Comicviewer/src/viewer.rs

use std::cell::{Cell, RefCell};
use std::collections::{HashMap, HashSet, VecDeque};
use std::rc::{Rc, Weak};
use std::sync::mpsc::{self, TryRecvError};
use std::thread;
use std::time::{Duration, Instant};

use gtk::gdk;
use gtk::glib;
use gtk::prelude::*;

use crate::archive::{ArchivePage, DecodedPage, decode_image_file, decode_page, list_pages};
use crate::browser::EntryKind;
use crate::database::Database;
use crate::zip_cache::ArchiveSource;

const CACHE_LIMIT_BYTES: usize = 256 * 1024 * 1024;
const CACHE_LIMIT_PAGES: usize = 16;
const FAST_CACHE_LIMIT_BYTES: usize = 1024 * 1024 * 1024;
const FAST_CACHE_LIMIT_PAGES: usize = 64;
const VIDEO_SEEK_STEP_US: i64 = 5_000_000;
const VIDEO_VOLUME_STEP: f64 = 0.05;
const IMAGE_ZOOM_STEP: f64 = 0.1;
const IMAGE_ZOOM_MIN: f64 = 0.1;
const IMAGE_ZOOM_MAX: f64 = 4.0;
const VIEWER_CONTROLLER_KEY: &str = "comicviewer-viewer-controller";
const MEDIA_VIEWER_CONTROLLER_KEY: &str = "comicviewer-media-viewer-controller";

fn clear_viewer_controller(window: &gtk::ApplicationWindow) {
    unsafe {
        if let Some(controller) = window.steal_data::<Rc<ViewerController>>(VIEWER_CONTROLLER_KEY) {
            controller.detach_window_controllers();
        }
        if let Some(controller) =
            window.steal_data::<Rc<MediaViewerController>>(MEDIA_VIEWER_CONTROLLER_KEY)
        {
            controller.prepare_for_navigation();
        }
    }
}

fn ensure_viewer_close_handler(window: &gtk::ApplicationWindow) {
    if window.has_css_class("viewer-close-handler") {
        return;
    }
    window.add_css_class("viewer-close-handler");
    window.connect_close_request(|window| {
        clear_viewer_controller(window);
        glib::Propagation::Proceed
    });
}

pub(crate) fn set_viewer_loading(window: &gtk::ApplicationWindow, loading: bool) {
    if !window.has_css_class("viewer-loading-key-handler") {
        window.add_css_class("viewer-loading-key-handler");
        let keys = gtk::EventControllerKey::new();
        keys.set_propagation_phase(gtk::PropagationPhase::Capture);
        let weak_window = window.downgrade();
        keys.connect_key_pressed(move |_, key, _, _| {
            let Some(window) = weak_window.upgrade() else {
                return glib::Propagation::Proceed;
            };
            if !window.has_css_class("viewer-loading") || !window.is_fullscreen() {
                return glib::Propagation::Proceed;
            }
            if key == gdk::Key::Escape
                || key
                    .to_unicode()
                    .is_some_and(|character| character.eq_ignore_ascii_case(&'f'))
            {
                window.unfullscreen();
                if let Some(titlebar) = window.titlebar() {
                    titlebar.set_visible(true);
                }
                return glib::Propagation::Stop;
            }
            glib::Propagation::Proceed
        });
        window.add_controller(keys);
    }
    if loading {
        window.add_css_class("viewer-loading");
    } else {
        window.remove_css_class("viewer-loading");
    }
}

pub(crate) fn set_viewer_header(
    window: &gtk::ApplicationWindow,
    header: &gtk::HeaderBar,
) -> gtk::Box {
    let host = window
        .titlebar()
        .and_downcast::<gtk::Box>()
        .unwrap_or_else(|| {
            let host = gtk::Box::new(gtk::Orientation::Horizontal, 0);
            host.set_hexpand(true);
            window.set_titlebar(Some(&host));
            host
        });
    while let Some(child) = host.first_child() {
        host.remove(&child);
    }
    header.set_hexpand(true);
    host.append(header);
    host.set_visible(!window.is_fullscreen());
    host
}

pub struct ViewerWindow;

pub struct SiblingNavigator {
    position: Rc<dyn Fn() -> Option<(usize, usize)>>,
    navigate: Rc<dyn Fn(SiblingTarget, gtk::ApplicationWindow) -> bool>,
    files: Rc<dyn Fn() -> Vec<SiblingFile>>,
    actions: Rc<SiblingActionResolver>,
}

type SiblingActionResolver = dyn Fn(&str) -> Option<SiblingFileActions>;

#[derive(Clone)]
pub struct SiblingFile {
    pub uri: String,
    pub name: String,
    pub kind: EntryKind,
}

#[derive(Clone)]
pub struct SiblingFileActions {
    pub favorite: FavoriteControl,
    pub download: FileDownloadControl,
}

impl SiblingNavigator {
    pub fn new(
        position: Rc<dyn Fn() -> Option<(usize, usize)>>,
        navigate: Rc<dyn Fn(SiblingTarget, gtk::ApplicationWindow) -> bool>,
        files: Rc<dyn Fn() -> Vec<SiblingFile>>,
        actions: Rc<SiblingActionResolver>,
    ) -> Self {
        Self {
            position,
            navigate,
            files,
            actions,
        }
    }

    fn open_relative(&self, forward: bool, window: gtk::ApplicationWindow) -> bool {
        (self.navigate)(SiblingTarget::Relative(forward), window)
    }

    fn open_index(&self, index: usize, window: gtk::ApplicationWindow) -> bool {
        (self.navigate)(SiblingTarget::Index(index), window)
    }

    fn open_edge(&self, end: bool, window: gtk::ApplicationWindow) -> bool {
        (self.navigate)(
            if end {
                SiblingTarget::Last
            } else {
                SiblingTarget::First
            },
            window,
        )
    }

    fn position(&self) -> Option<(usize, usize)> {
        (self.position)()
    }

    fn files(&self) -> Vec<SiblingFile> {
        (self.files)()
    }

    fn open_uri(&self, uri: &str, window: gtk::ApplicationWindow) -> bool {
        let files = self.files();
        let Some(index) = files.iter().position(|file| file.uri == uri) else {
            return false;
        };
        self.open_index(index, window)
    }

    fn actions(&self, uri: &str) -> Option<SiblingFileActions> {
        (self.actions)(uri)
    }
}

#[derive(Clone, Copy)]
pub enum SiblingTarget {
    Relative(bool),
    Index(usize),
    First,
    Last,
}

impl SiblingTarget {
    pub fn resolve(self, current: usize, count: usize) -> Option<usize> {
        match self {
            Self::Relative(forward) => sibling_index(current, count, forward),
            Self::Index(index) => (index < count && index != current).then_some(index),
            Self::First => (count > 0 && current > 0).then_some(0),
            Self::Last => count.checked_sub(1).filter(|last| current < *last),
        }
    }
}

#[derive(Clone)]
pub struct FavoriteControl {
    pub active: bool,
    pub toggle: Rc<dyn Fn() -> bool>,
}

#[derive(Clone)]
pub struct FileDownloadControl {
    pub download: Rc<dyn Fn(gtk::Window, gtk::Label)>,
}

pub struct ViewModeControl {
    pub selected: u32,
    pub change: Rc<dyn Fn(u32)>,
}

pub struct FileViewerControls {
    pub sibling_navigator: Option<SiblingNavigator>,
    pub favorite_control: FavoriteControl,
    pub download_control: FileDownloadControl,
    pub file_drop_control: FileDropControl,
    pub reuse_window: Option<gtk::ApplicationWindow>,
    pub view_mode_control: Option<ViewModeControl>,
}

#[derive(Clone)]
pub struct FileDropControl {
    pub handle: Rc<dyn Fn(Vec<gtk::gio::File>, gtk::Window)>,
}

pub(crate) fn install_file_drop_target(window: &gtk::ApplicationWindow, control: FileDropControl) {
    if window.has_css_class("comicviewer-file-drop-target") {
        return;
    }
    window.add_css_class("comicviewer-file-drop-target");
    let target = gtk::DropTarget::new(gdk::FileList::static_type(), gdk::DragAction::COPY);
    let weak_window = window.downgrade();
    target.connect_drop(move |_, value, _, _| {
        let Ok(file_list) = value.get::<gdk::FileList>() else {
            return false;
        };
        let Some(window) = weak_window.upgrade() else {
            return false;
        };
        (control.handle)(file_list.files(), window.upcast());
        true
    });
    window.add_controller(target);
}

impl ViewerWindow {
    pub fn open(
        application: &gtk::Application,
        source: ArchiveSource,
        database: Rc<Database>,
        fast_image_loading: bool,
        case_insensitive_sort: bool,
        view_mode_control: ViewModeControl,
        controls: FileViewerControls,
    ) {
        let FileViewerControls {
            sibling_navigator,
            favorite_control,
            download_control,
            file_drop_control,
            reuse_window,
            view_mode_control: _,
        } = controls;
        let title = source.display_name.clone();
        if let Some(window) = reuse_window.as_ref() {
            clear_viewer_controller(window);
        }
        let window = reuse_window.unwrap_or_else(|| {
            gtk::ApplicationWindow::builder()
                .application(application)
                .title(&title)
                .default_width(1100)
                .default_height(850)
                .build()
        });
        install_file_drop_target(&window, file_drop_control);
        ensure_viewer_close_handler(&window);
        set_viewer_loading(&window, false);
        window.set_title(Some(&title));
        let header = gtk::HeaderBar::new();
        header.set_title_widget(Some(&gtk::Label::new(Some(&title))));
        let favorite_button = gtk::Button::with_label(favorite_label(favorite_control.active));
        let download_button = gtk::Button::with_label("파일 다운로드");
        let file_list_button = gtk::ToggleButton::with_label("파일 목록");
        file_list_button.set_sensitive(sibling_navigator.is_some());
        file_list_button.set_active(window.has_css_class("viewer-file-list-visible"));
        header.pack_end(&download_button);
        header.pack_end(&favorite_button);
        header.pack_end(&file_list_button);
        let titlebar_host = set_viewer_header(&window, &header);

        let root = gtk::Box::new(gtk::Orientation::Vertical, 0);
        let toolbar = gtk::Box::new(gtk::Orientation::Horizontal, 6);
        toolbar.set_margin_top(8);
        toolbar.set_margin_bottom(8);
        toolbar.set_margin_start(8);
        toolbar.set_margin_end(8);
        let previous_button = gtk::Button::builder()
            .icon_name("go-previous-symbolic")
            .tooltip_text("이전")
            .build();
        let next_button = gtk::Button::builder()
            .icon_name("go-next-symbolic")
            .tooltip_text("다음")
            .build();
        let shift_back_button = gtk::Button::with_label("한 장 이전");
        let shift_forward_button = gtk::Button::with_label("한 장 다음");
        let page_label = gtk::Label::new(Some("- / -"));
        page_label.set_hexpand(true);
        let direction_dropdown = gtk::DropDown::from_strings(&["좌→우", "우→좌"]);
        direction_dropdown.set_selected(1);
        let mode_dropdown = gtk::DropDown::from_strings(&[
            "100%",
            "폭 맞춤",
            "높이 맞춤",
            "2페이지",
            "이어서 보기",
        ]);
        mode_dropdown.set_selected(view_mode_control.selected);
        toolbar.append(&previous_button);
        toolbar.append(&shift_back_button);
        toolbar.append(&shift_forward_button);
        toolbar.append(&next_button);
        toolbar.append(&page_label);
        toolbar.append(&direction_dropdown);
        toolbar.append(&mode_dropdown);

        let single_picture = page_picture();
        let single_box = gtk::Box::new(gtk::Orientation::Horizontal, 0);
        single_box.append(&single_picture);
        let single_scrolled = gtk::ScrolledWindow::builder()
            .hexpand(true)
            .vexpand(true)
            .child(&single_box)
            .build();
        let left_picture = page_picture();
        let right_picture = page_picture();
        let spread_box = gtk::Box::new(gtk::Orientation::Horizontal, 8);
        spread_box.set_homogeneous(true);
        spread_box.append(&left_picture);
        spread_box.append(&right_picture);
        let spread_scrolled = gtk::ScrolledWindow::builder()
            .hexpand(true)
            .vexpand(true)
            .child(&spread_box)
            .build();

        let continuous_box = gtk::Box::new(gtk::Orientation::Vertical, 8);
        continuous_box.set_halign(gtk::Align::Fill);
        let continuous_scrolled = gtk::ScrolledWindow::builder()
            .hexpand(true)
            .vexpand(true)
            .child(&continuous_box)
            .build();
        let stack = gtk::Stack::new();
        stack.set_hexpand(true);
        stack.set_vexpand(true);
        stack.add_named(&single_scrolled, Some("single"));
        stack.add_named(&spread_scrolled, Some("spread"));
        stack.add_named(&continuous_scrolled, Some("continuous"));

        let spinner = gtk::Spinner::new();
        spinner.set_halign(gtk::Align::Center);
        spinner.set_valign(gtk::Align::Center);
        let overlay = gtk::Overlay::new();
        overlay.set_child(Some(&stack));
        overlay.add_overlay(&spinner);
        let status_label = gtk::Label::builder()
            .label("ZIP 파일을 읽는 중...")
            .xalign(0.0)
            .margin_top(6)
            .margin_bottom(6)
            .margin_start(8)
            .margin_end(8)
            .build();
        let page_seek = navigation_scale();
        let page_seek_row = navigation_scale_row(&page_seek);
        page_seek.set_sensitive(false);
        root.append(&toolbar);
        root.append(&overlay);
        root.append(&page_seek_row);
        root.append(&status_label);
        let window_overlay = gtk::Overlay::new();
        window_overlay.set_child(Some(&root));
        let (navigation_message, navigation_message_label) = navigation_message();
        window_overlay.add_overlay(&navigation_message);
        window_overlay.set_hexpand(true);
        window_overlay.set_vexpand(true);
        let file_list = viewer_file_list();
        file_list.panel.set_visible(file_list_button.is_active());
        let viewer_layout = gtk::Box::new(gtk::Orientation::Horizontal, 0);
        viewer_layout.append(&window_overlay);
        viewer_layout.append(&file_list.panel);
        window.set_child(Some(&viewer_layout));

        let controller = Rc::new(ViewerController {
            window,
            titlebar_host,
            source,
            database,
            stack,
            single_scrolled,
            single_box,
            single_picture,
            left_picture,
            right_picture,
            spread_box,
            spread_scrolled,
            continuous_box,
            continuous_scrolled,
            spinner,
            page_label,
            page_seek,
            page_seek_row,
            toolbar,
            status_label,
            previous_button,
            next_button,
            shift_back_button,
            shift_forward_button,
            mode_dropdown,
            direction_dropdown,
            fast_image_loading,
            case_insensitive_sort,
            sibling_navigator,
            file_list_button,
            file_list_panel: file_list.panel,
            file_list: file_list.list,
            file_list_files: RefCell::new(Vec::new()),
            favorite_button,
            favorite_toggle: favorite_control.toggle,
            download_button,
            file_download: download_control.download,
            view_mode_change: view_mode_control.change,
            seek_hide_timer: RefCell::new(None),
            last_pointer_position: Cell::new(None),
            key_controller: RefCell::new(None),
            motion_controller: RefCell::new(None),
            fullscreen_key_controller: RefCell::new(None),
            fullscreen_click_controller: RefCell::new(None),
            fullscreen_ui_hide_timer: RefCell::new(None),
            fullscreen_ui_visible: Cell::new(false),
            fullscreen_notify_handler: RefCell::new(None),
            image_zoom: Cell::new(1.0),
            navigation_message,
            navigation_message_label,
            navigation_message_generation: Rc::new(Cell::new(0)),
            continuous_programmatic_scroll: Cell::new(false),
            view_layout_generation: Cell::new(0),
            single_animation_generation: Rc::new(AnimationState::default()),
            left_animation_generation: Rc::new(AnimationState::default()),
            right_animation_generation: Rc::new(AnimationState::default()),
            state: RefCell::new(ViewerState {
                pages: Vec::new(),
                anchor: 0,
                cache: HashMap::new(),
                requested: HashSet::new(),
                pending: VecDeque::new(),
                in_flight: 0,
                failed: HashMap::new(),
                access_clock: 0,
                continuous_rows: Vec::new(),
                continuous_bound: HashSet::new(),
            }),
        });
        controller.connect_signals();
        controller.fullscreen_changed();
        if controller.file_list_button.is_active() {
            controller.refresh_file_list();
        }
        unsafe {
            controller
                .window
                .set_data(VIEWER_CONTROLLER_KEY, Rc::clone(&controller));
        }
        controller.apply_view_mode();
        controller.window.present();
        controller.load_archive();
    }
}

