> Result<Self, Error> {
         collection_manager.rescan_library()?;
+        let selection = Selection {
+            active: Category::Artist,
+            artist: ArtistSelection::initialise(collection_manager.get_collection()),
+        };
         Ok(App {
             collection_manager,
-            selection: Selection {
+            selection,
-                active: Category::Artist,
-                artist: 0,
-                album: 0,
-                track: 0,
-            },
             running: true,
         })
     }
@@ -74,56 +167,62 @@ impl App {
     }
 
     fn increment_artist_selection(&mut self) {
-        if let Some(result) = self.selection.artist.checked_add(1) {
+        if let Some(ref mut artist_selection) = self.selection.artist {
-            let artists: &Vec<Artist> = self.collection_manager.get_collection();
+            let artists = &self.collection_manager.get_collection();
-            if (result as usize) < artists.len() {
+            artist_selection.increment(artists);
-                self.selection.artist = result;
-                self.selection.album = 0;
-                self.selection.track = 0;
-            }
         }
     }
 
     fn decrement_artist_selection(&mut self) {
-        if let Some(result) = self.selection.artist.checked_sub(1) {
+        if let Some(ref mut artist_selection) = self.selection.artist {
-            self.selection.artist = result;
+            let artists = &self.collection_manager.get_collection();
-            self.selection.album = 0;
+            artist_selection.decrement(artists);
-            self.selection.track = 0;
         }
     }
 
     fn increment_album_selection(&mut self) {
-        if let Some(result) = self.selection.album.checked_add(1) {
+        if let Some(ref mut artist_selection) = self.selection.artist {
-            let artists: &Vec<Artist> = self.collection_manager.get_collection();
+            if let Some(ref mut album_selection) = artist_selection.album {
-            let albums: &Vec<Album> = &artists[self.selection.artist as usize].albums;
+                let artists = &self.collection_manager.get_collection();
-            if (result as usize) < albums.len() {
+                let albums = &artists[artist_selection.index as usize].albums;
-                self.selection.album = result;
+                album_selection.increment(albums);
-                self.selection.track = 0;
             }
         }
     }
 
     fn decrement_album_selection(&mut self) {
-        if let Some(result) = self.selection.album.checked_sub(1) {
+        if let Some(ref mut artist_selection) = self.selection.artist {
-            self.selection.album = result;
+            if let Some(ref mut album_selection) = artist_selection.album {
-            self.selection.track = 0;
+                let artists = &self.collection_manager.get_collection();
+                let albums = &artists[artist_selection.index as usize].albums;
+                album_selection.decrement(albums);
+            }
         }
     }
 
     fn increment_track_selection(&mut self) {
-        if let Some(result) = self.selection.track.checked_add(1) {
+        if let Some(ref mut artist_selection) = self.selection.artist {
-            let artists: &Vec<Artist> = self.collection_manager.get_collection();
+            if let Some(ref mut album_selection) = artist_selection.album {
-            let albums: &Vec<Album> = &artists[self.selection.artist as usize].albums;
+                if let Some(ref mut track_selection) = album_selection.track {
-            let tracks: &Vec<Track> = &albums[self.selection.album as usize].tracks;
+                    let artists = &self.collection_manager.get_collection();
-            if (result as usize) < tracks.len() {
+                    let albums = &artists[artist_selection.index as usize].albums;
-                self.selection.track = result;
+                    let tracks = &albums[album_selection.index as usize].tracks;
+                    track_selection.increment(tracks);
+                }
             }
         }
     }
 
     fn decrement_track_selection(&mut self) {
-        if let Some(result) = self.selection.track.checked_sub(1) {
+        if let Some(ref mut artist_selection) = self.selection.artist {
-            self.selection.track = result;
+            if let Some(ref mut album_selection) = artist_selection.album {
+                if let Some(ref mut track_selection) = album_selection.track {
+                    let artists = &self.collection_manager.get_collection();
+                    let albums = &artists[artist_selection.index as usize].albums;
+                    let tracks = &albums[album_selection.index as usize].tracks;
+                    track_selection.decrement(tracks);
+                }
+            }
         }
     }
 
@@ -131,40 +230,92 @@ impl App {
         self.selection.active
     }
 
-    pub fn get_artists(&self) -> Vec<&ArtistId> {
+    fn get_artists(&self) -> Option<&Vec<Artist>> {
-        self.collection_manager
+        Some(&self.collection_manager.get_collection())
-            .get_collection()
-            .iter()
-            .map(|a| &a.id)
-            .collect()
     }
 
-    pub fn selected_artist(&self) -> usize {
+    fn get_albums(&self) -> Option<&Vec<Album>> {
-        self.selection.artist as usize
+        if let Some(artists) = self.get_artists() {
+            if let Some(artist_index) = self.selected_artist() {
+                Some(&artists[artist_index].albums)
+            } else {
+                None
+            }
+        } else {
+            None
+        }
     }
 
