// Copyright (C) 2023-2024 Stdware Collections
// SPDX-License-Identifier: Apache-2.0

#include "cocoawindowcontext_p.h"

#include <objc/runtime.h>
#include <AppKit/AppKit.h>

#include <Cocoa/Cocoa.h>

#include <QtGui/QGuiApplication>

#include "qwkglobal_p.h"
#include "systemwindow_p.h"

// https://forgetsou.github.io/2020/11/06/macos%E5%BC%80%E5%8F%91-%E5%85%B3%E9%97%AD-%E6%9C%80%E5%B0%8F%E5%8C%96-%E5%85%A8%E5%B1%8F%E5%B1%85%E4%B8%AD%E5%A4%84%E7%90%86(%E4%BB%BFMac%20QQ)/
// https://nyrra33.com/2019/03/26/changing-titlebars-height/

namespace QWK {

    struct NSWindowProxy;

    using ProxyList = QHash<WId, NSWindowProxy *>;
    Q_GLOBAL_STATIC(ProxyList, g_proxyList);

    using ProxyList2 = QHash<NSWindow *, NSWindowProxy *>;
    Q_GLOBAL_STATIC(ProxyList2, g_proxyIndexes);

}

struct QWK_NSWindowDelegate {
public:
    enum NSEventType {
        WillEnterFullScreen,
        DidEnterFullScreen,
        WillExitFullScreen,
        DidExitFullScreen,
        DidResize,
    };

    virtual ~QWK_NSWindowDelegate() = default;
    virtual void windowEvent(NSEventType eventType) = 0;
};

//
// Objective C++ Begin
//

@interface QWK_NSWindowObserver : NSObject {
}
@end

@implementation QWK_NSWindowObserver

- (id)init {
    self = [super init];
    if (self) {
        [[NSNotificationCenter defaultCenter] addObserver:self
                                                 selector:@selector(windowWillEnterFullScreen:)
                                                     name:NSWindowWillEnterFullScreenNotification
                                                   object:nil];
        [[NSNotificationCenter defaultCenter] addObserver:self
                                                 selector:@selector(windowDidEnterFullScreen:)
                                                     name:NSWindowDidEnterFullScreenNotification
                                                   object:nil];
        [[NSNotificationCenter defaultCenter] addObserver:self
                                                 selector:@selector(windowWillExitFullScreen:)
                                                     name:NSWindowWillExitFullScreenNotification
                                                   object:nil];
        [[NSNotificationCenter defaultCenter] addObserver:self
                                                 selector:@selector(windowDidExitFullScreen:)
                                                     name:NSWindowDidExitFullScreenNotification
                                                   object:nil];
        [[NSNotificationCenter defaultCenter] addObserver:self
                                                 selector:@selector(windowDidResize:)
                                                     name:NSWindowDidResizeNotification
                                                   object:nil];
    }
    return self;
}

- (void)dealloc {
    [[NSNotificationCenter defaultCenter] removeObserver:self];
    [super dealloc];
}

- (void)windowWillEnterFullScreen:(NSNotification *)notification {
    auto nswindow = reinterpret_cast<NSWindow *>(notification.object);
    if (auto proxy = QWK::g_proxyIndexes->value(nswindow)) {
        reinterpret_cast<QWK_NSWindowDelegate *>(proxy)->windowEvent(
            QWK_NSWindowDelegate::WillEnterFullScreen);
    }
}

- (void)windowDidEnterFullScreen:(NSNotification *)notification {
    auto nswindow = reinterpret_cast<NSWindow *>(notification.object);
    if (auto proxy = QWK::g_proxyIndexes->value(nswindow)) {
        reinterpret_cast<QWK_NSWindowDelegate *>(proxy)->windowEvent(
            QWK_NSWindowDelegate::DidEnterFullScreen);
    }
}

- (void)windowWillExitFullScreen:(NSNotification *)notification {
    auto nswindow = reinterpret_cast<NSWindow *>(notification.object);
    if (auto proxy = QWK::g_proxyIndexes->value(nswindow)) {
        reinterpret_cast<QWK_NSWindowDelegate *>(proxy)->windowEvent(
            QWK_NSWindowDelegate::WillExitFullScreen);
    }
}

