mod app;
mod config;
mod engine;
mod event;
mod generator;
mod keyboard;
mod session;
mod store;
mod ui;

use std::io;
use std::time::{Duration, Instant};

use anyhow::Result;
use clap::Parser;
use crossterm::event::{
    KeyCode, KeyEvent, KeyEventKind, KeyEventState, KeyModifiers, KeyboardEnhancementFlags,
    ModifierKeyCode, PopKeyboardEnhancementFlags, PushKeyboardEnhancementFlags,
};
use crossterm::execute;
use crossterm::terminal::{
    EnterAlternateScreen, LeaveAlternateScreen, disable_raw_mode, enable_raw_mode,
};
use ratatui::Terminal;
use ratatui::backend::CrosstermBackend;
use ratatui::layout::{Constraint, Direction, Layout, Rect};
use ratatui::style::{Modifier, Style};
use ratatui::text::{Line, Span};
use ratatui::widgets::{Block, Paragraph, Widget, Wrap};

use app::{App, AppScreen, DrillMode, MilestoneKind, StatusKind};
use engine::skill_tree::{DrillScope, find_key_branch};
use keyboard::display::key_display_name;
use keyboard::finger::Hand;
use event::{AppEvent, EventHandler};
use generator::code_syntax::{code_language_options, is_language_cached, language_by_key};
use generator::passage::{is_book_cached, passage_options};
use ui::components::dashboard::Dashboard;
use ui::components::keyboard_diagram::KeyboardDiagram;
use ui::components::skill_tree::{SkillTreeWidget, detail_line_count, selectable_branches};
use ui::components::stats_dashboard::StatsDashboard;
use ui::components::stats_sidebar::StatsSidebar;
use ui::components::typing_area::TypingArea;
use ui::layout::AppLayout;

#[derive(Parser)]
#[command(
    name = "keydr",
    version,
    about = "Terminal typing tutor with adaptive learning"
)]
struct Cli {
    #[arg(short, long, help = "Theme name")]
    theme: Option<String>,

    #[arg(short, long, help = "Keyboard layout (qwerty, dvorak, colemak)")]
    layout: Option<String>,

    #[arg(short, long, help = "Number of words per drill")]
    words: Option<usize>,
}

fn main() -> Result<()> {
    let cli = Cli::parse();

    let mut app = App::new();

    if let Some(words) = cli.words {
        app.config.word_count = words;
    }
    if let Some(theme_name) = cli.theme {
        if let Some(theme) = ui::theme::Theme::load(&theme_name) {
            let theme: &'static ui::theme::Theme = Box::leak(Box::new(theme));
            app.theme = theme;
            app.menu.theme = theme;
        }
    }

    enable_raw_mode()?;
    let mut stdout = io::stdout();
    execute!(stdout, EnterAlternateScreen)?;

    // Try to enable keyboard enhancement for Release event support
    let keyboard_enhanced = execute!(
        io::stdout(),
        PushKeyboardEnhancementFlags(
            KeyboardEnhancementFlags::REPORT_EVENT_TYPES
                | KeyboardEnhancementFlags::DISAMBIGUATE_ESCAPE_CODES,
        )
    )
    .is_ok();

    let backend = CrosstermBackend::new(stdout);
    let mut terminal = Terminal::new(backend)?;
    terminal.hide_cursor()?;

    let events = EventHandler::new(Duration::from_millis(100));

    let result = run_app(&mut terminal, &mut app, &events);

    if keyboard_enhanced {
        let _ = execute!(io::stdout(), PopKeyboardEnhancementFlags);
    }
    disable_raw_mode()?;
    execute!(terminal.backend_mut(), LeaveAlternateScreen)?;
    terminal.show_cursor()?;

    if let Err(err) = result {
        eprintln!("Error: {err:?}");
    }

    Ok(())
}

fn run_app(
    terminal: &mut Terminal<CrosstermBackend<io::Stdout>>,
    app: &mut App,
    events: &EventHandler,
) -> Result<()> {
    loop {
        terminal.draw(|frame| render(frame, app))?;

        match events.next()? {
            AppEvent::Key(key) => handle_key(app, key),
            AppEvent::Tick => {
                if (app.screen == AppScreen::PassageIntro
                    || app.screen == AppScreen::PassageDownloadProgress)
                    && app.passage_intro_downloading
                {
                    app.process_passage_download_tick();
                }
                if (app.screen == AppScreen::CodeIntro
                    || app.screen == AppScreen::CodeDownloadProgress)
                    && app.code_intro_downloading
                {
                    app.process_code_download_tick();
                }
                // Fallback: clear depressed keys after 150ms if no Release event received
                if let Some(last) = app.last_key_time {
                    if last.elapsed() > Duration::from_millis(150) && !app.depressed_keys.is_empty()
                    {
                        app.depressed_keys.clear();
                        app.last_key_time = None;
                    }
                    // Clear shift_held after 200ms as fallback
                    if last.elapsed() > Duration::from_millis(200) && app.shift_held {
                        app.shift_held = false;
                    }
                }
            }
            AppEvent::Resize(_, _) => {}
        }

        if app.should_quit {
            return Ok(());
        }
    }
}

fn handle_key(app: &mut App, key: KeyEvent) {
    // Track caps lock state via Kitty protocol metadata (KeyEventState::CAPS_LOCK).
    // This only works in terminals with native Kitty keyboard protocol support
    // (Kitty, WezTerm, foot, Ghostty). In tmux/mosh/SSH, the protocol is stripped
    // and crossterm infers SHIFT from character case, making it impossible to
    // distinguish Shift+a from CapsLock+a.
    app.caps_lock = key.state.contains(KeyEventState::CAPS_LOCK);

    // Track depressed keys and shift state for keyboard diagram
    match (&key.code, key.kind) {
        (KeyCode::Modifier(ModifierKeyCode::LeftShift | ModifierKeyCode::RightShift), KeyEventKind::Press) => {
            app.shift_held = true;
            app.last_key_time = Some(Instant::now());
            return; // Don't dispatch bare shift presses to screen handlers
        }
        (KeyCode::Modifier(ModifierKeyCode::LeftShift | ModifierKeyCode::RightShift), KeyEventKind::Release) => {
            app.shift_held = false;
            return;
        }
        (KeyCode::Char(ch), KeyEventKind::Press) => {
            app.depressed_keys.insert(ch.to_ascii_lowercase());
            app.last_key_time = Some(Instant::now());
            app.shift_held = key.modifiers.contains(KeyModifiers::SHIFT);
        }
        (KeyCode::Char(ch), KeyEventKind::Release) => {
            app.depressed_keys.remove(&ch.to_ascii_lowercase());
            return; // Don't process Release events as input
        }
        (KeyCode::Backspace, KeyEventKind::Press) => {
            app.depressed_keys.insert('\x08');
            app.last_key_time = Some(Instant::now());
            app.shift_held = key.modifiers.contains(KeyModifiers::SHIFT);
        }
        (KeyCode::Backspace, KeyEventKind::Release) => {
            app.depressed_keys.remove(&'\x08');
            return;
        }
        (KeyCode::Tab, KeyEventKind::Press) => {
            app.depressed_keys.insert('\t');
            app.last_key_time = Some(Instant::now());
            app.shift_held = key.modifiers.contains(KeyModifiers::SHIFT);
        }
        (KeyCode::Tab, KeyEventKind::Release) => {
            app.depressed_keys.remove(&'\t');
            return;
        }
        (KeyCode::Enter, KeyEventKind::Press) => {
            app.depressed_keys.insert('\n');
            app.last_key_time = Some(Instant::now());
            app.shift_held = key.modifiers.contains(KeyModifiers::SHIFT);
        }
        (KeyCode::Enter, KeyEventKind::Release) => {
            app.depressed_keys.remove(&'\n');
            return;
        }
        (_, KeyEventKind::Release) => return,
        _ => {
            app.shift_held = key.modifiers.contains(KeyModifiers::SHIFT);
        }
    }

    // Only process Press events — ignore Repeat to avoid inflating input
    if key.kind != KeyEventKind::Press {
        return;
    }

    if key.modifiers.contains(KeyModifiers::CONTROL) && key.code == KeyCode::Char('c') {
        app.should_quit = true;
        return;
    }

    // Milestone overlays are modal: any key dismisses exactly one popup and is consumed.
    if !app.milestone_queue.is_empty() {
        app.milestone_queue.pop_front();
        return;
    }

    match app.screen {
        AppScreen::Menu => handle_menu_key(app, key),
        AppScreen::Drill => handle_drill_key(app, key),
        AppScreen::DrillResult => handle_result_key(app, key),
        AppScreen::StatsDashboard => handle_stats_key(app, key),
        AppScreen::Settings => handle_settings_key(app, key),
        AppScreen::SkillTree => handle_skill_tree_key(app, key),
        AppScreen::CodeLanguageSelect => handle_code_language_key(app, key),
        AppScreen::PassageBookSelect => handle_passage_book_key(app, key),
        AppScreen::PassageIntro => handle_passage_intro_key(app, key),
        AppScreen::PassageDownloadProgress => handle_passage_download_progress_key(app, key),
        AppScreen::CodeIntro => handle_code_intro_key(app, key),
        AppScreen::CodeDownloadProgress => handle_code_download_progress_key(app, key),
        AppScreen::Keyboard => handle_keyboard_explorer_key(app, key),
    }
}

fn handle_menu_key(app: &mut App, key: KeyEvent) {
    match key.code {
        KeyCode::Char('q') | KeyCode::Esc => app.should_quit = true,
        KeyCode::Char('1') => {
            app.drill_mode = DrillMode::Adaptive;
            app.drill_scope = DrillScope::Global;
            app.start_drill();
        }
        KeyCode::Char('2') => {
            if app.config.code_onboarding_done {
                app.go_to_code_language_select();
            } else {
                app.go_to_code_intro();
            }
        }
        KeyCode::Char('3') => {
            if app.config.passage_onboarding_done {
                app.go_to_passage_book_select();
            } else {
                app.go_to_passage_intro();
            }
        }
        KeyCode::Char('t') => app.go_to_skill_tree(),
        KeyCode::Char('b') => app.go_to_keyboard(),
        KeyCode::Char('s') => app.go_to_stats(),
        KeyCode::Char('c') => app.go_to_settings(),
        KeyCode::Up | KeyCode::Char('k') => app.menu.prev(),
        KeyCode::Down | KeyCode::Char('j') => app.menu.next(),
        KeyCode::Enter => match app.menu.selected {
            0 => {
                app.drill_mode = DrillMode::Adaptive;
                app.drill_scope = DrillScope::Global;
                app.start_drill();
            }
            1 => {
                if app.config.code_onboarding_done {
                    app.go_to_code_language_select();
                } else {
                    app.go_to_code_intro();
                }
            }
            2 => {
                if app.config.passage_onboarding_done {
                    app.go_to_passage_book_select();
                } else {
                    app.go_to_passage_intro();
                }
            }
            3 => app.go_to_skill_tree(),
            4 => app.go_to_keyboard(),
            5 => app.go_to_stats(),
            6 => app.go_to_settings(),
            _ => {}
        },
        _ => {}
    }
}

fn handle_drill_key(app: &mut App, key: KeyEvent) {
    // Route Enter/Tab as typed characters during active drills
    if app.drill.is_some() {
        match key.code {
            KeyCode::Enter => {
                app.type_char('\n');
                return;
            }
            KeyCode::Tab => {
                app.type_char('\t');
                return;
            }
            KeyCode::BackTab => return, // Ignore Shift+Tab
            _ => {}
        }
    }

    match key.code {
        KeyCode::Esc => {
            let has_progress = app.drill.as_ref().is_some_and(|d| d.cursor > 0);
            if has_progress {
                app.finish_partial_drill();
            } else {
                app.go_to_menu();
            }
        }
        KeyCode::Backspace => app.backspace(),
        KeyCode::Char(ch) => app.type_char(ch),
        _ => {}
    }
}

fn handle_result_key(app: &mut App, key: KeyEvent) {
    if app.history_confirm_delete {
        match key.code {
            KeyCode::Char('y') => {
                app.delete_session();
                app.history_confirm_delete = false;
            }
            KeyCode::Char('n') | KeyCode::Esc => {
                app.history_confirm_delete = false;
            }
            _ => {}
        }
        return;
    }

    match key.code {
        KeyCode::Char('c') | KeyCode::Enter | KeyCode::Char(' ') => app.continue_drill(),
        KeyCode::Char('r') => app.retry_drill(),
        KeyCode::Char('q') | KeyCode::Esc => app.go_to_menu(),
        KeyCode::Char('s') => app.go_to_stats(),
        KeyCode::Char('x') => {
            if !app.drill_history.is_empty() {
                // On result screen, delete always targets the just-completed (most recent) session.
                app.history_selected = 0;
                app.history_confirm_delete = true;
            }
        }
        _ => {}
    }
}

fn handle_stats_key(app: &mut App, key: KeyEvent) {
    const STATS_TAB_COUNT: usize = 5;

