feat(tui): scroll long result names and page through results

Closes #55.

While [2] Results is focused the Info pane describes the highlighted
result, so a truncated path can be read in full. h/l (or the arrow keys)
scroll the filename column by display cells, 0 and $ jump to either end
of the highlighted name, and Home/End, g/G, PgUp/PgDn and Ctrl-f/b/d/u
move through the list; the same keys work while a filter is being typed.

Ctrl chords are no longer read as their bare letter: outside [2] they do
nothing, where before Ctrl-d deleted a search and Ctrl-c opened rooms.
Space after a filter that matches nothing no longer indexes an empty
list.

soulseek-rs/src/ui/main_tui/mod.rs

@@ -1034,4 +1034,225 @@ mod tests {
         assert!(downloads.is_dir(), "the folder is created here");
         assert_eq!(tui.download_dir, downloads_dir);
     }
+
+    fn results(n: usize) -> Vec<crate::models::FileDisplayData> {
+        (0..n)
+            .map(|i| crate::models::FileDisplayData {
+                filename: format!("@@x\\Music\\{i:02}.mp3"),
+                username: "bob".to_string(),
+                ..Default::default()
+            })
+            .collect()
+    }
+
+    fn results_tui(n: usize) -> MainTui {
+        let mut tui = with_session(TalkativeSession::default());
+        tui.state.results_items = results(n);
+        tui.state.focused_pane = FocusedPane::Results;
+        tui.state.results_pane_area =
+            Some(ratatui::layout::Rect::new(0, 0, 80, 13));
+        tui
+    }
+
+    fn press(tui: &mut MainTui, code: KeyCode) {
+        tui.handle_key_event(KeyEvent::new(code, KeyModifiers::NONE));
+    }
+
+    fn ctrl(tui: &mut MainTui, ch: char) {
+        tui.handle_key_event(KeyEvent::new(
+            KeyCode::Char(ch),
+            KeyModifiers::CONTROL,
+        ));
+    }
+
+    fn selected(tui: &MainTui) -> Option<usize> {
+        tui.state.results_table_state.selected()
+    }
+
+    #[test]
+    fn end_and_home_jump_to_the_last_and_first_result() {
+        let mut tui = results_tui(30);
+        press(&mut tui, KeyCode::End);
+        assert_eq!(selected(&tui), Some(29));
+        press(&mut tui, KeyCode::Home);
+        assert_eq!(selected(&tui), Some(0));
+        press(&mut tui, KeyCode::Char('G'));
+        assert_eq!(selected(&tui), Some(29));
+        press(&mut tui, KeyCode::Char('g'));
+        assert_eq!(selected(&tui), Some(0));
+    }
+
+    #[test]
+    fn page_keys_move_a_pane_of_rows_and_stop_at_the_edges() {
+        let mut tui = results_tui(30);
+        press(&mut tui, KeyCode::PageDown);
+        assert_eq!(selected(&tui), Some(10));
+        ctrl(&mut tui, 'f');
+        assert_eq!(selected(&tui), Some(20));
+        press(&mut tui, KeyCode::PageDown);
+        assert_eq!(selected(&tui), Some(29), "clamps instead of wrapping");
+        press(&mut tui, KeyCode::PageUp);
+        assert_eq!(selected(&tui), Some(19));
+        ctrl(&mut tui, 'b');
+        assert_eq!(selected(&tui), Some(9));
+        press(&mut tui, KeyCode::PageUp);
+        assert_eq!(selected(&tui), Some(0));
+        assert!(
+            !tui.state.show_browse && !tui.state.command_bar_active,
+            "ctrl-b pages up instead of opening browse"
+        );
+    }
+
+    #[test]
+    fn ctrl_d_and_ctrl_u_move_half_a_pane() {
+        let mut tui = results_tui(30);
+        ctrl(&mut tui, 'd');
+        assert_eq!(selected(&tui), Some(5));
+        ctrl(&mut tui, 'u');
+        assert_eq!(selected(&tui), Some(0));
+    }
+
+    #[test]
+    fn navigation_keys_do_nothing_without_results() {
+        let mut tui = results_tui(0);
+        tui.state.results_table_state.select(None);
+        press(&mut tui, KeyCode::End);
+        press(&mut tui, KeyCode::PageDown);
+        ctrl(&mut tui, 'd');
+        assert_eq!(selected(&tui), None);
+    }
+
+    #[test]
+    fn l_and_h_scroll_the_highlighted_name_up_to_its_end() {
+        let mut tui = results_tui(3);
+        tui.state.results_items[1].filename = "x".repeat(40);
+        tui.state.results_table_state.select(Some(1));
+        press(&mut tui, KeyCode::Char('l'));
+        assert_eq!(tui.state.results_name_offset, 8);
+        press(&mut tui, KeyCode::Right);
+        assert_eq!(tui.state.results_name_offset, 16);
+        press(&mut tui, KeyCode::Char('$'));
+        assert_eq!(tui.state.results_name_offset, 30);
+        press(&mut tui, KeyCode::Char('l'));
+        assert_eq!(tui.state.results_name_offset, 30, "stops at the end");
+        press(&mut tui, KeyCode::Char('h'));
+        assert_eq!(tui.state.results_name_offset, 22);
+        press(&mut tui, KeyCode::Left);
+        assert_eq!(tui.state.results_name_offset, 14);
+        press(&mut tui, KeyCode::Char('0'));
