Feat: collapsible help

src/services/dict_nav.rs

@@ -1,6 +1,8 @@
-use crate::model::categories;
+use crate::model::categories::{self, CatEntry, CATEGORIES};
 use crate::state::{DictFocus, UiState};
 
+use CatEntry::{Category, Section};
+
 pub fn toggle_focus(ui: &mut UiState) {
     ui.dict_focus = match ui.dict_focus {
         DictFocus::Categories => DictFocus::Words,
@@ -11,17 +13,86 @@ pub fn toggle_focus(ui: &mut UiState) {
 pub fn select_category(ui: &mut UiState, index: usize) {
     if index < categories::category_count() {
         ui.dict_category = index;
+        ui.dict_on_section = None;
+    }
+}
+
+#[derive(Clone, Copy)]
+enum VisibleItem {
+    Category(usize),
+    Section(usize),
+}
+
+fn visible_items(collapsed: &[bool]) -> Vec<VisibleItem> {
+    let mut result = Vec::new();
+    let mut section_idx = 0usize;
+    let mut cat_idx = 0usize;
+    let mut skipping = false;
+    for entry in CATEGORIES.iter() {
+        match entry {
+            Section(_) => {
+                let is_collapsed = collapsed.get(section_idx).copied().unwrap_or(false);
+                if is_collapsed {
+                    result.push(VisibleItem::Section(section_idx));
+                }
+                skipping = is_collapsed;
+                section_idx += 1;
+            }
+            Category(_) => {
+                if !skipping {
+                    result.push(VisibleItem::Category(cat_idx));
+                }
+                cat_idx += 1;
+            }
+        }
+    }
+    result
+}
+
+fn find_current(items: &[VisibleItem], ui: &UiState) -> usize {
+    if let Some(s) = ui.dict_on_section {
+        items
+            .iter()
+            .position(|v| matches!(v, VisibleItem::Section(idx) if *idx == s))
+            .unwrap_or(0)
+    } else {
+        items
+            .iter()
+            .position(|v| matches!(v, VisibleItem::Category(idx) if *idx == ui.dict_category))
+            .unwrap_or(0)
+    }
+}
+
+fn apply_selection(ui: &mut UiState, item: VisibleItem) {
+    match item {
+        VisibleItem::Category(idx) => {
+            ui.dict_category = idx;
+            ui.dict_on_section = None;
+        }
+        VisibleItem::Section(idx) => {
+            ui.dict_on_section = Some(idx);
+        }
     }
 }
 
 pub fn next_category(ui: &mut UiState) {
-    let count = categories::category_count();
-    ui.dict_category = (ui.dict_category + 1) % count;
+    let items = visible_items(&ui.dict_collapsed);
+    if items.is_empty() {
+        return;
+    }
+    let cur = find_current(&items, ui);
+    let next = (cur + 1) % items.len();
+    apply_selection(ui, items[next]);
 }
 
 pub fn prev_category(ui: &mut UiState) {
-    let count = categories::category_count();
-    ui.dict_category = (ui.dict_category + count - 1) % count;
+    let items = visible_items(&ui.dict_collapsed);
+    if items.is_empty() {
+        return;
+    }
+    let cur = find_current(&items, ui);
+    let next = (cur + items.len() - 1) % items.len();
+    apply_selection(ui, items[next]);
 }
 
 pub fn scroll_down(ui: &mut UiState, n: usize) {