/****************************************************************************
**
** Copyright (C) 2016 The Qt Company Ltd.
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** This file is part of the QtQuick module of the Qt Toolkit.
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** General Public License version 3 as published by the Free Software
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** packaging of this file. Please review the following information to
** ensure the GNU Lesser General Public License version 3 requirements
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** Alternatively, this file may be used under the terms of the GNU
** General Public License version 2.0 or (at your option) the GNU General
** Public license version 3 or any later version approved by the KDE Free
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****************************************************************************/

#include "qquickcontext2dcommandbuffer_p.h"
#include "qquickcanvasitem_p.h"
#include <qqml.h>
#include <QtCore/QMutex>
#include <QtQuick/qsgtexture.h>
#include <QtGui/QOpenGLContext>
#include <QtGui/QPaintEngine>
#include <QtGui/private/qopenglpaintengine_p.h>

#define HAS_SHADOW(offsetX, offsetY, blur, color) (color.isValid() && color.alpha() && (blur || offsetX || offsetY))

QT_BEGIN_NAMESPACE

void qt_image_boxblur(QImage& image, int radius, bool quality);

namespace {
    class ShadowImageMaker
    {
    public:
        virtual ~ShadowImageMaker() {}

        void paintShapeAndShadow(QPainter *p, qreal offsetX, qreal offsetY, qreal blur, const QColor &color)
        {
            QRectF bounds = boundingRect().translated(offsetX, offsetY).adjusted(-2*blur, -2*blur, 2*blur, 2*blur);
            QRect boundsAligned = bounds.toAlignedRect();

            QImage shadowImage(boundsAligned.size(), QImage::Format_ARGB32_Premultiplied);
            shadowImage.fill(0);

            QPainter shadowPainter(&shadowImage);
            shadowPainter.setRenderHints(p->renderHints());
            shadowPainter.translate(offsetX - boundsAligned.left(), offsetY - boundsAligned.top());
            paint(&shadowPainter);
            shadowPainter.end();

            if (blur > 0)
                qt_image_boxblur(shadowImage, qMax(1, qRound(blur / 2)), true);

            // blacken the image with shadow color...
            shadowPainter.begin(&shadowImage);
            shadowPainter.setCompositionMode(QPainter::CompositionMode_SourceIn);
            shadowPainter.fillRect(shadowImage.rect(), color);
            shadowPainter.end();

            p->drawImage(boundsAligned.topLeft(), shadowImage);
            paint(p);
        }

        virtual void paint(QPainter *p) const = 0;
        virtual QRectF boundingRect() const = 0;
    };

    class FillRectShadow : public ShadowImageMaker
    {
    public:
        FillRectShadow(const QRectF &rect, const QBrush &brush)
            : m_rect(rect.normalized())
            , m_brush(brush)
        {
        }

        void paint(QPainter *p) const Q_DECL_OVERRIDE { p->fillRect(m_rect, m_brush); }
        QRectF boundingRect() const Q_DECL_OVERRIDE { return m_rect; }

    private:
        QRectF m_rect;
        QBrush m_brush;
    };

    class FillPathShadow : public ShadowImageMaker
    {
    public:
        FillPathShadow(const QPainterPath &path, const QBrush &brush)
            : m_path(path)
            , m_brush(brush)
        {
        }

        void paint(QPainter *p) const Q_DECL_OVERRIDE { p->fillPath(m_path, m_brush); }
        QRectF boundingRect() const Q_DECL_OVERRIDE { return m_path.boundingRect(); }

    private:
        QPainterPath m_path;
        QBrush m_brush;
    };

    class StrokePathShadow : public ShadowImageMaker
    {
    public:
        StrokePathShadow(const QPainterPath &path, const QPen &pen)
            : m_path(path)
            , m_pen(pen)
        {
        }