#[derive(Clone, Copy, PartialEq, Eq)]
enum ViewMode {
    ActualSize,
    FitWidth,
    FitHeight,
    TwoPage,
    Continuous,
}

#[derive(Clone)]
struct CachedFrame {
    texture: gdk::MemoryTexture,
    delay: Duration,
}

struct CachedAnimation {
    frames: Vec<CachedFrame>,
    loop_count: Option<u32>,
}

impl std::ops::Deref for CachedAnimation {
    type Target = [CachedFrame];

    fn deref(&self) -> &Self::Target {
        &self.frames
    }
}

struct CachedPage {
    frames: Rc<CachedAnimation>,
    cost: usize,
    last_used: u64,
}

#[derive(Default)]
struct AnimationState {
    generation: Cell<u64>,
    timer: RefCell<Option<glib::SourceId>>,
    frames: RefCell<Option<Weak<CachedAnimation>>>,
}

impl AnimationState {
    fn cancel(&self) -> u64 {
        if let Some(timer) = self.timer.borrow_mut().take() {
            timer.remove();
        }
        self.frames.borrow_mut().take();
        let generation = self.generation.get().wrapping_add(1);
        self.generation.set(generation);
        generation
    }
}

struct ContinuousRow {
    frame: gtk::AspectFrame,
    picture: gtk::Picture,
    ratio: f32,
    animation_generation: Rc<AnimationState>,
}

struct ViewerState {
    pages: Vec<ArchivePage>,
    anchor: usize,
    cache: HashMap<usize, CachedPage>,
    requested: HashSet<usize>,
    pending: VecDeque<usize>,
    in_flight: usize,
    failed: HashMap<usize, String>,
    access_clock: u64,
    continuous_rows: Vec<ContinuousRow>,
    continuous_bound: HashSet<usize>,
}

struct ViewerController {
    window: gtk::ApplicationWindow,
    titlebar_host: gtk::Box,
    source: ArchiveSource,
    database: Rc<Database>,
    stack: gtk::Stack,
    single_scrolled: gtk::ScrolledWindow,
    single_box: gtk::Box,
    single_picture: gtk::Picture,
    left_picture: gtk::Picture,
    right_picture: gtk::Picture,
    spread_box: gtk::Box,
    spread_scrolled: gtk::ScrolledWindow,
    continuous_box: gtk::Box,
    continuous_scrolled: gtk::ScrolledWindow,
    spinner: gtk::Spinner,
    page_label: gtk::Label,
    page_seek: gtk::Scale,
    page_seek_row: gtk::Box,
    toolbar: gtk::Box,
    status_label: gtk::Label,
    previous_button: gtk::Button,
    next_button: gtk::Button,
    shift_back_button: gtk::Button,
    shift_forward_button: gtk::Button,
    mode_dropdown: gtk::DropDown,
    direction_dropdown: gtk::DropDown,
    fast_image_loading: bool,
    case_insensitive_sort: bool,
    sibling_navigator: Option<SiblingNavigator>,
    file_list_button: gtk::ToggleButton,
    file_list_panel: gtk::ScrolledWindow,
    file_list: gtk::ListBox,
    file_list_files: RefCell<Vec<SiblingFile>>,
    favorite_button: gtk::Button,
    favorite_toggle: Rc<dyn Fn() -> bool>,
    download_button: gtk::Button,
    file_download: Rc<dyn Fn(gtk::Window, gtk::Label)>,
    view_mode_change: Rc<dyn Fn(u32)>,
    seek_hide_timer: RefCell<Option<glib::SourceId>>,
    last_pointer_position: Cell<Option<(f64, f64)>>,
    key_controller: RefCell<Option<gtk::EventControllerKey>>,
    motion_controller: RefCell<Option<gtk::EventControllerMotion>>,
    fullscreen_key_controller: RefCell<Option<gtk::EventControllerKey>>,
    fullscreen_click_controller: RefCell<Option<gtk::GestureClick>>,
    fullscreen_ui_hide_timer: RefCell<Option<glib::SourceId>>,
    fullscreen_ui_visible: Cell<bool>,
    fullscreen_notify_handler: RefCell<Option<glib::SignalHandlerId>>,
    image_zoom: Cell<f64>,
    navigation_message: gtk::Box,
    navigation_message_label: gtk::Label,
    navigation_message_generation: Rc<Cell<u64>>,
    continuous_programmatic_scroll: Cell<bool>,
    view_layout_generation: Cell<u64>,
    single_animation_generation: Rc<AnimationState>,
    left_animation_generation: Rc<AnimationState>,
    right_animation_generation: Rc<AnimationState>,
    state: RefCell<ViewerState>,
}

impl ViewerController {
    fn connect_signals(self: &Rc<Self>) {
        let controller = Rc::downgrade(self);
        self.previous_button.connect_clicked(move |_| {
            if let Some(controller) = controller.upgrade() {
                controller.navigate(false);
            }
        });
        let controller = Rc::downgrade(self);
        self.next_button.connect_clicked(move |_| {
            if let Some(controller) = controller.upgrade() {
                controller.navigate(true);
            }
        });
        let controller = Rc::downgrade(self);
        self.shift_back_button.connect_clicked(move |_| {
            if let Some(controller) = controller.upgrade() {
                controller.shift_pairing(-1);
            }
        });
        let controller = Rc::downgrade(self);
        self.shift_forward_button.connect_clicked(move |_| {
            if let Some(controller) = controller.upgrade() {
                controller.shift_pairing(1);
            }
        });
        let controller = Rc::downgrade(self);
        self.mode_dropdown.connect_selected_notify(move |dropdown| {
            if let Some(controller) = controller.upgrade() {
                (controller.view_mode_change)(dropdown.selected());
                controller.image_zoom.set(1.0);
                controller.apply_view_mode();
            }
        });
        let controller = Rc::downgrade(self);
        self.direction_dropdown.connect_selected_notify(move |_| {
            if let Some(controller) = controller.upgrade() {
                controller.render();
            }
        });
        let controller = Rc::downgrade(self);
        self.favorite_button.connect_clicked(move |_| {
            if let Some(controller) = controller.upgrade() {
                let active = (controller.favorite_toggle)();
                controller.favorite_button.set_label(favorite_label(active));
            }
        });
        let controller = Rc::downgrade(self);
        self.download_button.connect_clicked(move |_| {
            if let Some(controller) = controller.upgrade() {
                (controller.file_download)(
                    controller.window.clone().upcast(),
                    controller.status_label.clone(),
                );
            }
        });
        let controller = Rc::downgrade(self);
        self.file_list_button.connect_toggled(move |button| {
            if let Some(controller) = controller.upgrade() {
                controller.file_list_panel.set_visible(
                    button.is_active()
                        && (!controller.window.is_fullscreen()
                            || controller.fullscreen_ui_visible.get()),
                );
                if button.is_active() {
                    controller.window.add_css_class("viewer-file-list-visible");
                } else {
                    controller
                        .window
                        .remove_css_class("viewer-file-list-visible");
                }
                if button.is_active() {
                    controller.refresh_file_list();
                }
            }
        });
        let controller = Rc::downgrade(self);
        self.file_list.connect_row_activated(move |_, row| {
            if let Some(controller) = controller.upgrade() {
                controller.open_file_list_row(row.index());
            }
        });
        let file_list_typeahead = Rc::new(RefCell::new(TypeaheadBuffer::default()));
        let file_list_keys = gtk::EventControllerKey::new();
        let controller = Rc::downgrade(self);
        file_list_keys.connect_key_pressed(move |_, key, _, modifiers| {
            let Some(controller) = controller.upgrade() else {
                return glib::Propagation::Proceed;
            };
            file_list_typeahead_select(
                &controller.file_list,
                &controller.file_list_files.borrow(),
                &mut file_list_typeahead.borrow_mut(),
                key,
                modifiers,
            )
        });
        self.file_list.add_controller(file_list_keys);
        let file_list_click = gtk::GestureClick::builder().button(3).build();
        let controller = Rc::downgrade(self);
        file_list_click.connect_pressed(move |_, _, x, y| {
            if let Some(controller) = controller.upgrade() {
                controller.show_file_list_context_menu(x, y);
            }
        });
        self.file_list.add_controller(file_list_click);
        let controller = Rc::downgrade(self);
        self.page_seek.connect_value_changed(move |scale| {
            let Some(controller) = controller.upgrade() else {
                return;
            };
            let page_count = controller.state.borrow().pages.len();
            if let Some(index) = page_seek_index(scale.value(), page_count) {
                controller.seek_page(index);
            }
        });

        let adjustment = self.continuous_scrolled.vadjustment();
        let controller = Rc::downgrade(self);
        adjustment.connect_value_changed(move |_| {
            if let Some(controller) = controller.upgrade() {
                controller.continuous_scrolled();
            }
        });
        let controller = Rc::downgrade(self);
        adjustment.connect_changed(move |_| {
            if let Some(controller) = controller.upgrade() {
                controller.continuous_scrolled();
            }
        });
        let controller = Rc::downgrade(self);
        self.continuous_scrolled
            .connect_notify_local(Some("width"), move |_, _| {
                if let Some(controller) = controller.upgrade() {
                    controller.resize_continuous_rows();
                }
            });
        let controller = Rc::downgrade(self);
        self.single_scrolled
            .connect_notify_local(Some("width"), move |_, _| {
                if let Some(controller) = controller.upgrade() {
                    controller.resize_single_picture();
                }
            });
        let controller = Rc::downgrade(self);
        self.single_scrolled
            .connect_notify_local(Some("height"), move |_, _| {
                if let Some(controller) = controller.upgrade() {
                    controller.resize_single_picture();
                }
            });
        let controller = Rc::downgrade(self);
        self.single_picture
            .connect_notify_local(Some("width"), move |_, _| {
                if let Some(controller) = controller.upgrade() {
                    controller.resize_single_picture();
                }
            });
        let controller = Rc::downgrade(self);
        self.spread_scrolled
            .connect_notify_local(Some("width"), move |_, _| {
                if let Some(controller) = controller.upgrade() {
                    controller.resize_spread_pictures();
                }
            });
        let controller = Rc::downgrade(self);
        self.spread_scrolled
            .connect_notify_local(Some("height"), move |_, _| {
                if let Some(controller) = controller.upgrade() {
                    controller.resize_spread_pictures();
                }
            });

        let scroll_controller = gtk::EventControllerScroll::new(
            gtk::EventControllerScrollFlags::VERTICAL | gtk::EventControllerScrollFlags::DISCRETE,
        );
        scroll_controller.set_propagation_phase(gtk::PropagationPhase::Capture);
        let controller = Rc::downgrade(self);
        scroll_controller.connect_scroll(move |scroll, _, delta_y| {
            let Some(controller) = controller.upgrade() else {
                return glib::Propagation::Proceed;
            };
            if scroll
                .current_event_state()
                .contains(gdk::ModifierType::CONTROL_MASK)
                && delta_y != 0.0
            {
                controller.adjust_image_zoom(delta_y < 0.0);
                return glib::Propagation::Stop;
            }
            if matches!(
                controller.view_mode(),
                ViewMode::ActualSize | ViewMode::FitWidth | ViewMode::Continuous
            ) || delta_y == 0.0
            {
                return glib::Propagation::Proceed;
            }
            controller.navigate(delta_y > 0.0);
            glib::Propagation::Stop
        });
        self.stack.add_controller(scroll_controller);

        let fullscreen_click = gtk::GestureClick::builder()
            .button(0)
            .propagation_phase(gtk::PropagationPhase::Capture)
            .build();
        let controller = Rc::downgrade(self);
        fullscreen_click.connect_pressed(move |_, _, _, _| {
            if let Some(controller) = controller.upgrade() {
                controller.controls_clicked();
            }
        });
        self.window.add_controller(fullscreen_click.clone());
        self.fullscreen_click_controller
            .replace(Some(fullscreen_click));

        let motion_controller = gtk::EventControllerMotion::new();
        motion_controller.set_propagation_phase(gtk::PropagationPhase::Capture);
        let controller = Rc::downgrade(self);
        motion_controller.connect_motion(move |_, x, y| {
            if let Some(controller) = controller.upgrade() {
                controller.pointer_moved(x, y);
            }
        });
        self.window.add_controller(motion_controller.clone());
        self.motion_controller.replace(Some(motion_controller));

        let fullscreen_keys = gtk::EventControllerKey::new();
        fullscreen_keys.set_propagation_phase(gtk::PropagationPhase::Capture);
        let controller = Rc::downgrade(self);
        fullscreen_keys.connect_key_pressed(move |_, key, _, _| {
            if let Some(controller) = controller.upgrade()
                && controller.window.is_fullscreen()
                && fullscreen_direction_key(key)
            {
                controller.hide_fullscreen_ui_now();
            }
            glib::Propagation::Proceed
        });
        self.window.add_controller(fullscreen_keys.clone());
        self.fullscreen_key_controller
            .replace(Some(fullscreen_keys));

        let key_controller = gtk::EventControllerKey::new();
        let controller = Rc::downgrade(self);
        key_controller.connect_key_pressed(move |_, key, _, modifiers| {
            let Some(controller) = controller.upgrade() else {
                return glib::Propagation::Proceed;
            };
            if !controller.window.is_fullscreen() {
                controller.hide_seek();
            }
            match key {
                gdk::Key::Home => {
                    controller.seek_edge(false);
                    glib::Propagation::Stop
                }
                gdk::Key::End => {
                    controller.seek_edge(true);
                    glib::Propagation::Stop
                }
                gdk::Key::Up | gdk::Key::KP_Up
                    if matches!(
                        controller.view_mode(),
                        ViewMode::ActualSize | ViewMode::FitWidth | ViewMode::Continuous
                    ) =>
                {
                    controller.scroll_vertically(false);
                    glib::Propagation::Stop
                }
                gdk::Key::Down | gdk::Key::KP_Down
                    if matches!(
                        controller.view_mode(),
                        ViewMode::ActualSize | ViewMode::FitWidth | ViewMode::Continuous
                    ) =>
                {
                    controller.scroll_vertically(true);
                    glib::Propagation::Stop
                }
                gdk::Key::Left | gdk::Key::KP_Left | gdk::Key::Page_Up => {
                    controller.navigate(false);
                    glib::Propagation::Stop
                }
                gdk::Key::Right | gdk::Key::KP_Right | gdk::Key::Page_Down | gdk::Key::space => {
                    controller.navigate(true);
                    glib::Propagation::Stop
                }
                _ if key.to_unicode() == Some('[') => {
                    controller.open_sibling(false);
                    glib::Propagation::Stop
                }
                _ if key.to_unicode() == Some(']') => {
                    controller.open_sibling(true);
                    glib::Propagation::Stop
                }
                gdk::Key::plus | gdk::Key::KP_Add => {
                    controller.adjust_image_zoom(true);
                    glib::Propagation::Stop
                }
                gdk::Key::minus | gdk::Key::KP_Subtract => {
                    controller.adjust_image_zoom(false);
                    glib::Propagation::Stop
                }
                _ if !shortcut_modifiers_blocked(modifiers)
                    && key
                        .to_unicode()
                        .is_some_and(|character| character.eq_ignore_ascii_case(&'l')) =>
                {
                    controller.toggle_file_list();
                    glib::Propagation::Stop
                }
                _ if key
                    .to_unicode()
                    .is_some_and(|character| character.eq_ignore_ascii_case(&'f')) =>
                {
                    controller.toggle_fullscreen();
                    glib::Propagation::Stop
                }
                gdk::Key::Escape if controller.window.is_fullscreen() => {
                    controller.window.unfullscreen();
                    glib::Propagation::Stop
                }
                _ => glib::Propagation::Proceed,
            }
        });
        self.window.add_controller(key_controller.clone());
        self.key_controller.replace(Some(key_controller));
        let controller = Rc::downgrade(self);
        let handler = self
            .window
            .connect_notify_local(Some("fullscreened"), move |_, _| {
                if let Some(controller) = controller.upgrade() {
                    controller.fullscreen_changed();
                }
            });
        self.fullscreen_notify_handler.replace(Some(handler));
    }