- (void)windowDidExitFullScreen:(NSNotification *)notification {
    auto nswindow = reinterpret_cast<NSWindow *>(notification.object);
    if (auto proxy = QWK::g_proxyIndexes->value(nswindow)) {
        reinterpret_cast<QWK_NSWindowDelegate *>(proxy)->windowEvent(
            QWK_NSWindowDelegate::DidExitFullScreen);
    }
}

- (void)windowDidResize:(NSNotification *)notification {
    auto nswindow = reinterpret_cast<NSWindow *>(notification.object);
    if (auto proxy = QWK::g_proxyIndexes->value(nswindow)) {
        reinterpret_cast<QWK_NSWindowDelegate *>(proxy)->windowEvent(
            QWK_NSWindowDelegate::DidResize);
    }
}

@end

//
// Objective C++ End
//

namespace QWK {

    struct NSWindowProxy : public QWK_NSWindowDelegate {
        enum class BlurMode {
            Dark,
            Light,
            None,
        };

        NSWindowProxy(NSWindow *macWindow) {
            nswindow = macWindow;
            g_proxyIndexes->insert(nswindow, this);
        }

        ~NSWindowProxy() override {
            g_proxyIndexes->remove(nswindow);
        }

        // Delegate
        void windowEvent(NSEventType eventType) override {
            switch (eventType) {
                case WillExitFullScreen: {
                    if (!screenRectCallback || !systemButtonVisible)
                        return;

                    // The system buttons will stuck at their default positions when the
                    // exit-fullscreen animation is running, we need to hide them until the
                    // animation finishes
                    for (const auto &button : systemButtons()) {
                        button.hidden = true;
                    }
                    break;
                }

                case DidExitFullScreen: {
                    if (!screenRectCallback || !systemButtonVisible)
                        return;

                    for (const auto &button : systemButtons()) {
                        button.hidden = false;
                    }
                    updateSystemButtonRect();
                    break;
                }

                case DidResize: {
                    if (!screenRectCallback || !systemButtonVisible) {
                        return;
                    }
                    updateSystemButtonRect();
                    break;
                }

                default:
                    break;
            }
        }

        // System buttons visibility
        void setSystemButtonVisible(bool visible) {
            systemButtonVisible = visible;
            for (const auto &button : systemButtons()) {
                button.hidden = !visible;
            }

            if (!screenRectCallback || !visible) {
                return;
            }
            updateSystemButtonRect();
        }

        // System buttons area
        void setScreenRectCallback(const ScreenRectCallback &callback) {
            screenRectCallback = callback;

            if (!callback || !systemButtonVisible) {
                return;
            }
            updateSystemButtonRect();
        }

        void updateSystemButtonRect() {
            const auto &buttons = systemButtons();
            const auto &leftButton = buttons[0];
            const auto &midButton = buttons[1];
            const auto &rightButton = buttons[2];

            auto titlebar = rightButton.superview;
            int titlebarHeight = titlebar.frame.size.height;

            auto spacing = midButton.frame.origin.x - leftButton.frame.origin.x;
            auto width = midButton.frame.size.width;
            auto height = midButton.frame.size.height;

            auto viewSize =
                nswindow.contentView ? nswindow.contentView.frame.size : nswindow.frame.size;
            QPoint center = screenRectCallback(QSize(viewSize.width, titlebarHeight)).center();

            // The origin of the NSWindow coordinate system is in the lower left corner, we
            // do the necessary transformations
            center.ry() = titlebarHeight - center.y();

            // Mid button
            NSPoint centerOrigin = {
                center.x() - width / 2,
                center.y() - height / 2,
            };
            [midButton setFrameOrigin:centerOrigin];

            // Left button
            NSPoint leftOrigin = {
                centerOrigin.x - spacing,
                centerOrigin.y,
            };
            [leftButton setFrameOrigin:leftOrigin];

            // Right button
            NSPoint rightOrigin = {
                centerOrigin.x + spacing,
                centerOrigin.y,
            };
            [rightButton setFrameOrigin:rightOrigin];
        }

        inline std::array<NSButton *, 3> systemButtons() {
            NSButton *closeBtn = [nswindow standardWindowButton:NSWindowCloseButton];
            NSButton *minimizeBtn = [nswindow standardWindowButton:NSWindowMiniaturizeButton];
            NSButton *zoomBtn = [nswindow standardWindowButton:NSWindowZoomButton];
            return {closeBtn, minimizeBtn, zoomBtn};
        }

        inline int titleBarHeight() const {
            NSButton *closeBtn = [nswindow standardWindowButton:NSWindowCloseButton];
            return closeBtn.superview.frame.size.height;
        }

