/****************************************************************************
**
** Copyright (C) 2014 Digia Plc and/or its subsidiary(-ies).
** Contact: http://www.qt-project.org/legal
**
** This file is part of the QtQml module of the Qt Toolkit.
**
** $QT_BEGIN_LICENSE:LGPL21$
** 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 or version 3 as published by the Free
** Software Foundation and appearing in the file LICENSE.LGPLv21 and
** LICENSE.LGPLv3 included in the packaging of this file. Please review the
** following information to ensure the GNU Lesser General Public License
** requirements will be met: https://www.gnu.org/licenses/lgpl.html and
** 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.
**
** $QT_END_LICENSE$
**
****************************************************************************/

#include "qquickcustomparticle_p.h"
#include <QtQuick/private/qquickshadereffectmesh_p.h>
#include <QtQuick/private/qsgshadersourcebuilder_p.h>
#include <cstdlib>

QT_BEGIN_NAMESPACE

static QSGGeometry::Attribute PlainParticle_Attributes[] = {
    QSGGeometry::Attribute::create(0, 2, GL_FLOAT, true),       // Position
    QSGGeometry::Attribute::create(1, 2, GL_FLOAT),             // TexCoord
    QSGGeometry::Attribute::create(2, 4, GL_FLOAT),             // Data
    QSGGeometry::Attribute::create(3, 4, GL_FLOAT),             // Vectors
    QSGGeometry::Attribute::create(4, 1, GL_FLOAT)              // r
};

static QSGGeometry::AttributeSet PlainParticle_AttributeSet =
{
    5, // Attribute Count
    (2 + 2 + 4 + 4 + 1) * sizeof(float),
    PlainParticle_Attributes
};

struct PlainVertex {
    float x;
    float y;
    float tx;
    float ty;
    float t;
    float lifeSpan;
    float size;
    float endSize;
    float vx;
    float vy;
    float ax;
    float ay;
    float r;
};

struct PlainVertices {
    PlainVertex v1;
    PlainVertex v2;
    PlainVertex v3;
    PlainVertex v4;
};

/*!
    \qmltype CustomParticle
    \instantiates QQuickCustomParticle
    \inqmlmodule QtQuick.Particles
    \inherits ParticlePainter
    \brief For specifying shaders to paint particles
    \ingroup qtquick-particles

*/

QQuickCustomParticle::QQuickCustomParticle(QQuickItem* parent)
    : QQuickParticlePainter(parent)
    , m_dirtyUniforms(true)
    , m_dirtyUniformValues(true)
    , m_dirtyTextureProviders(true)
    , m_dirtyProgram(true)
{
    setFlag(QQuickItem::ItemHasContents);
}

void QQuickCustomParticle::sceneGraphInvalidated()
{
    m_nodes.clear();
}

QQuickCustomParticle::~QQuickCustomParticle()
{
}

void QQuickCustomParticle::componentComplete()
{
    m_common.updateShader(this, Key::FragmentShader);
    updateVertexShader();
    reset();
    QQuickParticlePainter::componentComplete();
}


//Trying to keep the shader conventions the same as in qsgshadereffectitem
/*!
    \qmlproperty string QtQuick.Particles::CustomParticle::fragmentShader

    This property holds the fragment shader's GLSL source code.
    The default shader expects the texture coordinate to be passed from the
    vertex shader as "varying highp vec2 qt_TexCoord0", and it samples from a
    sampler2D named "source".
*/

void QQuickCustomParticle::setFragmentShader(const QByteArray &code)
{
    if (m_common.source.sourceCode[Key::FragmentShader].constData() == code.constData())
        return;
    m_common.source.sourceCode[Key::FragmentShader] = code;
    m_dirtyProgram = true;
    if (isComponentComplete()) {
        m_common.updateShader(this, Key::FragmentShader);
        reset();
    }
    emit fragmentShaderChanged();
}

/*!
    \qmlproperty string QtQuick.Particles::CustomParticle::vertexShader

    This property holds the vertex shader's GLSL source code.