    fn open_sibling(&self, forward: bool) {
        if let Some(navigate) = &self.sibling_navigator
            && navigate.open_relative(forward, self.window.clone())
        {
            self.detach_window_controllers();
        } else {
            self.show_navigation_error(forward);
        }
    }

    fn toggle_file_list(&self) {
        if !self.file_list_button.is_sensitive() {
            return;
        }
        let active = !self.file_list_button.is_active();
        self.file_list_button.set_active(active);
        if self.window.is_fullscreen() {
            self.file_list_panel.set_visible(active);
        }
    }

    fn refresh_file_list(&self) {
        while let Some(child) = self.file_list.first_child() {
            self.file_list.remove(&child);
        }
        let files = self
            .sibling_navigator
            .as_ref()
            .map(SiblingNavigator::files)
            .unwrap_or_default();
        let current = files
            .iter()
            .position(|file| file.uri == self.source.source_uri);
        for file in &files {
            self.file_list.append(&viewer_file_row(file));
        }
        *self.file_list_files.borrow_mut() = files;
        if let Some(row) = current.and_then(|index| self.file_list.row_at_index(index as i32)) {
            self.file_list.select_row(Some(&row));
        }
    }

    fn open_file_list_row(&self, index: i32) {
        let Some(uri) = self
            .file_list_files
            .borrow()
            .get(index as usize)
            .map(|file| file.uri.clone())
        else {
            return;
        };
        if uri == self.source.source_uri {
            return;
        }
        if let Some(navigator) = &self.sibling_navigator
            && navigator.open_uri(&uri, self.window.clone())
        {
            self.detach_window_controllers();
        }
    }

    fn show_file_list_context_menu(&self, x: f64, y: f64) {
        let Some((row, file)) = selected_viewer_file(&self.file_list, &self.file_list_files, x, y)
        else {
            return;
        };
        self.file_list.select_row(Some(&row));
        let Some(actions) = self
            .sibling_navigator
            .as_ref()
            .and_then(|navigator| navigator.actions(&file.uri))
        else {
            return;
        };
        show_viewer_file_context_menu(
            &row,
            &file,
            actions,
            &self.source.source_uri,
            &self.favorite_button,
            &self.window,
            &self.status_label,
        );
    }

    fn show_navigation_error(&self, forward: bool) {
        self.navigation_message_label
            .set_text(navigation_error_message(forward));
        self.navigation_message.set_visible(true);
        let message = self.navigation_message.clone();
        let generation = self.navigation_message_generation.get().wrapping_add(1);
        self.navigation_message_generation.set(generation);
        let current_generation = Rc::clone(&self.navigation_message_generation);
        glib::timeout_add_local_once(Duration::from_secs(2), move || {
            if current_generation.get() == generation {
                message.set_visible(false);
            }
        });
    }

    fn detach_window_controllers(&self) {
        self.stop_animations();
        if let Some(timer) = self.seek_hide_timer.borrow_mut().take() {
            timer.remove();
        }
        self.cancel_fullscreen_ui_timer();
        if let Some(handler) = self.fullscreen_notify_handler.borrow_mut().take() {
            self.window.disconnect(handler);
        }
        if let Some(controller) = self.key_controller.borrow_mut().take() {
            self.window.remove_controller(&controller);
        }
        if let Some(controller) = self.motion_controller.borrow_mut().take() {
            self.window.remove_controller(&controller);
        }
        if let Some(controller) = self.fullscreen_key_controller.borrow_mut().take() {
            self.window.remove_controller(&controller);
        }
        if let Some(controller) = self.fullscreen_click_controller.borrow_mut().take() {
            self.window.remove_controller(&controller);
        }
    }

    fn stop_animations(&self) {
        self.single_animation_generation.cancel();
        self.left_animation_generation.cancel();
        self.right_animation_generation.cancel();
        for row in &self.state.borrow().continuous_rows {
            row.animation_generation.cancel();
        }
    }

    fn show_seek_temporarily(self: &Rc<Self>) {
        if let Some(timer) = self.seek_hide_timer.borrow_mut().take() {
            timer.remove();
        }
        self.set_seek_visible(true);
        let controller = Rc::downgrade(self);
        let timer = glib::timeout_add_local_once(Duration::from_secs(5), move || {
            if let Some(controller) = controller.upgrade() {
                controller.seek_hide_timer.borrow_mut().take();
                controller.set_seek_visible(false);
            }
        });
        self.seek_hide_timer.replace(Some(timer));
    }

    fn pointer_moved(self: &Rc<Self>, x: f64, y: f64) {
        if self.last_pointer_position.get() == Some((x, y)) {
            return;
        }
        self.last_pointer_position.set(Some((x, y)));
    }

    fn controls_clicked(self: &Rc<Self>) {
        if self.window.is_fullscreen() {
            self.show_fullscreen_ui_temporarily();
        } else {
            self.show_seek_temporarily();
        }
    }

    fn hide_seek(self: &Rc<Self>) {
        if let Some(timer) = self.seek_hide_timer.borrow_mut().take() {
            timer.remove();
        }
        self.set_seek_visible(false);
    }

    fn set_seek_visible(self: &Rc<Self>, visible: bool) {
        if self.page_seek_row.is_visible() == visible {
            return;
        }
        self.page_seek_row.set_visible(visible);
        self.window.queue_allocate();
        let controller = Rc::downgrade(self);
        glib::idle_add_local_once(move || {
            if let Some(controller) = controller.upgrade() {
                controller.stack.queue_allocate();
                controller.resize_continuous_rows();
                controller.render();
            }
        });
    }

    fn toggle_fullscreen(&self) {
        if self.window.is_fullscreen() {
            self.window.unfullscreen();
        } else {
            self.window.fullscreen();
        }
    }

    fn fullscreen_changed(self: &Rc<Self>) {
        self.cancel_fullscreen_ui_timer();
        self.hide_seek();
        if self.window.is_fullscreen() {
            self.set_fullscreen_ui_visible(false);
        } else {
            self.fullscreen_ui_visible.set(true);
            self.titlebar_host.set_visible(true);
            self.toolbar.set_visible(true);
            self.status_label.set_visible(true);
            self.file_list_panel
                .set_visible(self.file_list_button.is_active());
        }
    }

    fn show_fullscreen_ui_temporarily(self: &Rc<Self>) {
        if !self.window.is_fullscreen() {
            return;
        }
        self.cancel_fullscreen_ui_timer();
        self.set_fullscreen_ui_visible(true);
        let controller = Rc::downgrade(self);
        let timer = glib::timeout_add_local_once(Duration::from_secs(5), move || {
            if let Some(controller) = controller.upgrade() {
                controller.fullscreen_ui_hide_timer.borrow_mut().take();
                controller.set_fullscreen_ui_visible(false);
            }
        });
        self.fullscreen_ui_hide_timer.replace(Some(timer));
    }

    fn hide_fullscreen_ui_now(self: &Rc<Self>) {
        if self.window.is_fullscreen() {
            self.cancel_fullscreen_ui_timer();
            self.set_fullscreen_ui_visible(false);
        }
    }

    fn cancel_fullscreen_ui_timer(&self) {
        if let Some(timer) = self.fullscreen_ui_hide_timer.borrow_mut().take() {
            timer.remove();
        }
    }

    fn set_fullscreen_ui_visible(self: &Rc<Self>, visible: bool) {
        self.fullscreen_ui_visible.set(visible);
        self.titlebar_host.set_visible(visible);
        self.toolbar.set_visible(visible);
        self.page_seek_row.set_visible(visible);
        self.status_label.set_visible(visible);
        self.file_list_panel
            .set_visible(visible && self.file_list_button.is_active());
        self.window.queue_allocate();
        let controller = Rc::downgrade(self);
        glib::idle_add_local_once(move || {
            if let Some(controller) = controller.upgrade() {
                controller.stack.queue_allocate();
                controller.resize_continuous_rows();
                controller.render();
            }
        });
    }

    fn load_archive(self: &Rc<Self>) {
        self.spinner.start();
        let path = self.source.local_path.clone();
        let case_insensitive_sort = self.case_insensitive_sort;
        let (sender, receiver) = mpsc::channel();
        thread::spawn(move || {
            let _ = sender.send(
                list_pages(&path, case_insensitive_sort).map_err(|error| format!("{error:#}")),
            );
        });
        let controller = Rc::downgrade(self);
        glib::timeout_add_local(Duration::from_millis(20), move || {
            match receiver.try_recv() {
                Ok(result) => {
                    if let Some(controller) = controller.upgrade() {
                        controller.finish_archive_load(result);
                    }
                    glib::ControlFlow::Break
                }
                Err(TryRecvError::Empty) => glib::ControlFlow::Continue,
                Err(TryRecvError::Disconnected) => glib::ControlFlow::Break,
            }
        });
    }

    fn finish_archive_load(self: &Rc<Self>, result: Result<Vec<ArchivePage>, String>) {
        match result {
            Ok(pages) if pages.is_empty() => {
                self.spinner.stop();
                self.status_label
                    .set_text("지원하는 이미지가 ZIP 파일에 없습니다.");
            }
            Ok(pages) => {
                let page_count = pages.len();
                let saved = self
                    .database
                    .load_progress(&self.source.source_uri)
                    .ok()
                    .flatten()
                    .unwrap_or(0)
                    .min(pages.len() - 1);
                let mut state = self.state.borrow_mut();
                state.pages = pages;
                state.anchor = saved;
                drop(state);
                self.page_seek
                    .set_range(0.0, navigation_scale_upper(page_count));
                self.page_seek.set_sensitive(page_count > 1);
                self.build_continuous_rows();
                self.render();
            }
            Err(error) => {
                self.spinner.stop();
                self.status_label.set_text(&error);
            }
        }
    }

    fn build_continuous_rows(self: &Rc<Self>) {
        while let Some(child) = self.continuous_box.first_child() {
            self.continuous_box.remove(&child);
        }
        let count = self.state.borrow().pages.len();
        let mut rows = Vec::with_capacity(count);
        let default_ratio = 2.0 / 3.0;
        let width = self.continuous_content_width();
        for _ in 0..count {
            let picture = gtk::Picture::new();
            picture.set_content_fit(gtk::ContentFit::Contain);
            picture.set_hexpand(true);
            picture.set_vexpand(false);
            picture.set_can_shrink(true);
            picture.set_size_request(1, 1);
            let frame = gtk::AspectFrame::new(0.5, 0.5, default_ratio, false);
            frame.set_hexpand(true);
            frame.set_size_request(-1, row_height(width, default_ratio));
            frame.set_child(Some(&picture));
            self.continuous_box.append(&frame);
            rows.push(ContinuousRow {
                frame,
                picture,
                ratio: default_ratio,
                animation_generation: Rc::new(AnimationState::default()),
            });
        }
        let mut state = self.state.borrow_mut();
        state.continuous_rows = rows;
        state.continuous_bound.clear();
    }

    fn view_mode(&self) -> ViewMode {
        match self.mode_dropdown.selected() {
            0 => ViewMode::ActualSize,
            2 => ViewMode::FitHeight,
            3 => ViewMode::TwoPage,
            4 => ViewMode::Continuous,
            _ => ViewMode::FitWidth,
        }
    }

    fn apply_view_mode(self: &Rc<Self>) {
        let mode = self.view_mode();
        self.shift_back_button
            .set_visible(mode == ViewMode::TwoPage);
        self.shift_forward_button
            .set_visible(mode == ViewMode::TwoPage);
        self.direction_dropdown
            .set_visible(mode == ViewMode::TwoPage);
        match mode {
            ViewMode::TwoPage => self.stack.set_visible_child_name("spread"),
            ViewMode::Continuous => self.stack.set_visible_child_name("continuous"),
            _ => self.stack.set_visible_child_name("single"),
        }
        match mode {
            ViewMode::Continuous => {
                set_picture_animation(
                    &self.single_picture,
                    None,
                    &self.single_animation_generation,
                );
                set_picture_animation(&self.left_picture, None, &self.left_animation_generation);
                set_picture_animation(&self.right_picture, None, &self.right_animation_generation);
            }
            ViewMode::TwoPage => {
                set_picture_animation(
                    &self.single_picture,
                    None,
                    &self.single_animation_generation,
                );
                self.clear_continuous_paintables();
            }
            _ => {
                set_picture_animation(&self.left_picture, None, &self.left_animation_generation);
                set_picture_animation(&self.right_picture, None, &self.right_animation_generation);
                self.clear_continuous_paintables();
            }
        }
        let actual = mode == ViewMode::ActualSize;
        self.single_box.set_hexpand(!actual);
        self.single_box.set_vexpand(mode == ViewMode::FitHeight);
        self.single_box.set_halign(match mode {
            ViewMode::ActualSize => gtk::Align::Start,
            ViewMode::FitHeight => gtk::Align::Center,
            _ => gtk::Align::Fill,
        });
        self.single_box.set_valign(if actual {
            gtk::Align::Start
        } else {
            gtk::Align::Fill
        });
        self.single_picture.set_can_shrink(!actual);
        self.single_picture.set_hexpand(mode == ViewMode::FitWidth);
        self.single_picture.set_vexpand(mode == ViewMode::FitHeight);
        if matches!(mode, ViewMode::ActualSize | ViewMode::FitWidth) {
            self.single_picture.set_content_fit(gtk::ContentFit::Fill);
            self.single_picture.set_valign(gtk::Align::Start);
            self.single_picture
                .set_halign(if mode == ViewMode::FitWidth {
                    gtk::Align::Fill
                } else {
                    gtk::Align::Start
                });
        } else {
            self.single_picture
                .set_content_fit(gtk::ContentFit::Contain);
            self.single_picture.set_valign(gtk::Align::Fill);
            self.single_picture
                .set_halign(if mode == ViewMode::FitHeight {
                    gtk::Align::Center
                } else {
                    gtk::Align::Fill
                });
            self.single_picture.set_size_request(-1, -1);
        }
        self.render();
        self.schedule_view_mode_refresh();
    }

    fn adjust_image_zoom(self: &Rc<Self>, zoom_in: bool) {
        let zoom = next_image_zoom(self.image_zoom.get(), zoom_in);
        if (zoom - self.image_zoom.get()).abs() < f64::EPSILON {
            return;
        }
        self.image_zoom.set(zoom);
        if (zoom - 1.0).abs() < f64::EPSILON {
            self.apply_view_mode();
            return;
        }
        match self.view_mode() {
            ViewMode::TwoPage => self.resize_spread_pictures(),
            ViewMode::Continuous => {
                self.resize_continuous_rows();
                self.continuous_scrolled();
            }
            _ => self.resize_single_picture(),
        }
        self.stack.queue_allocate();
    }

