/****************************************************************************
**
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** This file is part of the QtOpenGL module of the Qt Toolkit.
**
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** Alternatively, this file may be used under the terms of the GNU
** General Public License version 3.0 as published by the Free Software
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** packaging of this file.  Please review the following information to
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#include "qglengineshadermanager_p.h"
#include "qglengineshadersource_p.h"

#if defined(QT_DEBUG)
#include <QMetaEnum>
#endif


QT_BEGIN_NAMESPACE

const char* QGLEngineShaderManager::qglEngineShaderSourceCode[] = {
    0,0,0,0,0,0,0,0,0,0,
    0,0,0,0,0,0,0,0,0,0,
    0,0,0,0,0,0,0,0,0,0,
    0,0,0,0,0
};

QGLEngineShaderManager::QGLEngineShaderManager(QGLContext* context)
    : ctx(context),
      shaderProgNeedsChanging(true),
      srcPixelType(Qt::NoBrush),
      useGlobalOpacity(false),
      maskType(NoMask),
      useTextureCoords(false),
      compositionMode(QPainter::CompositionMode_SourceOver),
      simpleShaderProg(0),
      currentShaderProg(0)
{
    memset(compiledShaders, 0, sizeof(compiledShaders));

/*
    Rather than having the shader source array statically initialised, it is initialised
    here instead. This is to allow new shader names to be inserted or existing names moved
    around without having to change the order of the glsl strings. It is hoped this will
    make future hard-to-find runtime bugs more obvious and generally give more solid code.
*/
    static bool qglEngineShaderSourceCodePopulated = false;
    if (!qglEngineShaderSourceCodePopulated) {

        const char** code = qglEngineShaderSourceCode; // shortcut

        code[MainVertexShader] = qglslMainVertexShader;
        code[MainWithTexCoordsVertexShader] = qglslMainWithTexCoordsVertexShader;

        code[PositionOnlyVertexShader] = qglslPositionOnlyVertexShader;
        code[PositionWithPatternBrushVertexShader] = qglslPositionWithPatternBrushVertexShader;
        code[PositionWithLinearGradientBrushVertexShader] = qglslPositionWithLinearGradientBrushVertexShader;
        code[PositionWithConicalGradientBrushVertexShader] = qglslPositionWithConicalGradientBrushVertexShader;
        code[PositionWithRadialGradientBrushVertexShader] = qglslPositionWithRadialGradientBrushVertexShader;
        code[PositionWithTextureBrushVertexShader] = qglslPositionWithTextureBrushVertexShader;
        code[AffinePositionWithPatternBrushVertexShader] = qglslAffinePositionWithPatternBrushVertexShader;
        code[AffinePositionWithLinearGradientBrushVertexShader] = qglslAffinePositionWithLinearGradientBrushVertexShader;
        code[AffinePositionWithConicalGradientBrushVertexShader] = qglslAffinePositionWithConicalGradientBrushVertexShader;
        code[AffinePositionWithRadialGradientBrushVertexShader] = qglslAffinePositionWithRadialGradientBrushVertexShader;
        code[AffinePositionWithTextureBrushVertexShader] = qglslAffinePositionWithTextureBrushVertexShader;

        code[MainFragmentShader_CMO] = qglslMainFragmentShader_CMO;
        code[MainFragmentShader_CM] = qglslMainFragmentShader_CM;
        code[MainFragmentShader_MO] = qglslMainFragmentShader_MO;
        code[MainFragmentShader_M] = qglslMainFragmentShader_M;
        code[MainFragmentShader_CO] = qglslMainFragmentShader_CO;
        code[MainFragmentShader_C] = qglslMainFragmentShader_C;
        code[MainFragmentShader_O] = qglslMainFragmentShader_O;
        code[MainFragmentShader] = qglslMainFragmentShader;

        code[ImageSrcFragmentShader] = qglslImageSrcFragmentShader;
        code[NonPremultipliedImageSrcFragmentShader] = qglslNonPremultipliedImageSrcFragmentShader;
        code[SolidBrushSrcFragmentShader] = qglslSolidBrushSrcFragmentShader;
        code[TextureBrushSrcFragmentShader] = qglslTextureBrushSrcFragmentShader;
        code[PatternBrushSrcFragmentShader] = qglslPatternBrushSrcFragmentShader;
        code[LinearGradientBrushSrcFragmentShader] = qglslLinearGradientBrushSrcFragmentShader;
        code[RadialGradientBrushSrcFragmentShader] = qglslRadialGradientBrushSrcFragmentShader;
        code[ConicalGradientBrushSrcFragmentShader] = qglslConicalGradientBrushSrcFragmentShader;
        code[ShockingPinkSrcFragmentShader] = qglslShockingPinkSrcFragmentShader;

