#include "qxtglobalshortcut_p.h"
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#include <QVector>
#include <QWidget>
#include <QX11Info>
#include <X11/keysym.h>
#include <X11/Xlib.h>

#include <xcb/xcb.h>

#include "xcbkeyboard.h"

namespace {

/**
 * Creates first invisible application window
 * so X11 key press events can be received.
 *
 * This is used for Cinnamon and KDE.
 */
void createFirstWindow()
{
    static QWidget *w = nullptr;
    if (!w) {
        // Try hard so the window is not visible.

        // Tool tips won't show in taskbar.
        w = new QWidget(nullptr, Qt::ToolTip);

        // Move out of screen (if it's not possible to show the window minimized).
        w->resize(1, 1);
        w->move(-100000, -100000);

        // Show and hide quickly.
        w->showMinimized();
        w->hide();
    }
}

QVector<quint32> maskModifiers()
{
    return QVector<quint32>() << 0 << Mod2Mask << LockMask << (Mod2Mask | LockMask);
}

using X11ErrorHandler = int (*)(Display* display, XErrorEvent* event);

class QxtX11ErrorHandler final {
public:
    static bool error;

    static int qxtX11ErrorHandler(Display* display, XErrorEvent *event)
    {
        Q_UNUSED(display)
        switch (event->error_code)
        {
            case BadAccess:
            case BadValue:
            case BadWindow:
                if (event->request_code == 33 /* X_GrabKey */ ||
                        event->request_code == 34 /* X_UngrabKey */)
                {
                    error = true;
                    //TODO:
                    //char errstr[256];
                    //XGetErrorText(dpy, err->error_code, errstr, 256);
                }
        }
        return 0;
    }

    QxtX11ErrorHandler()
        : m_previousErrorHandler(nullptr)
    {
        error = false;
        m_previousErrorHandler = XSetErrorHandler(qxtX11ErrorHandler);
    }

    ~QxtX11ErrorHandler()
    {
        XSetErrorHandler(m_previousErrorHandler);
    }

private:
    X11ErrorHandler m_previousErrorHandler;
};

bool QxtX11ErrorHandler::error = false;

class QxtX11Data final {
public:
    QxtX11Data()
        : m_display(nullptr)
    {
        createFirstWindow();
        if ( QX11Info::isPlatformX11() )
            m_display = QX11Info::display();
    }

    bool isValid()
    {
        return QX11Info::isPlatformX11() && m_display != nullptr;
    }

    Display *display()
    {
        Q_ASSERT(isValid());
        return m_display;
    }

    Window rootWindow()
    {
        return DefaultRootWindow(display());
    }

    bool grabKey(quint32 keycode, quint32 modifiers, Window window)
    {
        QxtX11ErrorHandler errorHandler;

        for (const auto maskMods : maskModifiers()) {
            XGrabKey(display(), static_cast<int>(keycode), modifiers | maskMods, window, True,
                     GrabModeAsync, GrabModeAsync);
            if (errorHandler.error)
                break;
        }

        if (errorHandler.error) {
            ungrabKey(keycode, modifiers, window);
            return false;
        }

        return true;
    }

    bool ungrabKey(quint32 keycode, quint32 modifiers, Window window)
    {
        QxtX11ErrorHandler errorHandler;

        for (const auto maskMods : maskModifiers()) {
            XUngrabKey(display(), static_cast<int>(keycode), modifiers | maskMods, window);
        }

        return !errorHandler.error;
    }

private:
    Display *m_display;
};