    fn schedule_view_mode_refresh(self: &Rc<Self>) {
        let generation = self.view_layout_generation.get().wrapping_add(1);
        self.view_layout_generation.set(generation);
        self.stack.queue_allocate();
        self.window.queue_allocate();
        let controller = Rc::downgrade(self);
        glib::idle_add_local_once(move || {
            let Some(controller) = controller.upgrade() else {
                return;
            };
            if controller.view_layout_generation.get() != generation {
                return;
            }
            match controller.view_mode() {
                ViewMode::FitWidth => controller.resize_single_picture(),
                ViewMode::Continuous => controller.resize_continuous_rows(),
                _ => {}
            }
            controller.render();
            if controller.view_mode() == ViewMode::Continuous {
                controller.schedule_scroll_to_anchor();
            }
        });
    }

    fn navigate(self: &Rc<Self>, forward: bool) {
        let step = if self.view_mode() == ViewMode::TwoPage {
            2
        } else {
            1
        };
        let mut state = self.state.borrow_mut();
        if state.pages.is_empty() {
            return;
        }
        let next = if forward {
            state.anchor.saturating_add(step).min(state.pages.len() - 1)
        } else {
            state.anchor.saturating_sub(step)
        };
        if next == state.anchor {
            return;
        }
        state.anchor = next;
        drop(state);
        self.reset_single_scroll();
        self.render();
        if self.view_mode() == ViewMode::Continuous {
            self.schedule_scroll_to_anchor();
        }
    }

    fn seek_edge(self: &Rc<Self>, end: bool) {
        let count = self.state.borrow().pages.len();
        if count == 0 {
            return;
        }
        self.seek_page(if end { count - 1 } else { 0 });
    }

    fn scroll_vertically(&self, down: bool) {
        let adjustment = if self.view_mode() == ViewMode::Continuous {
            self.continuous_scrolled.vadjustment()
        } else {
            self.single_scrolled.vadjustment()
        };
        let step = adjustment.step_increment().max(64.0);
        let delta = if down { step } else { -step };
        let maximum = (adjustment.upper() - adjustment.page_size()).max(adjustment.lower());
        adjustment.set_value((adjustment.value() + delta).clamp(adjustment.lower(), maximum));
    }

    fn shift_pairing(self: &Rc<Self>, offset: isize) {
        let mut state = self.state.borrow_mut();
        if state.pages.is_empty() {
            return;
        }
        state.anchor = state
            .anchor
            .saturating_add_signed(offset)
            .min(state.pages.len() - 1);
        drop(state);
        self.render();
    }

    fn seek_page(self: &Rc<Self>, index: usize) {
        let mut state = self.state.borrow_mut();
        if state.pages.is_empty() {
            return;
        }
        let index = index.min(state.pages.len() - 1);
        if index == state.anchor {
            return;
        }
        state.anchor = index;
        drop(state);
        self.reset_single_scroll();
        self.render();
        if self.view_mode() == ViewMode::Continuous {
            self.schedule_scroll_to_anchor();
        }
    }

    fn render(self: &Rc<Self>) {
        let visible = self.visible_indices();
        if visible.is_empty() {
            return;
        }
        match self.view_mode() {
            ViewMode::TwoPage => self.render_spread(&visible),
            ViewMode::Continuous => self.render_continuous(&visible),
            _ => self.render_single(visible[0]),
        }
        self.update_navigation();
        self.request_pages(self.prefetch_indices(&visible));
        let state = self.state.borrow();
        let _ =
            self.database
                .save_progress(&self.source.source_uri, state.anchor, state.pages.len());
    }

    fn visible_indices(&self) -> Vec<usize> {
        let state = self.state.borrow();
        if state.pages.is_empty() {
            return Vec::new();
        }
        if self.view_mode() == ViewMode::TwoPage {
            spread_indices(state.anchor, state.pages.len()).to_vec()
        } else if self.view_mode() == ViewMode::Continuous {
            drop(state);
            self.continuous_visible_indices()
        } else {
            vec![state.anchor]
        }
    }

    fn prefetch_indices(&self, visible: &[usize]) -> Vec<usize> {
        let count = self.state.borrow().pages.len();
        prefetch_window(visible, count, self.fast_image_loading)
    }

    fn request_pages(self: &Rc<Self>, indices: Vec<usize>) {
        let mut state = self.state.borrow_mut();
        let mut prioritized = VecDeque::new();
        for index in indices {
            if index >= state.pages.len()
                || state.cache.contains_key(&index)
                || state.failed.contains_key(&index)
            {
                continue;
            }
            if state.requested.contains(&index) {
                if state.pending.contains(&index) {
                    prioritized.push_back(index);
                }
            } else {
                state.requested.insert(index);
                prioritized.push_back(index);
            }
        }
        let prioritized_set: HashSet<_> = prioritized.iter().copied().collect();
        state
            .pending
            .retain(|index| !prioritized_set.contains(index));
        prioritized.append(&mut state.pending);
        state.pending = prioritized;
        drop(state);
        self.pump_requests();
        self.update_spinner();
    }

    fn pump_requests(self: &Rc<Self>) {
        let concurrency = if self.fast_image_loading { 4 } else { 2 };
        while let Some((index, page)) = {
            let mut state = self.state.borrow_mut();
            if state.in_flight >= concurrency {
                None
            } else {
                state.pending.pop_front().map(|index| {
                    state.in_flight += 1;
                    (index, state.pages[index].clone())
                })
            }
        } {
            let path = self.source.local_path.clone();
            let (sender, receiver) = mpsc::channel();
            thread::spawn(move || {
                let result = decode_page(&path, &page).map_err(|error| format!("{error:#}"));
                let _ = sender.send(result);
            });
            let controller = Rc::downgrade(self);
            glib::timeout_add_local(Duration::from_millis(20), move || {
                match receiver.try_recv() {
                    Ok(result) => {
                        if let Some(controller) = controller.upgrade() {
                            controller.finish_page_load(index, result);
                        }
                        glib::ControlFlow::Break
                    }
                    Err(TryRecvError::Empty) => glib::ControlFlow::Continue,
                    Err(TryRecvError::Disconnected) => glib::ControlFlow::Break,
                }
            });
        }
    }

    fn finish_page_load(self: &Rc<Self>, index: usize, result: Result<DecodedPage, String>) {
        let mut state = self.state.borrow_mut();
        state.requested.remove(&index);
        state.in_flight = state.in_flight.saturating_sub(1);
        let mut decoded_ratio = None;
        match result {
            Ok(page) => {
                let ratio = page.width as f32 / page.height as f32;
                decoded_ratio = Some(ratio);
                let (frames, cost) = texture_frames(page);
                state.access_clock = state.access_clock.wrapping_add(1);
                let last_used = state.access_clock;
                state.cache.insert(
                    index,
                    CachedPage {
                        frames,
                        cost,
                        last_used,
                    },
                );
            }
            Err(error) => {
                state.failed.insert(index, error);
            }
        }
        drop(state);
        if let Some(ratio) = decoded_ratio {
            let frame = {
                let mut state = self.state.borrow_mut();
                state.continuous_rows.get_mut(index).map(|row| {
                    row.ratio = ratio;
                    row.frame.clone()
                })
            };
            if let Some(frame) = frame {
                frame.set_ratio(ratio);
                self.resize_continuous_rows();
            }
        }
        self.evict_cache();
        if self.visible_indices().contains(&index) {
            self.render_loaded_pages();
        }
        self.update_spinner();
        self.pump_requests();
    }

    fn render_loaded_pages(&self) {
        let visible = self.visible_indices();
        match self.view_mode() {
            ViewMode::TwoPage => self.render_spread(&visible),
            ViewMode::Continuous => self.render_continuous(&visible),
            _ if !visible.is_empty() => self.render_single(visible[0]),
            _ => {}
        }
    }

    fn render_single(&self, index: usize) {
        let state = self.state.borrow();
        let frames = state.cache.get(&index).map(|page| Rc::clone(&page.frames));
        self.status_label.set_text(&state.pages[index].name);
        drop(state);
        set_picture_animation(
            &self.single_picture,
            frames,
            &self.single_animation_generation,
        );
        self.resize_single_picture();
    }

    fn resize_single_picture(&self) {
        let dimensions = {
            let state = self.state.borrow();
            state
                .cache
                .get(&state.anchor)
                .and_then(|page| page.frames.first())
                .map(|frame| (frame.texture.width(), frame.texture.height()))
        };
        if let Some((texture_width, texture_height)) = dimensions {
            let zoom = self.image_zoom.get();
            if (zoom - 1.0).abs() >= f64::EPSILON {
                let (width, height) = zoomed_picture_request(
                    self.view_mode(),
                    self.single_scrolled.allocated_width().max(1),
                    self.single_scrolled.allocated_height().max(1),
                    texture_width,
                    texture_height,
                    zoom,
                );
                self.single_box.set_hexpand(true);
                self.single_box.set_vexpand(true);
                self.single_box.set_halign(gtk::Align::Fill);
                self.single_box.set_valign(gtk::Align::Fill);
                self.single_picture.set_can_shrink(false);
                self.single_picture.set_hexpand(false);
                self.single_picture.set_vexpand(false);
                self.single_picture.set_content_fit(gtk::ContentFit::Fill);
                self.single_picture.set_halign(gtk::Align::Center);
                self.single_picture.set_valign(gtk::Align::Center);
                self.single_picture.set_size_request(width, height);
            } else if let Some((width, height)) = single_picture_request(
                self.view_mode(),
                self.stack.allocated_width().max(1),
                texture_width,
                texture_height,
            ) {
                self.single_picture.set_size_request(width, height);
            }
        }
    }

    fn resize_spread_pictures(&self) {
        let zoom = self.image_zoom.get();
        if (zoom - 1.0).abs() < f64::EPSILON {
            self.spread_box.set_homogeneous(true);
            self.spread_box.set_halign(gtk::Align::Fill);
            self.spread_box.set_valign(gtk::Align::Fill);
            for picture in [&self.left_picture, &self.right_picture] {
                picture.set_can_shrink(true);
                picture.set_hexpand(true);
                picture.set_vexpand(true);
                picture.set_content_fit(gtk::ContentFit::Contain);
                picture.set_size_request(-1, -1);
            }
            return;
        }
        let visible = self.visible_indices();
        let state = self.state.borrow();
        let page_dimensions = |position: usize| {
            visible.get(position).and_then(|index| {
                state
                    .cache
                    .get(index)
                    .and_then(|page| page.frames.first())
                    .map(|frame| (frame.texture.width(), frame.texture.height()))
            })
        };
        let first = page_dimensions(0);
        let second = page_dimensions(1);
        let dimensions = if self.direction_dropdown.selected() == 1 {
            [second, first]
        } else {
            [first, second]
        };
        drop(state);
        let count = visible.len().max(1) as i32;
        let viewport_width = (self.spread_scrolled.allocated_width().max(1) - 8) / count;
        let viewport_height = self.spread_scrolled.allocated_height().max(1);
        self.spread_box.set_homogeneous(false);
        self.spread_box.set_halign(gtk::Align::Center);
        self.spread_box.set_valign(gtk::Align::Center);
        for (picture, dimensions) in [&self.left_picture, &self.right_picture]
            .into_iter()
            .zip(dimensions)
        {
            let Some((texture_width, texture_height)) = dimensions else {
                picture.set_size_request(1, 1);
                continue;
            };
            let (width, height) = zoomed_picture_request(
                ViewMode::FitHeight,
                viewport_width,
                viewport_height,
                texture_width,
                texture_height,
                zoom,
            );
            picture.set_can_shrink(false);
            picture.set_hexpand(false);
            picture.set_vexpand(false);
            picture.set_content_fit(gtk::ContentFit::Fill);
            picture.set_size_request(width, height);
        }
    }

    fn reset_single_scroll(&self) {
        if matches!(self.view_mode(), ViewMode::ActualSize | ViewMode::FitWidth) {
            let adjustment = self.single_scrolled.vadjustment();
            adjustment.set_value(adjustment.lower());
        }
    }

    fn render_spread(&self, indices: &[usize]) {
        let state = self.state.borrow();
        let first = indices
            .first()
            .and_then(|index| state.cache.get(index))
            .map(|page| Rc::clone(&page.frames));
        let second = indices
            .get(1)
            .and_then(|index| state.cache.get(index))
            .map(|page| Rc::clone(&page.frames));
        let status = indices
            .iter()
            .map(|index| state.pages[*index].name.as_str())
            .collect::<Vec<_>>()
            .join(" · ");
        drop(state);
        if self.direction_dropdown.selected() == 1 {
            set_picture_animation(&self.left_picture, second, &self.left_animation_generation);
            set_picture_animation(&self.right_picture, first, &self.right_animation_generation);
        } else {
            set_picture_animation(&self.left_picture, first, &self.left_animation_generation);
            set_picture_animation(
                &self.right_picture,
                second,
                &self.right_animation_generation,
            );
        }
        self.status_label.set_text(&status);
        self.resize_spread_pictures();
    }

    fn render_continuous(&self, visible: &[usize]) {
        let new_bound: HashSet<_> = visible.iter().copied().collect();
        let mut state = self.state.borrow_mut();
        let old_bound = state.continuous_bound.clone();
        let mut updates = Vec::new();
        for index in old_bound.difference(&new_bound) {
            let row = &state.continuous_rows[*index];
            updates.push((
                row.picture.clone(),
                None,
                Rc::clone(&row.animation_generation),
            ));
        }
        for index in &new_bound {
            state.access_clock = state.access_clock.wrapping_add(1);
            let clock = state.access_clock;
            let frames = state.cache.get_mut(index).map(|page| {
                page.last_used = clock;
                Rc::clone(&page.frames)
            });
            let row = &state.continuous_rows[*index];
            if !old_bound.contains(index) || row.picture.paintable().is_none() {
                updates.push((
                    row.picture.clone(),
                    frames,
                    Rc::clone(&row.animation_generation),
                ));
            }
        }
        state.continuous_bound = new_bound;
        let status = visible
            .first()
            .map(|index| state.pages[*index].name.clone());
        drop(state);
        for (picture, frames, generation) in updates {
            set_picture_animation(&picture, frames, &generation);
        }
        if let Some(status) = status {
            self.status_label.set_text(&status);
        }
    }

    fn continuous_scrolled(self: &Rc<Self>) {
        let pages_empty = self.state.borrow().pages.is_empty();
        if self.view_mode() != ViewMode::Continuous || pages_empty {
            return;
        }
        let visible = self.visible_indices();
        let new_anchor = visible.first().copied();
        let update_anchor = !self.continuous_programmatic_scroll.get();
        let changed =
            update_anchor && new_anchor.is_some_and(|index| index != self.state.borrow().anchor);
        if let Some(index) = new_anchor.filter(|_| update_anchor) {
            self.state.borrow_mut().anchor = index;
        }
        self.render_continuous(&visible);
        self.request_pages(self.prefetch_indices(&visible));
        self.update_navigation();
        self.update_spinner();
        if changed {
            let state = self.state.borrow();
            let _ = self.database.save_progress(
                &self.source.source_uri,
                state.anchor,
                state.pages.len(),
            );
        }
    }

