use super::{BoolExt, MacDisplay, NSRange, NSStringExt, ns_string, renderer};
use crate::{
    AnyWindowHandle, Bounds, Capslock, DisplayLink, ExternalPaths, FileDropEvent,
    ForegroundExecutor, KeyDownEvent, Keystroke, Modifiers, ModifiersChangedEvent, MouseButton,
    MouseDownEvent, MouseMoveEvent, MouseUpEvent, Pixels, PlatformAtlas, PlatformDisplay,
    PlatformInput, PlatformWindow, Point, PromptButton, PromptLevel, RequestFrameOptions,
    ScaledPixels, Size, Timer, WindowAppearance, WindowBackgroundAppearance, WindowBounds,
    WindowControlArea, WindowKind, WindowParams, platform::PlatformInputHandler, point, px, size,
};
use block::ConcreteBlock;
use cocoa::{
    appkit::{
        NSAppKitVersionNumber, NSAppKitVersionNumber12_0, NSApplication, NSBackingStoreBuffered,
        NSColor, NSEvent, NSEventModifierFlags, NSFilenamesPboardType, NSPasteboard, NSScreen,
        NSView, NSViewHeightSizable, NSViewWidthSizable, NSVisualEffectMaterial,
        NSVisualEffectState, NSVisualEffectView, NSWindow, NSWindowButton,
        NSWindowCollectionBehavior, NSWindowOcclusionState, NSWindowOrderingMode,
        NSWindowStyleMask, NSWindowTitleVisibility,
    },
    base::{id, nil},
    foundation::{
        NSArray, NSAutoreleasePool, NSDictionary, NSFastEnumeration, NSInteger, NSNotFound,
        NSOperatingSystemVersion, NSPoint, NSProcessInfo, NSRect, NSSize, NSString, NSUInteger,
        NSUserDefaults,
    },
};
use core_graphics::display::{CGDirectDisplayID, CGPoint, CGRect};
use ctor::ctor;
use futures::channel::oneshot;
use objc::{
    class,
    declare::ClassDecl,
    msg_send,
    runtime::{BOOL, Class, NO, Object, Protocol, Sel, YES},
    sel, sel_impl,
};
use parking_lot::Mutex;
use raw_window_handle as rwh;
use smallvec::SmallVec;
use std::{
    cell::Cell,
    ffi::{CStr, c_void},
    mem,
    ops::Range,
    path::PathBuf,
    ptr::{self, NonNull},
    rc::Rc,
    sync::{Arc, Weak},
    time::Duration,
};
use util::ResultExt;

const WINDOW_STATE_IVAR: &str = "windowState";

static mut WINDOW_CLASS: *const Class = ptr::null();
static mut PANEL_CLASS: *const Class = ptr::null();
static mut VIEW_CLASS: *const Class = ptr::null();
static mut BLURRED_VIEW_CLASS: *const Class = ptr::null();

#[allow(non_upper_case_globals)]
const NSWindowStyleMaskNonactivatingPanel: NSWindowStyleMask =
    NSWindowStyleMask::from_bits_retain(1 << 7);
#[allow(non_upper_case_globals)]
const NSNormalWindowLevel: NSInteger = 0;
#[allow(non_upper_case_globals)]
const NSPopUpWindowLevel: NSInteger = 101;
#[allow(non_upper_case_globals)]
const NSTrackingMouseEnteredAndExited: NSUInteger = 0x01;
#[allow(non_upper_case_globals)]
const NSTrackingMouseMoved: NSUInteger = 0x02;
#[allow(non_upper_case_globals)]
const NSTrackingActiveAlways: NSUInteger = 0x80;
#[allow(non_upper_case_globals)]
const NSTrackingInVisibleRect: NSUInteger = 0x200;
#[allow(non_upper_case_globals)]
const NSWindowAnimationBehaviorUtilityWindow: NSInteger = 4;
#[allow(non_upper_case_globals)]
const NSViewLayerContentsRedrawDuringViewResize: NSInteger = 2;
// https://developer.apple.com/documentation/appkit/nsdragoperation
type NSDragOperation = NSUInteger;
#[allow(non_upper_case_globals)]
const NSDragOperationNone: NSDragOperation = 0;
#[allow(non_upper_case_globals)]
const NSDragOperationCopy: NSDragOperation = 1;

#[link(name = "CoreGraphics", kind = "framework")]
unsafe extern "C" {
    // Widely used private APIs; Apple uses them for their Terminal.app.
    fn CGSMainConnectionID() -> id;
    fn CGSSetWindowBackgroundBlurRadius(
        connection_id: id,
        window_id: NSInteger,
        radius: i64,
    ) -> i32;
}

#[ctor]
unsafe fn build_classes() {
    unsafe {
        WINDOW_CLASS = build_window_class("GPUIWindow", class!(NSWindow));
        PANEL_CLASS = build_window_class("GPUIPanel", class!(NSPanel));
        VIEW_CLASS = {
            let mut decl = ClassDecl::new("GPUIView", class!(NSView)).unwrap();
            decl.add_ivar::<*mut c_void>(WINDOW_STATE_IVAR);
            unsafe {
                decl.add_method(sel!(dealloc), dealloc_view as extern "C" fn(&Object, Sel));

                decl.add_method(
                    sel!(performKeyEquivalent:),
                    handle_key_equivalent as extern "C" fn(&Object, Sel, id) -> BOOL,
                );
                decl.add_method(
                    sel!(keyDown:),
                    handle_key_down as extern "C" fn(&Object, Sel, id),
                );
                decl.add_method(
                    sel!(keyUp:),
                    handle_key_up as extern "C" fn(&Object, Sel, id),
                );
                decl.add_method(
                    sel!(mouseDown:),
                    handle_view_event as extern "C" fn(&Object, Sel, id),
                );
                decl.add_method(
                    sel!(mouseUp:),
                    handle_view_event as extern "C" fn(&Object, Sel, id),
                );
                decl.add_method(
                    sel!(rightMouseDown:),
                    handle_view_event as extern "C" fn(&Object, Sel, id),
                );
                decl.add_method(
                    sel!(rightMouseUp:),
                    handle_view_event as extern "C" fn(&Object, Sel, id),
                );
                decl.add_method(
                    sel!(otherMouseDown:),
                    handle_view_event as extern "C" fn(&Object, Sel, id),
                );
                decl.add_method(
                    sel!(otherMouseUp:),
                    handle_view_event as extern "C" fn(&Object, Sel, id),
                );
                decl.add_method(
                    sel!(mouseMoved:),
                    handle_view_event as extern "C" fn(&Object, Sel, id),
                );
                decl.add_method(
                    sel!(mouseExited:),
                    handle_view_event as extern "C" fn(&Object, Sel, id),
                );
                decl.add_method(
                    sel!(mouseDragged:),
                    handle_view_event as extern "C" fn(&Object, Sel, id),
                );
                decl.add_method(
                    sel!(scrollWheel:),
                    handle_view_event as extern "C" fn(&Object, Sel, id),
                );
                decl.add_method(
                    sel!(swipeWithEvent:),
                    handle_view_event as extern "C" fn(&Object, Sel, id),
                );
                decl.add_method(
                    sel!(flagsChanged:),
                    handle_view_event as extern "C" fn(&Object, Sel, id),
                );

                decl.add_method(
                    sel!(makeBackingLayer),
                    make_backing_layer as extern "C" fn(&Object, Sel) -> id,
                );

                decl.add_protocol(Protocol::get("CALayerDelegate").unwrap());
                decl.add_method(
                    sel!(viewDidChangeBackingProperties),
                    view_did_change_backing_properties as extern "C" fn(&Object, Sel),
                );
                decl.add_method(
                    sel!(setFrameSize:),
                    set_frame_size as extern "C" fn(&Object, Sel, NSSize),
                );
                decl.add_method(
                    sel!(displayLayer:),
                    display_layer as extern "C" fn(&Object, Sel, id),
                );

                decl.add_protocol(Protocol::get("NSTextInputClient").unwrap());
                decl.add_method(
                    sel!(validAttributesForMarkedText),
                    valid_attributes_for_marked_text as extern "C" fn(&Object, Sel) -> id,
                );
                decl.add_method(
                    sel!(hasMarkedText),
                    has_marked_text as extern "C" fn(&Object, Sel) -> BOOL,
                );
                decl.add_method(
                    sel!(markedRange),
                    marked_range as extern "C" fn(&Object, Sel) -> NSRange,
                );
                decl.add_method(
                    sel!(selectedRange),
                    selected_range as extern "C" fn(&Object, Sel) -> NSRange,
                );
                decl.add_method(
                    sel!(firstRectForCharacterRange:actualRange:),
                    first_rect_for_character_range
                        as extern "C" fn(&Object, Sel, NSRange, id) -> NSRect,
                );
                decl.add_method(
                    sel!(insertText:replacementRange:),
                    insert_text as extern "C" fn(&Object, Sel, id, NSRange),
                );
                decl.add_method(
                    sel!(setMarkedText:selectedRange:replacementRange:),
                    set_marked_text as extern "C" fn(&Object, Sel, id, NSRange, NSRange),
                );
                decl.add_method(sel!(unmarkText), unmark_text as extern "C" fn(&Object, Sel));
                decl.add_method(
                    sel!(attributedSubstringForProposedRange:actualRange:),
                    attributed_substring_for_proposed_range
                        as extern "C" fn(&Object, Sel, NSRange, *mut c_void) -> id,
                );
                decl.add_method(
                    sel!(viewDidChangeEffectiveAppearance),
                    view_did_change_effective_appearance as extern "C" fn(&Object, Sel),
                );