    // Confirmation dialog takes priority
    if app.history_confirm_delete {
        match key.code {
            KeyCode::Char('y') => {
                app.delete_session();
                app.history_confirm_delete = false;
            }
            KeyCode::Char('n') | KeyCode::Esc => {
                app.history_confirm_delete = false;
            }
            _ => {}
        }
        return;
    }

    // History tab has row navigation
    if app.stats_tab == 1 {
        match key.code {
            KeyCode::Esc | KeyCode::Char('q') => app.go_to_menu(),
            KeyCode::Char('j') | KeyCode::Down => {
                if !app.drill_history.is_empty() {
                    let max_visible = app.drill_history.len().min(20) - 1;
                    app.history_selected = (app.history_selected + 1).min(max_visible);
                }
            }
            KeyCode::Char('k') | KeyCode::Up => {
                app.history_selected = app.history_selected.saturating_sub(1);
            }
            KeyCode::Char('x') | KeyCode::Delete => {
                if !app.drill_history.is_empty() {
                    app.history_confirm_delete = true;
                }
            }
            KeyCode::Char('1') => app.stats_tab = 0,
            KeyCode::Char('2') => {} // already on history
            KeyCode::Char('3') => app.stats_tab = 2,
            KeyCode::Char('4') => app.stats_tab = 3,
            KeyCode::Char('5') => app.stats_tab = 4,
            KeyCode::Tab => app.stats_tab = (app.stats_tab + 1) % STATS_TAB_COUNT,
            KeyCode::BackTab => {
                app.stats_tab = if app.stats_tab == 0 {
                    STATS_TAB_COUNT - 1
                } else {
                    app.stats_tab - 1
                }
            }
            _ => {}
        }
        return;
    }

    match key.code {
        KeyCode::Esc | KeyCode::Char('q') => app.go_to_menu(),
        KeyCode::Char('1') => app.stats_tab = 0,
        KeyCode::Char('2') => app.stats_tab = 1,
        KeyCode::Char('3') => app.stats_tab = 2,
        KeyCode::Char('4') => app.stats_tab = 3,
        KeyCode::Char('5') => app.stats_tab = 4,
        KeyCode::Tab => app.stats_tab = (app.stats_tab + 1) % STATS_TAB_COUNT,
        KeyCode::BackTab => {
            app.stats_tab = if app.stats_tab == 0 {
                STATS_TAB_COUNT - 1
            } else {
                app.stats_tab - 1
            }
        }
        _ => {}
    }
}

fn handle_settings_key(app: &mut App, key: KeyEvent) {
    const MAX_SETTINGS: usize = 15;

    // Priority 1: dismiss status message
    if app.settings_status_message.is_some() {
        app.settings_status_message = None;
        return;
    }

    // Priority 2: export conflict dialog
    if app.settings_export_conflict {
        match key.code {
            KeyCode::Char('d') => {
                app.settings_export_conflict = false;
                app.export_data_overwrite();
            }
            KeyCode::Char('r') => {
                app.settings_export_conflict = false;
                app.export_data_rename();
            }
            KeyCode::Esc => {
                app.settings_export_conflict = false;
            }
            _ => {}
        }
        return;
    }

    // Priority 3: import confirmation dialog
    if app.settings_confirm_import {
        match key.code {
            KeyCode::Char('y') => {
                app.settings_confirm_import = false;
                app.import_data();
            }
            KeyCode::Char('n') | KeyCode::Esc => {
                app.settings_confirm_import = false;
            }
            _ => {}
        }
        return;
    }

    // Priority 4: editing a path field
    if app.settings_editing_download_dir || app.settings_editing_export_path || app.settings_editing_import_path {
        match key.code {
            KeyCode::Esc => {
                app.clear_settings_modals();
            }
            KeyCode::Backspace => {
                if app.settings_editing_download_dir {
                    if app.settings_selected == 5 {
                        app.config.code_download_dir.pop();
                    } else if app.settings_selected == 9 {
                        app.config.passage_download_dir.pop();
                    }
                } else if app.settings_editing_export_path {
                    app.settings_export_path.pop();
                } else if app.settings_editing_import_path {
                    app.settings_import_path.pop();
                }
            }
            KeyCode::Char(ch) if !key.modifiers.contains(KeyModifiers::CONTROL) => {
                if app.settings_editing_download_dir {
                    if app.settings_selected == 5 {
                        app.config.code_download_dir.push(ch);
                    } else if app.settings_selected == 9 {
                        app.config.passage_download_dir.push(ch);
                    }
                } else if app.settings_editing_export_path {
                    app.settings_export_path.push(ch);
                } else if app.settings_editing_import_path {
                    app.settings_import_path.push(ch);
                }
            }
            _ => {}
        }
        return;
    }

    match key.code {
        KeyCode::Esc => {
            let _ = app.config.save();
            app.go_to_menu();
        }
        KeyCode::Up | KeyCode::Char('k') => {
            if app.settings_selected > 0 {
                app.settings_selected -= 1;
            }
        }
        KeyCode::Down | KeyCode::Char('j') => {
            if app.settings_selected < MAX_SETTINGS {
                app.settings_selected += 1;
            }
        }
        KeyCode::Enter => {
            match app.settings_selected {
                5 | 9 => {
                    app.clear_settings_modals();
                    app.settings_editing_download_dir = true;
                }
                7 => app.start_code_downloads_from_settings(),
                11 => app.start_passage_downloads_from_settings(),
                12 => {
                    app.clear_settings_modals();
                    app.settings_editing_export_path = true;
                }
                13 => app.export_data(),
                14 => {
                    app.clear_settings_modals();
                    app.settings_editing_import_path = true;
                }
                15 => {
                    app.clear_settings_modals();
                    app.settings_confirm_import = true;
                }
                _ => app.settings_cycle_forward(),
            }
        }
        KeyCode::Right | KeyCode::Char('l') => {
            match app.settings_selected {
                5 | 7 | 9 | 11 | 12 | 13 | 14 | 15 => {} // path/button fields
                _ => app.settings_cycle_forward(),
            }
        }
        KeyCode::Left | KeyCode::Char('h') => {
            match app.settings_selected {
                5 | 7 | 9 | 11 | 12 | 13 | 14 | 15 => {} // path/button fields
                _ => app.settings_cycle_backward(),
            }
        }
        _ => {}
    }
}

fn handle_code_language_key(app: &mut App, key: KeyEvent) {
    let options = code_language_options();
    let len = options.len();
    if len == 0 {
        return;
    }

    match key.code {
        KeyCode::Esc | KeyCode::Char('q') => app.go_to_menu(),
        KeyCode::Up | KeyCode::Char('k') => {
            app.code_language_selected = app.code_language_selected.saturating_sub(1);
        }
        KeyCode::Down | KeyCode::Char('j') => {
            if app.code_language_selected + 1 < len {
                app.code_language_selected += 1;
            }
        }
        KeyCode::PageUp => {
            app.code_language_selected = app.code_language_selected.saturating_sub(10);
        }
        KeyCode::PageDown => {
            app.code_language_selected = (app.code_language_selected + 10).min(len - 1);
        }
        KeyCode::Home | KeyCode::Char('g') => {
            app.code_language_selected = 0;
        }
        KeyCode::End | KeyCode::Char('G') => {
            app.code_language_selected = len - 1;
        }
        KeyCode::Enter => {
            if app.code_language_selected >= options.len() {
                return;
            }
            let key = options[app.code_language_selected].0;
            if !is_code_language_disabled(app, key) {
                confirm_code_language_and_continue(app, &options);
            }
        }
        _ => {}
    }

    // Adjust scroll to keep selected item visible.
    // Use a rough viewport estimate; render will use exact terminal size.
    let viewport = 15usize;
    if app.code_language_selected < app.code_language_scroll {
        app.code_language_scroll = app.code_language_selected;
    } else if app.code_language_selected >= app.code_language_scroll + viewport {
        app.code_language_scroll = app.code_language_selected + 1 - viewport;
    }
}

fn code_language_requires_download(app: &App, key: &str) -> bool {
    if key == "all" {
        return false;
    }
    let Some(lang) = language_by_key(key) else {
        return false;
    };
    !lang.has_builtin && !is_language_cached(&app.config.code_download_dir, key)
}

fn is_code_language_disabled(app: &App, key: &str) -> bool {
    !app.config.code_downloads_enabled && code_language_requires_download(app, key)
}

fn confirm_code_language_and_continue(app: &mut App, options: &[(&str, String)]) {
    if app.code_language_selected >= options.len() {
        return;
    }
    app.config.code_language = options[app.code_language_selected].0.to_string();
    let _ = app.config.save();
    if app.config.code_onboarding_done {
        app.start_code_drill();
    } else {
        app.go_to_code_intro();
    }
}

fn handle_passage_book_key(app: &mut App, key: KeyEvent) {
    let options = passage_options();
    match key.code {
        KeyCode::Esc | KeyCode::Char('q') => app.go_to_menu(),
        KeyCode::Up | KeyCode::Char('k') => {
            app.passage_book_selected = app.passage_book_selected.saturating_sub(1);
        }
        KeyCode::Down | KeyCode::Char('j') => {
            if app.passage_book_selected + 1 < options.len() {
                app.passage_book_selected += 1;
            }
        }
        KeyCode::Char(ch) if ch.is_ascii_digit() => {
            let idx = (ch as usize).saturating_sub('1' as usize);
            if idx < options.len() {
                app.passage_book_selected = idx;
                let key = options[idx].0;
                if !is_passage_option_disabled(app, key) {
                    confirm_passage_book_and_continue(app, &options);
                }
            }
        }
        KeyCode::Enter => {
            if app.passage_book_selected < options.len() {
                let key = options[app.passage_book_selected].0;
                if !is_passage_option_disabled(app, key) {
                    confirm_passage_book_and_continue(app, &options);
                }
            }
        }
        _ => {}
    }
}

fn passage_option_requires_download(app: &App, key: &str) -> bool {
    key != "all" && key != "builtin" && !is_book_cached(&app.config.passage_download_dir, key)
}

fn is_passage_option_disabled(app: &App, key: &str) -> bool {
    !app.config.passage_downloads_enabled && passage_option_requires_download(app, key)
}

fn confirm_passage_book_and_continue(app: &mut App, options: &[(&'static str, String)]) {
    if app.passage_book_selected >= options.len() {
        return;
    }
    app.config.passage_book = options[app.passage_book_selected].0.to_string();
    let _ = app.config.save();

    if app.config.passage_onboarding_done {
        app.start_passage_drill();
    } else {
        app.go_to_passage_intro();
    }
}

fn handle_passage_intro_key(app: &mut App, key: KeyEvent) {
    const INTRO_FIELDS: usize = 4;

    if app.passage_intro_downloading {
        return;
    }

    match key.code {
        KeyCode::Esc | KeyCode::Char('q') => app.go_to_menu(),
        KeyCode::Up | KeyCode::Char('k') => {
            app.passage_intro_selected = app.passage_intro_selected.saturating_sub(1);
        }
        KeyCode::Down | KeyCode::Char('j') => {
            if app.passage_intro_selected + 1 < INTRO_FIELDS {
                app.passage_intro_selected += 1;
            }
        }
        KeyCode::Left | KeyCode::Char('h') => match app.passage_intro_selected {
            0 => app.passage_intro_downloads_enabled = !app.passage_intro_downloads_enabled,
            2 => {
                app.passage_intro_paragraph_limit = match app.passage_intro_paragraph_limit {
                    0 => 500,
                    1 => 0,
                    n => n.saturating_sub(25).max(1),
                };
            }
            _ => {}
        },
        KeyCode::Right | KeyCode::Char('l') => match app.passage_intro_selected {
            0 => app.passage_intro_downloads_enabled = !app.passage_intro_downloads_enabled,
            2 => {
                app.passage_intro_paragraph_limit = match app.passage_intro_paragraph_limit {
                    0 => 1,
                    n if n >= 500 => 0,
                    n => n + 25,
                };
            }
            _ => {}
        },
        KeyCode::Backspace => match app.passage_intro_selected {
            1 => {
                app.passage_intro_download_dir.pop();
            }
            2 => {
                app.passage_intro_paragraph_limit /= 10;
            }
            _ => {}
        },
        KeyCode::Char(ch) => match app.passage_intro_selected {
            1 if !key.modifiers.contains(KeyModifiers::CONTROL) => {
                app.passage_intro_download_dir.push(ch);
            }
            2 if ch.is_ascii_digit() => {
                let digit = (ch as u8 - b'0') as usize;
                app.passage_intro_paragraph_limit = app
                    .passage_intro_paragraph_limit
                    .saturating_mul(10)
                    .saturating_add(digit)
                    .min(50_000);
            }
            _ => {}
        },
        KeyCode::Enter => {
            if app.passage_intro_selected == 0 {
                app.passage_intro_downloads_enabled = !app.passage_intro_downloads_enabled;
                return;
            }
            if app.passage_intro_selected != 3 {
                return;
            }

            app.config.passage_downloads_enabled = app.passage_intro_downloads_enabled;
            app.config.passage_download_dir = app.passage_intro_download_dir.clone();
            app.config.passage_paragraphs_per_book = app.passage_intro_paragraph_limit;
            app.config.passage_onboarding_done = true;
            let _ = app.config.save();
            app.go_to_passage_book_select();
        }
        _ => {}
    }
}