    fn continuous_visible_indices(&self) -> Vec<usize> {
        let state = self.state.borrow();
        if state.pages.is_empty() {
            return Vec::new();
        }
        let adjustment = self.continuous_scrolled.vadjustment();
        let top = adjustment.value();
        let bottom = top + adjustment.page_size();
        if adjustment.page_size() <= 0.0 {
            return vec![state.anchor];
        }
        let bounds: Vec<_> = state
            .continuous_rows
            .iter()
            .map(|row| {
                row.frame
                    .compute_bounds(&self.continuous_box)
                    .map(|bounds| {
                        let row_top = f64::from(bounds.y());
                        (row_top, row_top + f64::from(bounds.height()))
                    })
            })
            .collect();
        let mut visible = intersecting_rows(&bounds, top, bottom);
        if visible.is_empty() {
            visible.push(state.anchor);
        }
        visible
    }

    fn schedule_scroll_to_anchor(self: &Rc<Self>) {
        if self.view_mode() != ViewMode::Continuous || self.state.borrow().pages.is_empty() {
            return;
        }
        let controller = Rc::downgrade(self);
        glib::idle_add_local_once(move || {
            if let Some(controller) = controller.upgrade() {
                controller.scroll_to_anchor();
            }
        });
    }

    fn scroll_to_anchor(&self) {
        let frame = {
            let state = self.state.borrow();
            let Some(row) = state.continuous_rows.get(state.anchor) else {
                return;
            };
            row.frame.clone()
        };
        let Some(bounds) = frame.compute_bounds(&self.continuous_box) else {
            return;
        };
        let adjustment = self.continuous_scrolled.vadjustment();
        let maximum = (adjustment.upper() - adjustment.page_size()).max(adjustment.lower());
        let target = centered_scroll_value(
            f64::from(bounds.y()),
            f64::from(bounds.height()),
            adjustment.page_size(),
            adjustment.lower(),
            maximum,
        );
        self.continuous_programmatic_scroll.set(true);
        adjustment.set_value(target);
        self.continuous_programmatic_scroll.set(false);
    }

    fn clear_continuous_paintables(&self) {
        let mut state = self.state.borrow_mut();
        let indices: Vec<_> = state.continuous_bound.drain().collect();
        let pictures: Vec<_> = indices
            .into_iter()
            .map(|index| {
                let row = &state.continuous_rows[index];
                (row.picture.clone(), Rc::clone(&row.animation_generation))
            })
            .collect();
        drop(state);
        for (picture, generation) in pictures {
            set_picture_animation(&picture, None, &generation);
        }
    }

    fn resize_continuous_rows(&self) {
        let zoom = self.image_zoom.get();
        let width = scaled_dimension(self.continuous_content_width(), zoom);
        let zoomed = (zoom - 1.0).abs() >= f64::EPSILON;
        self.continuous_box.set_halign(if zoomed {
            gtk::Align::Center
        } else {
            gtk::Align::Fill
        });
        let rows: Vec<_> = self
            .state
            .borrow()
            .continuous_rows
            .iter()
            .map(|row| (row.frame.clone(), row.ratio))
            .collect();
        for (frame, ratio) in rows {
            frame.set_hexpand(!zoomed);
            frame.set_size_request(if zoomed { width } else { -1 }, row_height(width, ratio));
        }
    }

    fn continuous_content_width(&self) -> i32 {
        continuous_content_width(self.stack.allocated_width())
    }

    fn evict_cache(&self) {
        let protected: HashSet<_> = self.visible_indices().into_iter().collect();
        let (byte_limit, page_limit) = if self.fast_image_loading {
            (FAST_CACHE_LIMIT_BYTES, FAST_CACHE_LIMIT_PAGES)
        } else {
            (CACHE_LIMIT_BYTES, CACHE_LIMIT_PAGES)
        };
        let mut state = self.state.borrow_mut();
        loop {
            let bytes: usize = state.cache.values().map(|page| page.cost).sum();
            if bytes <= byte_limit && state.cache.len() <= page_limit {
                break;
            }
            let candidate = state
                .cache
                .iter()
                .filter(|(index, _)| !protected.contains(index))
                .min_by_key(|(_, page)| page.last_used)
                .map(|(index, _)| *index);
            let Some(candidate) = candidate else {
                break;
            };
            state.cache.remove(&candidate);
        }
    }

    fn update_spinner(&self) {
        let state = self.state.borrow();
        let waiting = self
            .visible_indices()
            .iter()
            .any(|index| !state.cache.contains_key(index) && !state.failed.contains_key(index));
        if waiting {
            self.spinner.start();
        } else {
            self.spinner.stop();
        }
    }

    fn update_navigation(&self) {
        let (count, anchor) = {
            let state = self.state.borrow();
            (state.pages.len(), state.anchor)
        };
        if count == 0 {
            self.page_label.set_text("- / -");
            return;
        }
        let visible = self.visible_indices();
        let end = visible.last().copied().unwrap_or(anchor) + 1;
        if visible.len() > 1 && self.view_mode() == ViewMode::TwoPage {
            self.page_label
                .set_text(&format!("{}-{end} / {count}", anchor + 1));
        } else {
            self.page_label
                .set_text(&format!("{} / {count}", anchor + 1));
        }
        self.previous_button.set_sensitive(anchor > 0);
        self.next_button.set_sensitive(end < count);
        self.shift_back_button.set_sensitive(anchor > 0);
        self.shift_forward_button.set_sensitive(anchor + 1 < count);
        if (self.page_seek.value() - anchor as f64).abs() >= f64::EPSILON {
            self.page_seek.set_value(anchor as f64);
        }
    }
}

pub struct MediaViewerWindow;

impl MediaViewerWindow {
    pub fn open(
        application: &gtk::Application,
        source: ArchiveSource,
        kind: EntryKind,
        controls: FileViewerControls,
    ) {
        let FileViewerControls {
            sibling_navigator,
            favorite_control,
            download_control,
            file_drop_control,
            reuse_window,
            view_mode_control,
        } = controls;
        let title = source.display_name.clone();
        if let Some(window) = reuse_window.as_ref() {
            clear_viewer_controller(window);
        }
        let window = reuse_window.unwrap_or_else(|| {
            gtk::ApplicationWindow::builder()
                .application(application)
                .title(&title)
                .default_width(1100)
                .default_height(850)
                .build()
        });
        install_file_drop_target(&window, file_drop_control);
        ensure_viewer_close_handler(&window);
        set_viewer_loading(&window, false);
        window.set_title(Some(&title));
        let header = gtk::HeaderBar::new();
        header.set_title_widget(Some(&gtk::Label::new(Some(&title))));
        let favorite_button = gtk::Button::with_label(favorite_label(favorite_control.active));
        let download_button = gtk::Button::with_label("파일 다운로드");
        let file_list_button = gtk::ToggleButton::with_label("파일 목록");
        file_list_button.set_sensitive(sibling_navigator.is_some());
        file_list_button.set_active(window.has_css_class("viewer-file-list-visible"));
        let loop_check = gtk::CheckButton::with_label("반복 재생");
        loop_check.set_visible(kind == EntryKind::Video);
        let image_mode_dropdown = gtk::DropDown::from_strings(&["100%", "폭 맞춤", "높이 맞춤"]);
        let (image_mode_selected, image_mode_change) =
            view_mode_control.map_or((1, None), |control| {
                (
                    standalone_mode_index(control.selected),
                    Some(control.change),
                )
            });
        image_mode_dropdown.set_selected(image_mode_selected);
        image_mode_dropdown.set_visible(kind == EntryKind::Image);
        header.pack_start(&image_mode_dropdown);
        header.pack_end(&loop_check);
        header.pack_end(&download_button);
        header.pack_end(&favorite_button);
        header.pack_end(&file_list_button);
        let titlebar_host = set_viewer_header(&window, &header);

        let root = gtk::Box::new(gtk::Orientation::Vertical, 0);
        let stack = gtk::Stack::new();
        stack.set_hexpand(true);
        stack.set_vexpand(true);
        let picture = page_picture();
        let image_box = gtk::Box::new(gtk::Orientation::Horizontal, 0);
        image_box.append(&picture);
        let image_scrolled = gtk::ScrolledWindow::builder()
            .hexpand(true)
            .vexpand(true)
            .child(&image_box)
            .build();
        stack.add_named(&image_scrolled, Some("image"));
        let video = if kind == EntryKind::Video {
            gtk::Video::for_filename(Some(&source.local_path))
        } else {
            gtk::Video::new()
        };
        video.set_autoplay(true);
        video.set_hexpand(true);
        video.set_vexpand(true);
        let video_for_loop = video.clone();
        loop_check.connect_toggled(move |check| video_for_loop.set_loop(check.is_active()));
        stack.add_named(&video, Some("video"));
        let status_label = gtk::Label::builder()
            .label(&title)
            .xalign(0.0)
            .margin_top(6)
            .margin_bottom(6)
            .margin_start(8)
            .margin_end(8)
            .build();
        let media_seek = navigation_scale();
        let media_seek_row = navigation_scale_row(&media_seek);
        if let Some((current, count)) = sibling_navigator
            .as_ref()
            .and_then(SiblingNavigator::position)
        {
            media_seek.set_range(0.0, navigation_scale_upper(count));
            media_seek.set_value(current as f64);
            media_seek.set_sensitive(count > 1);
        } else {
            media_seek.set_sensitive(false);
        }
        root.append(&stack);
        root.append(&media_seek_row);
        root.append(&status_label);
        let window_overlay = gtk::Overlay::new();
        window_overlay.set_child(Some(&root));
        let (navigation_message, navigation_message_label) = navigation_message();
        window_overlay.add_overlay(&navigation_message);
        window_overlay.set_hexpand(true);
        window_overlay.set_vexpand(true);
        let file_list = viewer_file_list();
        file_list.panel.set_visible(file_list_button.is_active());
        let viewer_layout = gtk::Box::new(gtk::Orientation::Horizontal, 0);
        viewer_layout.append(&window_overlay);
        viewer_layout.append(&file_list.panel);
        window.set_child(Some(&viewer_layout));

        let controller = Rc::new(MediaViewerController {
            window,
            titlebar_host,
            source,
            kind,
            picture,
            image_box,
            image_scrolled,
            image_mode_dropdown,
            image_mode_change,
            image_dimensions: Cell::new(None),
            image_zoom: Cell::new(1.0),
            image_animation_generation: Rc::new(AnimationState::default()),
            video,
            stack,
            status_label,
            media_seek,
            media_seek_row,
            sibling_navigator,
            file_list_button,
            file_list_panel: file_list.panel,
            file_list: file_list.list,
            file_list_files: RefCell::new(Vec::new()),
            favorite_button,
            favorite_toggle: favorite_control.toggle,
            download_button,
            file_download: download_control.download,
            seek_generation: Cell::new(0),
            seek_opening: Cell::new(false),
            seek_hide_timer: RefCell::new(None),
            last_pointer_position: Cell::new(None),
            key_controller: RefCell::new(None),
            motion_controller: RefCell::new(None),
            fullscreen_key_controller: RefCell::new(None),
            fullscreen_click_controller: RefCell::new(None),
            fullscreen_ui_hide_timer: RefCell::new(None),
            fullscreen_ui_visible: Cell::new(false),
            fullscreen_notify_handler: RefCell::new(None),
            navigation_message,
            navigation_message_label,
            navigation_message_generation: Rc::new(Cell::new(0)),
        });
        if let Some(stream) = controller.video.media_stream() {
            let status_label = controller.status_label.clone();
            stream.connect_error_notify(move |stream| {
                if let Some(error) = stream.error() {
                    status_label.set_text(&format!("동영상을 재생할 수 없습니다: {error}"));
                }
            });
        }
        controller.connect_signals();
        controller.fullscreen_changed();
        if controller.file_list_button.is_active() {
            controller.refresh_file_list();
        }
        unsafe {
            controller
                .window
                .set_data(MEDIA_VIEWER_CONTROLLER_KEY, Rc::clone(&controller));
        }
        controller.apply_image_view_mode();
        controller.window.present();
        match kind {
            EntryKind::Image => controller.load_image(),
            EntryKind::Video => {
                controller.stack.set_visible_child_name("video");
                if let Some(stream) = controller.video.media_stream() {
                    stream.play();
                }
            }
            _ => {}
        }
    }
}

struct MediaViewerController {
    window: gtk::ApplicationWindow,
    titlebar_host: gtk::Box,
    source: ArchiveSource,
    kind: EntryKind,
    picture: gtk::Picture,
    image_box: gtk::Box,
    image_scrolled: gtk::ScrolledWindow,
    image_mode_dropdown: gtk::DropDown,
    image_mode_change: Option<Rc<dyn Fn(u32)>>,
    image_dimensions: Cell<Option<(i32, i32)>>,
    image_zoom: Cell<f64>,
    image_animation_generation: Rc<AnimationState>,
    video: gtk::Video,
    stack: gtk::Stack,
    status_label: gtk::Label,
    media_seek: gtk::Scale,
    media_seek_row: gtk::Box,
    sibling_navigator: Option<SiblingNavigator>,
    file_list_button: gtk::ToggleButton,
    file_list_panel: gtk::ScrolledWindow,
    file_list: gtk::ListBox,
    file_list_files: RefCell<Vec<SiblingFile>>,
    favorite_button: gtk::Button,
    favorite_toggle: Rc<dyn Fn() -> bool>,
    download_button: gtk::Button,
    file_download: Rc<dyn Fn(gtk::Window, gtk::Label)>,
    seek_generation: Cell<u64>,
    seek_opening: Cell<bool>,
    seek_hide_timer: RefCell<Option<glib::SourceId>>,
    last_pointer_position: Cell<Option<(f64, f64)>>,
    key_controller: RefCell<Option<gtk::EventControllerKey>>,
    motion_controller: RefCell<Option<gtk::EventControllerMotion>>,
    fullscreen_key_controller: RefCell<Option<gtk::EventControllerKey>>,
    fullscreen_click_controller: RefCell<Option<gtk::GestureClick>>,
    fullscreen_ui_hide_timer: RefCell<Option<glib::SourceId>>,
    fullscreen_ui_visible: Cell<bool>,
    fullscreen_notify_handler: RefCell<Option<glib::SignalHandlerId>>,
    navigation_message: gtk::Box,
    navigation_message_label: gtk::Label,
    navigation_message_generation: Rc<Cell<u64>>,
}

impl MediaViewerController {
    fn connect_signals(self: &Rc<Self>) {
        let fullscreen_click = gtk::GestureClick::builder()
            .button(0)
            .propagation_phase(gtk::PropagationPhase::Capture)
            .build();
        let controller = Rc::downgrade(self);
        fullscreen_click.connect_pressed(move |_, _, _, _| {
            if let Some(controller) = controller.upgrade() {
                controller.controls_clicked();
            }
        });
        self.window.add_controller(fullscreen_click.clone());
        self.fullscreen_click_controller
            .replace(Some(fullscreen_click));

        let motion_controller = gtk::EventControllerMotion::new();
        motion_controller.set_propagation_phase(gtk::PropagationPhase::Capture);
        let controller = Rc::downgrade(self);
        motion_controller.connect_motion(move |_, x, y| {
            if let Some(controller) = controller.upgrade() {
                controller.pointer_moved(x, y);
            }
        });
        self.window.add_controller(motion_controller.clone());
        self.motion_controller.replace(Some(motion_controller));

        let fullscreen_keys = gtk::EventControllerKey::new();
        fullscreen_keys.set_propagation_phase(gtk::PropagationPhase::Capture);
        let controller = Rc::downgrade(self);
        fullscreen_keys.connect_key_pressed(move |_, key, _, _| {
            if let Some(controller) = controller.upgrade()
                && controller.window.is_fullscreen()
                && fullscreen_direction_key(key)
            {
                controller.hide_fullscreen_ui_now();
            }
            glib::Propagation::Proceed
        });
        self.window.add_controller(fullscreen_keys.clone());
        self.fullscreen_key_controller
            .replace(Some(fullscreen_keys));