                // Suppress beep on keystrokes with modifier keys.
                decl.add_method(
                    sel!(doCommandBySelector:),
                    do_command_by_selector as extern "C" fn(&Object, Sel, Sel),
                );

                decl.add_method(
                    sel!(acceptsFirstMouse:),
                    accepts_first_mouse as extern "C" fn(&Object, Sel, id) -> BOOL,
                );

                decl.add_method(
                    sel!(characterIndexForPoint:),
                    character_index_for_point as extern "C" fn(&Object, Sel, NSPoint) -> u64,
                );
            }
            decl.register()
        };
        BLURRED_VIEW_CLASS = {
            let mut decl = ClassDecl::new("BlurredView", class!(NSVisualEffectView)).unwrap();
            unsafe {
                decl.add_method(
                    sel!(initWithFrame:),
                    blurred_view_init_with_frame as extern "C" fn(&Object, Sel, NSRect) -> id,
                );
                decl.add_method(
                    sel!(updateLayer),
                    blurred_view_update_layer as extern "C" fn(&Object, Sel),
                );
                decl.register()
            }
        };
    }
}

pub(crate) fn convert_mouse_position(position: NSPoint, window_height: Pixels) -> Point<Pixels> {
    point(
        px(position.x as f32),
        // macOS screen coordinates are relative to bottom left
        window_height - px(position.y as f32),
    )
}

unsafe fn build_window_class(name: &'static str, superclass: &Class) -> *const Class {
    unsafe {
        let mut decl = ClassDecl::new(name, superclass).unwrap();
        decl.add_ivar::<*mut c_void>(WINDOW_STATE_IVAR);
        decl.add_method(sel!(dealloc), dealloc_window as extern "C" fn(&Object, Sel));

        decl.add_method(
            sel!(canBecomeMainWindow),
            yes as extern "C" fn(&Object, Sel) -> BOOL,
        );
        decl.add_method(
            sel!(canBecomeKeyWindow),
            yes as extern "C" fn(&Object, Sel) -> BOOL,
        );
        decl.add_method(
            sel!(windowDidResize:),
            window_did_resize as extern "C" fn(&Object, Sel, id),
        );
        decl.add_method(
            sel!(windowDidChangeOcclusionState:),
            window_did_change_occlusion_state as extern "C" fn(&Object, Sel, id),
        );
        decl.add_method(
            sel!(windowWillEnterFullScreen:),
            window_will_enter_fullscreen as extern "C" fn(&Object, Sel, id),
        );
        decl.add_method(
            sel!(windowWillExitFullScreen:),
            window_will_exit_fullscreen as extern "C" fn(&Object, Sel, id),
        );
        decl.add_method(
            sel!(windowDidMove:),
            window_did_move as extern "C" fn(&Object, Sel, id),
        );
        decl.add_method(
            sel!(windowDidChangeScreen:),
            window_did_change_screen as extern "C" fn(&Object, Sel, id),
        );
        decl.add_method(
            sel!(windowDidBecomeKey:),
            window_did_change_key_status as extern "C" fn(&Object, Sel, id),
        );
        decl.add_method(
            sel!(windowDidResignKey:),
            window_did_change_key_status as extern "C" fn(&Object, Sel, id),
        );
        decl.add_method(
            sel!(windowShouldClose:),
            window_should_close as extern "C" fn(&Object, Sel, id) -> BOOL,
        );

        decl.add_method(sel!(close), close_window as extern "C" fn(&Object, Sel));

        decl.add_method(
            sel!(draggingEntered:),
            dragging_entered as extern "C" fn(&Object, Sel, id) -> NSDragOperation,
        );
        decl.add_method(
            sel!(draggingUpdated:),
            dragging_updated as extern "C" fn(&Object, Sel, id) -> NSDragOperation,
        );
        decl.add_method(
            sel!(draggingExited:),
            dragging_exited as extern "C" fn(&Object, Sel, id),
        );
        decl.add_method(
            sel!(performDragOperation:),
            perform_drag_operation as extern "C" fn(&Object, Sel, id) -> BOOL,
        );
        decl.add_method(
            sel!(concludeDragOperation:),
            conclude_drag_operation as extern "C" fn(&Object, Sel, id),
        );

        decl.register()
    }
}

struct MacWindowState {
    handle: AnyWindowHandle,
    executor: ForegroundExecutor,
    native_window: id,
    native_view: NonNull<Object>,
    blurred_view: Option<id>,
    display_link: Option<DisplayLink>,
    renderer: renderer::Renderer,
    request_frame_callback: Option<Box<dyn FnMut(RequestFrameOptions)>>,
    event_callback: Option<Box<dyn FnMut(PlatformInput) -> crate::DispatchEventResult>>,
    activate_callback: Option<Box<dyn FnMut(bool)>>,
    resize_callback: Option<Box<dyn FnMut(Size<Pixels>, f32)>>,
    moved_callback: Option<Box<dyn FnMut()>>,
    should_close_callback: Option<Box<dyn FnMut() -> bool>>,
    close_callback: Option<Box<dyn FnOnce()>>,
    appearance_changed_callback: Option<Box<dyn FnMut()>>,
    input_handler: Option<PlatformInputHandler>,
    last_key_equivalent: Option<KeyDownEvent>,
    synthetic_drag_counter: usize,
    traffic_light_position: Option<Point<Pixels>>,
    transparent_titlebar: bool,
    previous_modifiers_changed_event: Option<PlatformInput>,
    keystroke_for_do_command: Option<Keystroke>,
    do_command_handled: Option<bool>,
    external_files_dragged: bool,
    // Whether the next left-mouse click is also the focusing click.
    first_mouse: bool,
    fullscreen_restore_bounds: Bounds<Pixels>,
}

impl MacWindowState {
    fn move_traffic_light(&self) {
        if let Some(traffic_light_position) = self.traffic_light_position {
            if self.is_fullscreen() {
                // Moving traffic lights while fullscreen doesn't work,
                // see https://github.com/zed-industries/zed/issues/4712
                return;
            }

            let titlebar_height = self.titlebar_height();

            unsafe {
                let close_button: id = msg_send![
                    self.native_window,
                    standardWindowButton: NSWindowButton::NSWindowCloseButton
                ];
                let min_button: id = msg_send![
                    self.native_window,
                    standardWindowButton: NSWindowButton::NSWindowMiniaturizeButton
                ];
                let zoom_button: id = msg_send![
                    self.native_window,
                    standardWindowButton: NSWindowButton::NSWindowZoomButton
                ];

                let mut close_button_frame: CGRect = msg_send![close_button, frame];
                let mut min_button_frame: CGRect = msg_send![min_button, frame];
                let mut zoom_button_frame: CGRect = msg_send![zoom_button, frame];
                let mut origin = point(
                    traffic_light_position.x,
                    titlebar_height
                        - traffic_light_position.y
                        - px(close_button_frame.size.height as f32),
                );
                let button_spacing =
                    px((min_button_frame.origin.x - close_button_frame.origin.x) as f32);

                close_button_frame.origin = CGPoint::new(origin.x.into(), origin.y.into());
                let _: () = msg_send![close_button, setFrame: close_button_frame];
                origin.x += button_spacing;

                min_button_frame.origin = CGPoint::new(origin.x.into(), origin.y.into());
                let _: () = msg_send![min_button, setFrame: min_button_frame];
                origin.x += button_spacing;

                zoom_button_frame.origin = CGPoint::new(origin.x.into(), origin.y.into());
                let _: () = msg_send![zoom_button, setFrame: zoom_button_frame];
                origin.x += button_spacing;
            }
        }
    }

    fn start_display_link(&mut self) {
        self.stop_display_link();
        unsafe {
            if !self
                .native_window
                .occlusionState()
                .contains(NSWindowOcclusionState::NSWindowOcclusionStateVisible)
            {
                return;
            }
        }
        let display_id = unsafe { display_id_for_screen(self.native_window.screen()) };
        if let Some(mut display_link) =
            DisplayLink::new(display_id, self.native_view.as_ptr() as *mut c_void, step).log_err()
        {
            display_link.start().log_err();
            self.display_link = Some(display_link);
        }
    }

    fn stop_display_link(&mut self) {
        self.display_link = None;
    }

    fn is_maximized(&self) -> bool {
        unsafe {
            let bounds = self.bounds();
            let screen_size = self.native_window.screen().visibleFrame().into();
            bounds.size == screen_size
        }
    }

    fn is_fullscreen(&self) -> bool {
        unsafe {
            let style_mask = self.native_window.styleMask();
            style_mask.contains(NSWindowStyleMask::NSFullScreenWindowMask)
        }
    }

    fn bounds(&self) -> Bounds<Pixels> {
        let mut window_frame = unsafe { NSWindow::frame(self.native_window) };
        let screen_frame = unsafe {
            let screen = NSWindow::screen(self.native_window);
            NSScreen::frame(screen)
        };

        // Flip the y coordinate to be top-left origin
        window_frame.origin.y =
            screen_frame.size.height - window_frame.origin.y - window_frame.size.height;

