//////////////////////////////////////////////////////////////////////////////
//
// Copyright (c) 2004-2021 musikcube team
//
// All rights reserved.
//
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are met:
//
//    * Redistributions of source code must retain the above copyright notice,
//      this list of conditions and the following disclaimer.
//
//    * Redistributions in binary form must reproduce the above copyright
//      notice, this list of conditions and the following disclaimer in the
//      documentation and/or other materials provided with the distribution.
//
//    * Neither the name of the author nor the names of other contributors may
//      be used to endorse or promote products derived from this software
//      without specific prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
// AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
// IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
// ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
// LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
// CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
// SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
// INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
// CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
// ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
// POSSIBILITY OF SUCH DAMAGE.
//
//////////////////////////////////////////////////////////////////////////////

#include <stdafx.h>
#include <cursespp/Window.h>
#include <cursespp/IWindowGroup.h>
#include <cursespp/IInput.h>
#include <cursespp/ILayout.h>
#include <cursespp/Colors.h>
#include <cursespp/Screen.h>
#include <cursespp/Text.h>

#include <musikcore/runtime/Message.h>
#include <musikcore/runtime/MessageQueue.h>

#include <cassert>

using namespace cursespp;
using namespace musik::core::runtime;

static int NEXT_ID = 0;

static bool drawPending = false;
static bool freeze = false;
static Window* top = nullptr;
static Window* focused = nullptr;
static bool cursorVisible = false;

static MessageQueue messageQueue;
static std::shared_ptr<INavigationKeys> keys;

#if defined(DEBUG) || defined(_DEBUG)
    #ifdef WIN32
        static DWORD mainThreadId = GetCurrentThreadId();
        #define ASSERT_MAIN_THREAD() assert(GetCurrentThreadId() == mainThreadId);
    #else
        static pthread_t mainThreadId = pthread_self();
        #define ASSERT_MAIN_THREAD() assert(pthread_self() == mainThreadId);
    #endif
#else
    #define ASSERT_MAIN_THREAD()
#endif

const int Window::kLastReservedMessageId = INT_MAX;
const int Window::kFirstReservedMessageId = kLastReservedMessageId - 1024;
static const int kNotifyVisibilityChangedMessageId = Window::kFirstReservedMessageId + 1;

#define ENABLE_BOUNDS_CHECK 1

/* clangen says: we used to just be able to call wbkgd() prior to ncurses 6.2;
however, something changed internally that causes the drawing to get corrupted
if we don't call wbkgdset() first. this looks like a bug, and the release notes
mention wbkgd() was changed, but it's unclear what exactly happened... */
#ifndef WIN32
    #define wbkgd_internal(window, color) \
        wbkgdset(window, color); \
        wbkgd(window, color);
#else
    #define wbkgd_internal(window, color) \
        wbkgd(window, color);
#endif

static inline void DrawCursor(IInput* input) {
    if (input) {
        const Window* inputWindow = dynamic_cast<Window*>(input);
        if (inputWindow && inputWindow->GetContent()) {
            if (!cursorVisible) {
                curs_set(1);
                cursorVisible = true;
            }
            WINDOW* content = inputWindow->GetContent();
            if (content) {
                wtimeout(content, IDLE_TIMEOUT_MS);
                const int targetY = 0;
                const int targetX = (int) input->Position();
                wmove(content, targetY, targetX);
                wnoutrefresh(content);
            }
            return;
        }
    }
    if (cursorVisible) {
        curs_set(0);
        cursorVisible = false;
    }
}

static inline void DrawTooSmall() {
    static const std::string error = "terminal too small";
    int64_t color = Color(Color::TextError);
    wclear(stdscr);
    wmove(stdscr, 0, 0);
    wattron(stdscr, color);
    waddstr(stdscr, error.c_str());
    wattroff(stdscr, color);
}

bool Window::WriteToScreen(IInput* input) {
    ASSERT_MAIN_THREAD();

    if (drawPending && !freeze) {
        drawPending = false;
        update_panels();
        DrawCursor(input);
        doupdate();
        return true;
    }
    else if (freeze) {
        drawPending = false;
        DrawTooSmall();
    }

    return false;
}

void Window::InvalidateScreen() {
    ASSERT_MAIN_THREAD();

    werase(stdscr);
    drawPending = true;
}

void Window::Freeze() {
    if (!freeze) {
        freeze = true;
        Window::InvalidateScreen();
    }
}

void Window::Unfreeze() {
    if (freeze) {
        freeze = false;
        Window::InvalidateScreen();
    }
}

