frankensearch-tui 0.1.0

//! App shell: status bar, breadcrumbs, screen lifecycle.
//!
//! The [`AppShell`] owns the [`ScreenRegistry`], manages navigation between
//! screens, renders the chrome (status bar, breadcrumbs), and dispatches
//! input events to the active screen.

use std::cell::Cell;
use std::hash::{DefaultHasher, Hash, Hasher};

use ftui_core::geometry::Rect;
use ftui_render::frame::Frame;
use ftui_style::Style;
use ftui_text::{Line, Span};
use ftui_widgets::{
    Widget,
    block::Block,
    borders::{BorderType, Borders},
    paragraph::Paragraph,
};
use serde::{Deserialize, Serialize};

use crate::frame::{CachedLayout, CachedTabState};
use crate::input::{InputEvent, KeyAction, Keymap};
use crate::overlay::OverlayManager;
use crate::palette::{CommandPalette, PaletteState};
use crate::screen::{KeybindingHint, ScreenAction, ScreenContext, ScreenId, ScreenRegistry};
use crate::theme::Theme;

// ─── Shell Config ────────────────────────────────────────────────────────────

/// Configuration for the app shell.
#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct ShellConfig {
    /// Application title shown in the status bar.
    pub title: String,
    /// Theme preset to use.
    pub theme: Theme,
    /// Whether to show the status bar.
    pub show_status_bar: bool,
    /// Whether to show breadcrumbs (tab bar).
    pub show_breadcrumbs: bool,
}

impl Default for ShellConfig {
    fn default() -> Self {
        Self {
            title: "frankensearch".to_string(),
            theme: Theme::dark(),
            show_status_bar: true,
            show_breadcrumbs: true,
        }
    }
}

// ─── Status Line ─────────────────────────────────────────────────────────────

/// Status line content rendered at the bottom of the shell.
#[derive(Debug, Clone, Default)]
pub struct StatusLine {
    /// Left-aligned status text.
    pub left: String,
    /// Center status text.
    pub center: String,
    /// Right-aligned status text.
    pub right: String,
}

impl StatusLine {
    /// Create a new status line.
    #[must_use]
    pub fn new() -> Self {
        Self::default()
    }

    /// Set the left-aligned text.
    #[must_use]
    pub fn with_left(mut self, text: impl Into<String>) -> Self {
        self.left = text.into();
        self
    }

    /// Set the center text.
    #[must_use]
    pub fn with_center(mut self, text: impl Into<String>) -> Self {
        self.center = text.into();
        self
    }

    /// Set the right-aligned text.
    #[must_use]
    pub fn with_right(mut self, text: impl Into<String>) -> Self {
        self.right = text.into();
        self
    }
}

// ─── App Shell ───────────────────────────────────────────────────────────────

/// The main app shell that manages screens, chrome, and input dispatch.
pub struct AppShell {
    /// Shell configuration.
    pub config: ShellConfig,
    /// Screen registry.
    pub registry: ScreenRegistry,
    /// Currently active screen ID.
    pub active_screen: Option<ScreenId>,
    /// Keymap for input resolution.
    pub keymap: Keymap,
    /// Overlay manager.
    pub overlays: OverlayManager,
    /// Command palette.
    pub palette: CommandPalette,
    /// Status line content.
    pub status_line: StatusLine,
    /// Whether the app should quit.
    pub should_quit: bool,
    /// Last confirmed palette action ID (reset each `handle_input` call).
    last_palette_action: Option<String>,
    /// Terminal area captured from the most recent render pass.
    last_render_area: Cell<Rect>,
    /// Cached layout to avoid recomputing splits every frame.
    cached_layout: CachedLayout,
    /// Cached tab titles and selected index.
    cached_tabs: CachedTabState,
}

impl AppShell {
    fn build_help_overlay_request(&self) -> crate::overlay::OverlayRequest {
        let mut request = crate::overlay::OverlayRequest::new(
            crate::overlay::OverlayKind::Help,
            "Keyboard Shortcuts",
        )
        .with_body("Global shortcuts + active screen controls");

        if let Some(screen_id) = &self.active_screen
            && let Some(screen) = self.registry.get(screen_id)
        {
            let hints = screen.keybindings();
            if !hints.is_empty() {
                request.title = format!("Keyboard Shortcuts · {}", screen.title());
                request.actions = Self::encode_screen_keybindings(hints);
            }
        }

        request
    }

    fn encode_screen_keybindings(hints: &[KeybindingHint]) -> Vec<String> {
        hints
            .iter()
            .map(|hint| format!("{}|{}", hint.key, hint.description))
            .collect()
    }