        Bounds::new(
            point(
                px((window_frame.origin.x - screen_frame.origin.x) as f32),
                px((window_frame.origin.y + screen_frame.origin.y) as f32),
            ),
            size(
                px(window_frame.size.width as f32),
                px(window_frame.size.height as f32),
            ),
        )
    }

    fn content_size(&self) -> Size<Pixels> {
        let NSSize { width, height, .. } =
            unsafe { NSView::frame(self.native_window.contentView()) }.size;
        size(px(width as f32), px(height as f32))
    }

    fn scale_factor(&self) -> f32 {
        get_scale_factor(self.native_window)
    }

    fn titlebar_height(&self) -> Pixels {
        unsafe {
            let frame = NSWindow::frame(self.native_window);
            let content_layout_rect: CGRect = msg_send![self.native_window, contentLayoutRect];
            px((frame.size.height - content_layout_rect.size.height) as f32)
        }
    }

    fn window_bounds(&self) -> WindowBounds {
        if self.is_fullscreen() {
            WindowBounds::Fullscreen(self.fullscreen_restore_bounds)
        } else {
            WindowBounds::Windowed(self.bounds())
        }
    }
}

unsafe impl Send for MacWindowState {}

pub(crate) struct MacWindow(Arc<Mutex<MacWindowState>>);

impl MacWindow {
    pub fn open(
        handle: AnyWindowHandle,
        WindowParams {
            bounds,
            titlebar,
            kind,
            is_movable,
            focus,
            show,
            display_id,
            window_min_size,
        }: WindowParams,
        executor: ForegroundExecutor,
        renderer_context: renderer::Context,
    ) -> Self {
        unsafe {
            let pool = NSAutoreleasePool::new(nil);

            let () = msg_send![class!(NSWindow), setAllowsAutomaticWindowTabbing: NO];

            let mut style_mask;
            if let Some(titlebar) = titlebar.as_ref() {
                style_mask = NSWindowStyleMask::NSClosableWindowMask
                    | NSWindowStyleMask::NSMiniaturizableWindowMask
                    | NSWindowStyleMask::NSResizableWindowMask
                    | NSWindowStyleMask::NSTitledWindowMask;

                if titlebar.appears_transparent {
                    style_mask |= NSWindowStyleMask::NSFullSizeContentViewWindowMask;
                }
            } else {
                style_mask = NSWindowStyleMask::NSTitledWindowMask
                    | NSWindowStyleMask::NSFullSizeContentViewWindowMask;
            }

            let native_window: id = match kind {
                WindowKind::Normal => msg_send![WINDOW_CLASS, alloc],
                WindowKind::PopUp => {
                    style_mask |= NSWindowStyleMaskNonactivatingPanel;
                    msg_send![PANEL_CLASS, alloc]
                }
            };

            let display = display_id
                .and_then(MacDisplay::find_by_id)
                .unwrap_or_else(MacDisplay::primary);

            let mut target_screen = nil;
            let mut screen_frame = None;

            let screens = NSScreen::screens(nil);
            let count: u64 = cocoa::foundation::NSArray::count(screens);
            for i in 0..count {
                let screen = cocoa::foundation::NSArray::objectAtIndex(screens, i);
                let frame = NSScreen::frame(screen);
                let display_id = display_id_for_screen(screen);
                if display_id == display.0 {
                    screen_frame = Some(frame);
                    target_screen = screen;
                }
            }

            let screen_frame = screen_frame.unwrap_or_else(|| {
                let screen = NSScreen::mainScreen(nil);
                target_screen = screen;
                NSScreen::frame(screen)
            });

            let window_rect = NSRect::new(
                NSPoint::new(
                    screen_frame.origin.x + bounds.origin.x.0 as f64,
                    screen_frame.origin.y
                        + (display.bounds().size.height - bounds.origin.y).0 as f64,
                ),
                NSSize::new(bounds.size.width.0 as f64, bounds.size.height.0 as f64),
            );

            let native_window = native_window.initWithContentRect_styleMask_backing_defer_screen_(
                window_rect,
                style_mask,
                NSBackingStoreBuffered,
                NO,
                target_screen,
            );
            assert!(!native_window.is_null());
            let () = msg_send![
                native_window,
                registerForDraggedTypes:
                    NSArray::arrayWithObject(nil, NSFilenamesPboardType)
            ];
            let () = msg_send![
                native_window,
                setReleasedWhenClosed: NO
            ];

            let content_view = native_window.contentView();
            let native_view: id = msg_send![VIEW_CLASS, alloc];
            let native_view = NSView::initWithFrame_(native_view, NSView::bounds(content_view));
            assert!(!native_view.is_null());

            let mut window = Self(Arc::new(Mutex::new(MacWindowState {
                handle,
                executor,
                native_window,
                native_view: NonNull::new_unchecked(native_view),
                blurred_view: None,
                display_link: None,
                renderer: renderer::new_renderer(
                    renderer_context,
                    native_window as *mut _,
                    native_view as *mut _,
                    bounds.size.map(|pixels| pixels.0),
                    false,
                ),
                request_frame_callback: None,
                event_callback: None,
                activate_callback: None,
                resize_callback: None,
                moved_callback: None,
                should_close_callback: None,
                close_callback: None,
                appearance_changed_callback: None,
                input_handler: None,
                last_key_equivalent: None,
                synthetic_drag_counter: 0,
                traffic_light_position: titlebar
                    .as_ref()
                    .and_then(|titlebar| titlebar.traffic_light_position),
                transparent_titlebar: titlebar
                    .as_ref()
                    .map_or(true, |titlebar| titlebar.appears_transparent),
                previous_modifiers_changed_event: None,
                keystroke_for_do_command: None,
                do_command_handled: None,
                external_files_dragged: false,
                first_mouse: false,
                fullscreen_restore_bounds: Bounds::default(),
            })));

            (*native_window).set_ivar(
                WINDOW_STATE_IVAR,
                Arc::into_raw(window.0.clone()) as *const c_void,
            );
            native_window.setDelegate_(native_window);
            (*native_view).set_ivar(
                WINDOW_STATE_IVAR,
                Arc::into_raw(window.0.clone()) as *const c_void,
            );

            if let Some(title) = titlebar
                .as_ref()
                .and_then(|t| t.title.as_ref().map(AsRef::as_ref))
            {
                window.set_title(title);
            }

            native_window.setMovable_(is_movable as BOOL);

            if let Some(window_min_size) = window_min_size {
                native_window.setContentMinSize_(NSSize {
                    width: window_min_size.width.to_f64(),
                    height: window_min_size.height.to_f64(),
                });
            }

            if titlebar.map_or(true, |titlebar| titlebar.appears_transparent) {
                native_window.setTitlebarAppearsTransparent_(YES);
                native_window.setTitleVisibility_(NSWindowTitleVisibility::NSWindowTitleHidden);
            }

            native_view.setAutoresizingMask_(NSViewWidthSizable | NSViewHeightSizable);
            native_view.setWantsBestResolutionOpenGLSurface_(YES);

            // From winit crate: On Mojave, views automatically become layer-backed shortly after
            // being added to a native_window. Changing the layer-backedness of a view breaks the
            // association between the view and its associated OpenGL context. To work around this,
            // on we explicitly make the view layer-backed up front so that AppKit doesn't do it
            // itself and break the association with its context.
            native_view.setWantsLayer(YES);
            let _: () = msg_send![
            native_view,
            setLayerContentsRedrawPolicy: NSViewLayerContentsRedrawDuringViewResize
            ];

            content_view.addSubview_(native_view.autorelease());
            native_window.makeFirstResponder_(native_view);

            match kind {
                WindowKind::Normal => {
                    native_window.setLevel_(NSNormalWindowLevel);
                    native_window.setAcceptsMouseMovedEvents_(YES);
                }
                WindowKind::PopUp => {
                    // Use a tracking area to allow receiving MouseMoved events even when
                    // the window or application aren't active, which is often the case
                    // e.g. for notification windows.
                    let tracking_area: id = msg_send![class!(NSTrackingArea), alloc];
                    let _: () = msg_send![
                        tracking_area,
                        initWithRect: NSRect::new(NSPoint::new(0., 0.), NSSize::new(0., 0.))
                        options: NSTrackingMouseEnteredAndExited | NSTrackingMouseMoved | NSTrackingActiveAlways | NSTrackingInVisibleRect
                        owner: native_view
                        userInfo: nil
                    ];
                    let _: () =
                        msg_send![native_view, addTrackingArea: tracking_area.autorelease()];

                    native_window.setLevel_(NSPopUpWindowLevel);
                    let _: () = msg_send![
                        native_window,
                        setAnimationBehavior: NSWindowAnimationBehaviorUtilityWindow
                    ];
                    native_window.setCollectionBehavior_(
                        NSWindowCollectionBehavior::NSWindowCollectionBehaviorCanJoinAllSpaces |
                        NSWindowCollectionBehavior::NSWindowCollectionBehaviorFullScreenAuxiliary
                    );
                }
            }

            if focus && show {
                native_window.makeKeyAndOrderFront_(nil);
            } else if show {
                native_window.orderFront_(nil);
            }