        // Blur effect
        bool setBlurEffect(BlurMode mode) {
            static Class visualEffectViewClass = NSClassFromString(@"NSVisualEffectView");
            if (!visualEffectViewClass)
                return false;

            NSVisualEffectView *effectView = nil;
            NSView *const view = [nswindow contentView];
            for (NSView *subview in [[view superview] subviews]) {
                if ([subview isKindOfClass:visualEffectViewClass]) {
                    effectView = reinterpret_cast<NSVisualEffectView *>(subview);
                }
            }
            if (effectView == nil) {
                return false;
            }

            static const auto originalMaterial = effectView.material;
            static const auto originalBlendingMode = effectView.blendingMode;
            static const auto originalState = effectView.state;

            if (mode == BlurMode::None) {
                effectView.material = originalMaterial;
                effectView.blendingMode = originalBlendingMode;
                effectView.state = originalState;
                effectView.appearance = nil;
            } else {
                effectView.material = NSVisualEffectMaterialUnderWindowBackground;
                effectView.blendingMode = NSVisualEffectBlendingModeBehindWindow;
                effectView.state = NSVisualEffectStateFollowsWindowActiveState;

                if (mode == BlurMode::Dark) {
                    effectView.appearance =
                        [NSAppearance appearanceNamed:@"NSAppearanceNameVibrantDark"];
                } else {
                    effectView.appearance =
                        [NSAppearance appearanceNamed:@"NSAppearanceNameVibrantLight"];
                }
            }
            return true;
        }

        // System title bar
        void setSystemTitleBarVisible(const bool visible) {
            NSView *nsview = [nswindow contentView];
            if (!nsview) {
                return;
            }

            nsview.wantsLayer = YES;
            nswindow.styleMask |= NSWindowStyleMaskResizable;
            if (visible) {
                nswindow.styleMask &= ~NSWindowStyleMaskFullSizeContentView;
            } else {
                nswindow.styleMask |= NSWindowStyleMaskFullSizeContentView;
            }
            nswindow.titlebarAppearsTransparent = (visible ? NO : YES);
            nswindow.titleVisibility = (visible ? NSWindowTitleVisible : NSWindowTitleHidden);
            nswindow.hasShadow = YES;
            // nswindow.showsToolbarButton = NO;
            nswindow.movableByWindowBackground = NO;
            nswindow.movable = NO; // This line causes the window in the wrong position when
                                   // become fullscreen.
            //  For some unknown reason, we don't need the following hack in Qt versions below or
            //  equal to 6.2.4.
#if (QT_VERSION > QT_VERSION_CHECK(6, 2, 4))
            [nswindow standardWindowButton:NSWindowCloseButton].hidden = (visible ? NO : YES);
            [nswindow standardWindowButton:NSWindowMiniaturizeButton].hidden = (visible ? NO : YES);
            [nswindow standardWindowButton:NSWindowZoomButton].hidden = (visible ? NO : YES);
#endif
        }

        static void replaceImplementations() {
            Method method = class_getInstanceMethod(windowClass, @selector(setStyleMask:));
            oldSetStyleMask = reinterpret_cast<setStyleMaskPtr>(
                method_setImplementation(method, reinterpret_cast<IMP>(setStyleMask)));

            method =
                class_getInstanceMethod(windowClass, @selector(setTitlebarAppearsTransparent:));
            oldSetTitlebarAppearsTransparent =
                reinterpret_cast<setTitlebarAppearsTransparentPtr>(method_setImplementation(
                    method, reinterpret_cast<IMP>(setTitlebarAppearsTransparent)));

