Some kind of refactoring

src/services/help_nav.rs

@@ -0,0 +1,61 @@
+use crate::model::docs;
+use crate::state::{HelpFocus, UiState};
+
+pub fn toggle_focus(ui: &mut UiState) {
+    ui.help_focus = match ui.help_focus {
+        HelpFocus::Topics => HelpFocus::Content,
+        HelpFocus::Content => HelpFocus::Topics,
+    };
+}
+
+pub fn next_topic(ui: &mut UiState, n: usize) {
+    let count = docs::topic_count();
+    ui.help_topic = (ui.help_topic + n) % count;
+}
+
+pub fn prev_topic(ui: &mut UiState, n: usize) {
+    let count = docs::topic_count();
+    ui.help_topic = (ui.help_topic + count - (n % count)) % count;
+}
+
+pub fn scroll_down(ui: &mut UiState, n: usize) {
+    let s = ui.help_scroll_mut();
+    *s = s.saturating_add(n);
+}
+
+pub fn scroll_up(ui: &mut UiState, n: usize) {
+    let s = ui.help_scroll_mut();
+    *s = s.saturating_sub(n);
+}
+
+pub fn activate_search(ui: &mut UiState) {
+    ui.help_search_active = true;
+}
+
+pub fn clear_search(ui: &mut UiState) {
+    ui.help_search_query.clear();
+    ui.help_search_active = false;
+}
+
+pub fn search_input(ui: &mut UiState, c: char) {
+    ui.help_search_query.push(c);
+    if let Some((topic, line)) = docs::find_match(&ui.help_search_query) {
+        ui.help_topic = topic;
+        ui.help_scrolls[topic] = line;
+    }
+}
+
+pub fn search_backspace(ui: &mut UiState) {
+    ui.help_search_query.pop();
+    if ui.help_search_query.is_empty() {
+        return;
+    }
+    if let Some((topic, line)) = docs::find_match(&ui.help_search_query) {
+        ui.help_topic = topic;
+        ui.help_scrolls[topic] = line;
+    }
+}
+
+pub fn search_confirm(ui: &mut UiState) {
+    ui.help_search_active = false;
+}