            // Set the initial position of the window to the specified origin.
            // Although we already specified the position using `initWithContentRect_styleMask_backing_defer_screen_`,
            // the window position might be incorrect if the main screen (the screen that contains the window that has focus)
            //  is different from the primary screen.
            NSWindow::setFrameTopLeftPoint_(native_window, window_rect.origin);
            window.0.lock().move_traffic_light();

            pool.drain();

            window
        }
    }

    pub fn active_window() -> Option<AnyWindowHandle> {
        unsafe {
            let app = NSApplication::sharedApplication(nil);
            let main_window: id = msg_send![app, mainWindow];
            if main_window.is_null() {
                return None;
            }

            if msg_send![main_window, isKindOfClass: WINDOW_CLASS] {
                let handle = get_window_state(&*main_window).lock().handle;
                Some(handle)
            } else {
                None
            }
        }
    }

    pub fn ordered_windows() -> Vec<AnyWindowHandle> {
        unsafe {
            let app = NSApplication::sharedApplication(nil);
            let windows: id = msg_send![app, orderedWindows];
            let count: NSUInteger = msg_send![windows, count];

            let mut window_handles = Vec::new();
            for i in 0..count {
                let window: id = msg_send![windows, objectAtIndex:i];
                if msg_send![window, isKindOfClass: WINDOW_CLASS] {
                    let handle = get_window_state(&*window).lock().handle;
                    window_handles.push(handle);
                }
            }

            window_handles
        }
    }
}

impl Drop for MacWindow {
    fn drop(&mut self) {
        let mut this = self.0.lock();
        this.renderer.destroy();
        let window = this.native_window;
        this.display_link.take();
        unsafe {
            this.native_window.setDelegate_(nil);
        }
        this.input_handler.take();
        this.executor
            .spawn(async move {
                unsafe {
                    window.close();
                    window.autorelease();
                }
            })
            .detach();
    }
}

impl PlatformWindow for MacWindow {
    fn bounds(&self) -> Bounds<Pixels> {
        self.0.as_ref().lock().bounds()
    }

    fn window_bounds(&self) -> WindowBounds {
        self.0.as_ref().lock().window_bounds()
    }

    fn is_maximized(&self) -> bool {
        self.0.as_ref().lock().is_maximized()
    }

    fn content_size(&self) -> Size<Pixels> {
        self.0.as_ref().lock().content_size()
    }

    fn resize(&mut self, size: Size<Pixels>) {
        let this = self.0.lock();
        let window = this.native_window;
        this.executor
            .spawn(async move {
                unsafe {
                    window.setContentSize_(NSSize {
                        width: size.width.0 as f64,
                        height: size.height.0 as f64,
                    });
                }
            })
            .detach();
    }

    fn scale_factor(&self) -> f32 {
        self.0.as_ref().lock().scale_factor()
    }

    fn appearance(&self) -> WindowAppearance {
        unsafe {
            let appearance: id = msg_send![self.0.lock().native_window, effectiveAppearance];
            WindowAppearance::from_native(appearance)
        }
    }

    fn display(&self) -> Option<Rc<dyn PlatformDisplay>> {
        unsafe {
            let screen = self.0.lock().native_window.screen();
            if screen.is_null() {
                return None;
            }
            let device_description: id = msg_send![screen, deviceDescription];
            let screen_number: id = NSDictionary::valueForKey_(
                device_description,
                NSString::alloc(nil).init_str("NSScreenNumber"),
            );

            let screen_number: u32 = msg_send![screen_number, unsignedIntValue];

            Some(Rc::new(MacDisplay(screen_number)))
        }
    }

    fn mouse_position(&self) -> Point<Pixels> {
        let position = unsafe {
            self.0
                .lock()
                .native_window
                .mouseLocationOutsideOfEventStream()
        };
        convert_mouse_position(position, self.content_size().height)
    }

    fn modifiers(&self) -> Modifiers {
        unsafe {
            let modifiers: NSEventModifierFlags = msg_send![class!(NSEvent), modifierFlags];

            let control = modifiers.contains(NSEventModifierFlags::NSControlKeyMask);
            let alt = modifiers.contains(NSEventModifierFlags::NSAlternateKeyMask);
            let shift = modifiers.contains(NSEventModifierFlags::NSShiftKeyMask);
            let command = modifiers.contains(NSEventModifierFlags::NSCommandKeyMask);
            let function = modifiers.contains(NSEventModifierFlags::NSFunctionKeyMask);

            Modifiers {
                control,
                alt,
                shift,
                platform: command,
                function,
            }
        }
    }

    fn capslock(&self) -> Capslock {
        unsafe {
            let modifiers: NSEventModifierFlags = msg_send![class!(NSEvent), modifierFlags];

            Capslock {
                on: modifiers.contains(NSEventModifierFlags::NSAlphaShiftKeyMask),
            }
        }
    }

    fn set_input_handler(&mut self, input_handler: PlatformInputHandler) {
        self.0.as_ref().lock().input_handler = Some(input_handler);
    }

    fn take_input_handler(&mut self) -> Option<PlatformInputHandler> {
        self.0.as_ref().lock().input_handler.take()
    }

    fn prompt(
        &self,
        level: PromptLevel,
        msg: &str,
        detail: Option<&str>,
        answers: &[PromptButton],
    ) -> Option<oneshot::Receiver<usize>> {
        // macOs applies overrides to modal window buttons after they are added.
        // Two most important for this logic are:
        // * Buttons with "Cancel" title will be displayed as the last buttons in the modal
        // * Last button added to the modal via `addButtonWithTitle` stays focused
        // * Focused buttons react on "space"/" " keypresses
        // * Usage of `keyEquivalent`, `makeFirstResponder` or `setInitialFirstResponder` does not change the focus
        //
        // See also https://developer.apple.com/documentation/appkit/nsalert/1524532-addbuttonwithtitle#discussion
        // ```
        // By default, the first button has a key equivalent of Return,
        // any button with a title of “Cancel” has a key equivalent of Escape,
        // and any button with the title “Don’t Save” has a key equivalent of Command-D (but only if it’s not the first button).
        // ```
        //
        // To avoid situations when the last element added is "Cancel" and it gets the focus
        // (hence stealing both ESC and Space shortcuts), we find and add one non-Cancel button
        // last, so it gets focus and a Space shortcut.
        // This way, "Save this file? Yes/No/Cancel"-ish modals will get all three buttons mapped with a key.
        let latest_non_cancel_label = answers
            .iter()
            .enumerate()
            .rev()
            .find(|(_, label)| !label.is_cancel())
            .filter(|&(label_index, _)| label_index > 0);

        unsafe {
            let alert: id = msg_send![class!(NSAlert), alloc];
            let alert: id = msg_send![alert, init];
            let alert_style = match level {
                PromptLevel::Info => 1,
                PromptLevel::Warning => 0,
                PromptLevel::Critical => 2,
            };
            let _: () = msg_send![alert, setAlertStyle: alert_style];
            let _: () = msg_send![alert, setMessageText: ns_string(msg)];
            if let Some(detail) = detail {
                let _: () = msg_send![alert, setInformativeText: ns_string(detail)];
            }

            for (ix, answer) in answers
                .iter()
                .enumerate()
                .filter(|&(ix, _)| Some(ix) != latest_non_cancel_label.map(|(ix, _)| ix))
            {
                let button: id = msg_send![alert, addButtonWithTitle: ns_string(answer.label())];
                let _: () = msg_send![button, setTag: ix as NSInteger];

                if answer.is_cancel() {
                    // Bind Escape Key to Cancel Button
                    if let Some(key) = std::char::from_u32(super::events::ESCAPE_KEY as u32) {
                        let _: () =
                            msg_send![button, setKeyEquivalent: ns_string(&key.to_string())];
                    }
                }
            }
            if let Some((ix, answer)) = latest_non_cancel_label {
                let button: id = msg_send![alert, addButtonWithTitle: ns_string(answer.label())];
                let _: () = msg_send![button, setTag: ix as NSInteger];
            }

            let (done_tx, done_rx) = oneshot::channel();
            let done_tx = Cell::new(Some(done_tx));
            let block = ConcreteBlock::new(move |answer: NSInteger| {
                if let Some(done_tx) = done_tx.take() {
                    let _ = done_tx.send(answer.try_into().unwrap());
                }
            });
            let block = block.copy();
            let native_window = self.0.lock().native_window;
            let executor = self.0.lock().executor.clone();
            executor
                .spawn(async move {
                    let _: () = msg_send![
                        alert,
                        beginSheetModalForWindow: native_window
                        completionHandler: block
                    ];
                })
                .detach();

            Some(done_rx)
        }
    }

    fn activate(&self) {
        let window = self.0.lock().native_window;
        let executor = self.0.lock().executor.clone();
        executor
            .spawn(async move {
                unsafe {
                    let _: () = msg_send![window, makeKeyAndOrderFront: nil];
                }
            })
            .detach();
    }

    fn is_active(&self) -> bool {
        unsafe { self.0.lock().native_window.isKeyWindow() == YES }
    }

    // is_hovered is unused on macOS. See Window::is_window_hovered.
    fn is_hovered(&self) -> bool {
        false
    }

    fn set_title(&mut self, title: &str) {
        unsafe {
            let app = NSApplication::sharedApplication(nil);
            let window = self.0.lock().native_window;
            let title = ns_string(title);
            let _: () = msg_send![app, changeWindowsItem:window title:title filename:false];
            let _: () = msg_send![window, setTitle: title];
            self.0.lock().move_traffic_light();
        }
    }

    fn set_app_id(&mut self, _app_id: &str) {}

    fn set_background_appearance(&self, background_appearance: WindowBackgroundAppearance) {
        let mut this = self.0.as_ref().lock();

        let opaque = background_appearance == WindowBackgroundAppearance::Opaque;
        this.renderer.update_transparency(!opaque);

        unsafe {
            this.native_window.setOpaque_(opaque as BOOL);
            let background_color = if opaque {
                NSColor::colorWithSRGBRed_green_blue_alpha_(nil, 0f64, 0f64, 0f64, 1f64)
            } else {
                // Not using `+[NSColor clearColor]` to avoid broken shadow.
                NSColor::colorWithSRGBRed_green_blue_alpha_(nil, 0f64, 0f64, 0f64, 0.0001)
            };
            this.native_window.setBackgroundColor_(background_color);

            if NSAppKitVersionNumber < NSAppKitVersionNumber12_0 {
                // Whether `-[NSVisualEffectView respondsToSelector:@selector(_updateProxyLayer)]`.
                // On macOS Catalina/Big Sur `NSVisualEffectView` doesn’t own concrete sublayers
                // but uses a `CAProxyLayer`. Use the legacy WindowServer API.
                let blur_radius = if background_appearance == WindowBackgroundAppearance::Blurred {
                    80
                } else {
                    0
                };

                let window_number = this.native_window.windowNumber();
                CGSSetWindowBackgroundBlurRadius(CGSMainConnectionID(), window_number, blur_radius);
            } else {
                // On newer macOS `NSVisualEffectView` manages the effect layer directly. Using it
                // could have a better performance (it downsamples the backdrop) and more control
                // over the effect layer.
                if background_appearance != WindowBackgroundAppearance::Blurred {
                    if let Some(blur_view) = this.blurred_view {
                        NSView::removeFromSuperview(blur_view);
                        this.blurred_view = None;
                    }
                } else if this.blurred_view == None {
                    let content_view = this.native_window.contentView();
                    let frame = NSView::bounds(content_view);
                    let mut blur_view: id = msg_send![BLURRED_VIEW_CLASS, alloc];
                    blur_view = NSView::initWithFrame_(blur_view, frame);
                    blur_view.setAutoresizingMask_(NSViewWidthSizable | NSViewHeightSizable);

                    let _: () = msg_send![
                        content_view,
                        addSubview: blur_view
                        positioned: NSWindowOrderingMode::NSWindowBelow
                        relativeTo: nil
                    ];
                    this.blurred_view = Some(blur_view.autorelease());
                }
            }
        }
    }

    fn set_edited(&mut self, edited: bool) {
        unsafe {
            let window = self.0.lock().native_window;
            msg_send![window, setDocumentEdited: edited as BOOL]
        }

