/*  SPDX-License-Identifier: LGPL-2.0-or-later

    Copyright (C) 2013 Dominik Haumann <dhaumann@kde.org>

    This library is free software; you can redistribute it and/or
    modify it under the terms of the GNU Library General Public
    License as published by the Free Software Foundation; either
    version 2 of the License, or (at your option) any later version.

    This library is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
    Library General Public License for more details.

    You should have received a copy of the GNU Library General Public License
    along with this library; see the file COPYING.LIB.  If not, write to
    the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
    Boston, MA 02110-1301, USA.
*/

#include "katefadeeffect.h"

#include <QGraphicsOpacityEffect>
#include <QTimeLine>
#include <QWidget>

KateFadeEffect::KateFadeEffect(QWidget *widget)
    : QObject(widget)
    , m_widget(widget)
    , m_effect(nullptr) // effect only exists during fading animation
{
    m_timeLine = new QTimeLine(500, this);
    m_timeLine->setUpdateInterval(40);

    connect(m_timeLine, SIGNAL(valueChanged(qreal)), this, SLOT(opacityChanged(qreal)));
    connect(m_timeLine, SIGNAL(finished()), this, SLOT(animationFinished()));
}

bool KateFadeEffect::isHideAnimationRunning() const
{
    return (m_timeLine->direction() == QTimeLine::Backward) && (m_timeLine->state() == QTimeLine::Running);
}

bool KateFadeEffect::isShowAnimationRunning() const
{
    return (m_timeLine->direction() == QTimeLine::Forward) && (m_timeLine->state() == QTimeLine::Running);
}

void KateFadeEffect::fadeIn()
{
    // stop time line if still running
    if (m_timeLine->state() == QTimeLine::Running) {
        m_timeLine->stop();
    }

    // assign new graphics effect, old one is deleted in setGraphicsEffect()
    m_effect = new QGraphicsOpacityEffect(this);
    m_effect->setOpacity(0.0);
    m_widget->setGraphicsEffect(m_effect);

    // show widget and start fade in animation
    m_widget->show();
    m_timeLine->setDirection(QTimeLine::Forward);
    m_timeLine->start();
}

void KateFadeEffect::fadeOut()
{
    // stop time line if still running
    if (m_timeLine->state() == QTimeLine::Running) {
        m_timeLine->stop();
    }

    // assign new graphics effect, old one is deleted in setGraphicsEffect()
    m_effect = new QGraphicsOpacityEffect(this);
    m_effect->setOpacity(1.0);
    m_widget->setGraphicsEffect(m_effect);

    // start fade out animation
    m_timeLine->setDirection(QTimeLine::Backward);
    m_timeLine->start();
}

void KateFadeEffect::opacityChanged(qreal value)
{
    Q_ASSERT(m_effect);
    m_effect->setOpacity(value);
}

void KateFadeEffect::animationFinished()
{
    // fading finished: remove graphics effect, deletes the effect as well
    m_widget->setGraphicsEffect(nullptr);
    Q_ASSERT(!m_effect);

    if (m_timeLine->direction() == QTimeLine::Backward) {
        m_widget->hide();
        emit hideAnimationFinished();
    } else {
        emit showAnimationFinished();
    }
}