    /// Create a new app shell with the given config.
    #[must_use]
    pub fn new(config: ShellConfig) -> Self {
        Self {
            config,
            registry: ScreenRegistry::new(),
            active_screen: None,
            keymap: Keymap::default_bindings(),
            overlays: OverlayManager::new(),
            palette: CommandPalette::new(),
            status_line: StatusLine::new(),
            should_quit: false,
            last_palette_action: None,
            last_render_area: Cell::new(Rect::new(0, 0, 0, 0)),
            cached_layout: CachedLayout::new(),
            cached_tabs: CachedTabState::new(),
        }
    }

    /// Navigate to a screen by ID.
    pub fn navigate_to(&mut self, id: &ScreenId) {
        if self.registry.get(id).is_some() {
            // Blur the old screen.
            if let Some(old_id) = &self.active_screen {
                let old_id = old_id.clone();
                if let Some(screen) = self.registry.get_mut(&old_id) {
                    screen.on_blur();
                }
            }
            // Focus the new screen.
            self.active_screen = Some(id.clone());
            if let Some(screen) = self.registry.get_mut(id) {
                screen.on_focus();
            }
            // Invalidate tab cache since the active screen changed.
            self.cached_tabs.invalidate();
        }
    }

    /// Navigate to the next screen in tab order.
    pub fn next_screen(&mut self) {
        if let Some(current) = &self.active_screen
            && let Some(next) = self.registry.next_screen(current).cloned()
        {
            self.navigate_to(&next);
        }
    }

    /// Navigate to the previous screen in tab order.
    pub fn prev_screen(&mut self) {
        if let Some(current) = &self.active_screen
            && let Some(prev) = self.registry.prev_screen(current).cloned()
        {
            self.navigate_to(&prev);
        }
    }

    /// Build the screen context for the current state.
    #[must_use]
    pub fn screen_context(&self, area: Rect) -> ScreenContext {
        ScreenContext {
            active_screen: self
                .active_screen
                .clone()
                .unwrap_or_else(|| ScreenId::new("")),
            terminal_width: area.width,
            terminal_height: area.height,
            focused: true,
        }
    }

    /// Handle an input event. Returns `true` if the app should quit.
    ///
    /// Returns the confirmed palette action ID if the user selected a command.
    /// Callers should check `last_palette_action()` after calling this.
    #[allow(clippy::too_many_lines)]
    pub fn handle_input(&mut self, event: &InputEvent) -> bool {
        self.last_palette_action = None;

        if let InputEvent::Resize(width, height) = event {
            self.last_render_area.set(Rect::new(0, 0, *width, *height));
        }

        if self.last_render_area.get().width == 0 || self.last_render_area.get().height == 0 {
            // Fallback keeps context sane in non-interactive test harnesses.
            self.last_render_area.set(Rect::new(0, 0, 80, 24));
        }

        // If the command palette is open, route input there first.
        if self.palette.state() == &PaletteState::Open {
            if let InputEvent::Key(key, mods) = event {
                if let Some(action) = self.keymap.resolve(*key, *mods) {
                    match action {
                        KeyAction::TogglePalette | KeyAction::Dismiss => {
                            self.palette.close();
                            return false;
                        }
                        KeyAction::Up => {
                            self.palette.select_prev();
                            return false;
                        }
                        KeyAction::Down => {
                            self.palette.select_next();
                            return false;
                        }
                        KeyAction::Confirm => {
                            if let Some(action_id) = self.palette.confirm() {
                                self.last_palette_action = Some(action_id);
                            }
                            self.palette.close();
                            return false;
                        }
                        _ => {}
                    }
                }
                // Handle text input for palette search.
                match key {
                    ftui_core::event::KeyCode::Char(ch)
                        if !mods.intersects(
                            ftui_core::event::Modifiers::CTRL
                                | ftui_core::event::Modifiers::ALT
                                | ftui_core::event::Modifiers::SUPER,
                        ) =>
                    {
                        self.palette.push_char(*ch);
                        return false;
                    }
                    ftui_core::event::KeyCode::Backspace => {
                        self.palette.pop_char();
                        return false;
                    }
                    _ => {}
                }
            }
            return false;
        }

        // If an overlay is active, let it handle first.
        if self.overlays.has_active() {
            if let InputEvent::Key(key, mods) = event
                && let Some(action) = self.keymap.resolve(*key, *mods)
                && action == &KeyAction::Dismiss
            {
                self.overlays.dismiss();
                return false;
            }
            return false;
        }