        let keys = gtk::EventControllerKey::new();
        let controller = Rc::downgrade(self);
        keys.connect_key_pressed(move |_, key, _, modifiers| {
            let Some(controller) = controller.upgrade() else {
                return glib::Propagation::Proceed;
            };
            if modifiers.intersects(
                gdk::ModifierType::CONTROL_MASK
                    | gdk::ModifierType::ALT_MASK
                    | gdk::ModifierType::SUPER_MASK,
            ) {
                return glib::Propagation::Proceed;
            }
            if !controller.window.is_fullscreen() {
                controller.hide_seek();
            }
            match key {
                gdk::Key::Left | gdk::Key::KP_Left if controller.kind == EntryKind::Video => {
                    controller.seek_video(-VIDEO_SEEK_STEP_US);
                    glib::Propagation::Stop
                }
                gdk::Key::Right | gdk::Key::KP_Right if controller.kind == EntryKind::Video => {
                    controller.seek_video(VIDEO_SEEK_STEP_US);
                    glib::Propagation::Stop
                }
                gdk::Key::Up | gdk::Key::KP_Up if controller.kind == EntryKind::Video => {
                    controller.adjust_video_volume(VIDEO_VOLUME_STEP);
                    glib::Propagation::Stop
                }
                gdk::Key::Down | gdk::Key::KP_Down if controller.kind == EntryKind::Video => {
                    controller.adjust_video_volume(-VIDEO_VOLUME_STEP);
                    glib::Propagation::Stop
                }
                gdk::Key::Home => {
                    controller.open_edge(false);
                    glib::Propagation::Stop
                }
                gdk::Key::End => {
                    controller.open_edge(true);
                    glib::Propagation::Stop
                }
                gdk::Key::Up | gdk::Key::KP_Up
                    if controller.kind == EntryKind::Image
                        && matches!(
                            controller.image_view_mode(),
                            ViewMode::ActualSize | ViewMode::FitWidth
                        ) =>
                {
                    controller.scroll_image(false);
                    glib::Propagation::Stop
                }
                gdk::Key::Down | gdk::Key::KP_Down
                    if controller.kind == EntryKind::Image
                        && matches!(
                            controller.image_view_mode(),
                            ViewMode::ActualSize | ViewMode::FitWidth
                        ) =>
                {
                    controller.scroll_image(true);
                    glib::Propagation::Stop
                }
                _ if key.to_unicode() == Some('[') => {
                    controller.open_sibling(false);
                    glib::Propagation::Stop
                }
                _ if key.to_unicode() == Some(']') => {
                    controller.open_sibling(true);
                    glib::Propagation::Stop
                }
                gdk::Key::plus | gdk::Key::KP_Add if controller.kind == EntryKind::Image => {
                    controller.adjust_image_zoom(true);
                    glib::Propagation::Stop
                }
                gdk::Key::minus | gdk::Key::KP_Subtract if controller.kind == EntryKind::Image => {
                    controller.adjust_image_zoom(false);
                    glib::Propagation::Stop
                }
                _ if key
                    .to_unicode()
                    .is_some_and(|character| character.eq_ignore_ascii_case(&'l')) =>
                {
                    controller.toggle_file_list();
                    glib::Propagation::Stop
                }
                _ if key
                    .to_unicode()
                    .is_some_and(|character| character.eq_ignore_ascii_case(&'f')) =>
                {
                    controller.toggle_fullscreen();
                    glib::Propagation::Stop
                }
                gdk::Key::Escape if controller.window.is_fullscreen() => {
                    controller.window.unfullscreen();
                    glib::Propagation::Stop
                }
                _ => glib::Propagation::Proceed,
            }
        });
        self.window.add_controller(keys.clone());
        self.key_controller.replace(Some(keys));
        let controller = Rc::downgrade(self);
        let handler = self
            .window
            .connect_notify_local(Some("fullscreened"), move |_, _| {
                if let Some(controller) = controller.upgrade() {
                    controller.fullscreen_changed();
                }
            });
        self.fullscreen_notify_handler.replace(Some(handler));
        let controller = Rc::downgrade(self);
        self.favorite_button.connect_clicked(move |_| {
            if let Some(controller) = controller.upgrade() {
                let active = (controller.favorite_toggle)();
                controller.favorite_button.set_label(favorite_label(active));
            }
        });
        let controller = Rc::downgrade(self);
        self.download_button.connect_clicked(move |_| {
            if let Some(controller) = controller.upgrade() {
                (controller.file_download)(
                    controller.window.clone().upcast(),
                    controller.status_label.clone(),
                );
            }
        });
        let controller = Rc::downgrade(self);
        self.file_list_button.connect_toggled(move |button| {
            if let Some(controller) = controller.upgrade() {
                controller.file_list_panel.set_visible(
                    button.is_active()
                        && (!controller.window.is_fullscreen()
                            || controller.fullscreen_ui_visible.get()),
                );
                if button.is_active() {
                    controller.window.add_css_class("viewer-file-list-visible");
                } else {
                    controller
                        .window
                        .remove_css_class("viewer-file-list-visible");
                }
                if button.is_active() {
                    controller.refresh_file_list();
                }
            }
        });
        let controller = Rc::downgrade(self);
        self.file_list.connect_row_activated(move |_, row| {
            if let Some(controller) = controller.upgrade() {
                controller.open_file_list_row(row.index());
            }
        });
        let file_list_typeahead = Rc::new(RefCell::new(TypeaheadBuffer::default()));
        let file_list_keys = gtk::EventControllerKey::new();
        let controller = Rc::downgrade(self);
        file_list_keys.connect_key_pressed(move |_, key, _, modifiers| {
            let Some(controller) = controller.upgrade() else {
                return glib::Propagation::Proceed;
            };
            file_list_typeahead_select(
                &controller.file_list,
                &controller.file_list_files.borrow(),
                &mut file_list_typeahead.borrow_mut(),
                key,
                modifiers,
            )
        });
        self.file_list.add_controller(file_list_keys);
        let file_list_click = gtk::GestureClick::builder().button(3).build();
        let controller = Rc::downgrade(self);
        file_list_click.connect_pressed(move |_, _, x, y| {
            if let Some(controller) = controller.upgrade() {
                controller.show_file_list_context_menu(x, y);
            }
        });
        self.file_list.add_controller(file_list_click);
        if let Some(change) = self.image_mode_change.clone() {
            let controller = Rc::downgrade(self);
            self.image_mode_dropdown
                .connect_selected_notify(move |dropdown| {
                    if let Some(controller) = controller.upgrade() {
                        change(dropdown.selected());
                        controller.image_zoom.set(1.0);
                        controller.apply_image_view_mode();
                    }
                });
        }
        let controller = Rc::downgrade(self);
        self.image_scrolled
            .connect_notify_local(Some("width"), move |_, _| {
                if let Some(controller) = controller.upgrade() {
                    controller.resize_image_picture();
                }
            });
        let controller = Rc::downgrade(self);
        self.image_scrolled
            .connect_notify_local(Some("height"), move |_, _| {
                if let Some(controller) = controller.upgrade() {
                    controller.resize_image_picture();
                }
            });
        let image_scroll = gtk::EventControllerScroll::new(
            gtk::EventControllerScrollFlags::VERTICAL | gtk::EventControllerScrollFlags::DISCRETE,
        );
        image_scroll.set_propagation_phase(gtk::PropagationPhase::Capture);
        let controller = Rc::downgrade(self);
        image_scroll.connect_scroll(move |scroll, _, delta_y| {
            let Some(controller) = controller.upgrade() else {
                return glib::Propagation::Proceed;
            };
            if controller.kind == EntryKind::Image
                && scroll
                    .current_event_state()
                    .contains(gdk::ModifierType::CONTROL_MASK)
                && delta_y != 0.0
            {
                controller.adjust_image_zoom(delta_y < 0.0);
                glib::Propagation::Stop
            } else {
                glib::Propagation::Proceed
            }
        });
        self.image_scrolled.add_controller(image_scroll);
        let controller = Rc::downgrade(self);
        self.media_seek.connect_value_changed(move |scale| {
            let Some(controller) = controller.upgrade() else {
                return;
            };
            let Some(navigator) = &controller.sibling_navigator else {
                return;
            };
            let Some((_, count)) = navigator.position() else {
                return;
            };
            let Some(index) = page_seek_index(scale.value(), count) else {
                return;
            };
            controller.schedule_seek(index);
        });
    }

    fn refresh_file_list(&self) {
        while let Some(child) = self.file_list.first_child() {
            self.file_list.remove(&child);
        }
        let files = self
            .sibling_navigator
            .as_ref()
            .map(SiblingNavigator::files)
            .unwrap_or_default();
        let current = files
            .iter()
            .position(|file| file.uri == self.source.source_uri);
        for file in &files {
            self.file_list.append(&viewer_file_row(file));
        }
        *self.file_list_files.borrow_mut() = files;
        if let Some(row) = current.and_then(|index| self.file_list.row_at_index(index as i32)) {
            self.file_list.select_row(Some(&row));
        }
    }

    fn open_file_list_row(&self, index: i32) {
        let Some(uri) = self
            .file_list_files
            .borrow()
            .get(index as usize)
            .map(|file| file.uri.clone())
        else {
            return;
        };
        if uri == self.source.source_uri {
            return;
        }
        if let Some(navigator) = &self.sibling_navigator
            && navigator.open_uri(&uri, self.window.clone())
        {
            self.prepare_for_navigation();
        }
    }

    fn show_file_list_context_menu(&self, x: f64, y: f64) {
        let Some((row, file)) = selected_viewer_file(&self.file_list, &self.file_list_files, x, y)
        else {
            return;
        };
        self.file_list.select_row(Some(&row));
        let Some(actions) = self
            .sibling_navigator
            .as_ref()
            .and_then(|navigator| navigator.actions(&file.uri))
        else {
            return;
        };
        show_viewer_file_context_menu(
            &row,
            &file,
            actions,
            &self.source.source_uri,
            &self.favorite_button,
            &self.window,
            &self.status_label,
        );
    }

    fn image_view_mode(&self) -> ViewMode {
        match self.image_mode_dropdown.selected() {
            0 => ViewMode::ActualSize,
            2 => ViewMode::FitHeight,
            _ => ViewMode::FitWidth,
        }
    }

    fn toggle_file_list(&self) {
        if !self.file_list_button.is_sensitive() {
            return;
        }
        let active = !self.file_list_button.is_active();
        self.file_list_button.set_active(active);
        if self.window.is_fullscreen() {
            self.file_list_panel.set_visible(active);
        }
    }

    fn seek_video(&self, delta: i64) {
        let Some(stream) = self
            .video
            .media_stream()
            .filter(|stream| stream.is_seekable())
        else {
            return;
        };
        stream.seek(video_seek_target(
            stream.timestamp(),
            stream.duration(),
            delta,
        ));
    }

    fn adjust_video_volume(&self, delta: f64) {
        let Some(stream) = self.video.media_stream() else {
            return;
        };
        stream.set_volume(video_volume_target(stream.volume(), delta));
    }

    fn apply_image_view_mode(&self) {
        if self.kind != EntryKind::Image {
            return;
        }
        let mode = self.image_view_mode();
        let actual = mode == ViewMode::ActualSize;
        self.image_box.set_hexpand(!actual);
        self.image_box.set_vexpand(mode == ViewMode::FitHeight);
        self.image_box.set_halign(match mode {
            ViewMode::ActualSize => gtk::Align::Start,
            ViewMode::FitHeight => gtk::Align::Center,
            _ => gtk::Align::Fill,
        });
        self.image_box.set_valign(if actual {
            gtk::Align::Start
        } else {
            gtk::Align::Fill
        });
        self.picture.set_can_shrink(!actual);
        self.picture.set_hexpand(mode == ViewMode::FitWidth);
        self.picture.set_vexpand(mode == ViewMode::FitHeight);
        if matches!(mode, ViewMode::ActualSize | ViewMode::FitWidth) {
            self.picture.set_content_fit(gtk::ContentFit::Fill);
            self.picture.set_halign(if actual {
                gtk::Align::Start
            } else {
                gtk::Align::Fill
            });
            self.picture.set_valign(gtk::Align::Start);
        } else {
            self.picture.set_content_fit(gtk::ContentFit::Contain);
            self.picture.set_halign(if mode == ViewMode::FitHeight {
                gtk::Align::Center
            } else {
                gtk::Align::Fill
            });
            self.picture.set_valign(gtk::Align::Fill);
            self.picture.set_size_request(-1, -1);
        }
        self.resize_image_picture();
        self.stack.queue_allocate();
    }

    fn adjust_image_zoom(&self, zoom_in: bool) {
        if self.kind != EntryKind::Image {
            return;
        }
        let zoom = next_image_zoom(self.image_zoom.get(), zoom_in);
        if (zoom - self.image_zoom.get()).abs() < f64::EPSILON {
            return;
        }
        self.image_zoom.set(zoom);
        if (zoom - 1.0).abs() < f64::EPSILON {
            self.apply_image_view_mode();
        } else {
            self.resize_image_picture();
            self.stack.queue_allocate();
        }
    }

    fn resize_image_picture(&self) {
        let Some((texture_width, texture_height)) = self.image_dimensions.get() else {
            return;
        };
        let zoom = self.image_zoom.get();
        if (zoom - 1.0).abs() >= f64::EPSILON {
            let (width, height) = zoomed_picture_request(
                self.image_view_mode(),
                self.image_scrolled.allocated_width().max(1),
                self.image_scrolled.allocated_height().max(1),
                texture_width,
                texture_height,
                zoom,
            );
            self.image_box.set_hexpand(true);
            self.image_box.set_vexpand(true);
            self.image_box.set_halign(gtk::Align::Fill);
            self.image_box.set_valign(gtk::Align::Fill);
            self.picture.set_can_shrink(false);
            self.picture.set_hexpand(false);
            self.picture.set_vexpand(false);
            self.picture.set_content_fit(gtk::ContentFit::Fill);
            self.picture.set_halign(gtk::Align::Center);
            self.picture.set_valign(gtk::Align::Center);
            self.picture.set_size_request(width, height);
        } else if let Some((width, height)) = single_picture_request(
            self.image_view_mode(),
            self.stack.allocated_width().max(1),
            texture_width,
            texture_height,
        ) {
            self.picture.set_size_request(width, height);
        }
    }

    fn scroll_image(&self, down: bool) {
        let adjustment = self.image_scrolled.vadjustment();
        let step = adjustment.step_increment().max(64.0);
        let delta = if down { step } else { -step };
        let maximum = (adjustment.upper() - adjustment.page_size()).max(adjustment.lower());
        adjustment.set_value((adjustment.value() + delta).clamp(adjustment.lower(), maximum));
    }

    fn open_sibling(&self, forward: bool) {
        if let Some(navigate) = &self.sibling_navigator
            && navigate.open_relative(forward, self.window.clone())
        {
            self.prepare_for_navigation();
        } else {
            self.show_navigation_error(forward);
        }
    }

    fn open_edge(&self, end: bool) {
        if let Some(navigate) = &self.sibling_navigator
            && navigate.open_edge(end, self.window.clone())
        {
            self.prepare_for_navigation();
        } else {
            self.show_navigation_error(end);
        }
    }

    fn show_navigation_error(&self, forward: bool) {
        self.navigation_message_label
            .set_text(navigation_error_message(forward));
        self.navigation_message.set_visible(true);
        let message = self.navigation_message.clone();
        let generation = self.navigation_message_generation.get().wrapping_add(1);
        self.navigation_message_generation.set(generation);
        let current_generation = Rc::clone(&self.navigation_message_generation);
        glib::timeout_add_local_once(Duration::from_secs(2), move || {
            if current_generation.get() == generation {
                message.set_visible(false);
            }
        });
    }