fn handle_passage_download_progress_key(app: &mut App, key: KeyEvent) {
    match key.code {
        KeyCode::Esc | KeyCode::Char('q') => app.go_to_menu(),
        _ => {}
    }
}

fn handle_code_intro_key(app: &mut App, key: KeyEvent) {
    const INTRO_FIELDS: usize = 4;

    if app.code_intro_downloading {
        return;
    }

    match key.code {
        KeyCode::Esc | KeyCode::Char('q') => app.go_to_menu(),
        KeyCode::Up | KeyCode::Char('k') => {
            app.code_intro_selected = app.code_intro_selected.saturating_sub(1);
        }
        KeyCode::Down | KeyCode::Char('j') => {
            if app.code_intro_selected + 1 < INTRO_FIELDS {
                app.code_intro_selected += 1;
            }
        }
        KeyCode::Left | KeyCode::Char('h') => match app.code_intro_selected {
            0 => app.code_intro_downloads_enabled = !app.code_intro_downloads_enabled,
            2 => {
                app.code_intro_snippets_per_repo = match app.code_intro_snippets_per_repo {
                    0 => 200,
                    1 => 0,
                    n => n.saturating_sub(10).max(1),
                };
            }
            _ => {}
        },
        KeyCode::Right | KeyCode::Char('l') => match app.code_intro_selected {
            0 => app.code_intro_downloads_enabled = !app.code_intro_downloads_enabled,
            2 => {
                app.code_intro_snippets_per_repo = match app.code_intro_snippets_per_repo {
                    0 => 1,
                    n if n >= 200 => 0,
                    n => n + 10,
                };
            }
            _ => {}
        },
        KeyCode::Backspace => match app.code_intro_selected {
            1 => {
                app.code_intro_download_dir.pop();
            }
            2 => {
                app.code_intro_snippets_per_repo /= 10;
            }
            _ => {}
        },
        KeyCode::Char(ch) => match app.code_intro_selected {
            1 if !key.modifiers.contains(KeyModifiers::CONTROL) => {
                app.code_intro_download_dir.push(ch);
            }
            2 if ch.is_ascii_digit() => {
                let digit = (ch as u8 - b'0') as usize;
                app.code_intro_snippets_per_repo = app
                    .code_intro_snippets_per_repo
                    .saturating_mul(10)
                    .saturating_add(digit)
                    .min(10_000);
            }
            _ => {}
        },
        KeyCode::Enter => {
            if app.code_intro_selected == 0 {
                app.code_intro_downloads_enabled = !app.code_intro_downloads_enabled;
                return;
            }
            if app.code_intro_selected != 3 {
                return;
            }

            app.config.code_downloads_enabled = app.code_intro_downloads_enabled;
            app.config.code_download_dir = app.code_intro_download_dir.clone();
            app.config.code_snippets_per_repo = app.code_intro_snippets_per_repo;
            app.config.code_onboarding_done = true;
            let _ = app.config.save();
            app.go_to_code_language_select();
        }
        _ => {}
    }
}

fn handle_code_download_progress_key(app: &mut App, key: KeyEvent) {
    match key.code {
        KeyCode::Esc | KeyCode::Char('q') => {
            app.cancel_code_download();
            app.go_to_menu();
        }
        _ => {}
    }
}

fn handle_skill_tree_key(app: &mut App, key: KeyEvent) {
    const DETAIL_SCROLL_STEP: usize = 10;
    let max_scroll = skill_tree_detail_max_scroll(app);
    app.skill_tree_detail_scroll = app.skill_tree_detail_scroll.min(max_scroll);
    let branches = selectable_branches();
    match key.code {
        KeyCode::Esc | KeyCode::Char('q') => app.go_to_menu(),
        KeyCode::Up | KeyCode::Char('k') => {
            app.skill_tree_selected = app.skill_tree_selected.saturating_sub(1);
            app.skill_tree_detail_scroll = 0;
        }
        KeyCode::Down | KeyCode::Char('j') => {
            if app.skill_tree_selected + 1 < branches.len() {
                app.skill_tree_selected += 1;
                app.skill_tree_detail_scroll = 0;
            }
        }
        KeyCode::PageUp => {
            app.skill_tree_detail_scroll = app
                .skill_tree_detail_scroll
                .saturating_sub(DETAIL_SCROLL_STEP);
        }
        KeyCode::PageDown => {
            let max_scroll = skill_tree_detail_max_scroll(app);
            app.skill_tree_detail_scroll = app
                .skill_tree_detail_scroll
                .saturating_add(DETAIL_SCROLL_STEP)
                .min(max_scroll);
        }
        KeyCode::Char('u') if key.modifiers.contains(KeyModifiers::CONTROL) => {
            app.skill_tree_detail_scroll = app
                .skill_tree_detail_scroll
                .saturating_sub(DETAIL_SCROLL_STEP);
        }
        KeyCode::Char('d') if key.modifiers.contains(KeyModifiers::CONTROL) => {
            let max_scroll = skill_tree_detail_max_scroll(app);
            app.skill_tree_detail_scroll = app
                .skill_tree_detail_scroll
                .saturating_add(DETAIL_SCROLL_STEP)
                .min(max_scroll);
        }
        KeyCode::Enter => {
            if app.skill_tree_selected < branches.len() {
                let branch_id = branches[app.skill_tree_selected];
                let status = app.skill_tree.branch_status(branch_id).clone();
                if status == engine::skill_tree::BranchStatus::Available
                    || status == engine::skill_tree::BranchStatus::InProgress
                {
                    app.start_branch_drill(branch_id);
                }
            }
        }
        _ => {}
    }
}

fn skill_tree_detail_max_scroll(app: &App) -> usize {
    let (w, h) = crossterm::terminal::size().unwrap_or((120, 40));
    let screen = Rect::new(0, 0, w, h);
    let centered = skill_tree_popup_rect(screen);
    let inner = Rect::new(
        centered.x.saturating_add(1),
        centered.y.saturating_add(1),
        centered.width.saturating_sub(2),
        centered.height.saturating_sub(2),
    );

    let branches = selectable_branches();
    if branches.is_empty() {
        return 0;
    }
    let branch_list_height = branches.len() as u16 * 2 + 1;
    let layout = Layout::default()
        .direction(Direction::Vertical)
        .constraints([
            Constraint::Length(branch_list_height.min(inner.height.saturating_sub(6))),
            Constraint::Length(1),
            Constraint::Min(4),
            Constraint::Length(2),
        ])
        .split(inner);
    let detail_height = layout.get(2).map(|r| r.height as usize).unwrap_or(0);
    let selected = app
        .skill_tree_selected
        .min(branches.len().saturating_sub(1));
    let total_lines = detail_line_count(branches[selected]);
    total_lines.saturating_sub(detail_height)
}

fn skill_tree_popup_rect(area: Rect) -> Rect {
    let percent_x = if area.width < 120 { 95 } else { 85 };
    let percent_y = if area.height < 40 { 95 } else { 90 };
    ui::layout::centered_rect(percent_x, percent_y, area)
}

fn render(frame: &mut ratatui::Frame, app: &App) {
    let area = frame.area();
    let colors = &app.theme.colors;

    let bg = Block::default().style(Style::default().bg(colors.bg()));
    frame.render_widget(bg, area);

    // Milestone overlays are modal and shown before the underlying screen.
    if let Some(milestone) = app.milestone_queue.front() {
        render_milestone_overlay(frame, app, milestone);
        return;
    }

    match app.screen {
        AppScreen::Menu => render_menu(frame, app),
        AppScreen::Drill => render_drill(frame, app),
        AppScreen::DrillResult => render_result(frame, app),
        AppScreen::StatsDashboard => render_stats(frame, app),
        AppScreen::Settings => render_settings(frame, app),
        AppScreen::SkillTree => render_skill_tree(frame, app),
        AppScreen::CodeLanguageSelect => render_code_language_select(frame, app),
        AppScreen::PassageBookSelect => render_passage_book_select(frame, app),
        AppScreen::PassageIntro => render_passage_intro(frame, app),
        AppScreen::PassageDownloadProgress => render_passage_download_progress(frame, app),
        AppScreen::CodeIntro => render_code_intro(frame, app),
        AppScreen::CodeDownloadProgress => render_code_download_progress(frame, app),
        AppScreen::Keyboard => render_keyboard_explorer(frame, app),
    }
}

fn render_menu(frame: &mut ratatui::Frame, app: &App) {
    let area = frame.area();
    let colors = &app.theme.colors;

    let layout = Layout::default()
        .direction(Direction::Vertical)
        .constraints([
            Constraint::Length(3),
            Constraint::Min(0),
            Constraint::Length(1),
        ])
        .split(area);

    let streak_text = if app.profile.streak_days > 0 {
        format!(" | {} day streak", app.profile.streak_days)
    } else {
        String::new()
    };
    let total_keys = app.skill_tree.total_unique_keys;
    let unlocked = app.skill_tree.total_unlocked_count();
    let mastered = app.skill_tree.total_confident_keys(&app.ranked_key_stats);
    let header_info = format!(
        " Key Progress {unlocked}/{total_keys} ({mastered} mastered) | Target {} WPM{}",
        app.config.target_wpm, streak_text,
    );
    let header = Paragraph::new(Line::from(vec![
        Span::styled(
            " keydr ",
            Style::default()
                .fg(colors.header_fg())
                .bg(colors.header_bg())
                .add_modifier(Modifier::BOLD),
        ),
        Span::styled(
            &*header_info,
            Style::default()
                .fg(colors.text_pending())
                .bg(colors.header_bg()),
        ),
    ]))
    .style(Style::default().bg(colors.header_bg()));
    frame.render_widget(header, layout[0]);

    let menu_area = ui::layout::centered_rect(50, 80, layout[1]);
    frame.render_widget(&app.menu, menu_area);

    let footer = Paragraph::new(Line::from(vec![Span::styled(
        " [1-3] Start  [t] Skill Tree  [b] Keyboard  [s] Stats  [c] Settings  [q] Quit ",
        Style::default().fg(colors.text_pending()),
    )]));
    frame.render_widget(footer, layout[2]);
}

fn render_drill(frame: &mut ratatui::Frame, app: &App) {
    let area = frame.area();
    let colors = &app.theme.colors;

    if let Some(ref drill) = app.drill {
        let app_layout = AppLayout::new(area);
        let tier = app_layout.tier;

        let mode_name = match app.drill_mode {
            DrillMode::Adaptive => "Adaptive",
            DrillMode::Code => "Code (Unranked)",
            DrillMode::Passage => "Passage (Unranked)",
        };

        // For medium/narrow: show compact stats in header
        if !tier.show_sidebar() {
            let wpm = drill.wpm();
            let accuracy = drill.accuracy();
            let errors = drill.typo_count();
            let header_text =
                format!(" {mode_name} | WPM: {wpm:.0} | Acc: {accuracy:.1}% | Errors: {errors}");
            let header = Paragraph::new(Line::from(Span::styled(
                &*header_text,
                Style::default()
                    .fg(colors.header_fg())
                    .bg(colors.header_bg())
                    .add_modifier(Modifier::BOLD),
            )))
            .style(Style::default().bg(colors.header_bg()));
            frame.render_widget(header, app_layout.header);
        } else {
            let header_title = format!(" {mode_name} Drill ");
            let focus_text = if app.drill_mode == DrillMode::Adaptive {
                let focused = app
                    .skill_tree
                    .focused_key(app.drill_scope, &app.ranked_key_stats);
                if let Some(focused) = focused {
                    format!(" | Focus: '{focused}'")
                } else {
                    String::new()
                }
            } else {
                String::new()
            };
            let header = Paragraph::new(Line::from(vec![
                Span::styled(
                    &*header_title,
                    Style::default()
                        .fg(colors.header_fg())
                        .bg(colors.header_bg())
                        .add_modifier(Modifier::BOLD),
                ),
                Span::styled(
                    &*focus_text,
                    Style::default()
                        .fg(colors.focused_key())
                        .bg(colors.header_bg()),
                ),
            ]))
            .style(Style::default().bg(colors.header_bg()));
            frame.render_widget(header, app_layout.header);
        }

        // Build main area constraints based on tier
        let show_kbd = tier.show_keyboard(area.height);
        let show_progress = tier.show_progress_bar(area.height);