-    pub fn get_albums(&self) -> Vec<&AlbumId> {
+    fn get_tracks(&self) -> Option<&Vec<Track>> {
-        self.collection_manager.get_collection()[self.selection.artist as usize]
+        if let Some(albums) = self.get_albums() {
-            .albums
+            if let Some(album_index) = self.selected_album() {
-            .iter()
+                Some(&albums[album_index].tracks)
-            .map(|a| &a.id)
+            } else {
-            .collect()
+                None
+            }
+        } else {
+            None
+        }
     }
 
-    pub fn selected_album(&self) -> usize {
+    pub fn get_artist_ids(&self) -> Vec<&ArtistId> {
-        self.selection.album as usize
+        if let Some(artists) = self.get_artists() {
+            artists.iter().map(|a| &a.id).collect()
+        } else {
+            vec![]
+        }
     }
 
-    pub fn get_tracks(&self) -> Vec<&Track> {
+    pub fn get_album_ids(&self) -> Vec<&AlbumId> {
-        self.collection_manager.get_collection()[self.selection.artist as usize].albums
+        if let Some(albums) = self.get_albums() {
-            [self.selection.album as usize]
+            albums.iter().map(|a| &a.id).collect()
-            .tracks
+        } else {
-            .iter()
+            vec![]
-            .collect()
+        }
     }
 
-    pub fn selected_track(&self) -> usize {
+    pub fn get_track_ids(&self) -> Vec<&Track> {
-        self.selection.track as usize
+        if let Some(tracks) = self.get_tracks() {
+            tracks.iter().collect()
+        } else {
+            vec![]
+        }
+    }
+
+    pub fn selected_artist(&self) -> Option<usize> {
+        if let Some(ref artist_selection) = self.selection.artist {
+            Some(artist_selection.index as usize)
+        } else {
+            None
+        }
+    }
+
+    pub fn selected_album(&self) -> Option<usize> {
+        if let Some(ref artist_selection) = self.selection.artist {
+            if let Some(ref album_selection) = artist_selection.album {
+                Some(album_selection.index as usize)
+            } else {
+                None
+            }
+        } else {
+            None
+        }
+    }
+
+    pub fn selected_track(&self) -> Option<usize> {
+        if let Some(ref artist_selection) = self.selection.artist {
+            if let Some(ref album_selection) = artist_selection.album {
+                if let Some(ref track_selection) = album_selection.track {
+                    Some(track_selection.index as usize)
+                } else {
+                    None
+                }
+            } else {
+                None
+            }
+        } else {
+            None
+        }
     }
 
     pub fn quit(&mut self) {

src/tui/ui.rs

@@ -32,21 +32,23 @@ struct FrameAreas {
 struct SelectionList<'a> {
     list: List<'a>,
     state: ListState,
-    active: bool,
 }
 
 struct ArtistState<'a> {
     list: SelectionList<'a>,
+    active: bool,
 }
 
 struct AlbumState<'a> {
     list: SelectionList<'a>,
     info: Paragraph<'a>,
+    active: bool,
 }
 
 struct TrackState<'a> {
     list: SelectionList<'a>,
     info: Paragraph<'a>,
+    active: bool,
 }
 
 struct AppState<'a> {
@@ -58,10 +60,6 @@ struct AppState<'a> {
 pub struct Ui {}
 
 impl Ui {
-    const COLOR_FG: Color = Color::White;
-    const COLOR_BG: Color = Color::Black;
-    const COLOR_HL: Color = Color::DarkGray;
-
     pub fn new() -> Self {
         Ui {}
     }
@@ -124,7 +122,7 @@ impl Ui {
     }
 
     fn construct_artist_list(app: &App) -> ArtistState {
-        let artists = app.get_artists();
+        let artists = app.get_artist_ids();
         let list = List::new(
             artists
                 .iter()
@@ -135,21 +133,18 @@ impl Ui {
         let selected_artist = app.selected_artist();
 
         let mut state = ListState::default();
-        state.select(Some(selected_artist));
+        state.select(selected_artist);
 
         let active = app.get_active_category() == Category::Artist;
 
         ArtistState {
-            list: SelectionList {
+            list: SelectionList { list, state },
-                list,
+            active,
-                state,
-                active,
-            },
         }
     }
 
     fn construct_album_list(app: &App) -> AlbumState {
-        let albums = app.get_albums();
+        let albums = app.get_album_ids();
         let list = List::new(
             albums
                 .iter()
@@ -160,29 +155,29 @@ impl Ui {
         let selected_album = app.selected_album();
 
         let mut state = ListState::default();
-        state.select(Some(selected_album));
+        state.select(selected_album);
 
         let active = app.get_active_category() == Category::Album;
 
-        let album = albums[selected_album];
+        let album = selected_album.map(|i| albums[i]);
         let info = Paragraph::new(format!(
             "Title: {}\n\
              Year: {}",
-            album.title, album.year,
+            album.map(|a| a.title.as_str()).unwrap_or(""),
+            album
+                .map(|a| a.year.to_string())
+                .unwrap_or_else(|| "".to_string()),
         ));
 