        void paint(QPainter *p) const Q_DECL_OVERRIDE { p->strokePath(m_path, m_pen); }

        QRectF boundingRect() const Q_DECL_OVERRIDE
        {
            qreal d = qMax(qreal(1), m_pen.widthF());
            return m_path.boundingRect().adjusted(-d, -d, d, d);
        }

    private:
        QPainterPath m_path;
        QPen m_pen;
    };

    class DrawImageShadow : public ShadowImageMaker
    {
    public:
        DrawImageShadow(const QImage &image, const QPointF &offset)
            : m_image(image)
            , m_offset(offset)
        {
        }

        void paint(QPainter *p) const Q_DECL_OVERRIDE { p->drawImage(m_offset, m_image); }

        QRectF boundingRect() const Q_DECL_OVERRIDE { return QRectF(m_image.rect()).translated(m_offset); }

    private:
        QImage m_image;
        QPointF m_offset;
    };
}

static void fillRectShadow(QPainter* p, QRectF shadowRect, qreal offsetX, qreal offsetY, qreal blur, const QColor& color)
{
    FillRectShadow shadowMaker(shadowRect, p->brush());
    shadowMaker.paintShapeAndShadow(p, offsetX, offsetY, blur, color);
}

static void fillShadowPath(QPainter* p, const QPainterPath& path, qreal offsetX, qreal offsetY, qreal blur, const QColor& color)
{
    FillPathShadow shadowMaker(path, p->brush());
    shadowMaker.paintShapeAndShadow(p, offsetX, offsetY, blur, color);
}

static void strokeShadowPath(QPainter* p, const QPainterPath& path, qreal offsetX, qreal offsetY, qreal blur, const QColor& color)
{
    StrokePathShadow shadowMaker(path, p->pen());
    shadowMaker.paintShapeAndShadow(p, offsetX, offsetY, blur, color);
}

QPen QQuickContext2DCommandBuffer::makePen(const QQuickContext2D::State& state)
{
    QPen pen;
    pen.setWidthF(state.lineWidth);
    pen.setCapStyle(state.lineCap);
    pen.setJoinStyle(state.lineJoin);
    pen.setMiterLimit(state.miterLimit);
    pen.setBrush(state.strokeStyle);
    return pen;
}

void QQuickContext2DCommandBuffer::setPainterState(QPainter* p, const QQuickContext2D::State& state, const QPen& pen)
{
   p->setTransform(state.matrix * p->transform());

   if (pen != p->pen())
       p->setPen(pen);

   if (state.fillStyle != p->brush())
       p->setBrush(state.fillStyle);

   if (state.font != p->font())
       p->setFont(state.font);

   if (state.globalAlpha != p->opacity()) {
       p->setOpacity(state.globalAlpha);
   }

   if (state.globalCompositeOperation != p->compositionMode())
       p->setCompositionMode(state.globalCompositeOperation);

   p->setClipping(state.clip);
   if (state.clip)
       p->setClipPath(state.clipPath);
}

static void qt_drawImage(QPainter *p, QQuickContext2D::State& state, QImage image, const QRectF& sr, const QRectF& dr, bool shadow = false)
{
    Q_ASSERT(p);

    if (image.isNull())
        return;

    qreal sx = sr.x();
    qreal sy = sr.y();
    qreal sw = sr.width();
    qreal sh = sr.height();
    qreal dx = dr.x();
    qreal dy = dr.y();
    qreal dw = dr.width();
    qreal dh = dr.height();

    if (sw == -1 || sh == -1) {
        sw = image.width();
        sh = image.height();
    }
    if (sx != 0 || sy != 0 || sw != image.width() || sh != image.height())
        image = image.copy(sx, sy, sw, sh);

    if (sw != dw || sh != dh)
        image = image.scaled(dw, dh);