        // Changing the document edited state resets the traffic light position,
        // so we have to move it again.
        self.0.lock().move_traffic_light();
    }

    fn show_character_palette(&self) {
        let this = self.0.lock();
        let window = this.native_window;
        this.executor
            .spawn(async move {
                unsafe {
                    let app = NSApplication::sharedApplication(nil);
                    let _: () = msg_send![app, orderFrontCharacterPalette: window];
                }
            })
            .detach();
    }

    fn minimize(&self) {
        let window = self.0.lock().native_window;
        unsafe {
            window.miniaturize_(nil);
        }
    }

    fn zoom(&self) {
        let this = self.0.lock();
        let window = this.native_window;
        this.executor
            .spawn(async move {
                unsafe {
                    window.zoom_(nil);
                }
            })
            .detach();
    }

    fn toggle_fullscreen(&self) {
        let this = self.0.lock();
        let window = this.native_window;
        this.executor
            .spawn(async move {
                unsafe {
                    window.toggleFullScreen_(nil);
                }
            })
            .detach();
    }

    fn is_fullscreen(&self) -> bool {
        let this = self.0.lock();
        let window = this.native_window;

        unsafe {
            window
                .styleMask()
                .contains(NSWindowStyleMask::NSFullScreenWindowMask)
        }
    }

    fn on_request_frame(&self, callback: Box<dyn FnMut(RequestFrameOptions)>) {
        self.0.as_ref().lock().request_frame_callback = Some(callback);
    }

    fn on_input(&self, callback: Box<dyn FnMut(PlatformInput) -> crate::DispatchEventResult>) {
        self.0.as_ref().lock().event_callback = Some(callback);
    }

    fn on_active_status_change(&self, callback: Box<dyn FnMut(bool)>) {
        self.0.as_ref().lock().activate_callback = Some(callback);
    }

    fn on_hover_status_change(&self, _: Box<dyn FnMut(bool)>) {}

    fn on_resize(&self, callback: Box<dyn FnMut(Size<Pixels>, f32)>) {
        self.0.as_ref().lock().resize_callback = Some(callback);
    }

    fn on_moved(&self, callback: Box<dyn FnMut()>) {
        self.0.as_ref().lock().moved_callback = Some(callback);
    }

    fn on_should_close(&self, callback: Box<dyn FnMut() -> bool>) {
        self.0.as_ref().lock().should_close_callback = Some(callback);
    }

    fn on_close(&self, callback: Box<dyn FnOnce()>) {
        self.0.as_ref().lock().close_callback = Some(callback);
    }

    fn on_hit_test_window_control(&self, _callback: Box<dyn FnMut() -> Option<WindowControlArea>>) {
    }

    fn on_appearance_changed(&self, callback: Box<dyn FnMut()>) {
        self.0.lock().appearance_changed_callback = Some(callback);
    }

    fn draw(&self, scene: &crate::Scene) {
        let mut this = self.0.lock();
        this.renderer.draw(scene);
    }

    fn sprite_atlas(&self) -> Arc<dyn PlatformAtlas> {
        self.0.lock().renderer.sprite_atlas().clone()
    }

    fn gpu_specs(&self) -> Option<crate::GpuSpecs> {
        None
    }

    fn update_ime_position(&self, _bounds: Bounds<ScaledPixels>) {
        let executor = self.0.lock().executor.clone();
        executor
            .spawn(async move {
                unsafe {
                    let input_context: id =
                        msg_send![class!(NSTextInputContext), currentInputContext];
                    if input_context.is_null() {
                        return;
                    }
                    let _: () = msg_send![input_context, invalidateCharacterCoordinates];
                }
            })
            .detach()
    }

    fn titlebar_double_click(&self) {
        let this = self.0.lock();
        let window = this.native_window;
        this.executor
            .spawn(async move {
                unsafe {
                    let defaults: id = NSUserDefaults::standardUserDefaults();
                    let domain = NSString::alloc(nil).init_str("NSGlobalDomain");
                    let key = NSString::alloc(nil).init_str("AppleActionOnDoubleClick");

                    let dict: id = msg_send![defaults, persistentDomainForName: domain];
                    let action: id = if !dict.is_null() {
                        msg_send![dict, objectForKey: key]
                    } else {
                        nil
                    };

                    let action_str = if !action.is_null() {
                        CStr::from_ptr(NSString::UTF8String(action)).to_string_lossy()
                    } else {
                        "".into()
                    };

                    match action_str.as_ref() {
                        "Minimize" => {
                            window.miniaturize_(nil);
                        }
                        "Maximize" => {
                            window.zoom_(nil);
                        }
                        "Fill" => {
                            // There is no documented API for "Fill" action, so we'll just zoom the window
                            window.zoom_(nil);
                        }
                        _ => {
                            window.zoom_(nil);
                        }
                    }
                }
            })
            .detach();
    }
}

impl rwh::HasWindowHandle for MacWindow {
    fn window_handle(&self) -> Result<rwh::WindowHandle<'_>, rwh::HandleError> {
        // SAFETY: The AppKitWindowHandle is a wrapper around a pointer to an NSView
        unsafe {
            Ok(rwh::WindowHandle::borrow_raw(rwh::RawWindowHandle::AppKit(
                rwh::AppKitWindowHandle::new(self.0.lock().native_view.cast()),
            )))
        }
    }
}

impl rwh::HasDisplayHandle for MacWindow {
    fn display_handle(&self) -> Result<rwh::DisplayHandle<'_>, rwh::HandleError> {
        // SAFETY: This is a no-op on macOS
        unsafe {
            Ok(rwh::DisplayHandle::borrow_raw(
                rwh::AppKitDisplayHandle::new().into(),
            ))
        }
    }
}

fn get_scale_factor(native_window: id) -> f32 {
    let factor = unsafe {
        let screen: id = msg_send![native_window, screen];
        if screen.is_null() {
            return 1.0;
        }
        NSScreen::backingScaleFactor(screen) as f32
    };

    // We are not certain what triggers this, but it seems that sometimes
    // this method would return 0 (https://github.com/zed-industries/zed/issues/6412)
    // It seems most likely that this would happen if the window has no screen
    // (if it is off-screen), though we'd expect to see viewDidChangeBackingProperties before
    // it was rendered for real.
    // Regardless, attempt to avoid the issue here.
    if factor == 0.0 { 2. } else { factor }
}

unsafe fn get_window_state(object: &Object) -> Arc<Mutex<MacWindowState>> {
    unsafe {
        let raw: *mut c_void = *object.get_ivar(WINDOW_STATE_IVAR);
        let rc1 = Arc::from_raw(raw as *mut Mutex<MacWindowState>);
        let rc2 = rc1.clone();
        mem::forget(rc1);
        rc2
    }
}

unsafe fn drop_window_state(object: &Object) {
    unsafe {
        let raw: *mut c_void = *object.get_ivar(WINDOW_STATE_IVAR);
        Arc::from_raw(raw as *mut Mutex<MacWindowState>);
    }
}

extern "C" fn yes(_: &Object, _: Sel) -> BOOL {
    YES
}

extern "C" fn dealloc_window(this: &Object, _: Sel) {
    unsafe {
        drop_window_state(this);
        let _: () = msg_send![super(this, class!(NSWindow)), dealloc];
    }
}

extern "C" fn dealloc_view(this: &Object, _: Sel) {
    unsafe {
        drop_window_state(this);
        let _: () = msg_send![super(this, class!(NSView)), dealloc];
    }
}

extern "C" fn handle_key_equivalent(this: &Object, _: Sel, native_event: id) -> BOOL {
    handle_key_event(this, native_event, true)
}

extern "C" fn handle_key_down(this: &Object, _: Sel, native_event: id) {
    handle_key_event(this, native_event, false);
}

extern "C" fn handle_key_up(this: &Object, _: Sel, native_event: id) {
    handle_key_event(this, native_event, false);
}

