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 select_topic(ui: &mut UiState, index: usize) {
    if index < docs::topic_count() {
        ui.help_topic = index;
    }
}

pub fn next_topic(ui: &mut UiState, n: usize) {
    let count = docs::topic_count();
    ui.help_topic = (ui.help_topic + n) % count;
    ui.help_focused_block = None;
}

pub fn prev_topic(ui: &mut UiState, n: usize) {
    let count = docs::topic_count();
    ui.help_topic = (ui.help_topic + count - (n % count)) % count;
    ui.help_focused_block = None;
}

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;
}