IMessageQueue& Window::MessageQueue() {
    return messageQueue;
}

Window::Window(IWindow *parent) {
    this->frame = this->content = 0;
    this->framePanel = this->contentPanel = 0;
    this->parent = parent;
    this->height = 0;
    this->width = 0;
    this->x = 0;
    this->y = 0;
    this->lastAbsoluteX = 0;
    this->lastAbsoluteY = 0;
    this->contentColor = Color(Color::ContentColorDefault);
    this->frameColor = Color(Color::FrameDefault);
    this->focusedContentColor = Color(Color::ContentColorDefault);
    this->focusedFrameColor = Color(Color::FrameFocused);
    this->drawFrame = true;
    this->isVisibleInParent = false;
    this->isDirty = true;
    this->focusOrder = -1;
    this->id = NEXT_ID++;
    this->badBounds = false;
    Window::MessageQueue().Register(this);
}

Window::~Window() {
    Window::MessageQueue().Unregister(this);
    if (::top == this) { top = nullptr; }
    if (::focused == this) { focused = nullptr; }
    this->Destroy();
}

int Window::GetId() const {
    return this->id;
}

void Window::ProcessMessage(musik::core::runtime::IMessage &message) {
    if (message.Type() == kNotifyVisibilityChangedMessageId) {
        bool becameVisible = message.UserData1() != 0LL;
        if (becameVisible != this->lastNotifiedVisible) {
            this->lastNotifiedVisible = becameVisible;
            this->OnVisibilityChanged(becameVisible);
            if (this->parent) {
                this->parent->OnChildVisibilityChanged(becameVisible, this);
            }
        }
    }
}

bool Window::IsVisible() {
    ASSERT_MAIN_THREAD();

    return !this->badBounds && this->isVisibleInParent;
}

bool Window::IsFocused() {
    ASSERT_MAIN_THREAD();

    return ::focused == this;
}

void Window::BringToTop() {
    ASSERT_MAIN_THREAD();

    if (this->framePanel) {
        top_panel(this->framePanel);

        if (this->contentPanel && this->contentPanel != this->framePanel) {
            top_panel(this->contentPanel);
        }

        ::top = this;
    }
}

bool Window::IsTop() {
    ASSERT_MAIN_THREAD();

    return (::top == this);
}

void Window::SendToBottom() {
    ASSERT_MAIN_THREAD();

    if (this->framePanel) {
        bottom_panel(this->contentPanel);

        if (this->contentPanel != this->framePanel) {
            bottom_panel(this->framePanel);
        }
    }
}

void Window::Post(int messageType, int64_t user1, int64_t user2, int64_t delay) {
    messageQueue.Post(Message::Create(this, messageType, user1, user2), delay);
}

void Window::Broadcast(int messageType, int64_t user1, int64_t user2, int64_t delay) {
    messageQueue.Broadcast(Message::Create(nullptr, messageType, user1, user2), delay);
}

void Window::Debounce(int messageType, int64_t user1, int64_t user2, int64_t delay) {
    messageQueue.Debounce(Message::Create(this, messageType, user1, user2), delay);
}

void Window::Remove(int messageType) {
    messageQueue.Remove(this, messageType);
}

void Window::SetParent(IWindow* parent) {
    ASSERT_MAIN_THREAD();

    if (this->parent != parent) {
        IWindowGroup* group = dynamic_cast<IWindowGroup*>(this->parent);
        IWindow* oldParent = this->parent;
        bool visible = !!this->frame;

        if (visible) {
            this->Hide();
        }

        this->parent = parent;

        if (this->parent && visible) {
            this->Show();
        }

        if (parent) {
            this->OnAddedToParent(parent);
        }
        else {
            this->OnRemovedFromParent(oldParent);
        }
    }
}

void Window::RecreateForUpdatedDimensions() {
    this->Recreate();
    this->NotifyVisibilityChange(true);
    this->OnDimensionsChanged();
}

void Window::MoveAndResize(int x, int y, int width, int height) {
    ASSERT_MAIN_THREAD();

    bool sizeChanged = this->width != width || this->height != height;

    this->x = x;
    this->y = y;
    int absX = this->GetAbsoluteX();
    int absY = this->GetAbsoluteY();

    bool positionChanged =
        absX != this->lastAbsoluteX ||
        absY != this->lastAbsoluteY;

