// Copyright (C) 2016 The Qt Company Ltd.
// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR LGPL-3.0-only OR GPL-2.0-only OR GPL-3.0-only

/*!
    \class QAnimationGroup
    \inmodule QtCore
    \brief The QAnimationGroup class is an abstract base class for groups of animations.
    \since 4.6
    \ingroup animation

    An animation group is a container for animations (subclasses of
    QAbstractAnimation). A group is usually responsible for managing
    the \l{QAbstractAnimation::State}{state} of its animations, i.e.,
    it decides when to start, stop, resume, and pause them. Currently,
    Qt provides two such groups: QParallelAnimationGroup and
    QSequentialAnimationGroup. Look up their class descriptions for
    details.

    Since QAnimationGroup inherits from QAbstractAnimation, you can
    combine groups, and easily construct complex animation graphs.
    You can query QAbstractAnimation for the group it belongs to
    (using the \l{QAbstractAnimation::}{group()} function).

    To start a top-level animation group, you simply use the
    \l{QAbstractAnimation::}{start()} function from
    QAbstractAnimation. By a top-level animation group, we think of a
    group that itself is not contained within another group. Starting
    sub groups directly is not supported, and may lead to unexpected
    behavior.

    \omit OK, we'll put in a snippet on this here \endomit

    QAnimationGroup provides methods for adding and retrieving
    animations. Besides that, you can remove animations by calling
    \l removeAnimation(), and clear the animation group by calling
    clear(). You may keep track of changes in the group's
    animations by listening to QEvent::ChildAdded and
    QEvent::ChildRemoved events.

    \omit OK, let's find a snippet here as well. \endomit

    QAnimationGroup takes ownership of the animations it manages, and
    ensures that they are deleted when the animation group is deleted.

    \sa QAbstractAnimation, QVariantAnimation, {The Animation Framework}
*/

#include "qanimationgroup.h"
#include <QtCore/qdebug.h>
#include <QtCore/qcoreevent.h>
#include "qanimationgroup_p.h"

#include <algorithm>

QT_BEGIN_NAMESPACE


/*!
    Constructs a QAnimationGroup.
    \a parent is passed to QObject's constructor.
*/
QAnimationGroup::QAnimationGroup(QObject *parent)
    : QAbstractAnimation(*new QAnimationGroupPrivate, parent)
{
}

/*!
    \internal
*/
QAnimationGroup::QAnimationGroup(QAnimationGroupPrivate &dd, QObject *parent)
    : QAbstractAnimation(dd, parent)
{
}

/*!
    Destroys the animation group. It will also destroy all its animations.
*/
QAnimationGroup::~QAnimationGroup()
{
    Q_D(QAnimationGroup);
    // We need to clear the animations now while we are still a valid QAnimationGroup.
    // If we wait until ~QObject() the QAbstractAnimation's pointer back to us would
    // point to a QObject, not a valid QAnimationGroup.
    d->clear(true);
}

/*!
    Returns a pointer to the animation at \a index in this group. This
    function is useful when you need access to a particular animation.  \a
    index is between 0 and animationCount() - 1.

    \sa animationCount(), indexOfAnimation()
*/
QAbstractAnimation *QAnimationGroup::animationAt(int index) const
{
    Q_D(const QAnimationGroup);

    if (index < 0 || index >= d->animations.size()) {
        qWarning("QAnimationGroup::animationAt: index is out of bounds");
        return nullptr;
    }

    return d->animations.at(index);
}


/*!
    Returns the number of animations managed by this group.

    \sa indexOfAnimation(), addAnimation(), animationAt()
*/
int QAnimationGroup::animationCount() const
{
    Q_D(const QAnimationGroup);
    return d->animations.size();
}

/*!
    Returns the index of \a animation. The returned index can be passed
    to the other functions that take an index as an argument.

    \sa insertAnimation(), animationAt(), takeAnimation()
*/
int QAnimationGroup::indexOfAnimation(QAbstractAnimation *animation) const
{
    Q_D(const QAnimationGroup);
    return d->animations.indexOf(animation);
}

/*!
    Adds \a animation to this group. This will call insertAnimation with
    index equals to animationCount().

    \note The group takes ownership of the animation.

    \sa removeAnimation()
*/
void QAnimationGroup::addAnimation(QAbstractAnimation *animation)
{
    Q_D(QAnimationGroup);
    insertAnimation(d->animations.count(), animation);
}

/*!
    Inserts \a animation into this animation group at \a index.
    If \a index is 0 the animation is inserted at the beginning.
    If \a index is animationCount(), the animation is inserted at the end.

    \note The group takes ownership of the animation.