        // Resolve key actions.
        if let InputEvent::Key(key, mods) = event
            && let Some(action) = self.keymap.resolve(*key, *mods).cloned()
        {
            match action {
                KeyAction::Quit => {
                    self.should_quit = true;
                    return true;
                }
                KeyAction::NextScreen => {
                    self.next_screen();
                    return false;
                }
                KeyAction::PrevScreen => {
                    self.prev_screen();
                    return false;
                }
                KeyAction::ToggleHelp => {
                    if self
                        .overlays
                        .top()
                        .is_some_and(|o| o.kind == crate::overlay::OverlayKind::Help)
                    {
                        self.overlays.dismiss();
                    } else {
                        self.overlays.push(self.build_help_overlay_request());
                    }
                    return false;
                }
                KeyAction::TogglePalette => {
                    self.palette.toggle();
                    return false;
                }
                KeyAction::CycleTheme => {
                    self.config.theme = Theme::from_preset(self.config.theme.preset.next());
                    self.cached_tabs.invalidate();
                    return false;
                }
                _ => {}
            }
        }

        // Forward to active screen.
        if let Some(screen_id) = &self.active_screen {
            let screen_id = screen_id.clone();
            let ctx = self.screen_context(self.last_render_area.get());
            if let Some(screen) = self.registry.get_mut(&screen_id) {
                match screen.handle_input(event, &ctx) {
                    ScreenAction::Quit => {
                        self.should_quit = true;
                        return true;
                    }
                    ScreenAction::Navigate(target) => {
                        self.navigate_to(&target);
                    }
                    ScreenAction::OpenOverlay(name) => {
                        self.overlays.push(crate::overlay::OverlayRequest::new(
                            crate::overlay::OverlayKind::Custom(name.clone()),
                            name,
                        ));
                    }
                    ScreenAction::Consumed | ScreenAction::Ignored => {}
                }
            }
        }

        false
    }

    /// Get the last palette action confirmed by the user.
    ///
    /// Returns `Some(action_id)` if the user selected an action from the
    /// command palette during the last `handle_input()` call.
    #[must_use]
    pub fn last_palette_action(&self) -> Option<&str> {
        self.last_palette_action.as_deref()
    }

    /// Render the shell chrome and active screen.
    ///
    /// Uses cached layout and tab state to avoid redundant allocations
    /// when the terminal dimensions and screen configuration haven't changed.
    #[allow(clippy::too_many_lines)]
    pub fn render(&mut self, frame: &mut Frame) {
        let area = frame.bounds();
        self.last_render_area.set(area);
        let ctx = self.screen_context(area);

        // Cached layout avoids recomputing splits when area hasn't changed.
        // Copy the Rect values directly (Rect is Copy, 8 bytes) instead of
        // allocating a Vec clone every frame.
        let show_bc = self.config.show_breadcrumbs;
        let show_sb = self.config.show_status_bar;
        let num_screens = self.registry.len();
        let layout_chunks = self
            .cached_layout
            .get_or_compute(area, show_bc, show_sb, num_screens);
        let bc_area = if show_bc && num_screens > 1 {
            Some(layout_chunks[0])
        } else {
            None
        };
        let content_idx = usize::from(bc_area.is_some());
        let content_area = layout_chunks[content_idx];
        let status_area = if show_sb {
            Some(layout_chunks[content_idx + 1])
        } else {
            None
        };

        // Breadcrumbs / tabs (using cached titles and selected index).
        if let Some(bc_rect) = bc_area {
            let screen_ids = self.registry.screen_ids();
            let mut id_hasher = DefaultHasher::new();
            let mut title_hasher = DefaultHasher::new();
            for id in screen_ids {
                id.0.hash(&mut id_hasher);
                id.0.hash(&mut title_hasher);
                if let Some(screen) = self.registry.get(id) {
                    screen.title().hash(&mut title_hasher);
                }
            }
            let screen_ids_hash = id_hasher.finish();
            let title_signature = title_hasher.finish();
            let active_str = self.active_screen.as_ref().map(|id| id.0.as_str());

            if !self
                .cached_tabs
                .is_valid(screen_ids_hash, title_signature, active_str)
            {
                let titles: Vec<String> = screen_ids
                    .iter()
                    .map(|id| {
                        self.registry
                            .get(id)
                            .map_or_else(|| id.0.clone(), |s| s.title().to_string())
                    })
                    .collect();

                let selected = self
                    .active_screen
                    .as_ref()
                    .and_then(|active| screen_ids.iter().position(|id| id == active))
                    .unwrap_or(0);

                self.cached_tabs.update(
                    titles,
                    selected,
                    screen_ids_hash,
                    title_signature,
                    active_str,
                );
            }