    fn show_seek_temporarily(self: &Rc<Self>) {
        if let Some(timer) = self.seek_hide_timer.borrow_mut().take() {
            timer.remove();
        }
        if let Some((current, count)) = self
            .sibling_navigator
            .as_ref()
            .and_then(SiblingNavigator::position)
        {
            self.media_seek
                .set_range(0.0, navigation_scale_upper(count));
            self.media_seek.set_sensitive(count > 1);
            self.media_seek.set_value(current as f64);
        }
        self.set_seek_visible(true);
        let controller = Rc::downgrade(self);
        let timer = glib::timeout_add_local_once(Duration::from_secs(5), move || {
            if let Some(controller) = controller.upgrade() {
                controller.seek_hide_timer.borrow_mut().take();
                controller.set_seek_visible(false);
            }
        });
        self.seek_hide_timer.replace(Some(timer));
    }

    fn pointer_moved(self: &Rc<Self>, x: f64, y: f64) {
        if self.last_pointer_position.get() == Some((x, y)) {
            return;
        }
        self.last_pointer_position.set(Some((x, y)));
    }

    fn controls_clicked(self: &Rc<Self>) {
        if self.window.is_fullscreen() {
            self.show_fullscreen_ui_temporarily();
        } else {
            self.show_seek_temporarily();
        }
    }

    fn hide_seek(self: &Rc<Self>) {
        if let Some(timer) = self.seek_hide_timer.borrow_mut().take() {
            timer.remove();
        }
        self.set_seek_visible(false);
    }

    fn set_seek_visible(self: &Rc<Self>, visible: bool) {
        if self.media_seek_row.is_visible() == visible {
            return;
        }
        self.media_seek_row.set_visible(visible);
        self.window.queue_allocate();
        let controller = Rc::downgrade(self);
        glib::idle_add_local_once(move || {
            if let Some(controller) = controller.upgrade() {
                controller.stack.queue_allocate();
                controller.picture.queue_allocate();
                controller.video.queue_allocate();
            }
        });
    }

    fn schedule_seek(self: &Rc<Self>, index: usize) {
        let Some(navigator) = &self.sibling_navigator else {
            return;
        };
        if navigator
            .position()
            .is_none_or(|(current, _)| index == current)
            || self.seek_opening.get()
        {
            return;
        }
        let generation = self.seek_generation.get().wrapping_add(1);
        self.seek_generation.set(generation);
        let controller = Rc::downgrade(self);
        glib::timeout_add_local_once(Duration::from_millis(180), move || {
            let Some(controller) = controller.upgrade() else {
                return;
            };
            if controller.seek_generation.get() != generation || controller.seek_opening.get() {
                return;
            }
            let Some(navigator) = &controller.sibling_navigator else {
                return;
            };
            if navigator.open_index(index, controller.window.clone()) {
                controller.seek_opening.set(true);
                controller.prepare_for_navigation();
            }
        });
    }

    fn prepare_for_navigation(&self) {
        self.stop_playback();
        if let Some(timer) = self.seek_hide_timer.borrow_mut().take() {
            timer.remove();
        }
        self.cancel_fullscreen_ui_timer();
        if let Some(handler) = self.fullscreen_notify_handler.borrow_mut().take() {
            self.window.disconnect(handler);
        }
        if let Some(controller) = self.key_controller.borrow_mut().take() {
            self.window.remove_controller(&controller);
        }
        if let Some(controller) = self.motion_controller.borrow_mut().take() {
            self.window.remove_controller(&controller);
        }
        if let Some(controller) = self.fullscreen_key_controller.borrow_mut().take() {
            self.window.remove_controller(&controller);
        }
        if let Some(controller) = self.fullscreen_click_controller.borrow_mut().take() {
            self.window.remove_controller(&controller);
        }
    }

    fn stop_playback(&self) {
        self.image_animation_generation.cancel();
        if let Some(stream) = self.video.media_stream() {
            stream.pause();
        }
    }

    fn toggle_fullscreen(&self) {
        if self.window.is_fullscreen() {
            self.window.unfullscreen();
        } else {
            self.window.fullscreen();
        }
    }

    fn fullscreen_changed(self: &Rc<Self>) {
        self.cancel_fullscreen_ui_timer();
        self.hide_seek();
        if self.window.is_fullscreen() {
            self.set_fullscreen_ui_visible(false);
        } else {
            self.fullscreen_ui_visible.set(true);
            self.titlebar_host.set_visible(true);
            self.status_label.set_visible(true);
            self.file_list_panel
                .set_visible(self.file_list_button.is_active());
        }
    }

    fn show_fullscreen_ui_temporarily(self: &Rc<Self>) {
        if !self.window.is_fullscreen() {
            return;
        }
        self.cancel_fullscreen_ui_timer();
        self.set_fullscreen_ui_visible(true);
        let controller = Rc::downgrade(self);
        let timer = glib::timeout_add_local_once(Duration::from_secs(5), move || {
            if let Some(controller) = controller.upgrade() {
                controller.fullscreen_ui_hide_timer.borrow_mut().take();
                controller.set_fullscreen_ui_visible(false);
            }
        });
        self.fullscreen_ui_hide_timer.replace(Some(timer));
    }

    fn hide_fullscreen_ui_now(self: &Rc<Self>) {
        if self.window.is_fullscreen() {
            self.cancel_fullscreen_ui_timer();
            self.set_fullscreen_ui_visible(false);
        }
    }

    fn cancel_fullscreen_ui_timer(&self) {
        if let Some(timer) = self.fullscreen_ui_hide_timer.borrow_mut().take() {
            timer.remove();
        }
    }

    fn set_fullscreen_ui_visible(self: &Rc<Self>, visible: bool) {
        self.fullscreen_ui_visible.set(visible);
        self.titlebar_host.set_visible(visible);
        self.media_seek_row.set_visible(visible);
        self.status_label.set_visible(visible);
        self.file_list_panel
            .set_visible(visible && self.file_list_button.is_active());
        self.window.queue_allocate();
        let controller = Rc::downgrade(self);
        glib::idle_add_local_once(move || {
            if let Some(controller) = controller.upgrade() {
                controller.stack.queue_allocate();
                controller.picture.queue_allocate();
                controller.video.queue_allocate();
                controller.resize_image_picture();
            }
        });
    }

    fn load_image(self: &Rc<Self>) {
        self.stack.set_visible_child_name("image");
        self.status_label.set_text("이미지를 읽는 중...");
        let path = self.source.local_path.clone();
        let display_name = self.source.display_name.clone();
        let (sender, receiver) = mpsc::channel();
        thread::spawn(move || {
            let result =
                decode_image_file(&path, &display_name).map_err(|error| format!("{error:#}"));
            let _ = sender.send(result);
        });
        let controller = Rc::downgrade(self);
        glib::timeout_add_local(Duration::from_millis(20), move || {
            match receiver.try_recv() {
                Ok(result) => {
                    if let Some(controller) = controller.upgrade() {
                        controller.finish_image_load(result);
                    }
                    glib::ControlFlow::Break
                }
                Err(TryRecvError::Empty) => glib::ControlFlow::Continue,
                Err(TryRecvError::Disconnected) => glib::ControlFlow::Break,
            }
        });
    }

    fn finish_image_load(&self, result: Result<DecodedPage, String>) {
        match result {
            Ok(page) => {
                self.image_dimensions
                    .set(Some((page.width as i32, page.height as i32)));
                let (frames, _) = texture_frames(page);
                set_picture_animation(
                    &self.picture,
                    Some(frames),
                    &self.image_animation_generation,
                );
                self.apply_image_view_mode();
                self.status_label.set_text(&self.source.display_name);
            }
            Err(error) => self.status_label.set_text(&error),
        }
    }
}

fn favorite_label(active: bool) -> &'static str {
    if active {
        "즐겨찾기 제거"
    } else {
        "즐겨찾기 추가"
    }
}

struct ViewerFileList {
    panel: gtk::ScrolledWindow,
    list: gtk::ListBox,
}

#[derive(Default)]
struct TypeaheadBuffer {
    query: String,
    last_input: Option<Instant>,
}

fn file_list_typeahead_select(
    list: &gtk::ListBox,
    files: &[SiblingFile],
    state: &mut TypeaheadBuffer,
    key: gdk::Key,
    modifiers: gdk::ModifierType,
) -> glib::Propagation {
    let blocked = gdk::ModifierType::CONTROL_MASK
        | gdk::ModifierType::ALT_MASK
        | gdk::ModifierType::SUPER_MASK;
    if modifiers.intersects(blocked) {
        return glib::Propagation::Proceed;
    }
    if key == gdk::Key::Escape {
        state.query.clear();
        state.last_input = None;
        return glib::Propagation::Proceed;
    }
    if matches!(key, gdk::Key::space)
        || key.to_unicode().is_some_and(|character| {
            character.eq_ignore_ascii_case(&'f')
                || character.eq_ignore_ascii_case(&'l')
                || matches!(character, '[' | ']' | '+' | '-')
        })
    {
        return glib::Propagation::Proceed;
    }
    let now = Instant::now();
    if state
        .last_input
        .is_none_or(|last| now.duration_since(last) > Duration::from_millis(1200))
    {
        state.query.clear();
    }
    if key == gdk::Key::BackSpace {
        return if state.query.pop().is_some() {
            state.last_input = Some(now);
            glib::Propagation::Stop
        } else {
            glib::Propagation::Proceed
        };
    }
    let Some(character) = key.to_unicode().filter(|character| !character.is_control()) else {
        return glib::Propagation::Proceed;
    };
    let input = character.to_lowercase().collect::<String>();
    let repeated_single = state.query.chars().count() == 1 && state.query == input;
    if !repeated_single {
        state.query.push_str(&input);
    }
    state.last_input = Some(now);
    let selected = list.selected_row().map(|row| row.index() as usize);
    let start = if repeated_single {
        selected.map_or(0, |index| index + 1)
    } else {
        0
    };
    let found = find_sibling_prefix(files, &state.query, start);
    if let Some(row) = found.and_then(|index| list.row_at_index(index as i32)) {
        list.select_row(Some(&row));
        let _ = row.grab_focus();
    }
    glib::Propagation::Stop
}

fn fullscreen_direction_key(key: gdk::Key) -> bool {
    matches!(
        key,
        gdk::Key::Left
            | gdk::Key::Right
            | gdk::Key::Up
            | gdk::Key::Down
            | gdk::Key::KP_Left
            | gdk::Key::KP_Right
            | gdk::Key::KP_Up
            | gdk::Key::KP_Down
    )
}

fn shortcut_modifiers_blocked(modifiers: gdk::ModifierType) -> bool {
    modifiers.intersects(
        gdk::ModifierType::CONTROL_MASK
            | gdk::ModifierType::ALT_MASK
            | gdk::ModifierType::SUPER_MASK,
    )
}

fn find_sibling_prefix(files: &[SiblingFile], query: &str, start: usize) -> Option<usize> {
    if files.is_empty() {
        return None;
    }
    let query = query.to_lowercase();
    (0..files.len())
        .map(|offset| (start + offset) % files.len())
        .find(|index| files[*index].name.to_lowercase().starts_with(&query))
}

fn viewer_file_list() -> ViewerFileList {
    let list = gtk::ListBox::new();
    list.set_selection_mode(gtk::SelectionMode::Single);
    list.set_activate_on_single_click(false);
    let panel = gtk::ScrolledWindow::builder()
        .width_request(280)
        .vexpand(true)
        .child(&list)
        .build();
    panel.add_css_class("sidebar");
    panel.set_visible(false);
    ViewerFileList { panel, list }
}

fn viewer_file_row(file: &SiblingFile) -> gtk::ListBoxRow {
    let row = gtk::ListBoxRow::new();
    let content = gtk::Box::new(gtk::Orientation::Horizontal, 8);
    content.set_margin_top(7);
    content.set_margin_bottom(7);
    content.set_margin_start(8);
    content.set_margin_end(8);
    let icon_name = match file.kind {
        EntryKind::ZipArchive => "package-x-generic-symbolic",
        EntryKind::Video => "video-x-generic-symbolic",
        _ => "image-x-generic-symbolic",
    };
    let icon = gtk::Image::from_icon_name(icon_name);
    let label = gtk::Label::builder()
        .label(&file.name)
        .xalign(0.0)
        .hexpand(true)
        .ellipsize(gtk::pango::EllipsizeMode::Middle)
        .tooltip_text(&file.name)
        .build();
    content.append(&icon);
    content.append(&label);
    row.set_child(Some(&content));
    row
}

fn selected_viewer_file(
    list: &gtk::ListBox,
    files: &RefCell<Vec<SiblingFile>>,
    x: f64,
    y: f64,
) -> Option<(gtk::ListBoxRow, SiblingFile)> {
    let widget = list.pick(x, y, gtk::PickFlags::DEFAULT)?;
    let row = widget
        .clone()
        .downcast::<gtk::ListBoxRow>()
        .ok()
        .or_else(|| {
            widget
                .ancestor(gtk::ListBoxRow::static_type())
                .and_then(|widget| widget.downcast::<gtk::ListBoxRow>().ok())
        })?;
    let file = files.borrow().get(row.index() as usize)?.clone();
    Some((row, file))
}

fn show_viewer_file_context_menu(
    row: &gtk::ListBoxRow,
    file: &SiblingFile,
    actions: SiblingFileActions,
    current_uri: &str,
    current_favorite_button: &gtk::Button,
    window: &gtk::ApplicationWindow,
    status_label: &gtk::Label,
) {
    let popover = gtk::Popover::new();
    popover.set_parent(row);
    let buttons = gtk::Box::new(gtk::Orientation::Vertical, 4);
    buttons.set_margin_top(6);
    buttons.set_margin_bottom(6);
    buttons.set_margin_start(6);
    buttons.set_margin_end(6);
    let favorite_button = gtk::Button::with_label(favorite_label(actions.favorite.active));
    let download_button = gtk::Button::with_label("파일 다운로드...");
    buttons.append(&favorite_button);
    buttons.append(&download_button);
    popover.set_child(Some(&buttons));

    let toggle = actions.favorite.toggle;
    let update_current = file.uri == current_uri;
    let current_favorite_button = current_favorite_button.clone();
    let popover_to_close = popover.clone();
    favorite_button.connect_clicked(move |_| {
        let active = toggle();
        if update_current {
            current_favorite_button.set_label(favorite_label(active));
        }
        popover_to_close.popdown();
    });
    let download = actions.download.download;
    let window: gtk::Window = window.clone().upcast();
    let status_label = status_label.clone();
    let popover_to_close = popover.clone();
    download_button.connect_clicked(move |_| {
        popover_to_close.popdown();
        download(window.clone(), status_label.clone());
    });
    popover.popup();
}

fn standalone_mode_index(global_index: u32) -> u32 {
    match global_index {
        0 | 2 => global_index,
        _ => 1,
    }
}

fn page_picture() -> gtk::Picture {
    let picture = gtk::Picture::new();
    picture.set_content_fit(gtk::ContentFit::Contain);
    picture.set_hexpand(true);
    picture.set_vexpand(true);
    picture
}

fn navigation_scale() -> gtk::Scale {
    let scale = gtk::Scale::with_range(gtk::Orientation::Horizontal, 0.0, 1.0, 1.0);
    scale.set_draw_value(false);
    scale.set_hexpand(true);
    scale.set_height_request(32);
    scale.set_valign(gtk::Align::Center);
    scale.set_focusable(false);
    scale.set_margin_top(2);
    scale.set_margin_bottom(8);
    scale.set_margin_start(8);
    scale.set_margin_end(8);
    scale
}

