/****************************************************************************
**
** Copyright (C) 2015 The Qt Company Ltd.
** Contact: http://www.qt.io/licensing/
**
** This file is part of the Qt Quick Extras module of the Qt Toolkit.
**
** $QT_BEGIN_LICENSE:LGPL3$
** Commercial License Usage
** Licensees holding valid commercial Qt licenses may use this file in
** accordance with the commercial license agreement provided with the
** Software or, alternatively, in accordance with the terms contained in
** a written agreement between you and The Qt Company. For licensing terms
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** information use the contact form at http://www.qt.io/contact-us.
**
** GNU Lesser General Public License Usage
** Alternatively, this file may be used under the terms of the GNU Lesser
** General Public License version 3 as published by the Free Software
** Foundation and appearing in the file LICENSE.LGPLv3 included in the
** packaging of this file. Please review the following information to
** ensure the GNU Lesser General Public License version 3 requirements
** will be met: https://www.gnu.org/licenses/lgpl.html.
**
** GNU General Public License Usage
** Alternatively, this file may be used under the terms of the GNU
** General Public License version 2.0 or later as published by the Free
** Software Foundation and appearing in the file LICENSE.GPL included in
** the packaging of this file. Please review the following information to
** ensure the GNU General Public License version 2.0 requirements will be
** met: http://www.gnu.org/licenses/gpl-2.0.html.
**
** $QT_END_LICENSE$
**
****************************************************************************/

#include "qquickdrawer_p.h"

#include <QtGui/qstylehints.h>
#include <QtGui/private/qguiapplication_p.h>
#include <QtQuick/private/qquickwindow_p.h>
#include <QtQuick/private/qquickanimation_p.h>
#include <QtQuickControls/private/qquickcontrol_p_p.h>

QT_BEGIN_NAMESPACE

class QQuickDrawerPrivate : public QQuickControlPrivate
{
    Q_DECLARE_PUBLIC(QQuickDrawer)

public:
    QQuickDrawerPrivate() : edge(Qt::LeftEdge), offset(0), position(0),
        content(Q_NULLPTR), animation(Q_NULLPTR) { }

    void updateContent();
    bool handleMousePressEvent(QQuickItem *item, QMouseEvent *event);
    bool handleMouseMoveEvent(QQuickItem *item, QMouseEvent *event);
    bool handleMouseReleaseEvent(QQuickItem *item, QMouseEvent *event);

    Qt::Edge edge;
    qreal offset;
    qreal position;
    QPointF pressPoint;
    QQuickItem *content;
    QQuickPropertyAnimation *animation;
};

void QQuickDrawerPrivate::updateContent()
{
    Q_Q(QQuickDrawer);
    if (!content)
        return;

    switch (edge) {
    case Qt::LeftEdge:
        content->setX((position - 1.0) * content->width());
        break;
    case Qt::RightEdge:
        content->setX(q->width() + - position * content->width());
        break;
    case Qt::TopEdge:
        content->setY((position - 1.0) * content->height());
        break;
    case Qt::BottomEdge:
        content->setY(q->height() + - position * content->height());
        break;
    }
}

bool QQuickDrawerPrivate::handleMousePressEvent(QQuickItem *item, QMouseEvent *event)
{
    Q_Q(QQuickDrawer);
    pressPoint = q->mapFromItem(item, event->pos());

    if (qFuzzyIsNull(position)) {
        // only accept pressing at drag margins when fully closed
        switch (edge) {
        case Qt::LeftEdge:
            event->setAccepted(!QQuickWindowPrivate::dragOverThreshold(event->x(), Qt::XAxis, event));
            break;
        case Qt::RightEdge:
            event->setAccepted(!QQuickWindowPrivate::dragOverThreshold(q->width() - event->x(), Qt::XAxis, event));
            break;
        case Qt::TopEdge:
            event->setAccepted(!QQuickWindowPrivate::dragOverThreshold(event->y(), Qt::YAxis, event));
            break;
        case Qt::BottomEdge:
            event->setAccepted(!QQuickWindowPrivate::dragOverThreshold(q->height() - event->y(), Qt::YAxis, event));
            break;
        }
        offset = 0;
    } else {
        event->accept();
        offset = q->positionAt(pressPoint) - position;
    }