            let mut tab_spans: Vec<Span<'_>> = Vec::new();
            for (i, title) in self.cached_tabs.titles.iter().enumerate() {
                if i > 0 {
                    tab_spans.push(Span::styled(
                        " \u{2502} ",
                        Style::new().fg(self.config.theme.border.to_color()),
                    ));
                }
                if i == self.cached_tabs.selected {
                    tab_spans.push(Span::styled(
                        format!(" {title} "),
                        Style::new()
                            .fg(self.config.theme.highlight_fg.to_color())
                            .bg(self.config.theme.accent.to_color())
                            .bold(),
                    ));
                } else {
                    tab_spans.push(Span::styled(
                        format!(" {title} "),
                        Style::new().fg(self.config.theme.muted.to_color()).bg(self
                            .config
                            .theme
                            .bg
                            .to_color()),
                    ));
                }
            }
            let tab_line = Paragraph::new(Line::from_spans(tab_spans))
                .style(Style::new().bg(self.config.theme.bg.to_color()));

            tab_line.render(bc_rect, frame);
        }

        // Main content area.
        if let Some(screen_id) = &self.active_screen {
            if let Some(screen) = self.registry.get(screen_id) {
                screen.render(frame, &ctx);
            }
        } else {
            // No screen active — render placeholder.
            let block = Block::new()
                .borders(Borders::ALL)
                .border_type(BorderType::Rounded)
                .border_style(Style::new().fg(self.config.theme.border.to_color()))
                .style(
                    Style::new().bg(self.config.theme.bg.to_color()).fg(self
                        .config
                        .theme
                        .fg
                        .to_color()),
                );
            let placeholder = Paragraph::new("No screens registered").block(block);
            placeholder.render(content_area, frame);
        }

        // Status bar.
        if let Some(sb_rect) = status_area {
            let status_text = if self.status_line.center.is_empty() {
                format!(" {} ", self.config.title)
            } else {
                format!(
                    " {} \u{2502} {} ",
                    self.config.title, self.status_line.center
                )
            };

            let active_screen_hints = self
                .active_screen
                .as_ref()
                .and_then(|id| self.registry.get(id))
                .map_or(&[][..], |screen| screen.keybindings());
            let hints = Self::status_bar_hints(sb_rect.width, active_screen_hints);
            let left_content_len =
                self.status_line.left.len() + status_text.len() + self.status_line.right.len();
            let pad_width = (sb_rect.width as usize).saturating_sub(left_content_len + hints.len());
            let padding = " ".repeat(pad_width);

            let muted_style = Style::new().fg(self.config.theme.muted.to_color());

            let status_spans = vec![
                Span::styled(
                    self.status_line.left.clone(),
                    Style::new().fg(self.config.theme.status_bar_fg.to_color()),
                ),
                Span::styled(
                    status_text,
                    Style::new()
                        .fg(self.config.theme.status_bar_fg.to_color())
                        .bold(),
                ),
                Span::styled(
                    self.status_line.right.clone(),
                    Style::new().fg(self.config.theme.status_bar_fg.to_color()),
                ),
                Span::raw(padding),
                Span::styled(hints, muted_style),
            ];

            let status = Paragraph::new(Line::from_spans(status_spans))
                .style(Style::new().bg(self.config.theme.status_bar_bg.to_color()));

            status.render(sb_rect, frame);
        }
    }

    /// Build right-aligned keybinding hints for the status bar.
    fn status_bar_hints(width: u16, screen_hints: &[KeybindingHint]) -> String {
        if width < 60 {
            return String::new();
        }

        let mut base = if width < 90 {
            "Tab:Nav  ?:Help  ^T:Theme ".to_string()
        } else {
            "Tab:Nav  ?:Help  ^P:Cmd  ^T:Theme  q:Quit ".to_string()
        };

        if width >= 110 && !screen_hints.is_empty() {
            let contextual = screen_hints
                .iter()
                .take(2)
                .map(|hint| format!("{} {}", hint.key, hint.description))
                .collect::<Vec<_>>()
                .join("  ");
            if !contextual.is_empty() {
                base.push_str("| ");
                base.push_str(&contextual);
                base.push(' ');
            }
        }

        base
    }
}

#[cfg(test)]
mod tests {
    use std::any::Any;
    use std::sync::{Arc, Mutex};

    use ftui_render::frame::Frame;

    use crate::screen::{Screen, ScreenAction};

    use super::*;

    #[test]
    fn shell_config_default() {
        let config = ShellConfig::default();
        assert_eq!(config.title, "frankensearch");
        assert!(config.show_status_bar);
        assert!(config.show_breadcrumbs);
    }

    #[test]
    fn status_line_builder() {
        let status = StatusLine::new()
            .with_left("left")
            .with_center("center")
            .with_right("right");
        assert_eq!(status.left, "left");
        assert_eq!(status.center, "center");
        assert_eq!(status.right, "right");
    }

    #[test]
    fn shell_creation() {
        let shell = AppShell::new(ShellConfig::default());
        assert!(!shell.should_quit);
        assert!(shell.active_screen.is_none());
        assert!(shell.registry.is_empty());
    }