KeySym qtKeyToXKeySym(Qt::Key key, Qt::KeyboardModifiers mods)
{
    int i = 0;

    if ( mods.testFlag(Qt::KeypadModifier) ) {
        switch (key) {
        case Qt::Key_0: return XK_KP_Insert;
        case Qt::Key_1: return XK_KP_End;
        case Qt::Key_2: return XK_KP_Down;
        case Qt::Key_3: return XK_KP_Page_Down;
        case Qt::Key_4: return XK_KP_Left;
        case Qt::Key_5: return XK_KP_Begin;
        case Qt::Key_6: return XK_KP_Right;
        case Qt::Key_7: return XK_KP_Home;
        case Qt::Key_8: return XK_KP_Up;
        case Qt::Key_9: return XK_KP_Page_Up;
        default: break;
        }

        for (; KeyTbl[i] != 0; i += 2) {
            if (KeyTbl[i] == XK_Num_Lock)
                break;
        }
    } else {
        const auto keySym = XStringToKeysym(QKeySequence(key).toString().toLatin1().data());
        if (keySym != NoSymbol)
            return keySym;
    }

    for (; KeyTbl[i] != 0; i += 2) {
        if (KeyTbl[i + 1] == key)
            return KeyTbl[i];
    }

    return static_cast<ushort>(key);
}

} // namespace

#if QT_VERSION < QT_VERSION_CHECK(5,0,0)
bool QxtGlobalShortcutPrivate::eventFilter(void* message)
{
    XEvent *event = static_cast<XEvent *>(message);
    if (event->type == KeyPress)
    {
        XKeyEvent* key = reinterpret_cast<XKeyEvent *>(event);
        unsigned int keycode = key->keycode;
        unsigned int keystate = key->state;
#else
bool QxtGlobalShortcutPrivate::nativeEventFilter(const QByteArray & eventType,
    void * message, long * result)
{
    Q_UNUSED(result)

    xcb_key_press_event_t *kev = nullptr;
    if (eventType == "xcb_generic_event_t") {
        xcb_generic_event_t* ev = static_cast<xcb_generic_event_t *>(message);
        if ((ev->response_type & 127) == XCB_KEY_PRESS)
            kev = static_cast<xcb_key_press_event_t *>(message);
    }

    if (kev != nullptr) {
        unsigned int keycode = kev->detail;
        unsigned int keystate = 0;
        if(kev->state & XCB_MOD_MASK_1)
            keystate |= Mod1Mask;
        if(kev->state & XCB_MOD_MASK_CONTROL)
            keystate |= ControlMask;
        if(kev->state & XCB_MOD_MASK_4)
            keystate |= Mod4Mask;
        if(kev->state & XCB_MOD_MASK_SHIFT)
            keystate |= ShiftMask;
#endif
        activateShortcut(keycode,
            // Mod1Mask == Alt, Mod4Mask == Meta
            keystate & (ShiftMask | ControlMask | Mod1Mask | Mod4Mask));
    }
    return false;
}

quint32 QxtGlobalShortcutPrivate::nativeModifiers(Qt::KeyboardModifiers modifiers)
{
    // ShiftMask, LockMask, ControlMask, Mod1Mask, Mod2Mask, Mod3Mask, Mod4Mask, and Mod5Mask
    quint32 native = 0;
    if (modifiers & Qt::ShiftModifier)
        native |= ShiftMask;
    if (modifiers & Qt::ControlModifier)
        native |= ControlMask;
    if (modifiers & Qt::AltModifier)
        native |= Mod1Mask;
    if (modifiers & Qt::MetaModifier)
        native |= Mod4Mask;

    // TODO: resolve these?
    //if (modifiers & Qt::MetaModifier)
    //if (modifiers & Qt::KeypadModifier)
    //if (modifiers & Qt::GroupSwitchModifier)
    return native;
}

quint32 QxtGlobalShortcutPrivate::nativeKeycode(Qt::Key key, Qt::KeyboardModifiers mods)
{
    QxtX11Data x11;
    if (!x11.isValid())
        return 0;

    const KeySym keysym = qtKeyToXKeySym(key, mods);
    return XKeysymToKeycode(x11.display(), keysym);
}

bool QxtGlobalShortcutPrivate::registerShortcut(quint32 nativeKey, quint32 nativeMods)
{
    QxtX11Data x11;
    return x11.isValid() && x11.grabKey(nativeKey, nativeMods, x11.rootWindow());
}

bool QxtGlobalShortcutPrivate::unregisterShortcut(quint32 nativeKey, quint32 nativeMods)
{
    QxtX11Data x11;
    return x11.isValid() && x11.ungrabKey(nativeKey, nativeMods, x11.rootWindow());
}