+        assert_eq!(tui.state.results_name_offset, 0);
+        press(&mut tui, KeyCode::Char('h'));
+        assert_eq!(tui.state.results_name_offset, 0);
+    }
+
+    #[test]
+    fn scrolling_follows_the_highlighted_row_not_the_longest_one() {
+        let mut tui = results_tui(3);
+        tui.state.results_items[0].filename = "short.mp3".to_string();
+        tui.state.results_items[1].filename = "x".repeat(40);
+        tui.state.results_items[2].filename = "short.mp3".to_string();
+        press(&mut tui, KeyCode::Char('$'));
+        assert_eq!(tui.state.results_name_offset, 0, "row 0 fits already");
+        tui.state.results_table_state.select(Some(1));
+        press(&mut tui, KeyCode::Char('$'));
+        assert_eq!(tui.state.results_name_offset, 30);
+        tui.state.results_table_state.select(Some(2));
+        press(&mut tui, KeyCode::Char('h'));
+        assert_eq!(
+            tui.state.results_name_offset, 0,
+            "a step left lands within the row now highlighted"
+        );
+    }
+
+    #[test]
+    fn picking_another_search_starts_its_results_unscrolled() {
+        let mut tui = results_tui(3);
+        tui.state.results_items[1].filename = "x".repeat(40);
+        tui.state.results_table_state.select(Some(1));
+        press(&mut tui, KeyCode::Char('$'));
+        assert_eq!(tui.state.results_name_offset, 30);
+
+        tui.state.searches.push(crate::models::SearchEntry {
+            query: "other".to_string(),
+            status: SearchStatus::Active,
+            results: results(2),
+            known_files: 2,
+            owned: true,
+            start_time: std::time::Instant::now(),
+            cancel_flag: Arc::new(std::sync::atomic::AtomicBool::new(false)),
+        });
+        tui.state.searches_table_state.select(Some(0));
+        tui.state.focused_pane = FocusedPane::Searches;
+        press(&mut tui, KeyCode::Enter);
+        assert_eq!(tui.state.results_name_offset, 0);
+    }
+
+    #[test]
+    fn ctrl_keys_are_ignored_outside_the_results_pane() {
+        let mut tui = results_tui(3);
+        tui.state.searches.push(crate::models::SearchEntry {
+            query: "keep me".to_string(),
+            status: SearchStatus::Active,
+            results: Vec::new(),
+            known_files: 0,
+            owned: true,
+            start_time: std::time::Instant::now(),
+            cancel_flag: Arc::new(std::sync::atomic::AtomicBool::new(false)),
+        });
+        tui.state.searches_table_state.select(Some(0));
+        tui.state.focused_pane = FocusedPane::Searches;
+        ctrl(&mut tui, 'd');
+        assert_eq!(tui.state.searches.len(), 1, "ctrl-d is not d");
+        ctrl(&mut tui, 'b');
+        assert!(!tui.state.command_bar_active, "ctrl-b is not b");
+        ctrl(&mut tui, 'q');
+        assert!(!tui.state.should_exit, "ctrl-q is not q");
+    }
+
+    #[test]
+    fn ctrl_keys_page_while_a_filter_is_being_typed() {
+        let mut tui = results_tui(30);
+        press(&mut tui, KeyCode::Char('/'));
+        press(&mut tui, KeyCode::Char('m'));
+        ctrl(&mut tui, 'd');
+        assert_eq!(selected(&tui), Some(5));
+        assert_eq!(tui.state.results_filter_query, "m", "no d appended");
+        press(&mut tui, KeyCode::End);
+        assert_eq!(selected(&tui), Some(29));
+    }
+
+    #[test]
+    fn space_after_a_filter_that_matches_nothing_does_not_panic() {
+        let mut tui = results_tui(3);
+        press(&mut tui, KeyCode::Char('/'));
+        press(&mut tui, KeyCode::Char('z'));
+        press(&mut tui, KeyCode::Enter);
+        assert!(tui.state.results_filtered_items.is_empty());
+        press(&mut tui, KeyCode::Char(' '));
+        assert!(tui.state.results_selected_indices.is_empty());
+    }
+
+    fn screen_of(tui: &mut MainTui) -> String {
+        let backend = ratatui::backend::TestBackend::new(160, 40);
+        let mut terminal = ratatui::Terminal::new(backend).expect("backend");
+        terminal.draw(|frame| tui.render(frame)).expect("draw");
+        terminal.backend().to_string()
+    }
+
+    #[test]
+    fn the_info_pane_describes_the_highlighted_result() {
+        let mut tui = results_tui(3);
+        tui.state.results_items[1].filename =
+            "@@x\\Music\\Album\\Second Track.mp3".to_string();
+        tui.state.results_items[1].bitrate = Some(320);
+        tui.state.results_table_state.select(Some(1));
+
+        let screen = screen_of(&mut tui);
+        assert!(screen.contains("@@x/Music/Album"), "{screen}");
+        assert!(screen.contains("Bitrate"), "{screen}");
+
+        tui.state.focused_pane = FocusedPane::Downloads;
+        let screen = screen_of(&mut tui);
+        assert!(!screen.contains("@@x/Music/Album"), "{screen}");
+    }
 }