    return item == q;
}

bool QQuickDrawerPrivate::handleMouseMoveEvent(QQuickItem *item, QMouseEvent *event)
{
    Q_Q(QQuickDrawer);
    QPointF movePoint = q->mapFromItem(item, event->pos());

    if (!q->keepMouseGrab()) {
        bool overThreshold = false;
        if (edge == Qt::LeftEdge || edge == Qt::RightEdge)
            overThreshold = QQuickWindowPrivate::dragOverThreshold(movePoint.x() - pressPoint.x(), Qt::XAxis, event);
        else
            overThreshold = QQuickWindowPrivate::dragOverThreshold(movePoint.y() - pressPoint.y(), Qt::YAxis, event);

        if (window && overThreshold) {
            QQuickItem *grabber = q->window()->mouseGrabberItem();
            if (!grabber || !grabber->keepMouseGrab()) {
                q->grabMouse();
                q->setKeepMouseGrab(overThreshold);
            }
        }
    }

    if (q->keepMouseGrab())
        q->setPosition(q->positionAt(event->pos()) - offset);
    event->accept();

    return q->keepMouseGrab();
}

bool QQuickDrawerPrivate::handleMouseReleaseEvent(QQuickItem *item, QMouseEvent *event)
{
    Q_Q(QQuickDrawer);
    bool wasGrabbed = q->keepMouseGrab();
    if (wasGrabbed) {
//        int startDragVelocity = QGuiApplication::styleHints()->startDragVelocity();
//        if (startDragVelocity && QGuiApplicationPrivate::mouseEventCaps(event) & QTouchDevice::Velocity) {
//            QVector2D velocity = QGuiApplicationPrivate::mouseEventVelocity(event);
//            qreal vel = (edge == Qt::LeftEdge || edge == Qt::RightEdge) ? velocity.x() : velocity.y();
//            qDebug() << vel << "vs." << startDragVelocity;
//        }
        if (position < 0.3) {
            q->close();
        } else if (position > 0.7) {
            q->open();
        } else {
            switch (edge) {
            case Qt::LeftEdge:
                if (event->x() - pressPoint.x() > 0)
                    q->open();
                else
                    q->close();
                break;
            case Qt::RightEdge:
                if (event->x() - pressPoint.x() < 0)
                    q->open();
                else
                    q->close();
                break;
            case Qt::TopEdge:
                if (event->y() - pressPoint.y() > 0)
                    q->open();
                else
                    q->close();
                break;
            case Qt::BottomEdge:
                if (event->y() - pressPoint.y() < 0)
                    q->open();
                else
                    q->close();
                break;
            }
        }
        q->setKeepMouseGrab(false);
    } else {
        if (item == q)
            emit q->clicked();
    }
    pressPoint = QPoint();
    event->accept();
    return wasGrabbed;
}

QQuickDrawer::QQuickDrawer(QQuickItem *parent) :
    QQuickControl(*(new QQuickDrawerPrivate), parent)
{
    setZ(1);
    setFiltersChildMouseEvents(true);
    setAcceptedMouseButtons(Qt::LeftButton);
}

Qt::Edge QQuickDrawer::edge() const
{
    Q_D(const QQuickDrawer);
    return d->edge;
}

void QQuickDrawer::setEdge(Qt::Edge edge)
{
    Q_D(QQuickDrawer);
    if (d->edge != edge) {
        d->edge = edge;
        if (isComponentComplete())
            d->updateContent();
        emit edgeChanged();
    }
}

qreal QQuickDrawer::position() const
{
    Q_D(const QQuickDrawer);
    return d->position;
}

void QQuickDrawer::setPosition(qreal position)
{
    Q_D(QQuickDrawer);
    position = qBound(0.0, position, 1.0);
    if (!qFuzzyCompare(d->position, position)) {
        d->position = position;
        if (isComponentComplete())
            d->updateContent();
        emit positionChanged();
    }
}