        // Compute active branch count for progress area height
        let active_branches: Vec<engine::skill_tree::BranchId> =
            engine::skill_tree::BranchId::all()
                .iter()
                .copied()
                .filter(|&id| {
                    matches!(
                        app.skill_tree.branch_status(id),
                        engine::skill_tree::BranchStatus::InProgress
                            | engine::skill_tree::BranchStatus::Complete
                    )
                })
                .collect();

        let progress_height = if show_progress && area.height >= 25 {
            (active_branches.len().min(6) as u16 + 1).max(2) // +1 for overall line
        } else if show_progress && area.height >= 20 {
            2 // active branch + overall
        } else if show_progress {
            1 // active branch only
        } else {
            0
        };

        let kbd_height = if show_kbd {
            if tier.compact_keyboard() {
                6 // 3 rows + 2 border + 1 modifier space
            } else {
                8 // 5 rows (4 + space bar) + 2 border + 1 spacing
            }
        } else {
            0
        };

        let mut constraints: Vec<Constraint> = vec![Constraint::Min(5)];
        if progress_height > 0 {
            constraints.push(Constraint::Length(progress_height));
        }
        if show_kbd {
            constraints.push(Constraint::Length(kbd_height));
        }

        let main_layout = Layout::default()
            .direction(Direction::Vertical)
            .constraints(constraints)
            .split(app_layout.main);

        let typing = TypingArea::new(drill, app.theme);
        frame.render_widget(typing, main_layout[0]);

        let mut idx = 1;
        if progress_height > 0 {
            if app.drill_mode == DrillMode::Adaptive {
                let progress_widget = ui::components::branch_progress_list::BranchProgressList {
                    skill_tree: &app.skill_tree,
                    key_stats: &app.ranked_key_stats,
                    drill_scope: app.drill_scope,
                    active_branches: &active_branches,
                    theme: app.theme,
                    height: progress_height,
                };
                frame.render_widget(progress_widget, main_layout[idx]);
            } else {
                let source = app.drill_source_info.as_deref().unwrap_or("unknown source");
                let label = if app.drill_mode == DrillMode::Code {
                    " Code source "
                } else {
                    " Passage source "
                };
                let source_info = Paragraph::new(Line::from(vec![
                    Span::styled(
                        label,
                        Style::default()
                            .fg(colors.accent())
                            .add_modifier(Modifier::BOLD),
                    ),
                    Span::styled(source, Style::default().fg(colors.text_pending())),
                ]));
                frame.render_widget(source_info, main_layout[idx]);
            }
            idx += 1;
        }

        if show_kbd {
            let next_char = drill.target.get(drill.cursor).copied();
            let unlocked_keys = app.skill_tree.unlocked_keys(app.drill_scope);
            let kbd = KeyboardDiagram::new(
                next_char,
                &unlocked_keys,
                &app.depressed_keys,
                app.theme,
                &app.keyboard_model,
            )
            .compact(tier.compact_keyboard())
            .shift_held(app.shift_held)
            .caps_lock(app.caps_lock);
            frame.render_widget(kbd, main_layout[idx]);
        }

        if let Some(sidebar_area) = app_layout.sidebar {
            let sidebar = StatsSidebar::new(
                drill,
                app.last_result.as_ref(),
                &app.drill_history,
                app.config.target_wpm,
                app.theme,
            );
            frame.render_widget(sidebar, sidebar_area);
        }

        let footer = Paragraph::new(Line::from(Span::styled(
            " [ESC] End drill  [Backspace] Delete ",
            Style::default().fg(colors.text_pending()),
        )));
        frame.render_widget(footer, app_layout.footer);

    }
}

fn render_milestone_overlay(
    frame: &mut ratatui::Frame,
    app: &App,
    milestone: &app::KeyMilestonePopup,
) {
    let area = frame.area();
    let colors = &app.theme.colors;

    // Determine overlay size based on terminal height:
    // Large (>=25): full keyboard diagram
    // Medium (>=15): compact keyboard diagram
    // Small (<15): text only
    let kbd_mode = overlay_keyboard_mode(area.height);
    let overlay_height = match kbd_mode {
        2 => 18u16.min(area.height.saturating_sub(2)),
        1 => 14u16.min(area.height.saturating_sub(2)),
        _ => 10u16.min(area.height.saturating_sub(2)),
    };
    let overlay_width = 60u16.min(area.width.saturating_sub(4));

    let left = area.x + (area.width.saturating_sub(overlay_width)) / 2;
    let top = area.y + (area.height.saturating_sub(overlay_height)) / 2;
    let overlay_area = Rect::new(left, top, overlay_width, overlay_height);

    // Clear the area behind the overlay
    frame.render_widget(ratatui::widgets::Clear, overlay_area);

    let title = match milestone.kind {
        MilestoneKind::Unlock => " Key Unlocked! ",
        MilestoneKind::Mastery => " Key Mastered! ",
    };

    let block = Block::bordered()
        .title(title)
        .border_style(Style::default().fg(colors.accent()))
        .style(Style::default().bg(colors.bg()));
    let inner = block.inner(overlay_area);
    block.render(overlay_area, frame.buffer_mut());

    let mut lines: Vec<Line> = Vec::new();

    // Key display line
    let key_action = match milestone.kind {
        MilestoneKind::Unlock => "unlocked",
        MilestoneKind::Mastery => "mastered",
    };

    let key_names: Vec<String> = milestone
        .keys
        .iter()
        .map(|&ch| {
            let name = keyboard::display::key_display_name(ch);
            if name.is_empty() {
                format!("'{ch}'")
            } else {
                name.to_string()
            }
        })
        .collect();
    let keys_str = key_names.join(", ");

    lines.push(Line::from(""));
    lines.push(Line::from(Span::styled(
        format!("  You {key_action}: {keys_str}"),
        Style::default()
            .fg(colors.accent())
            .add_modifier(Modifier::BOLD),
    )));

    // Finger info (for unlocks)
    if matches!(milestone.kind, MilestoneKind::Unlock) {
        for (ch, finger_desc) in &milestone.finger_info {
            let key_label = {
                let name = keyboard::display::key_display_name(*ch);
                if name.is_empty() {
                    format!("'{ch}'")
                } else {
                    name.to_string()
                }
            };
            lines.push(Line::from(Span::styled(
                format!("  {key_label}: Use your {finger_desc}"),
                Style::default().fg(colors.fg()),
            )));

            // Shift key guidance for shifted characters
            let fa = app.keyboard_model.finger_for_char(*ch);
            if ch.is_ascii_uppercase()
                || (!ch.is_ascii_lowercase()
                    && !ch.is_ascii_digit()
                    && !ch.is_ascii_whitespace()
                    && *ch != ' ')
            {
                let shift_hint = if fa.hand == keyboard::finger::Hand::Left {
                    "Hold Right Shift (right pinky)"
                } else {
                    "Hold Left Shift (left pinky)"
                };
                lines.push(Line::from(Span::styled(
                    format!("  {shift_hint}"),
                    Style::default().fg(colors.text_pending()),
                )));
            }
        }
    }

    // Encouraging message (randomly selected at creation time)
    lines.push(Line::from(""));
    lines.push(Line::from(Span::styled(
        format!("  {}", milestone.message),
        Style::default().fg(colors.focused_key()),
    )));

    // Keyboard diagram (if space permits)
    if kbd_mode > 0 {
        let min_kbd_height: u16 = if kbd_mode == 2 { 6 } else { 4 };
        let remaining = inner.height.saturating_sub(lines.len() as u16 + 2);
        if remaining >= min_kbd_height {
            let kbd_y_start = inner.y + lines.len() as u16 + 1;
            let kbd_height = remaining.min(if kbd_mode == 2 { 8 } else { 6 });
            let kbd_area = Rect::new(inner.x, kbd_y_start, inner.width, kbd_height);
            let milestone_key = milestone.keys.first().copied();
            let unlocked_keys = app.skill_tree.unlocked_keys(app.drill_scope);
            let is_shifted = milestone_key.is_some_and(|ch| {
                ch.is_ascii_uppercase()
                    || app.keyboard_model.shifted_to_base(ch).is_some()
            });
            let kbd = KeyboardDiagram::new(
                None,
                &unlocked_keys,
                &app.depressed_keys,
                app.theme,
                &app.keyboard_model,
            )
            .selected_key(milestone_key)
            .compact(kbd_mode == 1)
            .shift_held(is_shifted)
            .caps_lock(app.caps_lock);
            frame.render_widget(kbd, kbd_area);
        }
    }

    // Render the text content
    let text_area = Rect::new(
        inner.x,
        inner.y,
        inner.width,
        inner.height.saturating_sub(1),
    );
    Paragraph::new(lines).render(text_area, frame.buffer_mut());

    // Footer
    let footer_y = inner.y + inner.height.saturating_sub(1);
    if footer_y < inner.y + inner.height {
        let footer_area = Rect::new(inner.x, footer_y, inner.width, 1);
        let footer = Paragraph::new(Line::from(Span::styled(
            "  Press any key to continue",
            Style::default().fg(colors.text_pending()),
        )));
        frame.render_widget(footer, footer_area);
    }
}

fn overlay_keyboard_mode(height: u16) -> u8 {
    if height >= 25 {
        2 // full
    } else if height >= 15 {
        1 // compact
    } else {
        0 // text only
    }
}

#[cfg(test)]
mod review_tests {
    use super::*;
    use crate::session::result::DrillResult;
    use chrono::{TimeDelta, Utc};

    fn test_result(ts_offset_secs: i64) -> DrillResult {
        DrillResult {
            wpm: 60.0,
            cpm: 300.0,
            accuracy: 98.0,
            correct: 49,
            incorrect: 1,
            total_chars: 50,
            elapsed_secs: 10.0,
            timestamp: Utc::now() + TimeDelta::seconds(ts_offset_secs),
            per_key_times: vec![],
            drill_mode: "adaptive".to_string(),
            ranked: true,
            partial: false,
            completion_percent: 100.0,
        }
    }

    #[test]
    fn milestone_overlay_blocks_underlying_input() {
        let mut app = App::new();
        app.screen = AppScreen::Drill;
        app.drill = Some(crate::session::drill::DrillState::new("abc"));
        app.milestone_queue
            .push_back(crate::app::KeyMilestonePopup {
                kind: crate::app::MilestoneKind::Unlock,
                keys: vec!['a'],
                finger_info: vec![('a', "left pinky".to_string())],
                message: "msg",
        });

        let before_cursor = app.drill.as_ref().map(|d| d.cursor).unwrap_or(0);
        handle_key(&mut app, KeyEvent::new(KeyCode::Char('x'), KeyModifiers::NONE));
        let after_cursor = app.drill.as_ref().map(|d| d.cursor).unwrap_or(0);

        assert_eq!(before_cursor, after_cursor);
        assert!(app.milestone_queue.is_empty());
    }

    #[test]
    fn milestone_queue_chains_before_result_actions() {
        let mut app = App::new();
        app.screen = AppScreen::DrillResult;
        app.milestone_queue
            .push_back(crate::app::KeyMilestonePopup {
                kind: crate::app::MilestoneKind::Unlock,
                keys: vec!['a'],
                finger_info: vec![('a', "left pinky".to_string())],
                message: "msg1",
            });
        app.milestone_queue
            .push_back(crate::app::KeyMilestonePopup {
                kind: crate::app::MilestoneKind::Mastery,
                keys: vec!['a'],
                finger_info: vec![('a', "left pinky".to_string())],
                message: "msg2",
            });

        handle_key(&mut app, KeyEvent::new(KeyCode::Char('q'), KeyModifiers::NONE));
        assert_eq!(app.screen, AppScreen::DrillResult);
        assert_eq!(app.milestone_queue.len(), 1);

        handle_key(&mut app, KeyEvent::new(KeyCode::Char('q'), KeyModifiers::NONE));
        assert_eq!(app.screen, AppScreen::DrillResult);
        assert!(app.milestone_queue.is_empty());

        // Now normal result action should apply.
        handle_key(&mut app, KeyEvent::new(KeyCode::Char('q'), KeyModifiers::NONE));
        assert_eq!(app.screen, AppScreen::Menu);
    }

    #[test]
    fn overlay_mode_height_boundaries() {
        assert_eq!(overlay_keyboard_mode(14), 0);
        assert_eq!(overlay_keyboard_mode(15), 1);
        assert_eq!(overlay_keyboard_mode(24), 1);
        assert_eq!(overlay_keyboard_mode(25), 2);
    }

    #[test]
    fn result_delete_shortcut_opens_confirmation_for_latest() {
        let mut app = App::new();
        app.screen = AppScreen::DrillResult;
        app.last_result = Some(test_result(2));
        app.drill_history = vec![test_result(1), test_result(2)];
        app.history_selected = 1;

        handle_key(&mut app, KeyEvent::new(KeyCode::Char('x'), KeyModifiers::NONE));

        assert!(app.history_confirm_delete);
        assert_eq!(app.history_selected, 0);
    }

    #[test]
    fn result_delete_confirmation_yes_deletes_latest() {
        let mut app = App::new();
        app.screen = AppScreen::DrillResult;
        app.last_result = Some(test_result(3));
        let older = test_result(1);
        let newer = test_result(2);
        app.drill_history = vec![older.clone(), newer.clone()];

        handle_key(&mut app, KeyEvent::new(KeyCode::Char('x'), KeyModifiers::NONE));
        handle_key(&mut app, KeyEvent::new(KeyCode::Char('y'), KeyModifiers::NONE));

        assert!(!app.history_confirm_delete);
        assert_eq!(app.drill_history.len(), 1);
        assert_eq!(app.drill_history[0].timestamp, older.timestamp);
    }

    #[test]
    fn result_delete_confirmation_cancel_keeps_history() {
        let mut app = App::new();
        app.screen = AppScreen::DrillResult;
        app.last_result = Some(test_result(2));
        app.drill_history = vec![test_result(1), test_result(2)];

        handle_key(&mut app, KeyEvent::new(KeyCode::Char('x'), KeyModifiers::NONE));
        handle_key(&mut app, KeyEvent::new(KeyCode::Char('n'), KeyModifiers::NONE));

        assert!(!app.history_confirm_delete);
        assert_eq!(app.drill_history.len(), 2);
    }