    The default shader passes the texture coordinate along to the fragment
    shader as "varying highp vec2 qt_TexCoord0".

    To aid writing a particle vertex shader, the following GLSL code is prepended
    to your vertex shader:
    \code
        attribute highp vec2 qt_ParticlePos;
        attribute highp vec2 qt_ParticleTex;
        attribute highp vec4 qt_ParticleData; //  x = time,  y = lifeSpan, z = size,  w = endSize
        attribute highp vec4 qt_ParticleVec; // x,y = constant velocity,  z,w = acceleration
        attribute highp float qt_ParticleR;
        uniform highp mat4 qt_Matrix;
        uniform highp float qt_Timestamp;
        varying highp vec2 qt_TexCoord0;
        void defaultMain() {
            qt_TexCoord0 = qt_ParticleTex;
            highp float size = qt_ParticleData.z;
            highp float endSize = qt_ParticleData.w;
            highp float t = (qt_Timestamp - qt_ParticleData.x) / qt_ParticleData.y;
            highp float currentSize = mix(size, endSize, t * t);
            if (t < 0. || t > 1.)
                currentSize = 0.;
            highp vec2 pos = qt_ParticlePos
                           - currentSize / 2. + currentSize * qt_ParticleTex   // adjust size
                           + qt_ParticleVec.xy * t * qt_ParticleData.y         // apply velocity vector..
                           + 0.5 * qt_ParticleVec.zw * pow(t * qt_ParticleData.y, 2.);
            gl_Position = qt_Matrix * vec4(pos.x, pos.y, 0, 1);
        }
    \endcode

    defaultMain() is the same code as in the default shader, you can call this for basic
    particle functions and then add additional variables for custom effects. Note that
    the vertex shader for particles is responsible for simulating the movement of particles
    over time, the particle data itself only has the starting position and spawn time.
*/

void QQuickCustomParticle::setVertexShader(const QByteArray &code)
{
    if (m_common.source.sourceCode[Key::VertexShader].constData() == code.constData())
        return;
    m_common.source.sourceCode[Key::VertexShader] = code;

    m_dirtyProgram = true;
    if (isComponentComplete()) {
        updateVertexShader();
        reset();
    }
    emit vertexShaderChanged();
}

void QQuickCustomParticle::updateVertexShader()
{
    m_common.disconnectPropertySignals(this, Key::VertexShader);
    qDeleteAll(m_common.signalMappers[Key::VertexShader]);
    m_common.uniformData[Key::VertexShader].clear();
    m_common.signalMappers[Key::VertexShader].clear();
    m_common.attributes.clear();
    m_common.attributes.append("qt_ParticlePos");
    m_common.attributes.append("qt_ParticleTex");
    m_common.attributes.append("qt_ParticleData");
    m_common.attributes.append("qt_ParticleVec");
    m_common.attributes.append("qt_ParticleR");

    UniformData d;
    d.name = "qt_Matrix";
    d.specialType = UniformData::Matrix;
    m_common.uniformData[Key::VertexShader].append(d);
    m_common.signalMappers[Key::VertexShader].append(0);

    d.name = "qt_Timestamp";
    d.specialType = UniformData::None;
    m_common.uniformData[Key::VertexShader].append(d);
    m_common.signalMappers[Key::VertexShader].append(0);

    const QByteArray &code = m_common.source.sourceCode[Key::VertexShader];
    if (!code.isEmpty())
        m_common.lookThroughShaderCode(this, Key::VertexShader, code);

    m_common.connectPropertySignals(this, Key::VertexShader);
}

void QQuickCustomParticle::reset()
{
    QQuickParticlePainter::reset();
    update();
}