    #[test]
    fn shell_config_serde_roundtrip() {
        let config = ShellConfig::default();
        let json = serde_json::to_string(&config).unwrap();
        let decoded: ShellConfig = serde_json::from_str(&json).unwrap();
        assert_eq!(decoded.title, config.title);
    }

    #[test]
    fn shell_quit_handling() {
        let mut shell = AppShell::new(ShellConfig::default());
        let event = InputEvent::Key(
            ftui_core::event::KeyCode::Char('q'),
            ftui_core::event::Modifiers::NONE,
        );
        let quit = shell.handle_input(&event);
        assert!(quit);
        assert!(shell.should_quit);
    }

    struct CaptureContextScreen {
        id: ScreenId,
        captured: Arc<Mutex<Option<(u16, u16)>>>,
    }

    impl CaptureContextScreen {
        fn new(id: &str, captured: Arc<Mutex<Option<(u16, u16)>>>) -> Self {
            Self {
                id: ScreenId::new(id),
                captured,
            }
        }
    }

    impl Screen for CaptureContextScreen {
        fn id(&self) -> &ScreenId {
            &self.id
        }

        fn title(&self) -> &'static str {
            "capture"
        }

        fn render(&self, _frame: &mut Frame, _ctx: &ScreenContext) {}

        fn handle_input(&mut self, _event: &InputEvent, ctx: &ScreenContext) -> ScreenAction {
            *self.captured.lock().expect("capture lock") =
                Some((ctx.terminal_width, ctx.terminal_height));
            ScreenAction::Consumed
        }

        fn as_any(&self) -> &dyn Any {
            self
        }

        fn as_any_mut(&mut self) -> &mut dyn Any {
            self
        }
    }

    #[test]
    fn handle_input_uses_last_render_area_for_context() {
        let mut shell = AppShell::new(ShellConfig::default());
        let captured = Arc::new(Mutex::new(None));
        let screen_id = ScreenId::new("capture");
        shell.registry.register(Box::new(CaptureContextScreen::new(
            "capture",
            captured.clone(),
        )));
        shell.navigate_to(&screen_id);

        shell.last_render_area.set(Rect::new(0, 0, 132, 47));
        let event = InputEvent::Key(
            ftui_core::event::KeyCode::Char('x'),
            ftui_core::event::Modifiers::NONE,
        );
        let _ = shell.handle_input(&event);

        let seen = captured
            .lock()
            .expect("capture lock")
            .expect("context captured");
        assert_eq!(seen, (132, 47));
    }

    #[test]
    fn palette_toggle_shortcut_closes_palette_when_open() {
        let mut shell = AppShell::new(ShellConfig::default());
        let toggle = InputEvent::Key(
            ftui_core::event::KeyCode::Char('p'),
            ftui_core::event::Modifiers::CTRL,
        );

        let _ = shell.handle_input(&toggle);
        assert_eq!(shell.palette.state(), &PaletteState::Open);

        let _ = shell.handle_input(&toggle);
        assert_eq!(shell.palette.state(), &PaletteState::Closed);
    }

    #[test]
    fn palette_accepts_shift_modified_characters() {
        let mut shell = AppShell::new(ShellConfig::default());
        let open = InputEvent::Key(
            ftui_core::event::KeyCode::Char('p'),
            ftui_core::event::Modifiers::CTRL,
        );
        let _ = shell.handle_input(&open);

        let shifted = InputEvent::Key(
            ftui_core::event::KeyCode::Char('A'),
            ftui_core::event::Modifiers::SHIFT,
        );
        let _ = shell.handle_input(&shifted);

        assert_eq!(shell.palette.query(), "A");
    }

    #[test]
    fn resize_event_refreshes_context_dimensions() {
        let mut shell = AppShell::new(ShellConfig::default());
        let captured = Arc::new(Mutex::new(None));
        let screen_id = ScreenId::new("capture");
        shell.registry.register(Box::new(CaptureContextScreen::new(
            "capture",
            captured.clone(),
        )));
        shell.navigate_to(&screen_id);

        let resize = InputEvent::Resize(111, 37);
        let _ = shell.handle_input(&resize);

        let key = InputEvent::Key(
            ftui_core::event::KeyCode::Char('x'),
            ftui_core::event::Modifiers::NONE,
        );
        let _ = shell.handle_input(&key);

        let seen = captured
            .lock()
            .expect("capture lock")
            .expect("context captured");
        assert_eq!(seen, (111, 37));
    }

    // ─── bd-n6x8 tests begin ───

    /// Minimal stub screen for navigation/lifecycle tests.
    struct StubScreen {
        id: ScreenId,
        title: &'static str,
        focused: Arc<Mutex<bool>>,
    }

    impl StubScreen {
        fn new(id: &str, title: &'static str) -> Self {
            Self {
                id: ScreenId::new(id),
                title,
                focused: Arc::new(Mutex::new(false)),
            }
        }