#if 0
            method = class_getInstanceMethod(windowClass, @selector(canBecomeKeyWindow));
            oldCanBecomeKeyWindow = reinterpret_cast<canBecomeKeyWindowPtr>(method_setImplementation(method, reinterpret_cast<IMP>(canBecomeKeyWindow)));

            method = class_getInstanceMethod(windowClass, @selector(canBecomeMainWindow));
            oldCanBecomeMainWindow = reinterpret_cast<canBecomeMainWindowPtr>(method_setImplementation(method, reinterpret_cast<IMP>(canBecomeMainWindow)));
#endif

            method = class_getInstanceMethod(windowClass, @selector(sendEvent:));
            oldSendEvent = reinterpret_cast<sendEventPtr>(
                method_setImplementation(method, reinterpret_cast<IMP>(sendEvent)));

            // Alloc
            windowObserver = [[QWK_NSWindowObserver alloc] init];
        }

        static void restoreImplementations() {
            Method method = class_getInstanceMethod(windowClass, @selector(setStyleMask:));
            method_setImplementation(method, reinterpret_cast<IMP>(oldSetStyleMask));
            oldSetStyleMask = nil;

            method =
                class_getInstanceMethod(windowClass, @selector(setTitlebarAppearsTransparent:));
            method_setImplementation(method,
                                     reinterpret_cast<IMP>(oldSetTitlebarAppearsTransparent));
            oldSetTitlebarAppearsTransparent = nil;

#if 0
            method = class_getInstanceMethod(windowClass, @selector(canBecomeKeyWindow));
            method_setImplementation(method, reinterpret_cast<IMP>(oldCanBecomeKeyWindow));
            oldCanBecomeKeyWindow = nil;

            method = class_getInstanceMethod(windowClass, @selector(canBecomeMainWindow));
            method_setImplementation(method, reinterpret_cast<IMP>(oldCanBecomeMainWindow));
            oldCanBecomeMainWindow = nil;
#endif

            method = class_getInstanceMethod(windowClass, @selector(sendEvent:));
            method_setImplementation(method, reinterpret_cast<IMP>(oldSendEvent));
            oldSendEvent = nil;

            // Delete
            [windowObserver release];
            windowObserver = nil;
        }

        static inline const Class windowClass = [NSWindow class];

    protected:
        static BOOL canBecomeKeyWindow(id obj, SEL sel) {
            if (g_proxyIndexes->contains(reinterpret_cast<NSWindow *>(obj))) {
                return YES;
            }

            if (oldCanBecomeKeyWindow) {
                return oldCanBecomeKeyWindow(obj, sel);
            }

            return YES;
        }

        static BOOL canBecomeMainWindow(id obj, SEL sel) {
            if (g_proxyIndexes->contains(reinterpret_cast<NSWindow *>(obj))) {
                return YES;
            }

            if (oldCanBecomeMainWindow) {
                return oldCanBecomeMainWindow(obj, sel);
            }

            return YES;
        }

        static void setStyleMask(id obj, SEL sel, NSWindowStyleMask styleMask) {
            if (g_proxyIndexes->contains(reinterpret_cast<NSWindow *>(obj))) {
                styleMask |= NSWindowStyleMaskFullSizeContentView;
            }

            if (oldSetStyleMask) {
                oldSetStyleMask(obj, sel, styleMask);
            }
        }

        static void setTitlebarAppearsTransparent(id obj, SEL sel, BOOL transparent) {
            if (g_proxyIndexes->contains(reinterpret_cast<NSWindow *>(obj))) {
                transparent = YES;
            }

            if (oldSetTitlebarAppearsTransparent) {
                oldSetTitlebarAppearsTransparent(obj, sel, transparent);
            }
        }

        static void sendEvent(id obj, SEL sel, NSEvent *event) {
            if (oldSendEvent) {
                oldSendEvent(obj, sel, event);
            }

#if 0
            const auto nswindow = reinterpret_cast<NSWindow *>(obj);
            const auto it = instances.find(nswindow);
            if (it == instances.end()) {
                return;
            }

            NSWindowProxy *proxy = it.value();
            if (event.type == NSEventTypeLeftMouseDown) {
                proxy->lastMouseDownEvent = event;
                QCoreApplication::processEvents();
                proxy->lastMouseDownEvent = nil;
            }
#endif
        }

    private:
        Q_DISABLE_COPY(NSWindowProxy)

        NSWindow *nswindow = nil;

        bool systemButtonVisible = true;
        ScreenRectCallback screenRectCallback;

        static inline QWK_NSWindowObserver *windowObserver = nil;

