/****************************************************************************
**
** Copyright (C) 2013 Digia Plc and/or its subsidiary(-ies).
** Contact: http://www.qt-project.org/legal
**
** This file is part of the QtQuick module of the Qt Toolkit.
**
** $QT_BEGIN_LICENSE:LGPL$
** 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 Digia.  For licensing terms and
** conditions see http://qt.digia.com/licensing.  For further information
** use the contact form at http://qt.digia.com/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 2.1 as published by the Free Software
** Foundation and appearing in the file LICENSE.LGPL included in the
** packaging of this file.  Please review the following information to
** ensure the GNU Lesser General Public License version 2.1 requirements
** will be met: http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html.
**
** In addition, as a special exception, Digia gives you certain additional
** rights.  These rights are described in the Digia Qt LGPL Exception
** version 1.1, included in the file LGPL_EXCEPTION.txt in this package.
**
** GNU General Public License Usage
** Alternatively, this file may be used under the terms of the GNU
** General Public License version 3.0 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 3.0 requirements will be
** met: http://www.gnu.org/copyleft/gpl.html.
**
**
** $QT_END_LICENSE$
**
****************************************************************************/

#include "qquickitemparticle_p.h"
#include <QtQuick/qsgnode.h>
#include <QTimer>
#include <QQmlComponent>
#include <QDebug>

QT_BEGIN_NAMESPACE

/*!
    \qmltype ItemParticle
    \instantiates QQuickItemParticle
    \inqmlmodule QtQuick.Particles 2
    \inherits ParticlePainter
    \brief For specifying a delegate to paint particles
    \ingroup qtquick-particles

*/


/*!
    \qmlmethod QtQuick.Particles::ItemParticle::freeze(Item item)

    Suspends the flow of time for the logical particle which item represents, allowing you to control its movement.
*/

/*!
    \qmlmethod QtQuick.Particles::ItemParticle::unfreeze(Item item)

    Restarts the flow of time for the logical particle which item represents, allowing it to be moved by the particle system again.
*/

/*!
    \qmlmethod QtQuick.Particles::ItemParticle::take(Item item, bool prioritize)

    Asks the ItemParticle to take over control of item. It will be emitted when there is a logical particle available.

    By default items form a queue when waiting for a logical particle, but if prioritize is true then it will go immediately to the
    head of the queue.
*/
/*!
    \qmlmethod QtQuick.Particles::ItemParticle::give(Item item)

    Orders the ItemParticle to give you control of the item. It will cease controlling it and the item will lose its association to the logical particle.
*/

/*!
    \qmlproperty bool QtQuick.Particles::ItemParticle::fade

    If true, the item will automatically be faded in and out
    at the ends of its lifetime. If false, you will have to
    implement any entry effect yourself.

    Default is true.
*/
/*!
    \qmlproperty Component QtQuick.Particles::ItemParticle::delegate

    An instance of the delegate will be created for every logical
    particle, and moved along with it.
*/

QQuickItemParticle::QQuickItemParticle(QQuickItem *parent) :
    QQuickParticlePainter(parent), m_fade(true), m_delegate(0)
{
    setFlag(QQuickItem::ItemHasContents);
    clock = new Clock(this);
    clock->start();
}

QQuickItemParticle::~QQuickItemParticle()
{
    delete clock;
}

void QQuickItemParticle::freeze(QQuickItem* item)
{
    m_stasis << item;
}


void QQuickItemParticle::unfreeze(QQuickItem* item)
{
    m_stasis.remove(item);
}

void QQuickItemParticle::take(QQuickItem *item, bool prioritize)
{
    if (prioritize)
        m_pendingItems.push_front(item);
    else
        m_pendingItems.push_back(item);
}

void QQuickItemParticle::give(QQuickItem *item)
{
    //TODO: This
    Q_UNUSED(item);
}

void QQuickItemParticle::initialize(int gIdx, int pIdx)
{
    m_loadables << m_system->groupData[gIdx]->data[pIdx];//defer to other thread
}