        code[MaskFragmentShader] = qglslMaskFragmentShader;
        code[RgbMaskFragmentShader] = ""; //###
        code[RgbMaskWithGammaFragmentShader] = ""; //###

        code[MultiplyCompositionModeFragmentShader] = ""; //###
        code[ScreenCompositionModeFragmentShader] = ""; //###
        code[OverlayCompositionModeFragmentShader] = ""; //###
        code[DarkenCompositionModeFragmentShader] = ""; //###
        code[LightenCompositionModeFragmentShader] = ""; //###
        code[ColorDodgeCompositionModeFragmentShader] = ""; //###
        code[ColorBurnCompositionModeFragmentShader] = ""; //###
        code[HardLightCompositionModeFragmentShader] = ""; //###
        code[SoftLightCompositionModeFragmentShader] = ""; //###
        code[DifferenceCompositionModeFragmentShader] = ""; //###
        code[ExclusionCompositionModeFragmentShader] = ""; //###

#if defined(QT_DEBUG)
        // Check that all the elements have been filled:
        for (int i = 0; i < TotalShaderCount; ++i) {
            if (qglEngineShaderSourceCode[i] == 0) {
                int enumIndex = staticMetaObject.indexOfEnumerator("ShaderName");
                QMetaEnum m = staticMetaObject.enumerator(enumIndex);

                qCritical() << "qglEngineShaderSourceCode: Source for" << m.valueToKey(i)
                            << "(shader" << i << ") missing!";
            }
        }
#endif
        qglEngineShaderSourceCodePopulated = true;
    }

    // Compile up the simple shader:
    simpleShaderProg = new QGLShaderProgram(ctx, this);
    compileNamedShader(MainVertexShader,              QGLShader::PartialVertexShader);
    compileNamedShader(PositionOnlyVertexShader,      QGLShader::PartialVertexShader);
    compileNamedShader(MainFragmentShader,            QGLShader::PartialFragmentShader);
    compileNamedShader(ShockingPinkSrcFragmentShader, QGLShader::PartialFragmentShader);
    simpleShaderProg->addShader(compiledShaders[MainVertexShader]);
    simpleShaderProg->addShader(compiledShaders[PositionOnlyVertexShader]);
    simpleShaderProg->addShader(compiledShaders[MainFragmentShader]);
    simpleShaderProg->addShader(compiledShaders[ShockingPinkSrcFragmentShader]);
    simpleShaderProg->link();
    if (!simpleShaderProg->isLinked()) {
        qCritical() << "Errors linking simple shader:"
                    << simpleShaderProg->log();
    }
}

QGLEngineShaderManager::~QGLEngineShaderManager()
{
    //###
}





void QGLEngineShaderManager::optimiseForBrushTransform(const QTransform &transform)
{
    Q_UNUSED(transform); // Currently ignored
}

void QGLEngineShaderManager::setSrcPixelType(Qt::BrushStyle style)
{
    srcPixelType = style;
    shaderProgNeedsChanging = true; //###
}

void QGLEngineShaderManager::setSrcPixelType(PixelSrcType type)
{
    srcPixelType = type;
    shaderProgNeedsChanging = true; //###
}

void QGLEngineShaderManager::setTextureCoordsEnabled(bool enabled)
{
    useTextureCoords = enabled;
    shaderProgNeedsChanging = true; //###
}

void QGLEngineShaderManager::setUseGlobalOpacity(bool useOpacity)
{
    useGlobalOpacity = useOpacity;
    shaderProgNeedsChanging = true; //###
}

void QGLEngineShaderManager::setMaskType(MaskType type)
{
    maskType = type;
    shaderProgNeedsChanging = true; //###
}

void QGLEngineShaderManager::setCompositionMode(QPainter::CompositionMode mode)
{
    compositionMode = mode;
    shaderProgNeedsChanging = true; //###
}

QGLShaderProgram* QGLEngineShaderManager::currentProgram()
{
    return currentShaderProg;
}

QGLShaderProgram* QGLEngineShaderManager::simpleProgram()
{
    return simpleShaderProg;
}




