#include "MouseEventSpy.h"

#include <QGuiApplication>
#include <QDebug>

MouseEventSpy::MouseEventSpy(QObject *parent) : QObject(parent)
{
}

/**
 * @brief Create instance if necessary.
 *
 * If no instance has been created yet, create new instance and install it as event filter
 * in QGuiApplication.
 *
 * @see MouseEventSpy::instance()
 */
void MouseEventSpy::init()
{
    instance();
}

/**
 * @brief Implements the singleton pattern.
 * @return Instance
 *
 * If no instance has been created yet, create new instance and install it as event filter
 * in QGuiApplication.
 */
MouseEventSpy* MouseEventSpy::instance()
{
    static MouseEventSpy* inst;
    if (inst == nullptr)
    {
        inst = new MouseEventSpy();
        QGuiApplication* app = qGuiApp;
        app->installEventFilter(inst);
    }
    return inst;
}

/**
 * @brief Expand QObject::eventFilter to react to MouseEvents.
 *
 * Restart timer each time a mouse event is detected.
 */
bool MouseEventSpy::eventFilter(QObject* watched, QEvent* event)
{
    QEvent::Type t = event->type();
    if (isMouseEvent(t)
            && event->spontaneous() // Take only mouse events from outside of Qt
            )
    {
        emit mouseEventDetected();
    }
    return QObject::eventFilter(watched, event);
}

/**
 * @brief Checks whether the event type is a mouse event.
 * @param t Event type
 * @return Returns whether the event type is a mouse event.
 */
bool MouseEventSpy::isMouseEvent(QEvent::Type t)
{
    return (t == QEvent::MouseButtonDblClick
            || t == QEvent::MouseButtonPress
            || t == QEvent::MouseButtonRelease
            || t == QEvent::MouseMove);
}