    //Strange OpenGL painting behavior here, without beginNativePainting/endNativePainting, only the first image is painted.
    p->beginNativePainting();

    if (shadow) {
        DrawImageShadow shadowMaker(image, QPointF(dx, dy));
        shadowMaker.paintShapeAndShadow(p, state.shadowOffsetX, state.shadowOffsetY, state.shadowBlur, state.shadowColor);
    } else {
        p->drawImage(dx, dy, image);
    }

    p->endNativePainting();
}

void QQuickContext2DCommandBuffer::replay(QPainter* p, QQuickContext2D::State& state, const QVector2D &scaleFactor)
{
    if (!p)
        return;

    reset();

    p->scale(scaleFactor.x(), scaleFactor.y());
    QTransform originMatrix = p->worldTransform();

    QPen pen = makePen(state);
    setPainterState(p, state, pen);

    while (hasNext()) {
        QQuickContext2D::PaintCommand cmd = takeNextCommand();
        switch (cmd) {
        case QQuickContext2D::UpdateMatrix:
        {
            state.matrix = takeMatrix();
            p->setWorldTransform(state.matrix * originMatrix);
            break;
        }
        case QQuickContext2D::ClearRect:
        {
            QPainter::CompositionMode  cm = p->compositionMode();
            p->setCompositionMode(QPainter::CompositionMode_Clear);
            p->fillRect(takeRect(), Qt::white);
            p->setCompositionMode(cm);
            break;
        }
        case QQuickContext2D::FillRect:
        {
            QRectF r = takeRect();
            if (HAS_SHADOW(state.shadowOffsetX, state.shadowOffsetY, state.shadowBlur, state.shadowColor))
                fillRectShadow(p, r, state.shadowOffsetX, state.shadowOffsetY, state.shadowBlur, state.shadowColor);
            else
                p->fillRect(r, p->brush());
            break;
        }
        case QQuickContext2D::ShadowColor:
        {
            state.shadowColor = takeColor();
            break;
        }
        case QQuickContext2D::ShadowBlur:
        {
            state.shadowBlur = takeShadowBlur();
            break;
        }
        case QQuickContext2D::ShadowOffsetX:
        {
            state.shadowOffsetX = takeShadowOffsetX();
            break;
        }
        case QQuickContext2D::ShadowOffsetY:
        {
            state.shadowOffsetY = takeShadowOffsetY();
            break;
        }
        case QQuickContext2D::FillStyle:
        {
            state.fillStyle = takeFillStyle();
            state.fillPatternRepeatX = takeBool();
            state.fillPatternRepeatY = takeBool();
            p->setBrush(state.fillStyle);
            break;
        }
        case QQuickContext2D::StrokeStyle:
        {
            state.strokeStyle = takeStrokeStyle();
            state.strokePatternRepeatX = takeBool();
            state.strokePatternRepeatY = takeBool();
            QPen nPen = p->pen();
            nPen.setBrush(state.strokeStyle);
            p->setPen(nPen);
            break;
        }
        case QQuickContext2D::LineWidth:
        {
            state.lineWidth = takeLineWidth();
            QPen nPen = p->pen();