    #[test]
    fn result_continue_shortcuts_start_next_drill() {
        let mut app = App::new();
        app.screen = AppScreen::DrillResult;
        app.last_result = Some(test_result(2));

        handle_key(&mut app, KeyEvent::new(KeyCode::Char('c'), KeyModifiers::NONE));
        assert_eq!(app.screen, AppScreen::Drill);

        app.screen = AppScreen::DrillResult;
        handle_key(&mut app, KeyEvent::new(KeyCode::Enter, KeyModifiers::NONE));
        assert_eq!(app.screen, AppScreen::Drill);

        app.screen = AppScreen::DrillResult;
        handle_key(
            &mut app,
            KeyEvent::new(KeyCode::Char(' '), KeyModifiers::NONE),
        );
        assert_eq!(app.screen, AppScreen::Drill);
    }

    #[test]
    fn result_continue_code_uses_last_language_params() {
        let mut app = App::new();
        app.screen = AppScreen::DrillResult;
        app.last_result = Some(test_result(2));
        app.drill_mode = DrillMode::Code;
        app.config.code_downloads_enabled = false;
        app.config.code_language = "python".to_string();
        app.last_code_drill_language = Some("rust".to_string());

        handle_key(&mut app, KeyEvent::new(KeyCode::Char('c'), KeyModifiers::NONE));

        assert_eq!(app.screen, AppScreen::Drill);
        assert_eq!(app.drill_mode, DrillMode::Code);
        assert_eq!(app.last_code_drill_language.as_deref(), Some("rust"));
    }

    /// Helper: count how many settings modal/edit flags are active
    fn modal_edit_count(app: &App) -> usize {
        [
            app.settings_confirm_import,
            app.settings_export_conflict,
            app.settings_editing_export_path,
            app.settings_editing_import_path,
            app.settings_editing_download_dir,
        ]
        .iter()
        .filter(|&&f| f)
        .count()
    }

    #[test]
    fn settings_modal_invariant_enter_export_path_clears_others() {
        let mut app = App::new();
        app.screen = AppScreen::Settings;

        // First, activate import confirmation
        app.settings_selected = 15; // Import Data
        handle_settings_key(
            &mut app,
            KeyEvent::new(KeyCode::Enter, KeyModifiers::NONE),
        );
        assert!(app.settings_confirm_import);
        assert!(modal_edit_count(&app) <= 1);

        // Cancel it
        handle_settings_key(
            &mut app,
            KeyEvent::new(KeyCode::Esc, KeyModifiers::NONE),
        );
        assert!(!app.settings_confirm_import);

        // Enter export path editing
        app.settings_selected = 12; // Export Path
        handle_settings_key(
            &mut app,
            KeyEvent::new(KeyCode::Enter, KeyModifiers::NONE),
        );
        assert!(app.settings_editing_export_path);
        assert!(modal_edit_count(&app) <= 1);

        // Esc out
        handle_settings_key(
            &mut app,
            KeyEvent::new(KeyCode::Esc, KeyModifiers::NONE),
        );
        assert!(!app.settings_editing_export_path);
    }

    #[test]
    fn settings_modal_invariant_enter_import_path_clears_others() {
        let mut app = App::new();
        app.screen = AppScreen::Settings;

        // Activate export path editing first
        app.settings_selected = 12;
        handle_settings_key(
            &mut app,
            KeyEvent::new(KeyCode::Enter, KeyModifiers::NONE),
        );
        assert!(app.settings_editing_export_path);

        // Esc out, then enter import path editing
        handle_settings_key(
            &mut app,
            KeyEvent::new(KeyCode::Esc, KeyModifiers::NONE),
        );
        app.settings_selected = 14; // Import Path
        handle_settings_key(
            &mut app,
            KeyEvent::new(KeyCode::Enter, KeyModifiers::NONE),
        );
        assert!(app.settings_editing_import_path);
        assert!(!app.settings_editing_export_path);
        assert!(modal_edit_count(&app) <= 1);
    }

    #[test]
    fn settings_confirm_import_dialog_y_n_esc() {
        let mut app = App::new();
        app.screen = AppScreen::Settings;

        // Trigger import confirmation
        app.settings_selected = 15;
        handle_settings_key(
            &mut app,
            KeyEvent::new(KeyCode::Enter, KeyModifiers::NONE),
        );
        assert!(app.settings_confirm_import);

        // 'n' cancels
        handle_settings_key(
            &mut app,
            KeyEvent::new(KeyCode::Char('n'), KeyModifiers::NONE),
        );
        assert!(!app.settings_confirm_import);

        // Trigger again
        app.settings_selected = 15;
        handle_settings_key(
            &mut app,
            KeyEvent::new(KeyCode::Enter, KeyModifiers::NONE),
        );
        assert!(app.settings_confirm_import);

        // Esc cancels
        handle_settings_key(
            &mut app,
            KeyEvent::new(KeyCode::Esc, KeyModifiers::NONE),
        );
        assert!(!app.settings_confirm_import);
    }

    #[test]
    fn settings_status_message_dismissed_on_keypress() {
        let mut app = App::new();
        app.screen = AppScreen::Settings;

        // Set a status message
        app.settings_status_message = Some(crate::app::StatusMessage {
            kind: StatusKind::Success,
            text: "test".to_string(),
        });

        // Any keypress should dismiss it
        handle_settings_key(
            &mut app,
            KeyEvent::new(KeyCode::Char('j'), KeyModifiers::NONE),
        );
        assert!(app.settings_status_message.is_none());
    }

    #[test]
    fn smart_rename_canonical_filename() {
        use crate::app::next_available_path;
        let dir = tempfile::TempDir::new().unwrap();
        let base = dir.path();

        // Create base file
        let base_path = base.join("keydr-export-2026-01-01.json");
        std::fs::write(&base_path, "{}").unwrap();

        // First rename: picks -1
        let result = next_available_path(base_path.to_str().unwrap());
        assert!(result.ends_with("keydr-export-2026-01-01-1.json"));

        // Create -1
        std::fs::write(base.join("keydr-export-2026-01-01-1.json"), "{}").unwrap();

        // From base: picks -2
        let result = next_available_path(base_path.to_str().unwrap());
        assert!(result.ends_with("keydr-export-2026-01-01-2.json"));

        // From -1 path: normalizes to base stem and picks -2
        let path_1 = base.join("keydr-export-2026-01-01-1.json");
        let result = next_available_path(path_1.to_str().unwrap());
        assert!(result.ends_with("keydr-export-2026-01-01-2.json"));
    }

    #[test]
    fn smart_rename_custom_filename() {
        use crate::app::next_available_path;
        let dir = tempfile::TempDir::new().unwrap();
        let base = dir.path();

        let custom_path = base.join("my-backup.json");
        std::fs::write(&custom_path, "{}").unwrap();

        let result = next_available_path(custom_path.to_str().unwrap());
        assert!(result.ends_with("my-backup-1.json"));

        std::fs::write(base.join("my-backup-1.json"), "{}").unwrap();
        let result = next_available_path(custom_path.to_str().unwrap());
        assert!(result.ends_with("my-backup-2.json"));
    }
}

fn render_result(frame: &mut ratatui::Frame, app: &App) {
    let area = frame.area();

    if let Some(ref result) = app.last_result {
        let centered = ui::layout::centered_rect(60, 70, area);
        let dashboard = Dashboard::new(result, app.theme);
        frame.render_widget(dashboard, centered);

        if app.history_confirm_delete && !app.drill_history.is_empty() {
            let colors = &app.theme.colors;
            let dialog_width = 34u16;
            let dialog_height = 5u16;
            let dialog_x = area.x + area.width.saturating_sub(dialog_width) / 2;
            let dialog_y = area.y + area.height.saturating_sub(dialog_height) / 2;
            let dialog_area = Rect::new(dialog_x, dialog_y, dialog_width, dialog_height);

            let idx = app.drill_history.len().saturating_sub(app.history_selected);
            let dialog_text = format!("Delete session #{idx}? (y/n)");

            frame.render_widget(ratatui::widgets::Clear, dialog_area);
            let dialog = Paragraph::new(vec![
                Line::from(""),
                Line::from(Span::styled(
                    format!("  {dialog_text}  "),
                    Style::default().fg(colors.fg()),
                )),
            ])
            .style(Style::default().bg(colors.bg()))
            .block(
                Block::bordered()
                    .title(" Confirm ")
                    .border_style(Style::default().fg(colors.error()))
                    .style(Style::default().bg(colors.bg())),
            );
            frame.render_widget(dialog, dialog_area);
        }
    }
}

fn render_stats(frame: &mut ratatui::Frame, app: &App) {
    let area = frame.area();
    let dashboard = StatsDashboard::new(
        &app.drill_history,
        &app.key_stats,
        app.stats_tab,
        app.config.target_wpm,
        app.skill_tree.total_unlocked_count(),
        app.skill_tree.total_confident_keys(&app.ranked_key_stats),
        app.skill_tree.total_unique_keys,
        app.theme,
        app.history_selected,
        app.history_confirm_delete,
        &app.keyboard_model,
    );
    frame.render_widget(dashboard, area);
}

fn render_settings(frame: &mut ratatui::Frame, app: &App) {
    let area = frame.area();
    let colors = &app.theme.colors;

    let centered = ui::layout::centered_rect(60, 80, area);

    let block = Block::bordered()
        .title(" Settings ")
        .border_style(Style::default().fg(colors.accent()))
        .style(Style::default().bg(colors.bg()));
    let inner = block.inner(centered);
    block.render(centered, frame.buffer_mut());

    let fields: Vec<(String, String, bool)> = vec![
        (
            "Target WPM".to_string(),
            format!("{}", app.config.target_wpm),
            false,
        ),
        ("Theme".to_string(), app.config.theme.clone(), false),
        (
            "Word Count".to_string(),
            format!("{}", app.config.word_count),
            false,
        ),
        (
            "Code Language".to_string(),
            app.config.code_language.clone(),
            false,
        ),
        (
            "Code Downloads".to_string(),
            if app.config.code_downloads_enabled {
                "On".to_string()
            } else {
                "Off".to_string()
            },
            false,
        ),
        (
            "Code Download Dir".to_string(),
            app.config.code_download_dir.clone(),
            true, // path field
        ),
        (
            "Snippets per Repo".to_string(),
            if app.config.code_snippets_per_repo == 0 {
                "Unlimited".to_string()
            } else {
                format!("{}", app.config.code_snippets_per_repo)
            },
            false,
        ),
        (
            "Download Code Now".to_string(),
            "Run downloader".to_string(),
            false,
        ),
        (
            "Passage Downloads".to_string(),
            if app.config.passage_downloads_enabled {
                "On".to_string()
            } else {
                "Off".to_string()
            },
            false,
        ),
        (
            "Passage Download Dir".to_string(),
            app.config.passage_download_dir.clone(),
            true, // path field
        ),
        (
            "Paragraphs per Book".to_string(),
            if app.config.passage_paragraphs_per_book == 0 {
                "Whole book".to_string()
            } else {
                format!("{}", app.config.passage_paragraphs_per_book)
            },
            false,
        ),
        (
            "Download Passages Now".to_string(),
            "Run downloader".to_string(),
            false,
        ),
        (
            "Export Path".to_string(),
            app.settings_export_path.clone(),
            true, // path field
        ),
        (
            "Export Data".to_string(),
            "Export now".to_string(),
            false,
        ),
        (
            "Import Path".to_string(),
            app.settings_import_path.clone(),
            true, // path field
        ),
        (
            "Import Data".to_string(),
            "Import now".to_string(),
            false,
        ),
    ];

    let header_height = if inner.height > 0 { 1 } else { 0 };
    let footer_height = if inner.height > header_height { 1 } else { 0 };
    let field_height = inner.height.saturating_sub(header_height + footer_height);

    let layout = Layout::default()
        .direction(Direction::Vertical)
        .constraints([
            Constraint::Length(header_height),
            Constraint::Length(field_height),
            Constraint::Length(footer_height),
        ])
        .split(inner);

    let header = Paragraph::new(Line::from(Span::styled(
        "  Use arrows to navigate, Enter/Right to change, ESC to save & exit",
        Style::default().fg(colors.text_pending()),
    )));
    header.render(layout[0], frame.buffer_mut());

    let row_height = 2u16;
    let visible_rows = (layout[1].height / row_height).max(1) as usize;
    let max_start = fields.len().saturating_sub(visible_rows);
    let start = app
        .settings_selected
        .saturating_sub(visible_rows.saturating_sub(1))
        .min(max_start);
    let end = (start + visible_rows).min(fields.len());
    let visible_fields = &fields[start..end];

    let field_layout = Layout::default()
        .direction(Direction::Vertical)
        .constraints(
            visible_fields
                .iter()
                .map(|_| Constraint::Length(row_height))
                .collect::<Vec<_>>(),
        )
        .split(layout[1]);

