Feat: collapsible help

crates/ratatui/src/category_list.rs

@@ -8,11 +8,17 @@ use crate::theme;
 pub struct CategoryItem<'a> {
     pub label: &'a str,
     pub is_section: bool,
+    pub collapsed: bool,
+}
+
+pub enum Selection {
+    Item(usize),
+    Section(usize),
 }
 
 pub struct CategoryList<'a> {
     items: &'a [CategoryItem<'a>],
-    selected: usize,
+    selection: Selection,
     focused: bool,
     title: &'a str,
     section_color: Color,
@@ -23,11 +29,11 @@ pub struct CategoryList<'a> {
 }
 
 impl<'a> CategoryList<'a> {
-    pub fn new(items: &'a [CategoryItem<'a>], selected: usize) -> Self {
+    pub fn new(items: &'a [CategoryItem<'a>], selection: Selection) -> Self {
         let theme = theme::get();
         Self {
             items,
-            selected,
+            selection,
             focused: false,
             title: "",
             section_color: theme.ui.text_dim,
@@ -63,25 +69,44 @@ impl<'a> CategoryList<'a> {
         self
     }
 
+    /// Build the visible items list, filtering out children of collapsed sections.
+    /// Returns (item, section_index_if_section, item_index_if_item).
+    fn visible_items(&self) -> Vec<(&CategoryItem<'a>, Option<usize>, Option<usize>)> {
+        let mut result = Vec::new();
+        let mut skipping = false;
+        let mut section_idx = 0usize;
+        let mut item_idx = 0usize;
+        for item in self.items.iter() {
+            if item.is_section {
+                skipping = item.collapsed;
+                result.push((item, Some(section_idx), None));
+                section_idx += 1;
+            } else if !skipping {
+                result.push((item, None, Some(item_idx)));
+                item_idx += 1;
+            } else {
+                item_idx += 1;
+            }
+        }
+        result
+    }
+
     pub fn render(self, frame: &mut Frame, area: Rect) {
         let theme = theme::get();
+        let visible = self.visible_items();
 
         let visible_height = area.height.saturating_sub(2) as usize;
-        let total_items = self.items.len();
+        let total_items = visible.len();
 
-        let selected_visual_idx = {
-            let mut visual = 0;
-            let mut selectable_count = 0;
-            for item in self.items.iter() {
-                if !item.is_section {
-                    if selectable_count == self.selected {
-                        break;
-                    }
-                    selectable_count += 1;
-                }
-                visual += 1;
-            }
-            visual
+        let selected_visual_idx = match &self.selection {
+            Selection::Item(sel) => visible
+                .iter()
+                .position(|(_, _, item_idx)| *item_idx == Some(*sel))
+                .unwrap_or(0),
+            Selection::Section(sel) => visible
+                .iter()
+                .position(|(_, sec_idx, _)| *sec_idx == Some(*sel))
+                .unwrap_or(0),
         };
 
         let scroll = if selected_visual_idx < visible_height / 2 {
@@ -92,24 +117,35 @@ impl<'a> CategoryList<'a> {
             selected_visual_idx.saturating_sub(visible_height / 2)
         };
 
-        let mut selectable_idx = self.items
-            .iter()
-            .take(scroll)
-            .filter(|e| !e.is_section)
-            .count();
-
         let is_dimmed = self.dimmed_color.is_some();
 
-        let items: Vec<ListItem> = self.items
+        let items: Vec<ListItem> = visible
             .iter()
             .skip(scroll)
             .take(visible_height)
-            .map(|item| {
+            .enumerate()
+            .map(|(vis_offset, (item, sec_idx, _itm_idx))| {
+                let visual_pos = scroll + vis_offset;
                 if item.is_section {
-                    let style = Style::new().fg(self.section_color);
-                    ListItem::new(format!("─ {} ─", item.label)).style(style)
+                    let is_selected =
+                        matches!(&self.selection, Selection::Section(s) if Some(*s) == *sec_idx);
+                    let arrow = if item.collapsed { "▸" } else { "▾" };
+                    let style = if is_selected && self.focused {
+                        Style::new()
+                            .fg(self.focused_color)
+                            .add_modifier(Modifier::BOLD)
+                    } else if is_selected {
+                        Style::new()
+                            .fg(self.selected_color)
+                            .add_modifier(Modifier::BOLD)
+                    } else {
+                        Style::new().fg(self.section_color)
+                    };
+                    let prefix = if is_selected && !is_dimmed { "> " } else { "" };
+                    ListItem::new(format!("{prefix}{arrow} {}", item.label)).style(style)
                 } else {
-                    let is_selected = selectable_idx == self.selected;
+                    let is_selected = visual_pos == selected_visual_idx
+                        && matches!(&self.selection, Selection::Item(_));
                     let style = if let Some(dim_color) = self.dimmed_color {
                         Style::new().fg(dim_color)
                     } else if is_selected && self.focused {
@@ -123,8 +159,11 @@ impl<'a> CategoryList<'a> {
                     } else {
                         Style::new().fg(self.normal_color)
                     };
-                    let prefix = if is_selected && !is_dimmed { "> " } else { "  " };
-                    selectable_idx += 1;
+                    let prefix = if is_selected && !is_dimmed {
+                        "> "
+                    } else {
+                        "  "
+                    };
                     ListItem::new(format!("{prefix}{}", item.label)).style(style)
                 }
             })

crates/ratatui/src/lib.rs

@@ -21,7 +21,7 @@ mod vu_meter;
 mod waveform;
 
 pub use active_patterns::{ActivePatterns, MuteStatus};
-pub use category_list::{CategoryItem, CategoryList};
+pub use category_list::{CategoryItem, CategoryList, Selection};
 pub use confirm::ConfirmModal;
 pub use editor::{fuzzy_match, CompletionCandidate, Editor};
 pub use file_browser::FileBrowserModal;