fn navigation_message() -> (gtk::Box, gtk::Label) {
    let message = gtk::Box::new(gtk::Orientation::Horizontal, 0);
    message.add_css_class("osd");
    message.set_halign(gtk::Align::Center);
    message.set_valign(gtk::Align::Center);
    message.set_can_target(false);
    message.set_margin_top(12);
    message.set_margin_bottom(12);
    message.set_margin_start(18);
    message.set_margin_end(18);
    message.set_visible(false);
    let label = gtk::Label::new(None);
    label.add_css_class("title-2");
    message.append(&label);
    (message, label)
}

fn navigation_error_message(forward: bool) -> &'static str {
    if forward {
        "더 이상 다음 파일이 없습니다."
    } else {
        "더 이상 이전 파일이 없습니다."
    }
}

fn navigation_scale_row(scale: &gtk::Scale) -> gtk::Box {
    let row = gtk::Box::new(gtk::Orientation::Horizontal, 0);
    row.set_height_request(42);
    row.set_hexpand(true);
    row.append(scale);
    row.set_visible(false);
    row
}

fn navigation_scale_upper(count: usize) -> f64 {
    count.saturating_sub(1).max(1) as f64
}

fn spread_indices(anchor: usize, count: usize) -> Vec<usize> {
    if count == 0 {
        return Vec::new();
    }
    let anchor = anchor.min(count - 1);
    let mut pages = vec![anchor];
    if anchor + 1 < count {
        pages.push(anchor + 1);
    }
    pages
}

fn row_height(width: i32, ratio: f32) -> i32 {
    ((width as f32 / ratio).round() as i32).clamp(1, 30_000)
}

fn single_picture_request(
    mode: ViewMode,
    viewport_width: i32,
    texture_width: i32,
    texture_height: i32,
) -> Option<(i32, i32)> {
    match mode {
        ViewMode::ActualSize => Some((texture_width, texture_height)),
        ViewMode::FitWidth => Some((
            -1,
            row_height(viewport_width, texture_width as f32 / texture_height as f32),
        )),
        _ => None,
    }
}

fn next_image_zoom(current: f64, zoom_in: bool) -> f64 {
    let direction = if zoom_in { 1.0 } else { -1.0 };
    ((((current + direction * IMAGE_ZOOM_STEP) * 10.0).round()) / 10.0)
        .clamp(IMAGE_ZOOM_MIN, IMAGE_ZOOM_MAX)
}

fn scaled_dimension(value: i32, zoom: f64) -> i32 {
    ((value.max(1) as f64 * zoom).round() as i32).clamp(1, 30_000)
}

fn zoomed_picture_request(
    mode: ViewMode,
    viewport_width: i32,
    viewport_height: i32,
    texture_width: i32,
    texture_height: i32,
    zoom: f64,
) -> (i32, i32) {
    let viewport_width = viewport_width.max(1);
    let viewport_height = viewport_height.max(1);
    let texture_width = texture_width.max(1);
    let texture_height = texture_height.max(1);
    let (base_width, base_height) = match mode {
        ViewMode::ActualSize => (texture_width, texture_height),
        ViewMode::FitWidth | ViewMode::Continuous => (
            viewport_width,
            row_height(viewport_width, texture_width as f32 / texture_height as f32),
        ),
        ViewMode::FitHeight | ViewMode::TwoPage => {
            let scale = (viewport_width as f64 / texture_width as f64)
                .min(viewport_height as f64 / texture_height as f64);
            (
                (texture_width as f64 * scale).round() as i32,
                (texture_height as f64 * scale).round() as i32,
            )
        }
    };
    (
        scaled_dimension(base_width, zoom.clamp(IMAGE_ZOOM_MIN, IMAGE_ZOOM_MAX)),
        scaled_dimension(base_height, zoom.clamp(IMAGE_ZOOM_MIN, IMAGE_ZOOM_MAX)),
    )
}

fn texture_frames(page: DecodedPage) -> (Rc<CachedAnimation>, usize) {
    let width = page.width;
    let height = page.height;
    let loop_count = page.loop_count;
    let mut cost = 0;
    let frames = page
        .frames
        .into_iter()
        .map(|frame| {
            cost += frame.rgba.len();
            let bytes = glib::Bytes::from_owned(frame.rgba);
            CachedFrame {
                texture: gdk::MemoryTexture::new(
                    width as i32,
                    height as i32,
                    gdk::MemoryFormat::R8g8b8a8,
                    &bytes,
                    width as usize * 4,
                ),
                delay: frame.delay,
            }
        })
        .collect();
    (Rc::new(CachedAnimation { frames, loop_count }), cost)
}

fn set_picture_animation(
    picture: &gtk::Picture,
    frames: Option<Rc<CachedAnimation>>,
    state: &Rc<AnimationState>,
) {
    if let Some(frames) = frames.as_ref()
        && state
            .frames
            .borrow()
            .as_ref()
            .and_then(Weak::upgrade)
            .is_some_and(|current| Rc::ptr_eq(&current, frames))
    {
        return;
    }
    let current = state.cancel();
    let Some(frames) = frames.filter(|frames| !frames.is_empty()) else {
        picture.set_paintable(gdk::Paintable::NONE);
        return;
    };
    state.frames.replace(Some(Rc::downgrade(&frames)));
    show_animation_frame(picture.downgrade(), frames, Rc::clone(state), current, 0, 0);
}

fn show_animation_frame(
    picture: glib::WeakRef<gtk::Picture>,
    frames: Rc<CachedAnimation>,
    state: Rc<AnimationState>,
    expected_generation: u64,
    index: usize,
    completed_loops: u32,
) {
    if state.generation.get() != expected_generation {
        return;
    }
    let Some(picture_widget) = picture.upgrade() else {
        return;
    };
    let frame = &frames[index];
    picture_widget.set_paintable(Some(&frame.texture));
    if frames.len() == 1 {
        return;
    }
    let delay = frame.delay;
    let next = (index + 1) % frames.len();
    let completed_loops = completed_loops + u32::from(next == 0);
    if next == 0
        && frames
            .loop_count
            .is_some_and(|loop_count| completed_loops >= loop_count)
    {
        return;
    }
    let callback_state = Rc::clone(&state);
    let timer = glib::timeout_add_local_once(delay, move || {
        callback_state.timer.borrow_mut().take();
        show_animation_frame(
            picture,
            frames,
            callback_state,
            expected_generation,
            next,
            completed_loops,
        );
    });
    state.timer.replace(Some(timer));
}

fn continuous_content_width(stack_width: i32) -> i32 {
    (stack_width - 24).max(320)
}

fn prefetch_window(visible: &[usize], count: usize, fast: bool) -> Vec<usize> {
    if visible.is_empty() || count == 0 {
        return Vec::new();
    }
    let (ahead, behind) = if fast { (12, 4) } else { (2, 1) };
    let mut indices = visible.to_vec();
    let last = *visible.last().unwrap();
    for offset in 1..=ahead {
        let index = last + offset;
        if index >= count {
            break;
        }
        indices.push(index);
    }
    let first = visible[0];
    for offset in 1..=behind.min(first) {
        indices.push(first - offset);
    }
    indices
}

fn intersecting_rows(bounds: &[Option<(f64, f64)>], top: f64, bottom: f64) -> Vec<usize> {
    bounds
        .iter()
        .enumerate()
        .filter_map(|(index, bounds)| {
            bounds
                .filter(|(row_top, row_bottom)| *row_bottom > top && *row_top < bottom)
                .map(|_| index)
        })
        .collect()
}

fn centered_scroll_value(
    row_top: f64,
    row_height: f64,
    viewport_height: f64,
    minimum: f64,
    maximum: f64,
) -> f64 {
    (row_top + row_height / 2.0 - viewport_height / 2.0).clamp(minimum, maximum)
}

fn page_seek_index(value: f64, count: usize) -> Option<usize> {
    (count > 0).then(|| (value.round().max(0.0) as usize).min(count - 1))
}

fn sibling_index(current: usize, count: usize, forward: bool) -> Option<usize> {
    if forward {
        (current + 1 < count).then_some(current + 1)
    } else {
        current.checked_sub(1)
    }
}

fn video_seek_target(timestamp: i64, duration: i64, delta: i64) -> i64 {
    let target = timestamp.saturating_add(delta).max(0);
    if duration > 0 {
        target.min(duration)
    } else {
        target
    }
}

fn video_volume_target(volume: f64, delta: f64) -> f64 {
    (volume + delta).clamp(0.0, 1.0)
}

#[cfg(test)]
mod tests {
    use super::*;

    #[test]
    fn spread_handles_last_odd_page() {
        assert_eq!(spread_indices(0, 3), [0, 1]);
        assert_eq!(spread_indices(2, 3), [2]);
    }

    #[test]
    fn shifted_pairing_starts_at_requested_page() {
        assert_eq!(spread_indices(1, 5), [1, 2]);
    }

    #[test]
    fn continuous_row_height_preserves_image_ratio() {
        assert_eq!(row_height(1200, 2.0 / 3.0), 1800);
        assert_eq!(row_height(1200, 1.5), 800);
        assert_eq!(continuous_content_width(1200), 1176);
        assert_eq!(continuous_content_width(0), 320);
        assert_eq!(
            single_picture_request(ViewMode::ActualSize, 1200, 800, 1600),
            Some((800, 1600))
        );
        assert_eq!(
            single_picture_request(ViewMode::FitWidth, 1200, 800, 1600),
            Some((-1, 2400))
        );
        assert_eq!(
            single_picture_request(ViewMode::FitHeight, 1200, 800, 1600),
            None
        );
        assert_eq!(standalone_mode_index(0), 0);
        assert_eq!(standalone_mode_index(1), 1);
        assert_eq!(standalone_mode_index(2), 2);
        assert_eq!(standalone_mode_index(3), 1);
        assert_eq!(standalone_mode_index(4), 1);
    }

    #[test]
    fn continuous_visibility_uses_real_unequal_row_bounds() {
        let bounds = [
            Some((0.0, 1800.0)),
            Some((1808.0, 2608.0)),
            Some((2616.0, 4416.0)),
        ];
        assert_eq!(intersecting_rows(&bounds, 1000.0, 1900.0), [0, 1]);
        assert_eq!(intersecting_rows(&bounds, 3000.0, 3800.0), [2]);
    }

    #[test]
    fn continuous_seek_centers_the_selected_row() {
        assert_eq!(
            centered_scroll_value(1_000.0, 800.0, 600.0, 0.0, 5_000.0),
            1_100.0
        );
        assert_eq!(centered_scroll_value(0.0, 400.0, 800.0, 0.0, 5_000.0), 0.0);
        assert_eq!(
            centered_scroll_value(5_000.0, 800.0, 600.0, 0.0, 5_000.0),
            5_000.0
        );
    }

    #[test]
    fn fast_loading_prefetches_a_larger_window() {
        assert_eq!(prefetch_window(&[10], 30, false), [10, 11, 12, 9]);
        assert_eq!(
            prefetch_window(&[10], 30, true),
            [
                10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 9, 8, 7, 6
            ]
        );
    }

    #[test]
    fn page_seek_rounds_and_clamps_to_archive() {
        assert_eq!(page_seek_index(3.6, 10), Some(4));
        assert_eq!(page_seek_index(20.0, 10), Some(9));
        assert_eq!(page_seek_index(0.0, 0), None);
    }

    #[test]
    fn navigation_scale_always_has_a_valid_range() {
        assert_eq!(navigation_scale_upper(0), 1.0);
        assert_eq!(navigation_scale_upper(1), 1.0);
        assert_eq!(navigation_scale_upper(2), 1.0);
        assert_eq!(navigation_scale_upper(10), 9.0);
    }

    #[test]
    fn sibling_navigation_stops_at_boundaries() {
        assert_eq!(sibling_index(1, 3, false), Some(0));
        assert_eq!(sibling_index(1, 3, true), Some(2));
        assert_eq!(sibling_index(0, 3, false), None);
        assert_eq!(sibling_index(2, 3, true), None);
        assert_eq!(SiblingTarget::First.resolve(2, 5), Some(0));
        assert_eq!(SiblingTarget::Last.resolve(1, 5), Some(4));
        assert_eq!(SiblingTarget::First.resolve(0, 5), None);
        assert_eq!(SiblingTarget::Last.resolve(4, 5), None);
        assert_eq!(SiblingTarget::Last.resolve(0, 0), None);
    }

    #[test]
    fn video_controls_clamp_seek_and_volume() {
        assert_eq!(video_seek_target(3_000_000, 20_000_000, -5_000_000), 0);
        assert_eq!(
            video_seek_target(18_000_000, 20_000_000, 5_000_000),
            20_000_000
        );
        assert_eq!(video_seek_target(18_000_000, 0, 5_000_000), 23_000_000);
        assert_eq!(video_volume_target(0.02, -0.05), 0.0);
        assert_eq!(video_volume_target(0.98, 0.05), 1.0);
        assert_eq!(video_volume_target(0.5, 0.05), 0.55);
    }

    #[test]
    fn viewer_file_typeahead_wraps_by_display_name() {
        let files = ["Alpha.zip", "beta.jpg", "Bravo.mp4"].map(|name| SiblingFile {
            uri: format!("file:///{name}"),
            name: name.into(),
            kind: EntryKind::Image,
        });

        assert_eq!(find_sibling_prefix(&files, "br", 0), Some(2));
        assert_eq!(find_sibling_prefix(&files, "b", 2), Some(2));
        assert_eq!(find_sibling_prefix(&files, "b", 3), Some(1));
    }

    #[test]
    fn fullscreen_direction_keys_hide_controls() {
        for key in [
            gdk::Key::Left,
            gdk::Key::Right,
            gdk::Key::Up,
            gdk::Key::Down,
            gdk::Key::KP_Left,
            gdk::Key::KP_Right,
            gdk::Key::KP_Up,
            gdk::Key::KP_Down,
        ] {
            assert!(fullscreen_direction_key(key));
        }
        assert!(!fullscreen_direction_key(gdk::Key::bracketleft));
        assert!(!fullscreen_direction_key(gdk::Key::bracketright));
        assert!(!fullscreen_direction_key(gdk::Key::f));
    }

    #[test]
    fn image_zoom_changes_by_ten_percent_and_clamps() {
        assert_eq!(next_image_zoom(1.0, true), 1.1);
        assert_eq!(next_image_zoom(1.0, false), 0.9);
        assert_eq!(next_image_zoom(IMAGE_ZOOM_MAX, true), IMAGE_ZOOM_MAX);
        assert_eq!(next_image_zoom(IMAGE_ZOOM_MIN, false), IMAGE_ZOOM_MIN);
    }

    #[test]
    fn file_list_shortcut_rejects_command_modifiers() {
        assert!(!shortcut_modifiers_blocked(gdk::ModifierType::SHIFT_MASK));
        assert!(shortcut_modifiers_blocked(gdk::ModifierType::CONTROL_MASK));
        assert!(shortcut_modifiers_blocked(gdk::ModifierType::ALT_MASK));
        assert!(shortcut_modifiers_blocked(gdk::ModifierType::SUPER_MASK));
    }

    #[test]
    fn zoomed_image_request_preserves_aspect_ratio() {
        assert_eq!(
            zoomed_picture_request(ViewMode::ActualSize, 1000, 800, 800, 1600, 1.1),
            (880, 1760)
        );
        assert_eq!(
            zoomed_picture_request(ViewMode::FitWidth, 1000, 800, 800, 1600, 0.9),
            (900, 1800)
        );
        assert_eq!(
            zoomed_picture_request(ViewMode::FitHeight, 1000, 800, 800, 1600, 1.1),
            (440, 880)
        );
    }

    #[test]
    fn navigation_boundary_messages_match_direction() {
        assert_eq!(
            navigation_error_message(false),
            "더 이상 이전 파일이 없습니다."
        );
        assert_eq!(
            navigation_error_message(true),
            "더 이상 다음 파일이 없습니다."
        );
    }
}