         AlbumState {
-            list: SelectionList {
+            list: SelectionList { list, state },
-                list,
-                state,
-                active,
-            },
             info,
+            active,
         }
     }
 
     fn construct_track_list(app: &App) -> TrackState {
-        let tracks = app.get_tracks();
+        let tracks = app.get_track_ids();
         let list = List::new(
             tracks
                 .iter()
@@ -193,32 +188,35 @@ impl Ui {
         let selected_track = app.selected_track();
 
         let mut state = ListState::default();
-        state.select(Some(selected_track));
+        state.select(selected_track);
 
         let active = app.get_active_category() == Category::Track;
 
-        let track = tracks[selected_track];
+        let track = selected_track.map(|i| tracks[i]);
         let info = Paragraph::new(format!(
             "Track: {}\n\
              Title: {}\n\
              Artist: {}\n\
              Format: {}",
-            track.number,
+            track
-            track.title,
+                .map(|t| t.number.to_string())
-            track.artist.join("; "),
+                .unwrap_or_else(|| "".to_string()),
-            match track.format {
+            track.map(|t| t.title.as_str()).unwrap_or(""),
-                TrackFormat::Flac => "FLAC",
+            track
-                TrackFormat::Mp3 => "MP3",
+                .map(|t| t.artist.join("; "))
-            },
+                .unwrap_or_else(|| "".to_string()),
+            track
+                .map(|t| match t.format {
+                    TrackFormat::Flac => "FLAC",
+                    TrackFormat::Mp3 => "MP3",
+                })
+                .unwrap_or(""),
         ));
 
         TrackState {
-            list: SelectionList {
+            list: SelectionList { list, state },
-                list,
-                state,
-                active,
-            },
             info,
+            active,
         }
     }
 
@@ -230,38 +228,44 @@ impl Ui {
         }
     }
 
-    fn style() -> Style {
+    fn style(_active: bool) -> Style {
-        Style::default().fg(Self::COLOR_FG).bg(Self::COLOR_BG)
+        Style::default().fg(Color::White).bg(Color::Black)
+    }
+
+    fn block_style(active: bool) -> Style {
+        Self::style(active)
     }
 
     fn highlight_style(active: bool) -> Style {
-        Style::default().bg(if active {
+        if active {
-            Self::COLOR_HL
+            Style::default().fg(Color::White).bg(Color::DarkGray)
         } else {
-            Self::COLOR_BG
+            Self::style(false)
-        })
+        }
     }
 
-    fn block<'a>(title: &str) -> Block<'a> {
+    fn block<'a>(title: &str, active: bool) -> Block<'a> {
         Block::default()
             .title_alignment(Alignment::Center)
             .borders(Borders::ALL)
             .border_type(BorderType::Rounded)
+            .style(Self::block_style(active))
             .title(format!(" {title} "))
     }
 
     fn render_list_widget<B: Backend>(
         title: &str,
         mut list: SelectionList,
+        active: bool,
         area: Rect,
         frame: &mut Frame<'_, B>,
     ) {
         frame.render_stateful_widget(
             list.list
-                .highlight_style(Self::highlight_style(list.active))
+                .highlight_style(Self::highlight_style(active))
                 .highlight_symbol(">> ")
-                .style(Self::style())
+                .style(Self::style(active))
-                .block(Self::block(title)),
+                .block(Self::block(title, active)),
             area,
             &mut list.state,
         );
@@ -270,11 +274,14 @@ impl Ui {
     fn render_info_widget<B: Backend>(
         title: &str,
         paragraph: Paragraph,
+        active: bool,
         area: Rect,
         frame: &mut Frame<'_, B>,
     ) {
         frame.render_widget(
-            paragraph.style(Self::style()).block(Self::block(title)),
+            paragraph
+                .style(Self::style(active))
+                .block(Self::block(title, active)),
             area,
         );
     }
@@ -284,7 +291,7 @@ impl Ui {
         area: ArtistArea,
         frame: &mut Frame<'_, B>,
     ) {
-        Self::render_list_widget("Artists", state.list, area.list, frame);
+        Self::render_list_widget("Artists", state.list, state.active, area.list, frame);
     }
 
     fn render_album_column<B: Backend>(
@@ -292,8 +299,8 @@ impl Ui {
         area: AlbumArea,
         frame: &mut Frame<'_, B>,
     ) {
-        Self::render_list_widget("Albums", state.list, area.list, frame);
+        Self::render_list_widget("Albums", state.list, state.active, area.list, frame);
-        Self::render_info_widget("Album info", state.info, area.info, frame);
+        Self::render_info_widget("Album info", state.info, state.active, area.info, frame);
     }
 
     fn render_track_column<B: Backend>(
@@ -301,8 +308,8 @@ impl Ui {
         area: TrackArea,
         frame: &mut Frame<'_, B>,
     ) {
-        Self::render_list_widget("Tracks", state.list, area.list, frame);
+        Self::render_list_widget("Tracks", state.list, state.active, area.list, frame);
-        Self::render_info_widget("Track info", state.info, area.info, frame);
+        Self::render_info_widget("Track info", state.info, state.active, area.info, frame);
     }
 
     pub fn render<B: Backend>(&mut self, app: &App, frame: &mut Frame<'_, B>) {