    for (row, (label, value, is_path)) in visible_fields.iter().enumerate() {
        let i = start + row;
        let is_selected = i == app.settings_selected;
        let indicator = if is_selected { " > " } else { "   " };

        let label_text = format!("{indicator}{label}:");
        let is_button = i == 7 || i == 11 || i == 13 || i == 15;
        let value_text = if is_button {
            format!("  [ {value} ]")
        } else {
            format!("  < {value} >")
        };

        let label_style = Style::default()
            .fg(if is_selected {
                colors.accent()
            } else {
                colors.fg()
            })
            .add_modifier(if is_selected {
                Modifier::BOLD
            } else {
                Modifier::empty()
            });

        let value_style = Style::default().fg(if is_selected {
            colors.focused_key()
        } else {
            colors.text_pending()
        });

        let is_editing_this_path = is_selected && *is_path && (
            app.settings_editing_download_dir
            || app.settings_editing_export_path
            || app.settings_editing_import_path
        );
        let lines = if *is_path {
            let path_line = if is_editing_this_path {
                format!("  {value}_")
            } else {
                format!("  {value}")
            };
            vec![
                Line::from(Span::styled(
                    if is_editing_this_path {
                        format!("{indicator}{label}: (editing)")
                    } else {
                        label_text
                    },
                    label_style,
                )),
                Line::from(Span::styled(path_line, value_style)),
            ]
        } else {
            vec![
                Line::from(Span::styled(label_text, label_style)),
                Line::from(Span::styled(value_text, value_style)),
            ]
        };
        Paragraph::new(lines).render(field_layout[row], frame.buffer_mut());
    }

    let any_path_editing = app.settings_editing_download_dir
        || app.settings_editing_export_path
        || app.settings_editing_import_path;
    let footer_hints: Vec<&str> = if any_path_editing {
        vec!["Editing path:", "[Type/Backspace] Modify", "[ESC] Done editing"]
    } else {
        vec![
            "[ESC] Save & back",
            "[Enter/arrows] Change value",
            "[Enter on path] Edit",
        ]
    };
    let footer_lines: Vec<Line> = pack_hint_lines(&footer_hints, layout[2].width as usize)
        .into_iter()
        .map(|line| Line::from(Span::styled(line, Style::default().fg(colors.accent()))))
        .collect();
    Paragraph::new(footer_lines)
        .wrap(Wrap { trim: false })
        .render(layout[2], frame.buffer_mut());

    // --- Overlay dialogs (rendered on top of settings) ---

    // Status message takes highest priority
    if let Some(ref msg) = app.settings_status_message {
        let border_color = match msg.kind {
            StatusKind::Success => colors.accent(),
            StatusKind::Error => colors.error(),
        };
        let title = match msg.kind {
            StatusKind::Success => " Success ",
            StatusKind::Error => " Error ",
        };
        let dialog_width = 56u16.min(area.width.saturating_sub(4));
        let dialog_height = 6u16;
        let dialog_x = area.x + area.width.saturating_sub(dialog_width) / 2;
        let dialog_y = area.y + area.height.saturating_sub(dialog_height) / 2;
        let dialog_area = Rect::new(dialog_x, dialog_y, dialog_width, dialog_height);

        frame.render_widget(ratatui::widgets::Clear, dialog_area);
        let dialog = Paragraph::new(vec![
            Line::from(""),
            Line::from(Span::styled(
                format!("  {}  ", msg.text),
                Style::default().fg(colors.fg()),
            )),
            Line::from(""),
            Line::from(Span::styled(
                "  Press any key",
                Style::default().fg(colors.text_pending()),
            )),
        ])
        .wrap(Wrap { trim: false })
        .style(Style::default().bg(colors.bg()))
        .block(
            Block::bordered()
                .title(title)
                .border_style(Style::default().fg(border_color))
                .style(Style::default().bg(colors.bg())),
        );
        frame.render_widget(dialog, dialog_area);
    } else if app.settings_export_conflict {
        let dialog_width = 52u16.min(area.width.saturating_sub(4));
        let dialog_height = 6u16;
        let dialog_x = area.x + area.width.saturating_sub(dialog_width) / 2;
        let dialog_y = area.y + area.height.saturating_sub(dialog_height) / 2;
        let dialog_area = Rect::new(dialog_x, dialog_y, dialog_width, dialog_height);

        frame.render_widget(ratatui::widgets::Clear, dialog_area);
        let dialog = Paragraph::new(vec![
            Line::from(""),
            Line::from(Span::styled(
                "  A file already exists at this path.",
                Style::default().fg(colors.fg()),
            )),
            Line::from(""),
            Line::from(Span::styled(
                "  [d] Overwrite  [r] Rename  [Esc] Cancel",
                Style::default().fg(colors.text_pending()),
            )),
        ])
        .style(Style::default().bg(colors.bg()))
        .block(
            Block::bordered()
                .title(" File Exists ")
                .border_style(Style::default().fg(colors.error()))
                .style(Style::default().bg(colors.bg())),
        );
        frame.render_widget(dialog, dialog_area);
    } else if app.settings_confirm_import {
        let dialog_width = 52u16.min(area.width.saturating_sub(4));
        let dialog_height = 7u16;
        let dialog_x = area.x + area.width.saturating_sub(dialog_width) / 2;
        let dialog_y = area.y + area.height.saturating_sub(dialog_height) / 2;
        let dialog_area = Rect::new(dialog_x, dialog_y, dialog_width, dialog_height);

        frame.render_widget(ratatui::widgets::Clear, dialog_area);
        let dialog = Paragraph::new(vec![
            Line::from(""),
            Line::from(Span::styled(
                "  This will erase your current data.",
                Style::default().fg(colors.fg()),
            )),
            Line::from(Span::styled(
                "  Export first if you want to keep it.",
                Style::default().fg(colors.text_pending()),
            )),
            Line::from(""),
            Line::from(Span::styled(
                "  Proceed? (y/n)",
                Style::default().fg(colors.fg()),
            )),
        ])
        .style(Style::default().bg(colors.bg()))
        .block(
            Block::bordered()
                .title(" Confirm Import ")
                .border_style(Style::default().fg(colors.error()))
                .style(Style::default().bg(colors.bg())),
        );
        frame.render_widget(dialog, dialog_area);
    }
}

fn wrapped_line_count(text: &str, width: usize) -> usize {
    if width == 0 {
        return 0;
    }
    let chars = text.chars().count().max(1);
    chars.div_ceil(width)
}

fn pack_hint_lines(hints: &[&str], width: usize) -> Vec<String> {
    if width == 0 || hints.is_empty() {
        return Vec::new();
    }

    let prefix = "  ";
    let separator = "  ";
    let mut out: Vec<String> = Vec::new();
    let mut current = prefix.to_string();
    let mut has_hint = false;

    for hint in hints {
        if hint.is_empty() {
            continue;
        }
        let candidate = if has_hint {
            format!("{current}{separator}{hint}")
        } else {
            format!("{current}{hint}")
        };
        if candidate.chars().count() <= width {
            current = candidate;
            has_hint = true;
        } else {
            if has_hint {
                out.push(current);
            }
            current = format!("{prefix}{hint}");
            has_hint = true;
        }
    }

    if has_hint {
        out.push(current);
    }
    out
}

fn render_code_language_select(frame: &mut ratatui::Frame, app: &App) {
    let area = frame.area();
    let colors = &app.theme.colors;
    let centered = ui::layout::centered_rect(50, 70, area);

    let block = Block::bordered()
        .title(" Select Code Language ")
        .border_style(Style::default().fg(colors.accent()))
        .style(Style::default().bg(colors.bg()));
    let inner = block.inner(centered);
    block.render(centered, frame.buffer_mut());

    let options = code_language_options();
    let cache_dir = &app.config.code_download_dir;
    let footer_hints = [
        "[Up/Down/PgUp/PgDn] Navigate",
        "[Enter] Confirm",
        "[ESC] Back",
    ];
    let disabled_notice =
        "  Some languages are disabled: enable network downloads in intro/settings.";
    let has_disabled = !app.config.code_downloads_enabled
        && options
            .iter()
            .any(|(key, _)| is_code_language_disabled(app, key));
    let width = inner.width as usize;
    let hint_lines_vec = pack_hint_lines(&footer_hints, width);
    let hint_lines = hint_lines_vec.len();
    let notice_lines = wrapped_line_count(disabled_notice, width);
    let total_height = inner.height as usize;
    let show_notice = has_disabled && total_height >= hint_lines + notice_lines + 3;
    let desired_footer_height = hint_lines + if show_notice { notice_lines } else { 0 };
    let footer_height = desired_footer_height.min(total_height.saturating_sub(1)) as u16;
    let (list_area, footer_area) = if footer_height > 0 {
        let chunks = Layout::default()
            .direction(Direction::Vertical)
            .constraints([Constraint::Min(1), Constraint::Length(footer_height)])
            .split(inner);
        (chunks[0], Some(chunks[1]))
    } else {
        (inner, None)
    };

    let viewport_height = (list_area.height as usize).saturating_sub(2).max(1);
    let scroll = app.code_language_scroll;

    let mut lines: Vec<Line> = Vec::new();

    // Show scroll indicator at top if scrolled down
    if scroll > 0 {
        lines.push(Line::from(Span::styled(
            format!("   ... {} more above ...", scroll),
            Style::default().fg(colors.text_pending()),
        )));
    } else {
        lines.push(Line::from(""));
    }

    let visible_end = (scroll + viewport_height).min(options.len());

    for i in scroll..visible_end {
        let (key, display) = &options[i];
        let is_selected = i == app.code_language_selected;
        let is_current = *key == app.config.code_language;
        let is_disabled = is_code_language_disabled(app, key);

        let indicator = if is_selected { " > " } else { "   " };
        let current_marker = if is_current { " (current)" } else { "" };

        // Determine availability label
        let availability = if *key == "all" {
            String::new()
        } else if let Some(lang) = language_by_key(key) {
            if lang.has_builtin {
                " (built-in)".to_string()
            } else if is_language_cached(cache_dir, key) {
                " (cached)".to_string()
            } else if is_disabled {
                " (disabled: download required)".to_string()
            } else {
                " (download required)".to_string()
            }
        } else {
            String::new()
        };

        let name_style = if is_disabled {
            Style::default().fg(colors.text_pending())
        } else if is_selected {
            Style::default()
                .fg(colors.accent())
                .add_modifier(Modifier::BOLD)
        } else {
            Style::default().fg(colors.fg())
        };
        let status_style = Style::default()
            .fg(colors.text_pending())
            .add_modifier(Modifier::DIM);

        let mut spans = vec![Span::styled(
            format!("{indicator}{display}{current_marker}"),
            name_style,
        )];
        if !availability.is_empty() {
            spans.push(Span::styled(availability, status_style));
        }
        lines.push(Line::from(spans));
    }

    // Show scroll indicator at bottom if more items below
    if visible_end < options.len() {
        lines.push(Line::from(Span::styled(
            format!("   ... {} more below ...", options.len() - visible_end),
            Style::default().fg(colors.text_pending()),
        )));
    } else {
        lines.push(Line::from(""));
    }

    Paragraph::new(lines).render(list_area, frame.buffer_mut());

    if let Some(footer) = footer_area {
        let mut footer_lines: Vec<Line> = hint_lines_vec
            .iter()
            .map(|line| Line::from(Span::styled(line.clone(), Style::default().fg(colors.text_pending()))))
            .collect();
        if show_notice {
            footer_lines.push(Line::from(Span::styled(
                disabled_notice,
                Style::default().fg(colors.text_pending()),
            )));
        }
        Paragraph::new(footer_lines)
            .wrap(Wrap { trim: false })
            .render(footer, frame.buffer_mut());
    }
}

fn render_passage_book_select(frame: &mut ratatui::Frame, app: &App) {
    let area = frame.area();
    let colors = &app.theme.colors;
    let centered = ui::layout::centered_rect(60, 70, area);

    let block = Block::bordered()
        .title(" Select Passage Source ")
        .border_style(Style::default().fg(colors.accent()))
        .style(Style::default().bg(colors.bg()));
    let inner = block.inner(centered);
    block.render(centered, frame.buffer_mut());

    let options = passage_options();
    let footer_hints = ["[Up/Down] Navigate", "[Enter] Confirm", "[ESC] Back"];
    let disabled_notice =
        "  Some sources are disabled: enable network downloads in intro/settings.";
    let has_disabled = !app.config.passage_downloads_enabled
        && options
            .iter()
            .any(|(key, _)| is_passage_option_disabled(app, key));
    let width = inner.width as usize;
    let hint_lines_vec = pack_hint_lines(&footer_hints, width);
    let hint_lines = hint_lines_vec.len();
    let notice_lines = wrapped_line_count(disabled_notice, width);
    let total_height = inner.height as usize;
    let show_notice = has_disabled && total_height >= hint_lines + notice_lines + 3;
    let desired_footer_height = hint_lines + if show_notice { notice_lines } else { 0 };
    let footer_height = desired_footer_height.min(total_height.saturating_sub(1)) as u16;
    let (list_area, footer_area) = if footer_height > 0 {
        let chunks = Layout::default()
            .direction(Direction::Vertical)
            .constraints([Constraint::Min(1), Constraint::Length(footer_height)])
            .split(inner);
        (chunks[0], Some(chunks[1]))
    } else {
        (inner, None)
    };

    let viewport_height = list_area.height as usize;
    let start = app
        .passage_book_selected
        .saturating_sub(viewport_height.saturating_sub(1));
    let end = (start + viewport_height).min(options.len());
    let mut lines: Vec<Line> = vec![];
    for (i, (key, label)) in options.iter().enumerate().skip(start).take(end - start) {
        let is_selected = i == app.passage_book_selected;
        let is_disabled = is_passage_option_disabled(app, key);
        let indicator = if is_selected { " > " } else { "   " };
        let availability = if *key == "all" {
            String::new()
        } else if *key == "builtin" {
            " (built-in)".to_string()
        } else if is_book_cached(&app.config.passage_download_dir, key) {
            " (cached)".to_string()
        } else if is_disabled {
            " (disabled: download required)".to_string()
        } else {
            " (download required)".to_string()
        };
        let name_style = if is_disabled {
            Style::default().fg(colors.text_pending())
        } else if is_selected {
            Style::default()
                .fg(colors.accent())
                .add_modifier(Modifier::BOLD)
        } else {
            Style::default().fg(colors.fg())
        };
        let status_style = Style::default()
            .fg(colors.text_pending())
            .add_modifier(Modifier::DIM);
        let mut spans = vec![Span::styled(
            format!("{indicator}[{}] {label}", i + 1),
            name_style,
        )];
        if !availability.is_empty() {
            spans.push(Span::styled(availability, status_style));
        }
        lines.push(Line::from(spans));
    }

