Scrollable slash commands (#1830)

Scrollable slash commands. Part 1 of the multi PR.

codex-rs/tui/src/bottom_pane/selection_popup_common.rs

@@ -0,0 +1,126 @@
+use ratatui::buffer::Buffer;
+use ratatui::layout::Rect;
+use ratatui::prelude::Constraint;
+use ratatui::style::Color;
+use ratatui::style::Modifier;
+use ratatui::style::Style;
+use ratatui::text::Line;
+use ratatui::text::Span;
+use ratatui::widgets::Block;
+use ratatui::widgets::BorderType;
+use ratatui::widgets::Borders;
+use ratatui::widgets::Cell;
+use ratatui::widgets::Row;
+use ratatui::widgets::Table;
+use ratatui::widgets::Widget;
+
+use super::scroll_state::ScrollState;
+
+/// A generic representation of a display row for selection popups.
+pub(crate) struct GenericDisplayRow {
+    pub name: String,
+    pub match_indices: Option<Vec<usize>>, // indices to bold (char positions)
+    pub is_current: bool,
+    pub description: Option<String>, // optional grey text after the name
+}
+
+impl GenericDisplayRow {}
+
+/// Render a list of rows using the provided ScrollState, with shared styling
+/// and behavior for selection popups.
+pub(crate) fn render_rows(
+    area: Rect,
+    buf: &mut Buffer,
+    rows_all: &[GenericDisplayRow],
+    state: &ScrollState,
+    max_results: usize,
+) {
+    let mut rows: Vec<Row> = Vec::new();
+    if rows_all.is_empty() {
+        rows.push(Row::new(vec![Cell::from(Line::from(Span::styled(
+            "no matches",
+            Style::default().add_modifier(Modifier::ITALIC | Modifier::DIM),
+        )))]));
+    } else {
+        let max_rows_from_area = area.height as usize;
+        let visible_rows = max_results
+            .min(rows_all.len())
+            .min(max_rows_from_area.max(1));
+
+        // Compute starting index based on scroll state and selection.
+        let mut start_idx = state.scroll_top.min(rows_all.len().saturating_sub(1));
+        if let Some(sel) = state.selected_idx {
+            if sel < start_idx {
+                start_idx = sel;
+            } else if visible_rows > 0 {
+                let bottom = start_idx + visible_rows - 1;
+                if sel > bottom {
+                    start_idx = sel + 1 - visible_rows;
+                }
+            }
+        }
+
+        for (i, row) in rows_all
+            .iter()
+            .enumerate()
+            .skip(start_idx)
+            .take(visible_rows)
+        {
+            let GenericDisplayRow {
+                name,
+                match_indices,
+                is_current,
+                description,
+            } = row;
+
+            // Highlight fuzzy indices when present.
+            let mut spans: Vec<Span> = Vec::with_capacity(name.len());
+            if let Some(idxs) = match_indices.as_ref() {
+                let mut idx_iter = idxs.iter().peekable();
+                for (char_idx, ch) in name.chars().enumerate() {
+                    let mut style = Style::default();
+                    if idx_iter.peek().is_some_and(|next| **next == char_idx) {
+                        idx_iter.next();
+                        style = style.add_modifier(Modifier::BOLD);
+                    }
+                    spans.push(Span::styled(ch.to_string(), style));
+                }
+            } else {
+                spans.push(Span::raw(name.clone()));
+            }
+
+            if let Some(desc) = description.as_ref() {
+                spans.push(Span::raw("  "));
+                spans.push(Span::styled(
+                    desc.clone(),
+                    Style::default()
+                        .fg(Color::DarkGray)
+                        .add_modifier(Modifier::DIM),
+                ));
+            }
+
+            let mut cell = Cell::from(Line::from(spans));
+            if Some(i) == state.selected_idx {
+                cell = cell.style(
+                    Style::default()
+                        .fg(Color::Yellow)
+                        .add_modifier(Modifier::BOLD),
+                );
+            } else if *is_current {
+                cell = cell.style(Style::default().fg(Color::Cyan));
+            }
+            rows.push(Row::new(vec![cell]));
+        }
+    }
+
+    let table = Table::new(rows, vec![Constraint::Percentage(100)])
+        .block(
+            Block::default()
+                .borders(Borders::LEFT)
+                .border_type(BorderType::QuadrantOutside)
+                .border_style(Style::default().fg(Color::DarkGray)),
+        )
+        .widths([Constraint::Percentage(100)]);
+
+    table.render(area, buf);
+}