            nPen.setWidthF(state.lineWidth);
            p->setPen(nPen);
            break;
        }
        case QQuickContext2D::LineCap:
        {
            state.lineCap = takeLineCap();
            QPen nPen = p->pen();
            nPen.setCapStyle(state.lineCap);
            p->setPen(nPen);
            break;
        }
        case QQuickContext2D::LineJoin:
        {
            state.lineJoin = takeLineJoin();
            QPen nPen = p->pen();
            nPen.setJoinStyle(state.lineJoin);
            p->setPen(nPen);
            break;
        }
        case QQuickContext2D::MiterLimit:
        {
            state.miterLimit = takeMiterLimit();
            QPen nPen = p->pen();
            nPen.setMiterLimit(state.miterLimit);
            p->setPen(nPen);
            break;
        }
        case QQuickContext2D::TextAlign:
        case QQuickContext2D::TextBaseline:
            break;
        case QQuickContext2D::Fill:
        {
            QPainterPath path = takePath();
            path.closeSubpath();
            if (HAS_SHADOW(state.shadowOffsetX, state.shadowOffsetY, state.shadowBlur, state.shadowColor))
                fillShadowPath(p,path, state.shadowOffsetX, state.shadowOffsetY, state.shadowBlur, state.shadowColor);
            else
                p->fillPath(path, p->brush());
            break;
        }
        case QQuickContext2D::Stroke:
        {
            if (HAS_SHADOW(state.shadowOffsetX, state.shadowOffsetY, state.shadowBlur, state.shadowColor))
                strokeShadowPath(p,takePath(), state.shadowOffsetX, state.shadowOffsetY, state.shadowBlur, state.shadowColor);
            else
                p->strokePath(takePath(), p->pen());
            break;
        }
        case QQuickContext2D::Clip:
        {
            state.clip = takeBool();
            state.clipPath = takePath();
            p->setClipping(state.clip);
            if (state.clip)
                p->setClipPath(state.clipPath);
            break;
        }
        case QQuickContext2D::GlobalAlpha:
        {
            state.globalAlpha = takeGlobalAlpha();
            p->setOpacity(state.globalAlpha);
            break;
        }
        case QQuickContext2D::GlobalCompositeOperation:
        {
            state.globalCompositeOperation = takeGlobalCompositeOperation();
            p->setCompositionMode(state.globalCompositeOperation);
            break;
        }
        case QQuickContext2D::DrawImage:
        {
            QRectF sr = takeRect();
            QRectF dr = takeRect();
            qt_drawImage(p, state, takeImage(), sr, dr, HAS_SHADOW(state.shadowOffsetX, state.shadowOffsetY, state.shadowBlur, state.shadowColor));
            break;
        }
        case QQuickContext2D::DrawPixmap:
        {
            QRectF sr = takeRect();
            QRectF dr = takeRect();

            QQmlRefPointer<QQuickCanvasPixmap> pix = takePixmap();
            Q_ASSERT(!pix.isNull());

            const bool hasShadow = HAS_SHADOW(state.shadowOffsetX, state.shadowOffsetY, state.shadowBlur, state.shadowColor);
            //TODO: generate shadow blur with shaders
            qt_drawImage(p, state, pix->image(), sr, dr, hasShadow);
            break;
        }
        case QQuickContext2D::GetImageData:
        {
            //TODO:
            break;
        }
        default:
            break;
        }
    }

    p->end();
}

QQuickContext2DCommandBuffer::QQuickContext2DCommandBuffer()
    : cmdIdx(0)
    , intIdx(0)
    , boolIdx(0)
    , realIdx(0)
    , rectIdx(0)
    , colorIdx(0)
    , matrixIdx(0)
    , brushIdx(0)
    , pathIdx(0)
    , imageIdx(0)
    , pixmapIdx(0)
{
    static bool registered = false;
    if (!registered) {
        qRegisterMetaType<QQuickContext2DCommandBuffer*>("QQuickContext2DCommandBuffer*");
        registered = true;
    }
}


QQuickContext2DCommandBuffer::~QQuickContext2DCommandBuffer()
{
}

void QQuickContext2DCommandBuffer::clear()
{
    commands.clear();
    ints.clear();
    bools.clear();
    reals.clear();
    rects.clear();
    colors.clear();
    matrixes.clear();
    brushes.clear();
    pathes.clear();
    images.clear();
    pixmaps.clear();
    reset();
}

void QQuickContext2DCommandBuffer::reset()
{
    cmdIdx = 0;
    intIdx = 0;
    boolIdx = 0;
    realIdx = 0;
    rectIdx = 0;
    colorIdx = 0;
    matrixIdx = 0;
    brushIdx = 0;
    pathIdx = 0;
    imageIdx = 0;
    pixmapIdx = 0;
}

QT_END_NAMESPACE