        #[expect(dead_code)]
        fn is_focused(&self) -> bool {
            *self.focused.lock().unwrap()
        }
    }

    impl Screen for StubScreen {
        fn id(&self) -> &ScreenId {
            &self.id
        }

        fn title(&self) -> &'static str {
            self.title
        }

        fn render(&self, _frame: &mut Frame, _ctx: &ScreenContext) {}

        fn handle_input(&mut self, _event: &InputEvent, _ctx: &ScreenContext) -> ScreenAction {
            ScreenAction::Ignored
        }

        fn on_focus(&mut self) {
            *self.focused.lock().unwrap() = true;
        }

        fn on_blur(&mut self) {
            *self.focused.lock().unwrap() = false;
        }

        fn as_any(&self) -> &dyn Any {
            self
        }

        fn as_any_mut(&mut self) -> &mut dyn Any {
            self
        }
    }

    #[test]
    fn status_line_default_is_empty() {
        let sl = StatusLine::default();
        assert!(sl.left.is_empty());
        assert!(sl.center.is_empty());
        assert!(sl.right.is_empty());
    }

    #[test]
    fn status_line_new_matches_default() {
        let n = StatusLine::new();
        let d = StatusLine::default();
        assert_eq!(n.left, d.left);
        assert_eq!(n.center, d.center);
        assert_eq!(n.right, d.right);
    }

    #[test]
    fn status_line_partial_builder_only_left() {
        let sl = StatusLine::new().with_left("L");
        assert_eq!(sl.left, "L");
        assert!(sl.center.is_empty());
        assert!(sl.right.is_empty());
    }

    #[test]
    fn status_line_partial_builder_only_right() {
        let sl = StatusLine::new().with_right("R");
        assert!(sl.left.is_empty());
        assert!(sl.center.is_empty());
        assert_eq!(sl.right, "R");
    }

    #[test]
    fn status_line_debug() {
        let sl = StatusLine::new().with_center("mid");
        let debug = format!("{sl:?}");
        assert!(debug.contains("StatusLine"));
    }

    #[test]
    fn status_line_clone() {
        let sl = StatusLine::new().with_left("L").with_center("C");
        #[allow(clippy::redundant_clone)]
        let cloned = sl.clone();
        assert_eq!(cloned.left, "L");
        assert_eq!(cloned.center, "C");
    }

    #[test]
    fn shell_config_debug() {
        let config = ShellConfig::default();
        let debug = format!("{config:?}");
        assert!(debug.contains("ShellConfig"));
        assert!(debug.contains("frankensearch"));
    }

    #[test]
    fn shell_config_clone() {
        let config = ShellConfig::default();
        #[allow(clippy::redundant_clone)]
        let cloned = config.clone();
        assert_eq!(cloned.title, "frankensearch");
        assert!(cloned.show_status_bar);
    }

    #[test]
    fn navigate_to_nonexistent_screen_is_noop() {
        let mut shell = AppShell::new(ShellConfig::default());
        let bad_id = ScreenId::new("nonexistent");
        shell.navigate_to(&bad_id);
        assert!(shell.active_screen.is_none());
    }

    #[test]
    fn navigate_to_valid_screen() {
        let mut shell = AppShell::new(ShellConfig::default());
        let id_a = ScreenId::new("a");
        shell
            .registry
            .register(Box::new(StubScreen::new("a", "Screen A")));
        shell.navigate_to(&id_a);
        assert_eq!(shell.active_screen.as_ref(), Some(&id_a));
    }

    #[test]
    fn navigate_blurs_old_focuses_new() {
        let mut shell = AppShell::new(ShellConfig::default());
        let focused_a = Arc::new(Mutex::new(false));
        let focused_b = Arc::new(Mutex::new(false));
        let screen_a = StubScreen {
            id: ScreenId::new("a"),
            title: "A",
            focused: Arc::clone(&focused_a),
        };
        let screen_b = StubScreen {
            id: ScreenId::new("b"),
            title: "B",
            focused: Arc::clone(&focused_b),
        };
        shell.registry.register(Box::new(screen_a));
        shell.registry.register(Box::new(screen_b));

        let id_a = ScreenId::new("a");
        let id_b = ScreenId::new("b");

        shell.navigate_to(&id_a);
        assert!(*focused_a.lock().unwrap());

        shell.navigate_to(&id_b);
        assert!(!*focused_a.lock().unwrap(), "old screen should be blurred");
        assert!(*focused_b.lock().unwrap(), "new screen should be focused");
    }