QSGNode *QQuickCustomParticle::updatePaintNode(QSGNode *oldNode, UpdatePaintNodeData *)
{
    QQuickShaderEffectNode *rootNode = static_cast<QQuickShaderEffectNode *>(oldNode);
    if (m_pleaseReset){
        delete rootNode;//Automatically deletes children
        rootNode = 0;
        m_nodes.clear();
        m_pleaseReset = false;
        m_dirtyProgram = true;
    }

    if (m_system && m_system->isRunning() && !m_system->isPaused()){
        rootNode = prepareNextFrame(rootNode);
        if (rootNode) {
            foreach (QSGGeometryNode* node, m_nodes)
                node->markDirty(QSGNode::DirtyGeometry);
            update();
        }
    }

    return rootNode;
}

QQuickShaderEffectNode *QQuickCustomParticle::prepareNextFrame(QQuickShaderEffectNode *rootNode)
{
    if (!rootNode)
        rootNode = buildCustomNodes();

    if (!rootNode)
        return 0;

    if (m_dirtyProgram) {
        const bool isES = QOpenGLContext::currentContext()->isOpenGLES();

        QQuickShaderEffectMaterial *material = static_cast<QQuickShaderEffectMaterial *>(rootNode->material());
        Q_ASSERT(material);

        Key s = m_common.source;
        QSGShaderSourceBuilder builder;
        if (s.sourceCode[Key::FragmentShader].isEmpty()) {
            builder.appendSourceFile(QStringLiteral(":/particles/shaders/customparticle.frag"));
            if (isES)
                builder.removeVersion();
            s.sourceCode[Key::FragmentShader] = builder.source();
            builder.clear();
        }

        builder.appendSourceFile(QStringLiteral(":/particles/shaders/customparticletemplate.vert"));
        if (isES)
            builder.removeVersion();

        if (s.sourceCode[Key::VertexShader].isEmpty())
            builder.appendSourceFile(QStringLiteral(":/particles/shaders/customparticle.vert"));
        s.sourceCode[Key::VertexShader] = builder.source() + s.sourceCode[Key::VertexShader];

        s.className = metaObject()->className();

        material->setProgramSource(s);
        material->attributes = m_common.attributes;
        foreach (QQuickShaderEffectNode* node, m_nodes)
            node->markDirty(QSGNode::DirtyMaterial);

        m_dirtyProgram = false;
        m_dirtyUniforms = true;
    }

    m_lastTime = m_system->systemSync(this) / 1000.;
    if (true) //Currently this is how we update timestamp... potentially over expensive.
        buildData(rootNode);
    return rootNode;
}

QQuickShaderEffectNode* QQuickCustomParticle::buildCustomNodes()
{
    if (!QOpenGLContext::currentContext())
        return 0;

    if (QOpenGLContext::currentContext()->isOpenGLES() && m_count * 4 > 0xffff) {
        printf("CustomParticle: Too many particles... \n");
        return 0;
    }

    if (m_count <= 0) {
        printf("CustomParticle: Too few particles... \n");
        return 0;
    }

    if (m_groups.isEmpty())
        return 0;

    QQuickShaderEffectNode *rootNode = 0;
    QQuickShaderEffectMaterial *material = new QQuickShaderEffectMaterial;
    m_dirtyProgram = true;

    foreach (const QString &str, m_groups){
        int gIdx = m_system->groupIds[str];
        int count = m_system->groupData[gIdx]->size();

        QQuickShaderEffectNode* node = new QQuickShaderEffectNode();
        m_nodes.insert(gIdx, node);

        node->setMaterial(material);