// Things to test if you're modifying this method:
//  U.S. layout:
//   - The IME consumes characters like 'j' and 'k', which makes paging through `less` in
//     the terminal behave incorrectly by default. This behavior should be patched by our
//     IME integration
//   - `alt-t` should open the tasks menu
//   - In vim mode, this keybinding should work:
//     ```
//        {
//          "context": "Editor && vim_mode == insert",
//          "bindings": {"j j": "vim::NormalBefore"}
//        }
//     ```
//     and typing 'j k' in insert mode with this keybinding should insert the two characters
//  Brazilian layout:
//   - `" space` should create an unmarked quote
//   - `" backspace` should delete the marked quote
//   - `" "`should create an unmarked quote and a second marked quote
//   - `" up` should insert a quote, unmark it, and move up one line
//   - `" cmd-down` should insert a quote, unmark it, and move to the end of the file
//   - `cmd-ctrl-space` and clicking on an emoji should type it
//  Czech (QWERTY) layout:
//   - in vim mode `option-4`  should go to end of line (same as $)
//  Japanese (Romaji) layout:
//   - type `a i left down up enter enter` should create an unmarked text "愛"
extern "C" fn handle_key_event(this: &Object, native_event: id, key_equivalent: bool) -> BOOL {
    let window_state = unsafe { get_window_state(this) };
    let mut lock = window_state.as_ref().lock();

    let window_height = lock.content_size().height;
    let event = unsafe { PlatformInput::from_native(native_event, Some(window_height)) };

    let Some(event) = event else {
        return NO;
    };

    let run_callback = |event: PlatformInput| -> BOOL {
        let mut callback = window_state.as_ref().lock().event_callback.take();
        let handled: BOOL = if let Some(callback) = callback.as_mut() {
            !callback(event).propagate as BOOL
        } else {
            NO
        };
        window_state.as_ref().lock().event_callback = callback;
        handled
    };

    match event {
        PlatformInput::KeyDown(mut key_down_event) => {
            // For certain keystrokes, macOS will first dispatch a "key equivalent" event.
            // If that event isn't handled, it will then dispatch a "key down" event. GPUI
            // makes no distinction between these two types of events, so we need to ignore
            // the "key down" event if we've already just processed its "key equivalent" version.
            if key_equivalent {
                lock.last_key_equivalent = Some(key_down_event.clone());
            } else if lock.last_key_equivalent.take().as_ref() == Some(&key_down_event) {
                return NO;
            }

            drop(lock);

            let is_composing =
                with_input_handler(this, |input_handler| input_handler.marked_text_range())
                    .flatten()
                    .is_some();

            // If we're composing, send the key to the input handler first;
            // otherwise we only send to the input handler if we don't have a matching binding.
            // The input handler may call `do_command_by_selector` if it doesn't know how to handle
            // a key. If it does so, it will return YES so we won't send the key twice.
            // We also do this for non-printing keys (like arrow keys and escape) as the IME menu
            // may need them even if there is no marked text;
            // however we skip keys with control or the input handler adds control-characters to the buffer.
            // and keys with function, as the input handler swallows them.
            if is_composing
                || (key_down_event.keystroke.key_char.is_none()
                    && !key_down_event.keystroke.modifiers.control
                    && !key_down_event.keystroke.modifiers.function)
            {
                {
                    let mut lock = window_state.as_ref().lock();
                    lock.keystroke_for_do_command = Some(key_down_event.keystroke.clone());
                    lock.do_command_handled.take();
                    drop(lock);
                }

                let handled: BOOL = unsafe {
                    let input_context: id = msg_send![this, inputContext];
                    msg_send![input_context, handleEvent: native_event]
                };
                window_state.as_ref().lock().keystroke_for_do_command.take();
                if let Some(handled) = window_state.as_ref().lock().do_command_handled.take() {
                    return handled as BOOL;
                } else if handled == YES {
                    return YES;
                }

                let handled = run_callback(PlatformInput::KeyDown(key_down_event));
                return handled;
            }

            let handled = run_callback(PlatformInput::KeyDown(key_down_event.clone()));
            if handled == YES {
                return YES;
            }

            if key_down_event.is_held {
                if let Some(key_char) = key_down_event.keystroke.key_char.as_ref() {
                    let handled = with_input_handler(&this, |input_handler| {
                        if !input_handler.apple_press_and_hold_enabled() {
                            input_handler.replace_text_in_range(None, &key_char);
                            return YES;
                        }
                        NO
                    });
                    if handled == Some(YES) {
                        return YES;
                    }
                }
            }

            // Don't send key equivalents to the input handler,
            // or macOS shortcuts like cmd-` will stop working.
            if key_equivalent {
                return NO;
            }

            unsafe {
                let input_context: id = msg_send![this, inputContext];
                msg_send![input_context, handleEvent: native_event]
            }
        }

        PlatformInput::KeyUp(_) => {
            drop(lock);
            run_callback(event)
        }

        _ => NO,
    }
}

extern "C" fn handle_view_event(this: &Object, _: Sel, native_event: id) {
    let window_state = unsafe { get_window_state(this) };
    let weak_window_state = Arc::downgrade(&window_state);
    let mut lock = window_state.as_ref().lock();
    let window_height = lock.content_size().height;
    let event = unsafe { PlatformInput::from_native(native_event, Some(window_height)) };

    if let Some(mut event) = event {
        match &mut event {
            PlatformInput::MouseDown(
                event @ MouseDownEvent {
                    button: MouseButton::Left,
                    modifiers: Modifiers { control: true, .. },
                    ..
                },
            ) => {
                // On mac, a ctrl-left click should be handled as a right click.
                *event = MouseDownEvent {
                    button: MouseButton::Right,
                    modifiers: Modifiers {
                        control: false,
                        ..event.modifiers
                    },
                    click_count: 1,
                    ..*event
                };
            }

            // Handles focusing click.
            PlatformInput::MouseDown(
                event @ MouseDownEvent {
                    button: MouseButton::Left,
                    ..
                },
            ) if (lock.first_mouse) => {
                *event = MouseDownEvent {
                    first_mouse: true,
                    ..*event
                };
                lock.first_mouse = false;
            }

            // Because we map a ctrl-left_down to a right_down -> right_up let's ignore
            // the ctrl-left_up to avoid having a mismatch in button down/up events if the
            // user is still holding ctrl when releasing the left mouse button
            PlatformInput::MouseUp(
                event @ MouseUpEvent {
                    button: MouseButton::Left,
                    modifiers: Modifiers { control: true, .. },
                    ..
                },
            ) => {
                *event = MouseUpEvent {
                    button: MouseButton::Right,
                    modifiers: Modifiers {
                        control: false,
                        ..event.modifiers
                    },
                    click_count: 1,
                    ..*event
                };
            }

            _ => {}
        };

        match &event {
            PlatformInput::MouseDown(_) => {
                drop(lock);
                unsafe {
                    let input_context: id = msg_send![this, inputContext];
                    msg_send![input_context, handleEvent: native_event]
                }
                lock = window_state.as_ref().lock();
            }
            PlatformInput::MouseMove(
                event @ MouseMoveEvent {
                    pressed_button: Some(_),
                    ..
                },
            ) => {
                // Synthetic drag is used for selecting long buffer contents while buffer is being scrolled.
                // External file drag and drop is able to emit its own synthetic mouse events which will conflict
                // with these ones.
                if !lock.external_files_dragged {
                    lock.synthetic_drag_counter += 1;
                    let executor = lock.executor.clone();
                    executor
                        .spawn(synthetic_drag(
                            weak_window_state,
                            lock.synthetic_drag_counter,
                            event.clone(),
                        ))
                        .detach();
                }
            }

            PlatformInput::MouseUp(MouseUpEvent { .. }) => {
                lock.synthetic_drag_counter += 1;
            }

            PlatformInput::ModifiersChanged(ModifiersChangedEvent {
                modifiers,
                capslock,
            }) => {
                // Only raise modifiers changed event when they have actually changed
                if let Some(PlatformInput::ModifiersChanged(ModifiersChangedEvent {
                    modifiers: prev_modifiers,
                    capslock: prev_capslock,
                })) = &lock.previous_modifiers_changed_event
                {
                    if prev_modifiers == modifiers && prev_capslock == capslock {
                        return;
                    }
                }

                lock.previous_modifiers_changed_event = Some(event.clone());
            }

            _ => {}
        }

        if let Some(mut callback) = lock.event_callback.take() {
            drop(lock);
            callback(event);
            window_state.lock().event_callback = Some(callback);
        }
    }
}

extern "C" fn window_did_change_occlusion_state(this: &Object, _: Sel, _: id) {
    let window_state = unsafe { get_window_state(this) };
    let lock = &mut *window_state.lock();
    unsafe {
        if lock
            .native_window
            .occlusionState()
            .contains(NSWindowOcclusionState::NSWindowOcclusionStateVisible)
        {
            lock.start_display_link();
        } else {
            lock.stop_display_link();
        }
    }
}

extern "C" fn window_did_resize(this: &Object, _: Sel, _: id) {
    let window_state = unsafe { get_window_state(this) };
    window_state.as_ref().lock().move_traffic_light();
}

extern "C" fn window_will_enter_fullscreen(this: &Object, _: Sel, _: id) {
    let window_state = unsafe { get_window_state(this) };
    let mut lock = window_state.as_ref().lock();
    lock.fullscreen_restore_bounds = lock.bounds();

    let min_version = NSOperatingSystemVersion::new(15, 3, 0);

    if is_macos_version_at_least(min_version) {
        unsafe {
            lock.native_window.setTitlebarAppearsTransparent_(NO);
        }
    }
}

extern "C" fn window_will_exit_fullscreen(this: &Object, _: Sel, _: id) {
    let window_state = unsafe { get_window_state(this) };
    let mut lock = window_state.as_ref().lock();

    let min_version = NSOperatingSystemVersion::new(15, 3, 0);

    if is_macos_version_at_least(min_version) && lock.transparent_titlebar {
        unsafe {
            lock.native_window.setTitlebarAppearsTransparent_(YES);
        }
    }
}

pub(crate) fn is_macos_version_at_least(version: NSOperatingSystemVersion) -> bool {
    unsafe { NSProcessInfo::processInfo(nil).isOperatingSystemAtLeastVersion(version) }
}

extern "C" fn window_did_move(this: &Object, _: Sel, _: id) {
    let window_state = unsafe { get_window_state(this) };
    let mut lock = window_state.as_ref().lock();
    if let Some(mut callback) = lock.moved_callback.take() {
        drop(lock);
        callback();
        window_state.lock().moved_callback = Some(callback);
    }
}

extern "C" fn window_did_change_screen(this: &Object, _: Sel, _: id) {
    let window_state = unsafe { get_window_state(this) };
    let mut lock = window_state.as_ref().lock();
    lock.start_display_link();
}

extern "C" fn window_did_change_key_status(this: &Object, selector: Sel, _: id) {
    let window_state = unsafe { get_window_state(this) };
    let lock = window_state.lock();
    let is_active = unsafe { lock.native_window.isKeyWindow() == YES };