    if (sizeChanged || positionChanged || this->badBounds || !this->content) {
        this->lastAbsoluteX = absX;
        this->lastAbsoluteY = absY;
        this->width = width;
        this->height = height;
        if (this->isVisibleInParent) {
            this->RecreateForUpdatedDimensions();
        }
    }
    else {
        this->DestroyIfBadBounds();
    }
}

void Window::DestroyIfBadBounds() {
    if (this->CheckForBoundsError()) {
        this->badBounds = true;
        this->Destroy();
    }
}

void Window::SetSize(int width, int height) {
    ASSERT_MAIN_THREAD();

    if (this->width != width || this->height != height) {
        this->width = width;
        this->height = height;
        this->RecreateForUpdatedDimensions();
    }
    else {
        this->DestroyIfBadBounds();
    }
}

void Window::SetPosition(int x, int y) {
    ASSERT_MAIN_THREAD();

    this->x = x;
    this->y = y;
    int absX = this->GetAbsoluteX();
    int absY = this->GetAbsoluteY();

    if (absX != this->lastAbsoluteX || absY != this->lastAbsoluteY) {
        this->lastAbsoluteX = absX;
        this->lastAbsoluteY = absY;
        this->RecreateForUpdatedDimensions();
    }
    else {
        this->DestroyIfBadBounds();
    }
}

void Window::OnDimensionsChanged() {
    this->Invalidate();
}

void Window::OnVisibilityChanged(bool visible) {
    /* for subclass use */
}

void Window::OnFocusChanged(bool focused) {
    /* for subclass use */
}

void Window::OnRedraw() {
    /* for subclass use */
}

void Window::OnAddedToParent(IWindow* newParent) {
    /* for subclass use */
}

void Window::OnRemovedFromParent(IWindow* oldParent) {
    /* for subclass use */
}

void Window::OnChildVisibilityChanged(bool visible, IWindow* child) {
    /* for subclass use */
}

void Window::DecorateFrame() {
    /* for subclass use */
}

void Window::Redraw() {
    ASSERT_MAIN_THREAD();

    this->isDirty = true;

    if (this->IsVisible() && this->IsParentVisible()) {
        if (this->parent && !this->parent->IsVisible()) {
            return;
        }

        if (!this->frame) {
            this->Create();
        }

        if (this->frame) {
#if defined(__FreeBSD__) || (NCURSES_VERSION_PATCH >= 20200301)
            /* but depending on curses version we'll get redraw artifacts if we do or don't
            repaint the background. the changelog mentions changes to wbkgd() and wbkgrnd()
            at revision 20200301, but it's unclear if this is the actual root cause or not. */
            this->RepaintBackground();
#endif
            this->OnRedraw();
            this->Invalidate();
            this->isDirty = false;
            return;
        }
    }
}

int Window::GetWidth() const {
    ASSERT_MAIN_THREAD();

    return this->width;
}

int Window::GetHeight() const {
    ASSERT_MAIN_THREAD();

    return this->height;
}

int Window::GetContentHeight() const {
    ASSERT_MAIN_THREAD();

    if (!this->drawFrame) {
        return this->height;
    }

    return this->height ? this->height - 2 : 0;
}

int Window::GetContentWidth() const {
    ASSERT_MAIN_THREAD();

    if (!this->drawFrame) {
        return this->width;
    }

    return this->width ? this->width - 2 : 0;
}

int Window::GetX() const {
    ASSERT_MAIN_THREAD();

    return this->x;
}

int Window::GetY() const {
    ASSERT_MAIN_THREAD();

    return this->y;
}

void Window::SetContentColor(Color color) {
    ASSERT_MAIN_THREAD();

    this->contentColor = (color == Color::Default)
        ? Color::ContentColorDefault : color;

    this->RepaintBackground();
    this->Redraw();
}

void Window::SetFocusedContentColor(Color color) {
    ASSERT_MAIN_THREAD();

    this->focusedContentColor = (color == Color::Default)
        ? Color::ContentColorDefault : color;

    this->RepaintBackground();
    this->Redraw();
}

void Window::SetFrameColor(Color color) {
    ASSERT_MAIN_THREAD();

    this->frameColor = (color == Color::Default)
        ? Color::FrameDefault : color;

    this->RepaintBackground();
    this->Redraw();
}

void Window::SetFocusedFrameColor(Color color) {
    ASSERT_MAIN_THREAD();

    this->focusedFrameColor = (color == Color::Default)
        ? Color::FrameFocused : color;

    this->RepaintBackground();
    this->Redraw();
}

void Window::DrawFrameAndTitle() {
    ASSERT_MAIN_THREAD();

    box(this->frame, 0, 0);