        //Create Particle Geometry
        int vCount = count * 4;
        int iCount = count * 6;
        QSGGeometry *g = new QSGGeometry(PlainParticle_AttributeSet, vCount, iCount);
        g->setDrawingMode(GL_TRIANGLES);
        node->setGeometry(g);
        node->setFlag(QSGNode::OwnsGeometry, true);
        PlainVertex *vertices = (PlainVertex *) g->vertexData();
        for (int p=0; p < count; ++p) {
            commit(gIdx, p);
            vertices[0].tx = 0;
            vertices[0].ty = 0;

            vertices[1].tx = 1;
            vertices[1].ty = 0;

            vertices[2].tx = 0;
            vertices[2].ty = 1;

            vertices[3].tx = 1;
            vertices[3].ty = 1;
            vertices += 4;
        }
        quint16 *indices = g->indexDataAsUShort();
        for (int i=0; i < count; ++i) {
            int o = i * 4;
            indices[0] = o;
            indices[1] = o + 1;
            indices[2] = o + 2;
            indices[3] = o + 1;
            indices[4] = o + 3;
            indices[5] = o + 2;
            indices += 6;
        }
    }

    QHash<int, QQuickShaderEffectNode*>::const_iterator it = m_nodes.begin();
    rootNode = it.value();
    rootNode->setFlag(QSGNode::OwnsMaterial, true);
    for (++it; it != m_nodes.end(); ++it)
        rootNode->appendChildNode(it.value());

    return rootNode;
}

void QQuickCustomParticle::sourceDestroyed(QObject *object)
{
    m_common.sourceDestroyed(object);
}

void QQuickCustomParticle::propertyChanged(int mappedId)
{
    bool textureProviderChanged;
    m_common.propertyChanged(this, mappedId, &textureProviderChanged);
    m_dirtyTextureProviders |= textureProviderChanged;
    m_dirtyUniformValues = true;
    update();
}


void QQuickCustomParticle::buildData(QQuickShaderEffectNode *rootNode)
{
    if (!rootNode)
        return;
    for (int shaderType = 0; shaderType < Key::ShaderTypeCount; ++shaderType) {
        for (int i = 0; i < m_common.uniformData[shaderType].size(); ++i) {
            if (m_common.uniformData[shaderType].at(i).name == "qt_Timestamp")
                m_common.uniformData[shaderType][i].value = qVariantFromValue(m_lastTime);
        }
    }
    m_common.updateMaterial(rootNode, static_cast<QQuickShaderEffectMaterial *>(rootNode->material()),
                            m_dirtyUniforms, true, m_dirtyTextureProviders);
    foreach (QQuickShaderEffectNode* node, m_nodes)
        node->markDirty(QSGNode::DirtyMaterial);
    m_dirtyUniforms = m_dirtyUniformValues = m_dirtyTextureProviders = false;
}

void QQuickCustomParticle::initialize(int gIdx, int pIdx)
{
    QQuickParticleData* datum = m_system->groupData[gIdx]->data[pIdx];
    datum->r = rand()/(qreal)RAND_MAX;
}

void QQuickCustomParticle::commit(int gIdx, int pIdx)
{
    if (m_nodes[gIdx] == 0)
        return;

    QQuickParticleData* datum = m_system->groupData[gIdx]->data[pIdx];
    PlainVertices *particles = (PlainVertices *) m_nodes[gIdx]->geometry()->vertexData();
    PlainVertex *vertices = (PlainVertex *)&particles[pIdx];
    for (int i=0; i<4; ++i) {
        vertices[i].x = datum->x - m_systemOffset.x();
        vertices[i].y = datum->y - m_systemOffset.y();
        vertices[i].t = datum->t;
        vertices[i].lifeSpan = datum->lifeSpan;
        vertices[i].size = datum->size;
        vertices[i].endSize = datum->endSize;
        vertices[i].vx = datum->vx;
        vertices[i].vy = datum->vy;
        vertices[i].ax = datum->ax;
        vertices[i].ay = datum->ay;
        vertices[i].r = datum->r;
    }
}

void QQuickCustomParticle::itemChange(ItemChange change, const ItemChangeData &value)
{
    if (change == QQuickItem::ItemSceneChange)
        m_common.updateWindow(value.window);
    QQuickParticlePainter::itemChange(change, value);
}


QT_END_NAMESPACE