    // When opening a pop-up while the application isn't active, Cocoa sends a spurious
    // `windowDidBecomeKey` message to the previous key window even though that window
    // isn't actually key. This causes a bug if the application is later activated while
    // the pop-up is still open, making it impossible to activate the previous key window
    // even if the pop-up gets closed. The only way to activate it again is to de-activate
    // the app and re-activate it, which is a pretty bad UX.
    // The following code detects the spurious event and invokes `resignKeyWindow`:
    // in theory, we're not supposed to invoke this method manually but it balances out
    // the spurious `becomeKeyWindow` event and helps us work around that bug.
    if selector == sel!(windowDidBecomeKey:) && !is_active {
        unsafe {
            let _: () = msg_send![lock.native_window, resignKeyWindow];
            return;
        }
    }

    let executor = lock.executor.clone();
    drop(lock);
    executor
        .spawn(async move {
            let mut lock = window_state.as_ref().lock();
            if let Some(mut callback) = lock.activate_callback.take() {
                drop(lock);
                callback(is_active);
                window_state.lock().activate_callback = Some(callback);
            };
        })
        .detach();
}

extern "C" fn window_should_close(this: &Object, _: Sel, _: id) -> BOOL {
    let window_state = unsafe { get_window_state(this) };
    let mut lock = window_state.as_ref().lock();
    if let Some(mut callback) = lock.should_close_callback.take() {
        drop(lock);
        let should_close = callback();
        window_state.lock().should_close_callback = Some(callback);
        should_close as BOOL
    } else {
        YES
    }
}

extern "C" fn close_window(this: &Object, _: Sel) {
    unsafe {
        let close_callback = {
            let window_state = get_window_state(this);
            let mut lock = window_state.as_ref().lock();
            lock.close_callback.take()
        };

        if let Some(callback) = close_callback {
            callback();
        }

        let _: () = msg_send![super(this, class!(NSWindow)), close];
    }
}

extern "C" fn make_backing_layer(this: &Object, _: Sel) -> id {
    let window_state = unsafe { get_window_state(this) };
    let window_state = window_state.as_ref().lock();
    window_state.renderer.layer_ptr() as id
}

extern "C" fn view_did_change_backing_properties(this: &Object, _: Sel) {
    let window_state = unsafe { get_window_state(this) };
    let mut lock = window_state.as_ref().lock();

    let scale_factor = lock.scale_factor();
    let size = lock.content_size();
    let drawable_size = size.to_device_pixels(scale_factor);
    unsafe {
        let _: () = msg_send![
            lock.renderer.layer(),
            setContentsScale: scale_factor as f64
        ];
    }

    lock.renderer.update_drawable_size(drawable_size);

    if let Some(mut callback) = lock.resize_callback.take() {
        let content_size = lock.content_size();
        let scale_factor = lock.scale_factor();
        drop(lock);
        callback(content_size, scale_factor);
        window_state.as_ref().lock().resize_callback = Some(callback);
    };
}

extern "C" fn set_frame_size(this: &Object, _: Sel, size: NSSize) {
    let window_state = unsafe { get_window_state(this) };
    let mut lock = window_state.as_ref().lock();

    let new_size = Size::<Pixels>::from(size);
    let old_size = unsafe {
        let old_frame: NSRect = msg_send![this, frame];
        Size::<Pixels>::from(old_frame.size)
    };

    if old_size == new_size {
        return;
    }

    unsafe {
        let _: () = msg_send![super(this, class!(NSView)), setFrameSize: size];
    }

    let scale_factor = lock.scale_factor();
    let drawable_size = new_size.to_device_pixels(scale_factor);
    lock.renderer.update_drawable_size(drawable_size);

    if let Some(mut callback) = lock.resize_callback.take() {
        let content_size = lock.content_size();
        let scale_factor = lock.scale_factor();
        drop(lock);
        callback(content_size, scale_factor);
        window_state.lock().resize_callback = Some(callback);
    };
}

extern "C" fn display_layer(this: &Object, _: Sel, _: id) {
    let window_state = unsafe { get_window_state(this) };
    let mut lock = window_state.lock();
    if let Some(mut callback) = lock.request_frame_callback.take() {
        #[cfg(not(feature = "macos-blade"))]
        lock.renderer.set_presents_with_transaction(true);
        lock.stop_display_link();
        drop(lock);
        callback(Default::default());

        let mut lock = window_state.lock();
        lock.request_frame_callback = Some(callback);
        #[cfg(not(feature = "macos-blade"))]
        lock.renderer.set_presents_with_transaction(false);
        lock.start_display_link();
    }
}

unsafe extern "C" fn step(view: *mut c_void) {
    let view = view as id;
    let window_state = unsafe { get_window_state(&*view) };
    let mut lock = window_state.lock();

    if let Some(mut callback) = lock.request_frame_callback.take() {
        drop(lock);
        callback(Default::default());
        window_state.lock().request_frame_callback = Some(callback);
    }
}

extern "C" fn valid_attributes_for_marked_text(_: &Object, _: Sel) -> id {
    unsafe { msg_send![class!(NSArray), array] }
}

extern "C" fn has_marked_text(this: &Object, _: Sel) -> BOOL {
    let has_marked_text_result =
        with_input_handler(this, |input_handler| input_handler.marked_text_range()).flatten();

    has_marked_text_result.is_some() as BOOL
}

extern "C" fn marked_range(this: &Object, _: Sel) -> NSRange {
    let marked_range_result =
        with_input_handler(this, |input_handler| input_handler.marked_text_range()).flatten();

    marked_range_result.map_or(NSRange::invalid(), |range| range.into())
}

extern "C" fn selected_range(this: &Object, _: Sel) -> NSRange {
    let selected_range_result = with_input_handler(this, |input_handler| {
        input_handler.selected_text_range(false)
    })
    .flatten();

    selected_range_result.map_or(NSRange::invalid(), |selection| selection.range.into())
}

extern "C" fn first_rect_for_character_range(
    this: &Object,
    _: Sel,
    range: NSRange,
    _: id,
) -> NSRect {
    let frame = get_frame(this);
    with_input_handler(this, |input_handler| {
        input_handler.bounds_for_range(range.to_range()?)
    })
    .flatten()
    .map_or(
        NSRect::new(NSPoint::new(0., 0.), NSSize::new(0., 0.)),
        |bounds| {
            NSRect::new(
                NSPoint::new(
                    frame.origin.x + bounds.origin.x.0 as f64,
                    frame.origin.y + frame.size.height
                        - bounds.origin.y.0 as f64
                        - bounds.size.height.0 as f64,
                ),
                NSSize::new(bounds.size.width.0 as f64, bounds.size.height.0 as f64),
            )
        },
    )
}

fn get_frame(this: &Object) -> NSRect {
    unsafe {
        let state = get_window_state(this);
        let lock = state.lock();
        let mut frame = NSWindow::frame(lock.native_window);
        let content_layout_rect: CGRect = msg_send![lock.native_window, contentLayoutRect];
        let style_mask: NSWindowStyleMask = msg_send![lock.native_window, styleMask];
        if !style_mask.contains(NSWindowStyleMask::NSFullSizeContentViewWindowMask) {
            frame.origin.y -= frame.size.height - content_layout_rect.size.height;
        }
        frame
    }
}

extern "C" fn insert_text(this: &Object, _: Sel, text: id, replacement_range: NSRange) {
    unsafe {
        let is_attributed_string: BOOL =
            msg_send![text, isKindOfClass: [class!(NSAttributedString)]];
        let text: id = if is_attributed_string == YES {
            msg_send![text, string]
        } else {
            text
        };

        let text = text.to_str();
        let replacement_range = replacement_range.to_range();
        with_input_handler(this, |input_handler| {
            input_handler.replace_text_in_range(replacement_range, &text)
        });
    }
}

extern "C" fn set_marked_text(
    this: &Object,
    _: Sel,
    text: id,
    selected_range: NSRange,
    replacement_range: NSRange,
) {
    unsafe {
        let is_attributed_string: BOOL =
            msg_send![text, isKindOfClass: [class!(NSAttributedString)]];
        let text: id = if is_attributed_string == YES {
            msg_send![text, string]
        } else {
            text
        };
        let selected_range = selected_range.to_range();
        let replacement_range = replacement_range.to_range();
        let text = text.to_str();
        with_input_handler(this, |input_handler| {
            input_handler.replace_and_mark_text_in_range(replacement_range, &text, selected_range)
        });
    }
}
extern "C" fn unmark_text(this: &Object, _: Sel) {
    with_input_handler(this, |input_handler| input_handler.unmark_text());
}

extern "C" fn attributed_substring_for_proposed_range(
    this: &Object,
    _: Sel,
    range: NSRange,
    actual_range: *mut c_void,
) -> id {
    with_input_handler(this, |input_handler| {
        let range = range.to_range()?;
        if range.is_empty() {
            return None;
        }
        let mut adjusted: Option<Range<usize>> = None;

        let selected_text = input_handler.text_for_range(range.clone(), &mut adjusted)?;
        if let Some(adjusted) = adjusted {
            if adjusted != range {
                unsafe { (actual_range as *mut NSRange).write(NSRange::from(adjusted)) };
            }
        }
        unsafe {
            let string: id = msg_send![class!(NSAttributedString), alloc];
            let string: id = msg_send![string, initWithString: ns_string(&selected_text)];
            Some(string)
        }
    })
    .flatten()
    .unwrap_or(nil)
}