        // NSEvent *lastMouseDownEvent = nil;

        using setStyleMaskPtr = void (*)(id, SEL, NSWindowStyleMask);
        static inline setStyleMaskPtr oldSetStyleMask = nil;

        using setTitlebarAppearsTransparentPtr = void (*)(id, SEL, BOOL);
        static inline setTitlebarAppearsTransparentPtr oldSetTitlebarAppearsTransparent = nil;

        using canBecomeKeyWindowPtr = BOOL (*)(id, SEL);
        static inline canBecomeKeyWindowPtr oldCanBecomeKeyWindow = nil;

        using canBecomeMainWindowPtr = BOOL (*)(id, SEL);
        static inline canBecomeMainWindowPtr oldCanBecomeMainWindow = nil;

        using sendEventPtr = void (*)(id, SEL, NSEvent *);
        static inline sendEventPtr oldSendEvent = nil;
    };

    static inline NSWindow *mac_getNSWindow(const WId windowId) {
        const auto nsview = reinterpret_cast<NSView *>(windowId);
        return [nsview window];
    }

    static inline NSWindowProxy *ensureWindowProxy(const WId windowId) {
        if (g_proxyList->isEmpty()) {
            NSWindowProxy::replaceImplementations();
        }

        auto it = g_proxyList->find(windowId);
        if (it == g_proxyList->end()) {
            NSWindow *nswindow = mac_getNSWindow(windowId);
            const auto proxy = new NSWindowProxy(nswindow);
            it = g_proxyList->insert(windowId, proxy);
        }
        return it.value();
    }

    static inline void releaseWindowProxy(const WId windowId) {
        if (auto proxy = g_proxyList->take(windowId)) {
            proxy->setSystemTitleBarVisible(true);
            delete proxy;
        } else {
            return;
        }

        if (g_proxyList->isEmpty()) {
            NSWindowProxy::restoreImplementations();
        }
    }

    class CocoaWindowEventFilter : public SharedEventFilter {
    public:
        explicit CocoaWindowEventFilter(AbstractWindowContext *context);
        ~CocoaWindowEventFilter() override;

        enum WindowStatus {
            Idle,
            WaitingRelease,
            PreparingMove,
            Moving,
        };

    protected:
        bool sharedEventFilter(QObject *object, QEvent *event) override;

    private:
        AbstractWindowContext *m_context;
        bool m_cursorShapeChanged;
        WindowStatus m_windowStatus;
    };

    CocoaWindowEventFilter::CocoaWindowEventFilter(AbstractWindowContext *context)
        : m_context(context), m_cursorShapeChanged(false), m_windowStatus(Idle) {
        m_context->installSharedEventFilter(this);
    }

    CocoaWindowEventFilter::~CocoaWindowEventFilter() = default;

    bool CocoaWindowEventFilter::sharedEventFilter(QObject *obj, QEvent *event) {
        Q_UNUSED(obj)

        auto type = event->type();
        if (type < QEvent::MouseButtonPress || type > QEvent::MouseMove) {
            return false;
        }
        auto host = m_context->host();
        auto window = m_context->window();
        auto delegate = m_context->delegate();
        auto me = static_cast<const QMouseEvent *>(event);

        QPoint scenePos = getMouseEventScenePos(me);
        QPoint globalPos = getMouseEventGlobalPos(me);

        bool inTitleBar = m_context->isInTitleBarDraggableArea(scenePos);
        switch (type) {
            case QEvent::MouseButtonPress: {
                switch (me->button()) {
                    case Qt::LeftButton: {
                        if (inTitleBar) {
                            // If we call startSystemMove() now but release the mouse without actual
                            // movement, there will be no MouseReleaseEvent, so we defer it when the
                            // mouse is actually moving for the first time
                            m_windowStatus = PreparingMove;
                            event->accept();
                            return true;
                        }
                        break;
                    }
                    case Qt::RightButton: {
                        m_context->showSystemMenu(globalPos);
                        break;
                    }
                    default:
                        break;
                }
                m_windowStatus = WaitingRelease;
                break;
            }