void QQuickItemParticle::commit(int, int)
{
}

void QQuickItemParticle::tick(int time)
{
    Q_UNUSED(time);//only needed because QTickAnimationProxy expects one
    foreach (QQuickItem* item, m_deletables){
        if (m_fade)
            item->setOpacity(0.);
        item->setVisible(false);
        QQuickItemParticleAttached* mpa;
        if ((mpa = qobject_cast<QQuickItemParticleAttached*>(qmlAttachedPropertiesObject<QQuickItemParticle>(item))))
            mpa->detach();//reparent as well?
        //TODO: Delete iff we created it
        m_activeCount--;
    }
    m_deletables.clear();

    foreach (QQuickParticleData* d, m_loadables){
        if (m_stasis.contains(d->delegate))
            qWarning() << "Current model particles prefers overwrite:false";
        //remove old item from the particle that is dying to make room for this one
        if (d->delegate)
            m_deletables << d->delegate;
        d->delegate = 0;
        if (!m_pendingItems.isEmpty()){
            d->delegate = m_pendingItems.front();
            m_pendingItems.pop_front();
        }else if (m_delegate){
            d->delegate = qobject_cast<QQuickItem*>(m_delegate->create(qmlContext(this)));
        }
        if (d->delegate && d){//###Data can be zero if creating an item leads to a reset - this screws things up.
            d->delegate->setX(d->curX() - d->delegate->width()/2);//TODO: adjust for system?
            d->delegate->setY(d->curY() - d->delegate->height()/2);
            QQuickItemParticleAttached* mpa = qobject_cast<QQuickItemParticleAttached*>(qmlAttachedPropertiesObject<QQuickItemParticle>(d->delegate));
            if (mpa){
                mpa->m_mp = this;
                mpa->attach();
            }
            d->delegate->setParentItem(this);
            if (m_fade)
                d->delegate->setOpacity(0.);
            d->delegate->setVisible(false);//Will be set to true when we prepare the next frame
            m_activeCount++;
        }
    }
    m_loadables.clear();
}

void QQuickItemParticle::reset()
{
    QQuickParticlePainter::reset();
    m_loadables.clear();
    //TODO: Cleanup items?
    //deletables?
}


QSGNode* QQuickItemParticle::updatePaintNode(QSGNode* n, UpdatePaintNodeData* d)
{
    //Dummy update just to get painting tick
    if (m_pleaseReset){
        m_pleaseReset = false;
        //Refill loadables, delayed here so as to only happen once per frame max
        //### Constant resetting might lead to m_loadables never being populated when tick() occurs
        foreach (const QString group, m_groups){
            int gIdx = m_system->groupIds[group];
            foreach (QQuickParticleData* d, m_system->groupData[gIdx]->data)
                if (!d->delegate && d->t != -1  && d->stillAlive())
                    m_loadables << d;
        }
    }
    prepareNextFrame();

    update();//Get called again
    if (n)
        n->markDirty(QSGNode::DirtyMaterial);
    return QQuickItem::updatePaintNode(n,d);
}

void QQuickItemParticle::prepareNextFrame()
{
    if (!m_system)
        return;
    qint64 timeStamp = m_system->systemSync(this);
    qreal curT = timeStamp/1000.0;
    qreal dt = curT - m_lastT;
    m_lastT = curT;
    if (!m_activeCount)
        return;

    //TODO: Size, better fade?
    foreach (const QString &str, m_groups){
        int gIdx = m_system->groupIds[str];
        int count = m_system->groupData[gIdx]->size();

        for (int i=0; i<count; i++){
            QQuickParticleData* data = m_system->groupData[gIdx]->data[i];
            QQuickItem* item = data->delegate;
            if (!item)
                continue;
            qreal t = ((timeStamp/1000.0) - data->t) / data->lifeSpan;
            if (m_stasis.contains(item)) {
                data->t += dt;//Stasis effect
                continue;
            }
            if (t >= 1.0){//Usually happens from load
                m_deletables << item;
                data->delegate = 0;
            }else{//Fade
                data->delegate->setVisible(true);
                if (m_fade){
                    qreal o = 1.;
                    if (t<0.2)
                        o = t*5;
                    if (t>0.8)
                        o = (1-t)*5;
                    item->setOpacity(o);
                }
            }
            item->setX(data->curX() - item->width()/2 - m_systemOffset.x());
            item->setY(data->curY() - item->height()/2 - m_systemOffset.y());
        }
    }
}

QQuickItemParticleAttached *QQuickItemParticle::qmlAttachedProperties(QObject *object)
{
    return new QQuickItemParticleAttached(object);
}

QT_END_NAMESPACE