    #[test]
    fn next_screen_with_no_active_is_noop() {
        let mut shell = AppShell::new(ShellConfig::default());
        shell.registry.register(Box::new(StubScreen::new("a", "A")));
        shell.next_screen();
        assert!(shell.active_screen.is_none());
    }

    #[test]
    fn prev_screen_with_no_active_is_noop() {
        let mut shell = AppShell::new(ShellConfig::default());
        shell.registry.register(Box::new(StubScreen::new("a", "A")));
        shell.prev_screen();
        assert!(shell.active_screen.is_none());
    }

    #[test]
    fn screen_context_with_no_active_uses_empty_id() {
        let shell = AppShell::new(ShellConfig::default());
        let ctx = shell.screen_context(Rect::new(0, 0, 100, 50));
        assert_eq!(ctx.active_screen, ScreenId::new(""));
        assert_eq!(ctx.terminal_width, 100);
        assert_eq!(ctx.terminal_height, 50);
        assert!(ctx.focused);
    }

    #[test]
    fn screen_context_with_active_screen() {
        let mut shell = AppShell::new(ShellConfig::default());
        shell
            .registry
            .register(Box::new(StubScreen::new("s1", "S1")));
        shell.navigate_to(&ScreenId::new("s1"));
        let ctx = shell.screen_context(Rect::new(0, 0, 80, 24));
        assert_eq!(ctx.active_screen, ScreenId::new("s1"));
    }

    #[test]
    fn last_palette_action_initially_none() {
        let shell = AppShell::new(ShellConfig::default());
        assert!(shell.last_palette_action().is_none());
    }

    #[test]
    fn palette_backspace_removes_char() {
        let mut shell = AppShell::new(ShellConfig::default());
        // Open palette
        let open = InputEvent::Key(
            ftui_core::event::KeyCode::Char('p'),
            ftui_core::event::Modifiers::CTRL,
        );
        let _ = shell.handle_input(&open);

        // Type "ab"
        let a = InputEvent::Key(
            ftui_core::event::KeyCode::Char('a'),
            ftui_core::event::Modifiers::NONE,
        );
        let b = InputEvent::Key(
            ftui_core::event::KeyCode::Char('b'),
            ftui_core::event::Modifiers::NONE,
        );
        let _ = shell.handle_input(&a);
        let _ = shell.handle_input(&b);
        assert_eq!(shell.palette.query(), "ab");

        // Backspace
        let bs = InputEvent::Key(
            ftui_core::event::KeyCode::Backspace,
            ftui_core::event::Modifiers::NONE,
        );
        let _ = shell.handle_input(&bs);
        assert_eq!(shell.palette.query(), "a");
    }

    #[test]
    fn palette_esc_closes() {
        let mut shell = AppShell::new(ShellConfig::default());
        let open = InputEvent::Key(
            ftui_core::event::KeyCode::Char('p'),
            ftui_core::event::Modifiers::CTRL,
        );
        let _ = shell.handle_input(&open);
        assert_eq!(shell.palette.state(), &PaletteState::Open);

        let esc = InputEvent::Key(
            ftui_core::event::KeyCode::Escape,
            ftui_core::event::Modifiers::NONE,
        );
        let _ = shell.handle_input(&esc);
        assert_eq!(shell.palette.state(), &PaletteState::Closed);
    }

    #[test]
    fn palette_enter_closes_and_clears() {
        let mut shell = AppShell::new(ShellConfig::default());
        let open = InputEvent::Key(
            ftui_core::event::KeyCode::Char('p'),
            ftui_core::event::Modifiers::CTRL,
        );
        let _ = shell.handle_input(&open);
        assert_eq!(shell.palette.state(), &PaletteState::Open);

        let enter = InputEvent::Key(
            ftui_core::event::KeyCode::Enter,
            ftui_core::event::Modifiers::NONE,
        );
        let quit = shell.handle_input(&enter);
        assert!(!quit);
        assert_eq!(shell.palette.state(), &PaletteState::Closed);
    }

    #[test]
    fn overlay_esc_dismisses() {
        let mut shell = AppShell::new(ShellConfig::default());
        shell.last_render_area.set(Rect::new(0, 0, 80, 24));

        // Open help overlay with '?'
        let help = InputEvent::Key(
            ftui_core::event::KeyCode::Char('?'),
            ftui_core::event::Modifiers::NONE,
        );
        let _ = shell.handle_input(&help);
        assert!(shell.overlays.has_active());

        // Dismiss with Esc
        let esc = InputEvent::Key(
            ftui_core::event::KeyCode::Escape,
            ftui_core::event::Modifiers::NONE,
        );
        let _ = shell.handle_input(&esc);
        assert!(!shell.overlays.has_active());
    }