            case QEvent::MouseButtonRelease: {
                switch (m_windowStatus) {
                    case PreparingMove:
                    case Moving: {
                        m_windowStatus = Idle;
                        event->accept();
                        return true;
                    }
                    case WaitingRelease: {
                        m_windowStatus = Idle;
                        break;
                    }
                    default: {
                        if (inTitleBar) {
                            event->accept();
                            return true;
                        }
                        break;
                    }
                }
                break;
            }

            case QEvent::MouseMove: {
                switch (m_windowStatus) {
                    case Moving: {
                        return true;
                    }
                    case PreparingMove: {
                        m_windowStatus = Moving;
                        startSystemMove(window);
                        event->accept();
                        return true;
                    }
                    default:
                        break;
                }
                break;
            }

            case QEvent::MouseButtonDblClick: {
                if (me->button() == Qt::LeftButton && inTitleBar &&
                    !delegate->isHostSizeFixed(host)) {
                    Qt::WindowStates windowState = delegate->getWindowState(host);
                    if (!(windowState & Qt::WindowFullScreen)) {
                        if (windowState & Qt::WindowMaximized) {
                            delegate->setWindowState(host, windowState & ~Qt::WindowMaximized);
                        } else {
                            delegate->setWindowState(host, windowState | Qt::WindowMaximized);
                        }
                        event->accept();
                        return true;
                    }
                }
                break;
            }

            default:
                break;
        }
        return false;
    }

    CocoaWindowContext::CocoaWindowContext() : AbstractWindowContext() {
        cocoaWindowEventFilter = std::make_unique<CocoaWindowEventFilter>(this);
    }

    CocoaWindowContext::~CocoaWindowContext() {
        releaseWindowProxy(windowId);
    }

    QString CocoaWindowContext::key() const {
        return QStringLiteral("cocoa");
    }

    void CocoaWindowContext::virtual_hook(int id, void *data) {
        switch (id) {
            case SystemButtonAreaChangedHook: {
                ensureWindowProxy(windowId)->setScreenRectCallback(m_systemButtonAreaCallback);
                return;
            }

            default:
                break;
        }
        AbstractWindowContext::virtual_hook(id, data);
    }

    QVariant CocoaWindowContext::windowAttribute(const QString &key) const {
        if (key == QStringLiteral("title-bar-height")) {
            if (!m_windowHandle)
                return 0;
            return ensureWindowProxy(windowId)->titleBarHeight();
        }
        return AbstractWindowContext::windowAttribute(key);
    }

    void CocoaWindowContext::winIdChanged() {
        // If the original window id is valid, remove all resources related
        if (windowId) {
            releaseWindowProxy(windowId);
            windowId = 0;
        }

        if (!m_windowHandle) {
            return;
        }

        // Allocate new resources
        windowId = m_windowHandle->winId();
        ensureWindowProxy(windowId)->setSystemTitleBarVisible(false);
    }

    bool CocoaWindowContext::windowAttributeChanged(const QString &key, const QVariant &attribute,
                                                    const QVariant &oldAttribute) {
        Q_UNUSED(oldAttribute)

        if (key == QStringLiteral("no-system-buttons")) {
            if (attribute.type() != QVariant::Bool)
                return false;
            ensureWindowProxy(windowId)->setSystemButtonVisible(!attribute.toBool());
            return true;
        }

        if (key == QStringLiteral("blur-effect")) {
            auto mode = NSWindowProxy::BlurMode::None;
            if (attribute.type() == QVariant::Bool) {
                if (attribute.toBool()) {
                    NSString *osxMode =
                        [[NSUserDefaults standardUserDefaults] stringForKey:@"AppleInterfaceStyle"];
                    mode = [osxMode isEqualToString:@"Dark"] ? NSWindowProxy::BlurMode::Dark
                                                             : NSWindowProxy::BlurMode::Light;
                }
            } else if (attribute.type() == QVariant::String) {
                auto value = attribute.toString();
                if (value == QStringLiteral("dark")) {
                    mode = NSWindowProxy::BlurMode::Dark;
                } else if (value == QStringLiteral("light")) {
                    mode = NSWindowProxy::BlurMode::Light;
                } else if (value == QStringLiteral("none")) {
                    // ...
                } else {
                    return false;
                }
            } else {
                return false;
            }
            return ensureWindowProxy(windowId)->setBlurEffect(mode);
        }

        return false;
    }

}
