// Copyright (C) 2020 The Qt Company Ltd.
// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR GPL-3.0-only WITH Qt-GPL-exception-1.0
#include "navigation2d.h"
#include <utils/hostosinfo.h>
#include <designersettings.h>
#include <qmldesignerplugin.h>

#include <QGestureEvent>
#include <QScrollBar>
#include <QWheelEvent>
#include <QMetaMethod>

#include <cmath>

namespace QmlDesigner {

void Navigation2dFilter::scroll(const QPointF &direction, QScrollBar *sbx, QScrollBar *sby)
{
    auto doScroll = [](QScrollBar *sb, float distance) {
        if (sb) {
            // max - min + pageStep = sceneRect.size * scale
            float d1 = sb->maximum() - sb->minimum();
            float d2 = d1 + sb->pageStep();

            float val = (distance / d2) * d1;
            sb->setValue(sb->value() - val);
        }
    };

    doScroll(sbx, direction.x());
    doScroll(sby, direction.y());
}

Navigation2dFilter::Navigation2dFilter(QWidget *parent)
    : QObject(parent)
{
    if (parent)
        parent->grabGesture(Qt::PinchGesture);
}

bool Navigation2dFilter::eventFilter(QObject *object, QEvent *event)
{
    if (event->type() == QEvent::Gesture)
        return gestureEvent(static_cast<QGestureEvent *>(event));
    else if (event->type() == QEvent::Wheel)
        return wheelEvent(static_cast<QWheelEvent *>(event));

    return QObject::eventFilter(object, event);
}

bool Navigation2dFilter::gestureEvent(QGestureEvent *event)
{
    if (QPinchGesture *pinch = static_cast<QPinchGesture *>(event->gesture(Qt::PinchGesture))) {
        QPinchGesture::ChangeFlags changeFlags = pinch->changeFlags();
        if (changeFlags.testFlag(QPinchGesture::ScaleFactorChanged)) {
            emit zoomChanged(-(1.0 - pinch->scaleFactor()), pinch->startCenterPoint());
            event->accept();
            return true;
        }
    }
    return false;
}

bool Navigation2dFilter::wheelEvent(QWheelEvent *event)
{
    bool isMac = Utils::HostOsInfo::isMacHost();
    bool controlPressed = event->modifiers().testFlag(Qt::ControlModifier);

    if (isMac)
        controlPressed = controlPressed || event->modifiers().testFlag(Qt::MetaModifier);

    if (!controlPressed) {
        if (event->source() == Qt::MouseEventSynthesizedBySystem) {
            emit panChanged(QPointF(event->pixelDelta()));
            event->accept();
            return true;
        }
        return false;
    }

    auto zoomChangedSignal = QMetaMethod::fromSignal(&Navigation2dFilter::zoomChanged);
    bool zoomChangedConnected = QObject::isSignalConnected(zoomChangedSignal);

    if (zoomChangedConnected) {
        double speed = 1.0 / 200.0;
        if (QPointF delta = event->pixelDelta(); !delta.isNull() && isMac) {
            double dist = std::abs(delta.x()) > std::abs(delta.y()) ? -delta.x() : delta.y();
            emit zoomChanged(dist * speed, event->position());
            event->accept();
            return true;
        } else if (QPointF delta = event->angleDelta(); !delta.isNull()) {

            const double globalMouseSpeed = designerSettings().editorZoomFactor();
            speed = globalMouseSpeed / 20.0;

            constexpr double degreePerStep = 15.;
            constexpr double stepCount = 8.;
            double dist = std::abs(delta.x()) > std::abs(delta.y()) ? -delta.x() : delta.y();
            dist = dist / (stepCount*degreePerStep);
            emit zoomChanged(dist * speed, event->position());
            event->accept();
            return true;
        }
        return false;
    }

    auto zoomInSignal = QMetaMethod::fromSignal(&Navigation2dFilter::zoomIn);
    bool zoomInConnected = QObject::isSignalConnected(zoomInSignal);

    auto zoomOutSignal = QMetaMethod::fromSignal(&Navigation2dFilter::zoomOut);
    bool zoomOutConnected = QObject::isSignalConnected(zoomOutSignal);

    if (zoomInConnected && zoomOutConnected) {
        if (QPointF angle = event->angleDelta(); !angle.isNull()) {
            double delta = std::abs(angle.x()) > std::abs(angle.y()) ? angle.x() : angle.y();
            if (delta > 0)
                emit zoomIn();
            else
                emit zoomOut();
             event->accept();
            return true;
        }
    }

    return false;
}

} // End namespace QmlDesigner.