    Paragraph::new(lines).render(list_area, frame.buffer_mut());

    if let Some(footer) = footer_area {
        let mut footer_lines: Vec<Line> = hint_lines_vec
            .iter()
            .map(|line| Line::from(Span::styled(line.clone(), Style::default().fg(colors.text_pending()))))
            .collect();
        if show_notice {
            footer_lines.push(Line::from(Span::styled(
                disabled_notice,
                Style::default().fg(colors.text_pending()),
            )));
        }
        Paragraph::new(footer_lines)
            .wrap(Wrap { trim: false })
            .render(footer, frame.buffer_mut());
    }
}

fn render_passage_intro(frame: &mut ratatui::Frame, app: &App) {
    let area = frame.area();
    let colors = &app.theme.colors;
    let centered = ui::layout::centered_rect(75, 80, area);

    let block = Block::bordered()
        .title(" Passage Downloads Setup ")
        .border_style(Style::default().fg(colors.accent()))
        .style(Style::default().bg(colors.bg()));
    let inner = block.inner(centered);
    block.render(centered, frame.buffer_mut());

    let paragraphs_value = if app.passage_intro_paragraph_limit == 0 {
        "whole book".to_string()
    } else {
        app.passage_intro_paragraph_limit.to_string()
    };

    let fields = vec![
        (
            "Enable network downloads",
            if app.passage_intro_downloads_enabled {
                "On".to_string()
            } else {
                "Off".to_string()
            },
        ),
        ("Download directory", app.passage_intro_download_dir.clone()),
        ("Paragraphs per book (0 = whole)", paragraphs_value),
        ("Start passage drill", "Confirm".to_string()),
    ];

    let mut lines = vec![
        Line::from(Span::styled(
            "Configure passage source settings before your first passage drill.",
            Style::default()
                .fg(colors.fg())
                .add_modifier(Modifier::BOLD),
        )),
        Line::from(Span::styled(
            "Downloads are lazy: books are fetched only when first needed.",
            Style::default().fg(colors.text_pending()),
        )),
        Line::from(Span::styled(
            "If you exit without confirming, this dialog will appear again next time.",
            Style::default().fg(colors.text_pending()),
        )),
        Line::from(""),
    ];

    for (i, (label, value)) in fields.iter().enumerate() {
        let is_selected = i == app.passage_intro_selected;
        let indicator = if is_selected { " > " } else { "   " };
        let label_style = if is_selected {
            Style::default()
                .fg(colors.accent())
                .add_modifier(Modifier::BOLD)
        } else {
            Style::default().fg(colors.fg())
        };
        let value_style = if is_selected {
            Style::default().fg(colors.focused_key())
        } else {
            Style::default().fg(colors.text_pending())
        };

        lines.push(Line::from(Span::styled(
            format!("{indicator}{label}"),
            label_style,
        )));
        if i == 1 {
            lines.push(Line::from(Span::styled(format!("   {value}"), value_style)));
        } else if i == 3 {
            lines.push(Line::from(Span::styled(
                format!("   [{value}]"),
                value_style,
            )));
        } else {
            lines.push(Line::from(Span::styled(
                format!("   < {value} >"),
                value_style,
            )));
        }
        lines.push(Line::from(""));
    }

    if app.passage_intro_downloading {
        let total_books = app.passage_intro_download_total.max(1);
        let done_books = app.passage_intro_downloaded.min(total_books);
        let total_bytes = app.passage_intro_download_bytes_total;
        let done_bytes = app
            .passage_intro_download_bytes
            .min(total_bytes.max(app.passage_intro_download_bytes));
        let width = 30usize;
        let fill = if total_bytes > 0 {
            ((done_bytes as usize).saturating_mul(width)) / (total_bytes as usize)
        } else {
            0
        };
        let bar = format!(
            "{}{}",
            "=".repeat(fill),
            " ".repeat(width.saturating_sub(fill))
        );
        let progress_text = if total_bytes > 0 {
            format!(" Downloading current book: [{bar}] {done_bytes}/{total_bytes} bytes")
        } else {
            format!(" Downloading current book: {done_bytes} bytes")
        };
        lines.push(Line::from(Span::styled(
            progress_text,
            Style::default()
                .fg(colors.accent())
                .add_modifier(Modifier::BOLD),
        )));
        if !app.passage_intro_current_book.is_empty() {
            lines.push(Line::from(Span::styled(
                format!(
                    " Current: {}  (book {}/{})",
                    app.passage_intro_current_book,
                    done_books.saturating_add(1).min(total_books),
                    total_books
                ),
                Style::default().fg(colors.text_pending()),
            )));
        }
    }
    let hint_lines = if app.passage_intro_downloading {
        Vec::new()
    } else {
        pack_hint_lines(
            &[
                "[Up/Down] Navigate",
                "[Left/Right] Adjust",
                "[Type/Backspace] Edit",
                "[Enter] Confirm",
                "[ESC] Cancel",
            ],
            inner.width as usize,
        )
    };
    let footer_height = if hint_lines.is_empty() {
        0
    } else {
        (hint_lines.len() + 1) as u16 // add spacer line above hints
    };
    let (content_area, footer_area) = if footer_height > 0 && footer_height < inner.height {
        let chunks = Layout::default()
            .direction(Direction::Vertical)
            .constraints([Constraint::Min(1), Constraint::Length(footer_height)])
            .split(inner);
        (chunks[0], Some(chunks[1]))
    } else {
        (inner, None)
    };
    Paragraph::new(lines).render(content_area, frame.buffer_mut());
    if let Some(footer) = footer_area {
        let mut footer_lines = vec![Line::from("")];
        footer_lines.extend(
            hint_lines
                .into_iter()
                .map(|hint| Line::from(Span::styled(hint, Style::default().fg(colors.text_pending())))),
        );
        Paragraph::new(footer_lines)
            .wrap(Wrap { trim: false })
            .render(footer, frame.buffer_mut());
    }
}

fn render_passage_download_progress(frame: &mut ratatui::Frame, app: &App) {
    let area = frame.area();
    let colors = &app.theme.colors;
    let centered = ui::layout::centered_rect(60, 35, area);

    let block = Block::bordered()
        .title(" Downloading Passage Source ")
        .border_style(Style::default().fg(colors.accent()))
        .style(Style::default().bg(colors.bg()));
    let inner = block.inner(centered);
    block.render(centered, frame.buffer_mut());

    let total_bytes = app.passage_intro_download_bytes_total;
    let done_bytes = app
        .passage_intro_download_bytes
        .min(total_bytes.max(app.passage_intro_download_bytes));
    let width = 36usize;
    let fill = if total_bytes > 0 {
        ((done_bytes as usize).saturating_mul(width)) / (total_bytes as usize)
    } else {
        0
    };
    let bar = format!(
        "{}{}",
        "=".repeat(fill),
        " ".repeat(width.saturating_sub(fill))
    );

    let book_name = if app.passage_intro_current_book.is_empty() {
        "Preparing download...".to_string()
    } else {
        app.passage_intro_current_book.clone()
    };

    let lines = vec![
        Line::from(Span::styled(
            format!(" Book: {book_name}"),
            Style::default()
                .fg(colors.fg())
                .add_modifier(Modifier::BOLD),
        )),
        Line::from(""),
        Line::from(Span::styled(
            if total_bytes > 0 {
                format!(" [{bar}] {done_bytes}/{total_bytes} bytes")
            } else {
                format!(" Downloaded: {done_bytes} bytes")
            },
            Style::default().fg(colors.accent()),
        )),
    ];

    Paragraph::new(lines).render(inner, frame.buffer_mut());
}

fn render_code_intro(frame: &mut ratatui::Frame, app: &App) {
    let area = frame.area();
    let colors = &app.theme.colors;
    let centered = ui::layout::centered_rect(75, 80, area);

    let block = Block::bordered()
        .title(" Code Downloads Setup ")
        .border_style(Style::default().fg(colors.accent()))
        .style(Style::default().bg(colors.bg()));
    let inner = block.inner(centered);
    block.render(centered, frame.buffer_mut());

    let snippets_value = if app.code_intro_snippets_per_repo == 0 {
        "unlimited".to_string()
    } else {
        app.code_intro_snippets_per_repo.to_string()
    };

    let fields = vec![
        (
            "Enable network downloads",
            if app.code_intro_downloads_enabled {
                "On".to_string()
            } else {
                "Off".to_string()
            },
        ),
        ("Download directory", app.code_intro_download_dir.clone()),
        ("Snippets per repo (0 = unlimited)", snippets_value),
        ("Start code drill", "Confirm".to_string()),
    ];

    let mut lines = vec![
        Line::from(Span::styled(
            "Configure code source settings before your first code drill.",
            Style::default()
                .fg(colors.fg())
                .add_modifier(Modifier::BOLD),
        )),
        Line::from(Span::styled(
            "Downloads are lazy: code is fetched only when first needed.",
            Style::default().fg(colors.text_pending()),
        )),
        Line::from(Span::styled(
            "If you exit without confirming, this dialog will appear again next time.",
            Style::default().fg(colors.text_pending()),
        )),
        Line::from(""),
    ];

    for (i, (label, value)) in fields.iter().enumerate() {
        let is_selected = i == app.code_intro_selected;
        let indicator = if is_selected { " > " } else { "   " };
        let label_style = if is_selected {
            Style::default()
                .fg(colors.accent())
                .add_modifier(Modifier::BOLD)
        } else {
            Style::default().fg(colors.fg())
        };
        let value_style = if is_selected {
            Style::default().fg(colors.focused_key())
        } else {
            Style::default().fg(colors.text_pending())
        };

        lines.push(Line::from(Span::styled(
            format!("{indicator}{label}"),
            label_style,
        )));
        if i == 1 {
            lines.push(Line::from(Span::styled(format!("   {value}"), value_style)));
        } else if i == 3 {
            lines.push(Line::from(Span::styled(
                format!("   [{value}]"),
                value_style,
            )));
        } else {
            lines.push(Line::from(Span::styled(
                format!("   < {value} >"),
                value_style,
            )));
        }
        lines.push(Line::from(""));
    }

    if app.code_intro_downloading {
        let total_repos = app.code_intro_download_total.max(1);
        let done_repos = app.code_intro_downloaded.min(total_repos);
        let total_bytes = app.code_intro_download_bytes_total;
        let done_bytes = app
            .code_intro_download_bytes
            .min(total_bytes.max(app.code_intro_download_bytes));
        let width = 30usize;
        let fill = if total_bytes > 0 {
            ((done_bytes as usize).saturating_mul(width)) / (total_bytes as usize)
        } else {
            0
        };
        let bar = format!(
            "{}{}",
            "=".repeat(fill),
            " ".repeat(width.saturating_sub(fill))
        );
        let progress_text = if total_bytes > 0 {
            format!(" Downloading: [{bar}] {done_bytes}/{total_bytes} bytes")
        } else {
            format!(" Downloading: {done_bytes} bytes")
        };
        lines.push(Line::from(Span::styled(
            progress_text,
            Style::default()
                .fg(colors.accent())
                .add_modifier(Modifier::BOLD),
        )));
        if !app.code_intro_current_repo.is_empty() {
            lines.push(Line::from(Span::styled(
                format!(
                    " Current: {}  (repo {}/{})",
                    app.code_intro_current_repo,
                    done_repos.saturating_add(1).min(total_repos),
                    total_repos
                ),
                Style::default().fg(colors.text_pending()),
            )));
        }
    }
    let hint_lines = if app.code_intro_downloading {
        Vec::new()
    } else {
        pack_hint_lines(
            &[
                "[Up/Down] Navigate",
                "[Left/Right] Adjust",
                "[Type/Backspace] Edit",
                "[Enter] Confirm",
                "[ESC] Cancel",
            ],
            inner.width as usize,
        )
    };
    let footer_height = if hint_lines.is_empty() {
        0
    } else {
        (hint_lines.len() + 1) as u16 // add spacer line above hints
    };
    let (content_area, footer_area) = if footer_height > 0 && footer_height < inner.height {
        let chunks = Layout::default()
            .direction(Direction::Vertical)
            .constraints([Constraint::Min(1), Constraint::Length(footer_height)])
            .split(inner);
        (chunks[0], Some(chunks[1]))
    } else {
        (inner, None)
    };
    Paragraph::new(lines).render(content_area, frame.buffer_mut());
    if let Some(footer) = footer_area {
        let mut footer_lines = vec![Line::from("")];
        footer_lines.extend(
            hint_lines
                .into_iter()
                .map(|hint| Line::from(Span::styled(hint, Style::default().fg(colors.text_pending())))),
        );
        Paragraph::new(footer_lines)
            .wrap(Wrap { trim: false })
            .render(footer, frame.buffer_mut());
    }
}