    #[test]
    fn help_opens_with_question_mark() {
        let mut shell = AppShell::new(ShellConfig::default());
        shell.last_render_area.set(Rect::new(0, 0, 80, 24));

        let help = InputEvent::Key(
            ftui_core::event::KeyCode::Char('?'),
            ftui_core::event::Modifiers::NONE,
        );

        let _ = shell.handle_input(&help);
        assert!(shell.overlays.has_active());

        // When overlay is active, non-Dismiss keys are swallowed
        let _ = shell.handle_input(&help);
        assert!(
            shell.overlays.has_active(),
            "overlay stays open on repeat ?"
        );
    }

    #[test]
    fn tab_key_triggers_next_screen() {
        let mut shell = AppShell::new(ShellConfig::default());
        shell.last_render_area.set(Rect::new(0, 0, 80, 24));
        shell.registry.register(Box::new(StubScreen::new("a", "A")));
        shell.registry.register(Box::new(StubScreen::new("b", "B")));
        shell.navigate_to(&ScreenId::new("a"));

        let tab = InputEvent::Key(
            ftui_core::event::KeyCode::Tab,
            ftui_core::event::Modifiers::NONE,
        );
        let _ = shell.handle_input(&tab);
        assert_eq!(shell.active_screen.as_ref(), Some(&ScreenId::new("b")));
    }

    #[test]
    fn shift_tab_triggers_prev_screen() {
        let mut shell = AppShell::new(ShellConfig::default());
        shell.last_render_area.set(Rect::new(0, 0, 80, 24));
        shell.registry.register(Box::new(StubScreen::new("a", "A")));
        shell.registry.register(Box::new(StubScreen::new("b", "B")));
        shell.navigate_to(&ScreenId::new("b"));

        let shift_tab = InputEvent::Key(
            ftui_core::event::KeyCode::BackTab,
            ftui_core::event::Modifiers::SHIFT,
        );
        let _ = shell.handle_input(&shift_tab);
        assert_eq!(shell.active_screen.as_ref(), Some(&ScreenId::new("a")));
    }

    #[test]
    fn overlay_active_blocks_screen_input() {
        let mut shell = AppShell::new(ShellConfig::default());
        shell.last_render_area.set(Rect::new(0, 0, 80, 24));
        let captured = Arc::new(Mutex::new(None));
        shell
            .registry
            .register(Box::new(CaptureContextScreen::new("cap", captured.clone())));
        shell.navigate_to(&ScreenId::new("cap"));

        // Open overlay
        let help = InputEvent::Key(
            ftui_core::event::KeyCode::Char('?'),
            ftui_core::event::Modifiers::NONE,
        );
        let _ = shell.handle_input(&help);
        assert!(shell.overlays.has_active());

        // Send a key that would normally reach the screen
        let x = InputEvent::Key(
            ftui_core::event::KeyCode::Char('x'),
            ftui_core::event::Modifiers::NONE,
        );
        let _ = shell.handle_input(&x);
        // Screen should NOT have received the event
        assert!(captured.lock().unwrap().is_none());
    }

    #[test]
    fn palette_ctrl_char_not_inserted() {
        let mut shell = AppShell::new(ShellConfig::default());
        let open = InputEvent::Key(
            ftui_core::event::KeyCode::Char('p'),
            ftui_core::event::Modifiers::CTRL,
        );
        let _ = shell.handle_input(&open);

        // Ctrl+A should NOT be inserted as text
        let ctrl_a = InputEvent::Key(
            ftui_core::event::KeyCode::Char('a'),
            ftui_core::event::Modifiers::CTRL,
        );
        let _ = shell.handle_input(&ctrl_a);
        assert_eq!(shell.palette.query(), "");
    }

    #[test]
    fn palette_alt_char_not_inserted() {
        let mut shell = AppShell::new(ShellConfig::default());
        let open = InputEvent::Key(
            ftui_core::event::KeyCode::Char('p'),
            ftui_core::event::Modifiers::CTRL,
        );
        let _ = shell.handle_input(&open);

        let alt_x = InputEvent::Key(
            ftui_core::event::KeyCode::Char('x'),
            ftui_core::event::Modifiers::ALT,
        );
        let _ = shell.handle_input(&alt_x);
        assert_eq!(shell.palette.query(), "");
    }

    #[test]
    fn handle_input_does_not_quit_on_non_quit_key() {
        let mut shell = AppShell::new(ShellConfig::default());
        shell.last_render_area.set(Rect::new(0, 0, 80, 24));
        let event = InputEvent::Key(
            ftui_core::event::KeyCode::Char('a'),
            ftui_core::event::Modifiers::NONE,
        );
        let quit = shell.handle_input(&event);
        assert!(!quit);
        assert!(!shell.should_quit);
    }

    // ─── bd-n6x8 tests end ───
}