    \sa takeAnimation(), addAnimation(), indexOfAnimation(), removeAnimation()
*/
void QAnimationGroup::insertAnimation(int index, QAbstractAnimation *animation)
{
    Q_D(QAnimationGroup);

    if (index < 0 || index > d->animations.size()) {
        qWarning("QAnimationGroup::insertAnimation: index is out of bounds");
        return;
    }

    if (QAnimationGroup *oldGroup = animation->group()) {
        oldGroup->removeAnimation(animation);
        // ensure we don't insert out of bounds if oldGroup == this
        index = qMin(index, d->animations.size());
    }

    d->animations.insert(index, animation);
    QAbstractAnimationPrivate::get(animation)->group = this;
    // this will make sure that ChildAdded event is sent to 'this'
    animation->setParent(this);
    d->animationInsertedAt(index);
}

/*!
    Removes \a animation from this group. The ownership of \a animation is
    transferred to the caller.

    \sa takeAnimation(), insertAnimation(), addAnimation()
*/
void QAnimationGroup::removeAnimation(QAbstractAnimation *animation)
{
    Q_D(QAnimationGroup);

    if (!animation) {
        qWarning("QAnimationGroup::remove: cannot remove null animation");
        return;
    }
    int index = d->animations.indexOf(animation);
    if (index == -1) {
        qWarning("QAnimationGroup::remove: animation is not part of this group");
        return;
    }

    takeAnimation(index);
}

/*!
    Returns the animation at \a index and removes it from the animation group.

    \note The ownership of the animation is transferred to the caller.

    \sa removeAnimation(), addAnimation(), insertAnimation(), indexOfAnimation()
*/
QAbstractAnimation *QAnimationGroup::takeAnimation(int index)
{
    Q_D(QAnimationGroup);
    if (index < 0 || index >= d->animations.size()) {
        qWarning("QAnimationGroup::takeAnimation: no animation at index %d", index);
        return nullptr;
    }
    QAbstractAnimation *animation = d->animations.at(index);
    QAbstractAnimationPrivate::get(animation)->group = nullptr;
    // ### removing from list before doing setParent to avoid infinite recursion
    // in ChildRemoved event
    d->animations.removeAt(index);
    animation->setParent(nullptr);
    d->animationRemoved(index, animation);
    return animation;
}

/*!
    Removes and deletes all animations in this animation group, and resets the current
    time to 0.

    \sa addAnimation(), removeAnimation()
*/
void QAnimationGroup::clear()
{
    Q_D(QAnimationGroup);
    d->clear(false);
}

/*!
    \reimp
*/
bool QAnimationGroup::event(QEvent *event)
{
    Q_D(QAnimationGroup);
    if (event->type() == QEvent::ChildAdded) {
        QChildEvent *childEvent = static_cast<QChildEvent *>(event);
        if (QAbstractAnimation *a = qobject_cast<QAbstractAnimation *>(childEvent->child())) {
            if (a->group() != this)
                addAnimation(a);
        }
    } else if (event->type() == QEvent::ChildRemoved) {
        QChildEvent *childEvent = static_cast<QChildEvent *>(event);
        // You can only rely on the child being a QObject because in the QEvent::ChildRemoved
        // case it might be called from the destructor. Casting down to QAbstractAnimation then
        // entails undefined behavior, so compare items as QObjects (which std::find does internally):
        const QList<QAbstractAnimation *>::const_iterator it
            = std::find(d->animations.cbegin(), d->animations.cend(), childEvent->child());
        if (it != d->animations.cend())
            takeAnimation(it - d->animations.cbegin());
    }
    return QAbstractAnimation::event(event);
}

void QAnimationGroupPrivate::clear(bool onDestruction)
{
    const QList<QAbstractAnimation *> animationsCopy = animations; // taking a copy
    animations.clear();
    // Clearing backwards so the indices doesn't change while we remove animations.
    for (int i = animationsCopy.count() - 1; i >= 0; --i) {
        QAbstractAnimation *animation = animationsCopy.at(i);
        animation->setParent(nullptr);
        QAbstractAnimationPrivate::get(animation)->group = nullptr;
        // If we are in ~QAnimationGroup() it is not safe to called the virtual
        // animationRemoved method, which can still be a method in a
        // QAnimationGroupPrivate derived class that assumes q_ptr is still
        // a valid derived class of QAnimationGroup.
        if (!onDestruction)
            animationRemoved(i, animation);
        delete animation;
    }
}

void QAnimationGroupPrivate::animationRemoved(int index, QAbstractAnimation *)
{
    Q_Q(QAnimationGroup);
    Q_UNUSED(index);
    if (animations.isEmpty()) {
        currentTime = 0;
        q->stop();
    }
}

QT_END_NAMESPACE

#include "moc_qanimationgroup.cpp"