    /* draw the title, if one is specified */
    size_t titleLen = u8len(this->title);
    if (titleLen > 0) {
        int max = this->width - 4; /* 4 = corner + space + space + corner */
        if (max > 3) { /* 3 = first character plus ellipse (e.g. 'F..')*/
            std::string adjusted = " " + text::Ellipsize(this->title, (size_t) max - 2) + " ";
            wmove(this->frame, 0, 2);
            checked_waddstr(this->frame, adjusted.c_str());
        }
    }

    this->DecorateFrame();
}

void Window::RepaintBackground() {
    ASSERT_MAIN_THREAD();

    bool focused = IsFocused();

    if (this->drawFrame &&
        this->frameColor != Color::Default &&
        this->frame &&
        this->content != this->frame)
    {
        werase(this->frame);
        wbkgd_internal(this->frame, focused? this->focusedFrameColor : this->frameColor);
        this->DrawFrameAndTitle();
    }

    if (this->content) {
        werase(this->content);
        wbkgd_internal(this->content, focused ? this->focusedContentColor : this->contentColor);
    }

    this->Invalidate();
}

WINDOW* Window::GetContent() const {
    ASSERT_MAIN_THREAD();

    return this->content;
}

WINDOW* Window::GetFrame() const {
    ASSERT_MAIN_THREAD();

    return this->frame;
}

int Window::GetFocusOrder() {
    ASSERT_MAIN_THREAD();

    return this->focusOrder;
}

void Window::SetFocusOrder(int order) {
    ASSERT_MAIN_THREAD();

    this->focusOrder = order;
}

void Window::Show() {
    ASSERT_MAIN_THREAD();

    if (parent && !parent->IsVisible()) {
        /* remember that someone tried to make us visible, but don't do
        anything because we could corrupt the display */
        this->isVisibleInParent = true;
        this->NotifyVisibilityChange(false);
        return;
    }

    if (this->badBounds) {
        if (!this->CheckForBoundsError()) {
            this->Recreate();
            this->badBounds = false;
        }
        this->isVisibleInParent = true;
        this->NotifyVisibilityChange(false);
    }
    else {
        if (this->framePanel) {
            if (!this->isVisibleInParent) {
                show_panel(this->framePanel);

                if (this->contentPanel && this->framePanel != this->contentPanel) {
                    show_panel(this->contentPanel);
                }

                this->isVisibleInParent = true;
                drawPending = true;
            }
        }
        else {
            this->RecreateForUpdatedDimensions();
            this->isVisibleInParent = true;
        }

        if (this->isDirty) {
            this->Redraw();
        }

        this->NotifyVisibilityChange(true);
    }
}

void Window::Recreate() {
    this->Destroy();
    this->Create();
}

void Window::OnParentVisibilityChanged(bool visible) {
    if (!visible && this->isVisibleInParent) {
        if (this->framePanel) {
            this->Destroy();
        }
    }
    else if (visible && this->isVisibleInParent) {
        if (this->framePanel) {
            this->Redraw();
        }
        else {
            this->Recreate();
        }
    }
}

bool Window::CheckForBoundsError() {
    if (this->parent && ((Window *) this->parent)->CheckForBoundsError()) {
        return true;
    }

    int const screenCy = Screen::GetHeight();
    int const screenCx = Screen::GetWidth();

    int const cx = this->GetWidth();
    int const cy = this->GetHeight();

    if (cx <= 0 || cy <= 0) {
        return true;
    }

    if (cx > screenCx || cy > screenCy) {
        return true;
    }

    if (this->drawFrame && (cx < 3 || cy < 3)) {
        /* if a frame is visible, the minimum x and y dimensions are
        2 cells -- the left+right (and top+bottom) border, plus the
        content area (at least 1 cell) */
        return true;
    }

    if (!this->parent) {
        return false;
    }

    const int parentWidth = this->parent->GetContentWidth();
    const int parentHeight = this->parent->GetContentHeight();

    if (this->width > parentWidth || this->height > parentHeight) {
        return true;
    }

    const int right = this->x + cx;
    const int bottom = this->y + cy;