fn render_code_download_progress(frame: &mut ratatui::Frame, app: &App) {
    let area = frame.area();
    let colors = &app.theme.colors;
    let centered = ui::layout::centered_rect(60, 35, area);

    let block = Block::bordered()
        .title(" Downloading Code Source ")
        .border_style(Style::default().fg(colors.accent()))
        .style(Style::default().bg(colors.bg()));
    let inner = block.inner(centered);
    block.render(centered, frame.buffer_mut());

    let total_bytes = app.code_intro_download_bytes_total;
    let done_bytes = app
        .code_intro_download_bytes
        .min(total_bytes.max(app.code_intro_download_bytes));
    let width = 36usize;
    let fill = if total_bytes > 0 {
        ((done_bytes as usize).saturating_mul(width)) / (total_bytes as usize)
    } else {
        0
    };
    let bar = format!(
        "{}{}",
        "=".repeat(fill),
        " ".repeat(width.saturating_sub(fill))
    );

    let repo_name = if app.code_intro_current_repo.is_empty() {
        "Preparing download...".to_string()
    } else {
        app.code_intro_current_repo.clone()
    };

    let lines = vec![
        Line::from(Span::styled(
            format!(" Repo: {repo_name}"),
            Style::default()
                .fg(colors.fg())
                .add_modifier(Modifier::BOLD),
        )),
        Line::from(""),
        Line::from(Span::styled(
            if total_bytes > 0 {
                format!(" [{bar}] {done_bytes}/{total_bytes} bytes")
            } else {
                format!(" Downloaded: {done_bytes} bytes")
            },
            Style::default().fg(colors.accent()),
        )),
        Line::from(""),
        Line::from(Span::styled(
            " [ESC] Cancel",
            Style::default().fg(colors.text_pending()),
        )),
    ];

    Paragraph::new(lines).render(inner, frame.buffer_mut());
}

fn render_skill_tree(frame: &mut ratatui::Frame, app: &App) {
    let area = frame.area();
    let centered = skill_tree_popup_rect(area);
    let widget = SkillTreeWidget::new(
        &app.skill_tree,
        &app.ranked_key_stats,
        app.skill_tree_selected,
        app.skill_tree_detail_scroll,
        app.theme,
    );
    frame.render_widget(widget, centered);
}

fn handle_keyboard_explorer_key(app: &mut App, key: KeyEvent) {
    match key.code {
        KeyCode::Esc => app.go_to_menu(),
        KeyCode::Char('q') if app.keyboard_explorer_selected.is_none() => app.go_to_menu(),
        KeyCode::Char(ch) => {
            app.keyboard_explorer_selected = Some(ch);
            app.key_accuracy(ch, false);
            app.key_accuracy(ch, true);
        }
        KeyCode::Tab => {
            app.keyboard_explorer_selected = Some('\t');
            app.key_accuracy('\t', false);
            app.key_accuracy('\t', true);
        }
        KeyCode::Enter => {
            app.keyboard_explorer_selected = Some('\n');
            app.key_accuracy('\n', false);
            app.key_accuracy('\n', true);
        }
        KeyCode::Backspace => {
            app.keyboard_explorer_selected = Some('\x08');
            app.key_accuracy('\x08', false);
            app.key_accuracy('\x08', true);
        }
        _ => {}
    }
}

fn render_keyboard_explorer(frame: &mut ratatui::Frame, app: &App) {
    let area = frame.area();
    let colors = &app.theme.colors;

    let layout = Layout::default()
        .direction(Direction::Vertical)
        .constraints([
            Constraint::Length(3), // header
            Constraint::Length(8), // keyboard diagram
            Constraint::Min(3),   // detail panel
            Constraint::Length(1), // footer
        ])
        .split(area);

    // Header
    let header_lines = vec![
        Line::from(""),
        Line::from(Span::styled(
            " Keyboard Explorer ",
            Style::default()
                .fg(colors.accent())
                .add_modifier(Modifier::BOLD),
        )),
        Line::from(Span::styled(
            "Press any key to see details",
            Style::default().fg(colors.text_pending()),
        )),
    ];
    let header = Paragraph::new(header_lines)
        .alignment(ratatui::layout::Alignment::Center);
    frame.render_widget(header, layout[0]);

    // Keyboard diagram
    let unlocked = app.skill_tree.unlocked_keys(DrillScope::Global);
    let kbd = KeyboardDiagram::new(
        None,
        &unlocked,
        &app.depressed_keys,
        app.theme,
        &app.keyboard_model,
    )
    .selected_key(app.keyboard_explorer_selected)
    .shift_held(app.shift_held)
    .caps_lock(app.caps_lock);
    frame.render_widget(kbd, layout[1]);

    // Detail panel
    render_keyboard_detail_panel(frame, app, layout[2]);

    // Footer
    let footer = Paragraph::new(Line::from(vec![Span::styled(
        " [ESC] Back ",
        Style::default().fg(colors.text_pending()),
    )]));
    frame.render_widget(footer, layout[3]);
}

fn render_keyboard_detail_panel(frame: &mut ratatui::Frame, app: &App, area: Rect) {
    let colors = &app.theme.colors;

    let selected = match app.keyboard_explorer_selected {
        Some(ch) => ch,
        None => {
            let hint = Paragraph::new(Line::from(Span::styled(
                "Press a key to see its details",
                Style::default().fg(colors.text_pending()),
            )))
            .alignment(ratatui::layout::Alignment::Center)
            .block(
                Block::bordered()
                    .border_style(Style::default().fg(colors.border()))
                    .title(" Key Details "),
            );
            frame.render_widget(hint, area);
            return;
        }
    };

    // Build display name for title
    let display_name = key_display_name(selected);
    let title = if display_name.is_empty() {
        format!(" Key Details: '{}' ", selected)
    } else {
        format!(" Key Details: {} ", display_name)
    };

    let block = Block::bordered()
        .border_style(Style::default().fg(colors.border()))
        .title(Span::styled(
            title,
            Style::default()
                .fg(colors.accent())
                .add_modifier(Modifier::BOLD),
        ));
    let inner = block.inner(area);
    frame.render_widget(block, area);

    let finger = app.keyboard_model.finger_for_char(selected);
    let is_shifted = selected.is_uppercase()
        || matches!(
            selected,
            '!' | '@' | '#' | '$' | '%' | '^' | '&' | '*' | '(' | ')' | '_' | '+'
                | '{' | '}' | '|' | ':' | '"' | '<' | '>' | '?' | '~'
        );
    let shift_guidance = if is_shifted {
        if finger.hand == Hand::Left {
            "Hold Right Shift (right pinky)".to_string()
        } else {
            "Hold Left Shift (left pinky)".to_string()
        }
    } else {
        "No".to_string()
    };

    let unlocked_keys = app.skill_tree.unlocked_keys(DrillScope::Global);
    let is_unlocked = unlocked_keys.contains(&selected);
    let focus_key = app
        .skill_tree
        .focused_key(DrillScope::Global, &app.ranked_key_stats);
    let in_focus = focus_key == Some(selected);

    let overall_stat = app.key_stats.get_stat(selected);
    let ranked_stat = app.ranked_key_stats.get_stat(selected);
    let overall_acc = app
        .explorer_accuracy_cache_overall
        .filter(|(key, _, _)| *key == selected);
    let ranked_acc = app
        .explorer_accuracy_cache_ranked
        .filter(|(key, _, _)| *key == selected);

    let fmt_avg_time = |stat: Option<&crate::engine::key_stats::KeyStat>| -> String {
        if let Some(stat) = stat {
            if stat.sample_count > 0 {
                return format!("{:.0}ms", stat.filtered_time_ms);
            }
        }
        "No data".to_string()
    };
    let fmt_best_time = |stat: Option<&crate::engine::key_stats::KeyStat>| -> String {
        if let Some(stat) = stat {
            if stat.sample_count > 0 {
                let best = if stat.best_time_ms < f64::MAX {
                    stat.best_time_ms
                } else {
                    stat.filtered_time_ms
                };
                return format!("{best:.0}ms");
            }
        }
        "No data".to_string()
    };
    let fmt_samples = |stat: Option<&crate::engine::key_stats::KeyStat>| -> String {
        stat.map(|s| s.sample_count.to_string())
            .unwrap_or_else(|| "0".to_string())
    };
    let fmt_acc = |entry: Option<(char, usize, usize)>| -> String {
        if let Some((_, correct, total)) = entry {
            if total > 0 {
                let pct = (correct as f64 / total as f64) * 100.0;
                return format!("{:.1}% ({}/{})", pct, correct, total);
            }
        }
        "No data".to_string()
    };

    let (branch_name, level_name) = if let Some((branch, level, pos)) = find_key_branch(selected) {
        (branch.name.to_string(), format!("{level} (key #{pos})"))
    } else {
        ("Unknown".to_string(), "Unknown".to_string())
    };

    // Ranked-only mastery display (same semantics as skill tree per-key progress)
    let ranked_conf = app.ranked_key_stats.get_confidence(selected).min(1.0);
    let mastery_bar_width = 10usize;
    let filled = (ranked_conf * mastery_bar_width as f64).round() as usize;
    let mastery_bar = format!(
        "{}{}",
        "\u{2588}".repeat(filled),
        "\u{2591}".repeat(mastery_bar_width.saturating_sub(filled))
    );
    let mastery_text = format!("{mastery_bar} {:>3.0}%", ranked_conf * 100.0);

    let mut left_col: Vec<String> = vec![
        format!("Finger: {}", finger.description()),
        format!("Shift: {shift_guidance}"),
        format!("Overall Avg Time: {}", fmt_avg_time(overall_stat)),
        format!("Overall Best Time: {}", fmt_best_time(overall_stat)),
        format!("Overall Samples: {}", fmt_samples(overall_stat)),
        format!("Overall Accuracy: {}", fmt_acc(overall_acc)),
    ];

    let mut right_col: Vec<String> = vec![
        format!("Branch: {branch_name}"),
        format!("Level: {level_name}"),
        format!("Unlocked: {}", if is_unlocked { "Yes" } else { "No" }),
        format!("In Focus?: {}", if in_focus { "Yes" } else { "No" }),
    ];
    if is_unlocked {
        right_col.push(format!("Mastery: {mastery_text}"));
    } else {
        right_col.push("Mastery: Locked".to_string());
    }
    right_col.push(format!("Ranked Avg Time: {}", fmt_avg_time(ranked_stat)));
    right_col.push(format!("Ranked Best Time: {}", fmt_best_time(ranked_stat)));
    right_col.push(format!("Ranked Samples: {}", fmt_samples(ranked_stat)));
    right_col.push(format!("Ranked Accuracy: {}", fmt_acc(ranked_acc)));

    if left_col.is_empty() {
        left_col.push("No data yet".to_string());
    }
    if right_col.is_empty() {
        right_col.push("No data yet".to_string());
    }

    let mut lines: Vec<Line> = Vec::new();
    let split_gap = 3usize;
    let left_width = inner.width.saturating_sub(split_gap as u16) as usize / 2;
    let right_width = inner.width as usize - left_width.saturating_sub(0) - split_gap;
    let row_count = left_col.len().max(right_col.len());
    for i in 0..row_count {
        let left = left_col.get(i).map(String::as_str).unwrap_or("");
        let right = right_col.get(i).map(String::as_str).unwrap_or("");
        let mut left_fit: String = left.chars().take(left_width).collect();
        if left_fit.len() < left_width {
            left_fit.push_str(&" ".repeat(left_width - left_fit.len()));
        }
        let right_fit: String = right.chars().take(right_width).collect();
        lines.push(Line::from(vec![
            Span::styled(" ", Style::default().fg(colors.fg())),
            Span::styled(left_fit, Style::default().fg(colors.fg())),
            Span::styled(" | ", Style::default().fg(colors.border())),
            Span::styled(right_fit, Style::default().fg(colors.fg())),
        ]));
    }

    let paragraph = Paragraph::new(lines).wrap(Wrap { trim: false });
    frame.render_widget(paragraph, inner);
}