QQuickItem *QQuickDrawer::contentItem() const
{
    Q_D(const QQuickDrawer);
    return d->content;
}

void QQuickDrawer::setContentItem(QQuickItem *item)
{
    Q_D(QQuickDrawer);
    if (d->content != item) {
        delete d->content;
        d->content = item;
        if (item)
            item->setParentItem(this);
        if (isComponentComplete())
            d->updateContent();
        emit contentItemChanged();
    }
}

QQuickPropertyAnimation *QQuickDrawer::animation() const
{
    Q_D(const QQuickDrawer);
    return d->animation;
}

void QQuickDrawer::setAnimation(QQuickPropertyAnimation *animation)
{
    Q_D(QQuickDrawer);
    if (d->animation != animation) {
        delete d->animation;
        d->animation = animation;
        if (animation) {
            animation->setTargetObject(this);
            animation->setProperty(QStringLiteral("position"));
        }
        emit animationChanged();
    }
}

void QQuickDrawer::open()
{
    Q_D(QQuickDrawer);
    if (d->animation) {
        d->animation->stop();
        d->animation->setFrom(d->position);
        d->animation->setTo(1.0);
        d->animation->start();
    } else {
        setPosition(1.0);
    }
}

void QQuickDrawer::close()
{
    Q_D(QQuickDrawer);
    if (d->animation) {
        d->animation->stop();
        d->animation->setFrom(d->position);
        d->animation->setTo(0.0);
        d->animation->start();
    } else {
        setPosition(0.0);
    }
}

bool QQuickDrawer::childMouseEventFilter(QQuickItem *child, QEvent *event)
{
    Q_D(QQuickDrawer);
    switch (event->type()) {
    case QEvent::MouseButtonPress:
        return d->handleMousePressEvent(child, static_cast<QMouseEvent *>(event));
    case QEvent::MouseMove:
        return d->handleMouseMoveEvent(child, static_cast<QMouseEvent *>(event));
    case QEvent::MouseButtonRelease:
        return d->handleMouseReleaseEvent(child, static_cast<QMouseEvent *>(event));
    default:
        return false;
    }
}

void QQuickDrawer::mousePressEvent(QMouseEvent *event)
{
    Q_D(QQuickDrawer);
    QQuickControl::mousePressEvent(event);
    d->handleMousePressEvent(this, event);
}

void QQuickDrawer::mouseMoveEvent(QMouseEvent *event)
{
    Q_D(QQuickDrawer);
    QQuickControl::mouseMoveEvent(event);
    d->handleMouseMoveEvent(this, event);
}

void QQuickDrawer::mouseReleaseEvent(QMouseEvent *event)
{
    Q_D(QQuickDrawer);
    QQuickControl::mouseReleaseEvent(event);
    d->handleMouseReleaseEvent(this, event);
}

void QQuickDrawer::mouseUngrabEvent()
{
    Q_D(QQuickDrawer);
    QQuickControl::mouseUngrabEvent();
    d->pressPoint = QPoint();
}

void QQuickDrawer::geometryChanged(const QRectF &newGeometry, const QRectF &oldGeometry)
{
    Q_D(QQuickDrawer);
    QQuickControl::geometryChanged(newGeometry, oldGeometry);
    if (isComponentComplete())
        d->updateContent();
}

void QQuickDrawer::componentComplete()
{
    Q_D(QQuickDrawer);
    QQuickControl::componentComplete();
    d->updateContent();
}

qreal QQuickDrawer::positionAt(const QPointF &point) const
{
    Q_D(const QQuickDrawer);
    if (!d->content)
        return 0.0;

    switch (d->edge) {
    case Qt::TopEdge:
        return point.y() / d->content->height();
    case Qt::LeftEdge:
        return point.x() / d->content->width();
    case Qt::RightEdge:
        return (width() - point.x()) / d->content->width();
    case Qt::BottomEdge:
        return (height() - point.y()) / d->content->height();
    default:
        return 0;
    }
}

QT_END_NAMESPACE