    if (right > parentWidth || bottom > parentHeight) {
        return true;
    }

    return false;
}

int Window::GetAbsoluteX() const {
    ASSERT_MAIN_THREAD();

    return this->parent ? (this->x + parent->GetAbsoluteX()) : this->x;
}

int Window::GetAbsoluteY() const {
    ASSERT_MAIN_THREAD();

    return this->parent ? (this->y + parent->GetAbsoluteY()) : this->y;
}

void Window::SetFrameTitle(const std::string& title) {
    ASSERT_MAIN_THREAD();

    this->title = title;
    this->Destroy();
    this->Redraw();
}

std::string Window::GetFrameTitle() const {
    ASSERT_MAIN_THREAD();

    return this->title;
}

void Window::Create() {
    ASSERT_MAIN_THREAD();

    assert(this->frame == nullptr);
    assert(this->content == nullptr);
    assert(this->framePanel == nullptr);
    assert(this->contentPanel == nullptr);

    if (this->parent && !this->parent->IsVisible()) {
        return;
    }

    bool hadBadBounds = this->badBounds;
    this->badBounds = this->CheckForBoundsError();

    if (this->badBounds) {
        this->Destroy();
        return;
    }

    /* else we have valid bounds. this->x and this->y are specified in
    relative space; find their absolute offset based on our parent. */

    int absoluteXOffset = 0;
    int absoluteYOffset = 0;

    if (this->parent) {
        absoluteXOffset = this->parent->GetAbsoluteX();
        absoluteYOffset = this->parent->GetAbsoluteY();

        if (parent->IsFrameVisible()) {
            absoluteXOffset += 1;
            absoluteYOffset += 1;
        }
    }

    this->frame = newwin(
        this->height,
        this->width,
        absoluteYOffset + this->y,
        absoluteXOffset + this->x);

    if (this->frame) { /* can fail if the screen size is too small. */
        /* resolve our current colors colors */

        bool focused = this->IsFocused();

        int64_t currentFrameColor = focused
            ? this->focusedFrameColor : this->frameColor;

        int64_t currentContentColor = focused
            ? this->focusedContentColor : this->contentColor;

        /* create the corresponding panel. required for z-ordering. */

        this->framePanel = new_panel(this->frame);

        /* if we were asked not to draw a frame, we'll set the frame equal to
        the content view, and use the content views colors*/

        if (!this->drawFrame) {
            this->content = this->frame;
            this->RepaintBackground();
        }

        /* otherwise we'll draw a box around the frame, and create a content
        sub-window inside */

        else {
            this->content = newwin(
                this->height - 2,
                this->width - 2,
                absoluteYOffset + this->y + 1,
                absoluteXOffset + this->x + 1);

            if (!this->content) {
                /* should never happen. if there's enough room for this->frame,
                there's enough room for this->content */
                this->Destroy();
                return;
            }

            this->contentPanel = new_panel(this->content);
            this->RepaintBackground();
            this->DrawFrameAndTitle();
        }

        this->Show();

        if (hadBadBounds && this->isVisibleInParent) {
            this->NotifyVisibilityChange(true);
        }
        else if (!hadBadBounds && this->badBounds) {
            this->NotifyVisibilityChange(false);
        }
    }
}

void Window::Hide() {
    ASSERT_MAIN_THREAD();

    this->Blur();

    if (this->frame) {
        if (this->isVisibleInParent) {
            this->Destroy();
            this->isVisibleInParent = false;
        }
    }
    else {
        if (this->isVisibleInParent) {
            this->isVisibleInParent = false;
        }
    }

    this->NotifyVisibilityChange(false);
}

void Window::Destroy() {
    ASSERT_MAIN_THREAD();

    if (this->frame) {
        del_panel(this->framePanel);
        delwin(this->frame);

        if (this->content != this->frame) {
            del_panel(this->contentPanel);
            delwin(this->content);
        }
    }

    this->framePanel = this->contentPanel = 0;
    this->content = this->frame = 0;
    this->isDirty = true;

    this->NotifyVisibilityChange(false);
}

void Window::SetFrameVisible(bool enabled) {
    ASSERT_MAIN_THREAD();

    if (enabled != this->drawFrame) {
        this->drawFrame = enabled;

        if (this->frame || this->content) {
            this->Destroy();
            this->Show();
        }
    }
}

bool Window::IsFrameVisible() {
    ASSERT_MAIN_THREAD();

