feat: add native LSP hover action and popup

src/tui.rs

@@ -29,7 +29,7 @@ use unicode_segmentation::UnicodeSegmentation;
 use unicode_width::UnicodeWidthStr;
 
 use crate::{
-    editor::{Editor, Input, Mode, Palette},
+    editor::{Editor, Hover, Input, Mode, Palette},
     files::{DockSide, FilePicker, FilePresentation, FileView},
     plugin::{Diagnostic, DiagnosticSeverity},
     session::EditorSession,
@@ -631,6 +631,67 @@ fn draw(
             editor.selection_navigation_hint(),
         );
     }
+    if let Some(hover) = editor.hover() {
+        draw_hover(frame, hover, viewport);
+    }
+}
+
+fn draw_hover(frame: &mut Frame, hover: &Hover, area: Rect) {
+    if area.width == 0 || area.height == 0 {
+        return;
+    }
+    let [_, column, _] = Layout::horizontal([
+        Constraint::Fill(1),
+        Constraint::Length(area.width.min(84)),
+        Constraint::Fill(1),
+    ])
+    .areas(area);
+    let [_, panel, _] = Layout::vertical([
+        Constraint::Fill(1),
+        Constraint::Length(
+            area.height
+                .min(hover.lines().len().saturating_add(3).min(18) as u16),
+        ),
+        Constraint::Fill(1),
+    ])
+    .areas(column);
+    frame.render_widget(Clear, panel);
+    let bordered = panel.height >= 4 && panel.width >= 4;
+    let block = Block::default()
+        .borders(if bordered {
+            Borders::ALL
+        } else {
+            Borders::NONE
+        })
+        .border_style(Style::default().fg(Color::Cyan))
+        .title(" Hover ");
+    let content = if bordered { block.inner(panel) } else { panel };
+    if bordered {
+        frame.render_widget(block, panel);
+    }
+    let [text_area, help_area] = Layout::vertical([
+        Constraint::Fill(1),
+        Constraint::Length(u16::from(content.height >= 3)),
+    ])
+    .areas(content);
+    let lines: Vec<Line> = hover
+        .lines()
+        .skip(hover.top)
+        .take(usize::from(text_area.height))
+        .map(|line| {
+            Line::from(visible_line(
+                line,
+                display_column(line, hover.left),
+                usize::from(text_area.width),
+            ))
+        })
+        .collect();
+    frame.render_widget(Paragraph::new(lines), text_area);
+    frame.render_widget(
+        Paragraph::new("Arrows/Ctrl+h/j/k/l scroll · Esc close")
+            .style(Style::default().fg(Color::DarkGray)),
+        help_area,
+    );
 }
 
 fn dock_layout(area: Rect, side: DockSide, focused: bool) -> (Rect, Option<Rect>) {
@@ -977,6 +1038,44 @@ mod tests {
             .join("\n")
     }
 
+    #[test]
+    fn hover_scroll_renders_whole_graphemes_in_tiny_workspace() {
+        let mut editor = Editor::open(None, vec![]).unwrap();
+        editor.show_hover("x界e\u{301}👩‍🚀z\nlast".into()).unwrap();
+        let mut terminal = Terminal::new(ratatui::backend::TestBackend::new(6, 1)).unwrap();
+        let mut syntax = SyntaxCache::new();
+        let (mut top, mut left) = (0, 0);
+        for _ in 0..2 {
+            editor.handle(Input::Right);
+        }
+        let rendered = terminal
+            .draw(|frame| draw(frame, &editor, &mut top, &mut left, &mut syntax))
+            .unwrap();
+        assert_eq!(rendered.buffer[(2, 0)].symbol(), "e\u{301}");
+        assert_eq!(rendered.buffer[(3, 0)].symbol(), "👩‍🚀");
+        assert_eq!(rendered.buffer[(5, 0)].symbol(), "z");
+        assert_eq!(
+            terminal.get_cursor_position().unwrap(),
+            ratatui::layout::Position::new(2, 0)
+        );
+        assert_eq!((top, left), (0, 0));
+        editor.handle(Input::Down);
+        editor.handle(Input::Home);
+        terminal
+            .draw(|frame| draw(frame, &editor, &mut top, &mut left, &mut syntax))
+            .unwrap();
+        assert!(screen_text(&terminal).ends_with("last"));
+        for (width, height) in [(1, 1), (2, 2), (3, 3), (4, 4)] {
+            let mut terminal =
+                Terminal::new(ratatui::backend::TestBackend::new(width, height)).unwrap();
+            terminal
+                .draw(|frame| draw(frame, &editor, &mut top, &mut left, &mut syntax))
+                .unwrap();
+        }
+        assert_eq!(editor.cursor(), crate::editor::Cursor::default());
+        assert_eq!(editor.lines(), &[""]);
+    }
+
     fn annotation(
         start: (usize, usize),
         end: (usize, usize),