// We ignore which selector it asks us to do because the user may have
// bound the shortcut to something else.
extern "C" fn do_command_by_selector(this: &Object, _: Sel, _: Sel) {
    let state = unsafe { get_window_state(this) };
    let mut lock = state.as_ref().lock();
    let keystroke = lock.keystroke_for_do_command.take();
    let mut event_callback = lock.event_callback.take();
    drop(lock);

    if let Some((keystroke, mut callback)) = keystroke.zip(event_callback.as_mut()) {
        let handled = (callback)(PlatformInput::KeyDown(KeyDownEvent {
            keystroke,
            is_held: false,
        }));
        state.as_ref().lock().do_command_handled = Some(!handled.propagate);
    }

    state.as_ref().lock().event_callback = event_callback;
}

extern "C" fn view_did_change_effective_appearance(this: &Object, _: Sel) {
    unsafe {
        let state = get_window_state(this);
        let mut lock = state.as_ref().lock();
        if let Some(mut callback) = lock.appearance_changed_callback.take() {
            drop(lock);
            callback();
            state.lock().appearance_changed_callback = Some(callback);
        }
    }
}

extern "C" fn accepts_first_mouse(this: &Object, _: Sel, _: id) -> BOOL {
    let window_state = unsafe { get_window_state(this) };
    let mut lock = window_state.as_ref().lock();
    lock.first_mouse = true;
    YES
}

extern "C" fn character_index_for_point(this: &Object, _: Sel, position: NSPoint) -> u64 {
    let position = screen_point_to_gpui_point(this, position);
    with_input_handler(this, |input_handler| {
        input_handler.character_index_for_point(position)
    })
    .flatten()
    .map(|index| index as u64)
    .unwrap_or(NSNotFound as u64)
}

fn screen_point_to_gpui_point(this: &Object, position: NSPoint) -> Point<Pixels> {
    let frame = get_frame(this);
    let window_x = position.x - frame.origin.x;
    let window_y = frame.size.height - (position.y - frame.origin.y);
    let position = point(px(window_x as f32), px(window_y as f32));
    position
}

extern "C" fn dragging_entered(this: &Object, _: Sel, dragging_info: id) -> NSDragOperation {
    let window_state = unsafe { get_window_state(this) };
    let position = drag_event_position(&window_state, dragging_info);
    let paths = external_paths_from_event(dragging_info);
    if let Some(event) =
        paths.map(|paths| PlatformInput::FileDrop(FileDropEvent::Entered { position, paths }))
    {
        if send_new_event(&window_state, event) {
            window_state.lock().external_files_dragged = true;
            return NSDragOperationCopy;
        }
    }
    NSDragOperationNone
}

extern "C" fn dragging_updated(this: &Object, _: Sel, dragging_info: id) -> NSDragOperation {
    let window_state = unsafe { get_window_state(this) };
    let position = drag_event_position(&window_state, dragging_info);
    if send_new_event(
        &window_state,
        PlatformInput::FileDrop(FileDropEvent::Pending { position }),
    ) {
        NSDragOperationCopy
    } else {
        NSDragOperationNone
    }
}

extern "C" fn dragging_exited(this: &Object, _: Sel, _: id) {
    let window_state = unsafe { get_window_state(this) };
    send_new_event(
        &window_state,
        PlatformInput::FileDrop(FileDropEvent::Exited),
    );
    window_state.lock().external_files_dragged = false;
}

extern "C" fn perform_drag_operation(this: &Object, _: Sel, dragging_info: id) -> BOOL {
    let window_state = unsafe { get_window_state(this) };
    let position = drag_event_position(&window_state, dragging_info);
    send_new_event(
        &window_state,
        PlatformInput::FileDrop(FileDropEvent::Submit { position }),
    )
    .to_objc()
}

fn external_paths_from_event(dragging_info: *mut Object) -> Option<ExternalPaths> {
    let mut paths = SmallVec::new();
    let pasteboard: id = unsafe { msg_send![dragging_info, draggingPasteboard] };
    let filenames = unsafe { NSPasteboard::propertyListForType(pasteboard, NSFilenamesPboardType) };
    if filenames == nil {
        return None;
    }
    for file in unsafe { filenames.iter() } {
        let path = unsafe {
            let f = NSString::UTF8String(file);
            CStr::from_ptr(f).to_string_lossy().into_owned()
        };
        paths.push(PathBuf::from(path))
    }
    Some(ExternalPaths(paths))
}

extern "C" fn conclude_drag_operation(this: &Object, _: Sel, _: id) {
    let window_state = unsafe { get_window_state(this) };
    send_new_event(
        &window_state,
        PlatformInput::FileDrop(FileDropEvent::Exited),
    );
}

async fn synthetic_drag(
    window_state: Weak<Mutex<MacWindowState>>,
    drag_id: usize,
    event: MouseMoveEvent,
) {
    loop {
        Timer::after(Duration::from_millis(16)).await;
        if let Some(window_state) = window_state.upgrade() {
            let mut lock = window_state.lock();
            if lock.synthetic_drag_counter == drag_id {
                if let Some(mut callback) = lock.event_callback.take() {
                    drop(lock);
                    callback(PlatformInput::MouseMove(event.clone()));
                    window_state.lock().event_callback = Some(callback);
                }
            } else {
                break;
            }
        }
    }
}

fn send_new_event(window_state_lock: &Mutex<MacWindowState>, e: PlatformInput) -> bool {
    let window_state = window_state_lock.lock().event_callback.take();
    if let Some(mut callback) = window_state {
        callback(e);
        window_state_lock.lock().event_callback = Some(callback);
        true
    } else {
        false
    }
}

fn drag_event_position(window_state: &Mutex<MacWindowState>, dragging_info: id) -> Point<Pixels> {
    let drag_location: NSPoint = unsafe { msg_send![dragging_info, draggingLocation] };
    convert_mouse_position(drag_location, window_state.lock().content_size().height)
}

fn with_input_handler<F, R>(window: &Object, f: F) -> Option<R>
where
    F: FnOnce(&mut PlatformInputHandler) -> R,
{
    let window_state = unsafe { get_window_state(window) };
    let mut lock = window_state.as_ref().lock();
    if let Some(mut input_handler) = lock.input_handler.take() {
        drop(lock);
        let result = f(&mut input_handler);
        window_state.lock().input_handler = Some(input_handler);
        Some(result)
    } else {
        None
    }
}

unsafe fn display_id_for_screen(screen: id) -> CGDirectDisplayID {
    unsafe {
        let device_description = NSScreen::deviceDescription(screen);
        let screen_number_key: id = NSString::alloc(nil).init_str("NSScreenNumber");
        let screen_number = device_description.objectForKey_(screen_number_key);
        let screen_number: NSUInteger = msg_send![screen_number, unsignedIntegerValue];
        screen_number as CGDirectDisplayID
    }
}

extern "C" fn blurred_view_init_with_frame(this: &Object, _: Sel, frame: NSRect) -> id {
    unsafe {
        let view = msg_send![super(this, class!(NSVisualEffectView)), initWithFrame: frame];
        // Use a colorless semantic material. The default value `AppearanceBased`, though not
        // manually set, is deprecated.
        NSVisualEffectView::setMaterial_(view, NSVisualEffectMaterial::Selection);
        NSVisualEffectView::setState_(view, NSVisualEffectState::Active);
        view
    }
}

extern "C" fn blurred_view_update_layer(this: &Object, _: Sel) {
    unsafe {
        let _: () = msg_send![super(this, class!(NSVisualEffectView)), updateLayer];
        let layer: id = msg_send![this, layer];
        if !layer.is_null() {
            remove_layer_background(layer);
        }
    }
}

unsafe fn remove_layer_background(layer: id) {
    unsafe {
        let _: () = msg_send![layer, setBackgroundColor:nil];

        let class_name: id = msg_send![layer, className];
        if class_name.isEqualToString("CAChameleonLayer") {
            // Remove the desktop tinting effect.
            let _: () = msg_send![layer, setHidden: YES];
            return;
        }

        let filters: id = msg_send![layer, filters];
        if !filters.is_null() {
            // Remove the increased saturation.
            // The effect of a `CAFilter` or `CIFilter` is determined by its name, and the
            // `description` reflects its name and some parameters. Currently `NSVisualEffectView`
            // uses a `CAFilter` named "colorSaturate". If one day they switch to `CIFilter`, the
            // `description` will still contain "Saturat" ("... inputSaturation = ...").
            let test_string: id = NSString::alloc(nil).init_str("Saturat").autorelease();
            let count = NSArray::count(filters);
            for i in 0..count {
                let description: id = msg_send![filters.objectAtIndex(i), description];
                let hit: BOOL = msg_send![description, containsString: test_string];
                if hit == NO {
                    continue;
                }

                let all_indices = NSRange {
                    location: 0,
                    length: count,
                };
                let indices: id = msg_send![class!(NSMutableIndexSet), indexSet];
                let _: () = msg_send![indices, addIndexesInRange: all_indices];
                let _: () = msg_send![indices, removeIndex:i];
                let filtered: id = msg_send![filters, objectsAtIndexes: indices];
                let _: () = msg_send![layer, setFilters: filtered];
                break;
            }
        }

        let sublayers: id = msg_send![layer, sublayers];
        if !sublayers.is_null() {
            let count = NSArray::count(sublayers);
            for i in 0..count {
                let sublayer = sublayers.objectAtIndex(i);
                remove_layer_background(sublayer);
            }
        }
    }
}