    return this->drawFrame;
}

IWindow* Window::GetParent() const {
    ASSERT_MAIN_THREAD();

    return this->parent;
}

void Window::Clear() {
    ASSERT_MAIN_THREAD();

    if (this->content) {
        werase(this->content);
        wmove(this->content, 0, 0);
    }

    bool focused = this->IsFocused();
    int64_t contentColor = focused ? this->focusedContentColor : this->contentColor;
    int64_t frameColor = focused ? this->focusedFrameColor : this->frameColor;

    if (this->content == this->frame && this->frame) {
        wbkgd_internal(this->frame, contentColor);
    }
    else if (this->frame && this->content) {
        wbkgd_internal(this->frame, frameColor);
        wbkgd_internal(this->content, contentColor);
    }
}

void Window::Invalidate() {
    ASSERT_MAIN_THREAD();

    if (this->isVisibleInParent) {
        if (this->frame) {
            drawPending = true;
        }
    }
}

bool Window::IsParentVisible() {
    ASSERT_MAIN_THREAD();

    if (this->parent == nullptr) {
        return true;
    }

    auto p = this->GetParent();
    while (p) {
        if (!p->IsVisible()) {
            return false;
        }
        p = p->GetParent();
    }

    return true;
}

void Window::Focus() {
    ASSERT_MAIN_THREAD();

    if (::focused != this) {
        if (::focused) { ::focused->Blur(); }
        ::focused = this;
        this->isDirty = true;
        this->OnFocusChanged(true);
        this->RepaintBackground();
        this->Redraw();
    }
}

void Window::Blur() {
    ASSERT_MAIN_THREAD();

    if (::focused == this) {
        ::focused = nullptr;
        this->isDirty = true;
        this->OnFocusChanged(false);
        this->RepaintBackground();
        this->Redraw();
    }
}

void Window::SetNavigationKeys(std::shared_ptr<INavigationKeys> keys) {
    ASSERT_MAIN_THREAD();

    ::keys = keys;
}

bool Window::ProcessMouseEvent(const IMouseHandler::Event& mouseEvent) {
    this->MouseEvent(this, &mouseEvent);
    return false;
}

bool Window::FocusInParent() {
    ASSERT_MAIN_THREAD();

    auto layout = dynamic_cast<ILayout*>(this->GetParent());
    if (layout) {
        return layout->SetFocus(shared_from_this());
    }
    return false;
}

void Window::NotifyVisibilityChange(bool becameVisible) {
    this->Debounce(kNotifyVisibilityChangedMessageId, becameVisible ? 1LL : 0LL, 0, 0);
}

/* default keys for navigating around sub-views. apps can override this shim to
provide VIM-like keybindings, if it wants... */
static class DefaultNavigationKeys : public INavigationKeys {
    public:
        virtual bool Up(const std::string& key) override { return Up() == key; }
        virtual bool Down(const std::string& key) override { return Down() == key; }
        virtual bool Left(const std::string& key) override { return Left() == key; }
        virtual bool Right(const std::string& key) override { return Right() == key; }
        virtual bool Next(const std::string& key) override { return Next() == key; }
        virtual bool Prev(const std::string& key) override { return Prev() == key; }
        virtual bool Mode(const std::string& key) override { return Mode() == key; }
        virtual bool PageUp(const std::string& key) override { return PageUp() == key; }
        virtual bool PageDown(const std::string& key) override { return PageDown() == key; }
        virtual bool Home(const std::string& key) override { return Home() == key; }
        virtual bool End(const std::string& key) override { return End() == key; }

        virtual std::string Up() override { return "KEY_UP"; }
        virtual std::string Down() override { return "KEY_DOWN"; }
        virtual std::string Left() override { return "KEY_LEFT"; }
        virtual std::string Right() override { return "KEY_RIGHT"; }
        virtual std::string Next() override { return "KEY_TAB"; }
        virtual std::string Prev() override { return "KEY_BTAB"; }
        virtual std::string Mode() override  { return "^["; }
        virtual std::string PageUp() override { return "KEY_PPAGE"; }
        virtual std::string PageDown() override { return "KEY_NPAGE"; }
        virtual std::string Home() override { return "KEY_HOME"; }
        virtual std::string End() override { return "KEY_END"; }
} defaultNavigationKeys;

INavigationKeys& Window::NavigationKeys() {
    if (::keys) {
        return *::keys.get();
    }

    return defaultNavigationKeys;
}