// Select & use the correct shader program using the current state.
// Returns true if program needed changing.
bool QGLEngineShaderManager::useCorrectShaderProg()
{
    if (!shaderProgNeedsChanging)
        return false;

    QGLEngineShaderProg requiredProgram;
    requiredProgram.program = 0;

    // Choose vertex shader main function
    QGLEngineShaderManager::ShaderName mainVertexShaderName = InvalidShaderName;
    if (useTextureCoords)
        mainVertexShaderName = MainWithTexCoordsVertexShader;
    else
        mainVertexShaderName = MainVertexShader;
    compileNamedShader(mainVertexShaderName, QGLShader::PartialVertexShader);
    requiredProgram.mainVertexShader = compiledShaders[mainVertexShaderName];

    // Choose vertex shader shader position function (which typically also sets
    // varyings) and the source pixel (srcPixel) fragment shader function:
    QGLEngineShaderManager::ShaderName positionVertexShaderName = InvalidShaderName;
    QGLEngineShaderManager::ShaderName srcPixelFragShaderName = InvalidShaderName;
    bool isAffine = brushTransform.isAffine();
    if ( (srcPixelType >= Qt::Dense1Pattern) && (srcPixelType <= Qt::DiagCrossPattern) ) {
        if (isAffine)
            positionVertexShaderName = AffinePositionWithPatternBrushVertexShader;
        else
            positionVertexShaderName = PositionWithPatternBrushVertexShader;

        srcPixelFragShaderName = PatternBrushSrcFragmentShader;
    }
    else switch (srcPixelType) {
        default:
        case Qt::NoBrush:
            qCritical("QGLEngineShaderManager::useCorrectShaderProg() - I'm scared, Qt::NoBrush style is set");
            break;
        case QGLEngineShaderManager::ImageSrc:
            srcPixelFragShaderName = ImageSrcFragmentShader;
            positionVertexShaderName = PositionOnlyVertexShader;
            break;
        case QGLEngineShaderManager::NonPremultipliedImageSrc:
            srcPixelFragShaderName = NonPremultipliedImageSrcFragmentShader;
            positionVertexShaderName = PositionOnlyVertexShader;
            break;
        case Qt::SolidPattern:
            srcPixelFragShaderName = SolidBrushSrcFragmentShader;
            positionVertexShaderName = PositionOnlyVertexShader;
            break;
        case Qt::LinearGradientPattern:
            srcPixelFragShaderName = LinearGradientBrushSrcFragmentShader;
            positionVertexShaderName = isAffine ? AffinePositionWithLinearGradientBrushVertexShader
                                                : PositionWithLinearGradientBrushVertexShader;
            break;
        case Qt::ConicalGradientPattern:
            srcPixelFragShaderName = ConicalGradientBrushSrcFragmentShader;
            positionVertexShaderName = isAffine ? AffinePositionWithConicalGradientBrushVertexShader
                                                : PositionWithConicalGradientBrushVertexShader;
            break;
        case Qt::RadialGradientPattern:
            srcPixelFragShaderName = RadialGradientBrushSrcFragmentShader;
            positionVertexShaderName = isAffine ? AffinePositionWithRadialGradientBrushVertexShader
                                                : PositionWithRadialGradientBrushVertexShader;
            break;
        case Qt::TexturePattern:
            srcPixelFragShaderName = TextureBrushSrcFragmentShader;
            positionVertexShaderName = isAffine ? AffinePositionWithTextureBrushVertexShader
                                                : PositionWithTextureBrushVertexShader;
            break;
    };
    compileNamedShader(positionVertexShaderName, QGLShader::PartialVertexShader);
    compileNamedShader(srcPixelFragShaderName, QGLShader::PartialFragmentShader);
    requiredProgram.positionVertexShader = compiledShaders[positionVertexShaderName];
    requiredProgram.srcPixelFragShader = compiledShaders[srcPixelFragShaderName];


    const bool hasCompose = compositionMode > QPainter::CompositionMode_Plus;
    const bool hasMask = maskType != QGLEngineShaderManager::NoMask;

    // Choose fragment shader main function:
    QGLEngineShaderManager::ShaderName mainFragShaderName;

    if (hasCompose && hasMask && useGlobalOpacity)
        mainFragShaderName = MainFragmentShader_CMO;
    if (hasCompose && hasMask && !useGlobalOpacity)
        mainFragShaderName = MainFragmentShader_CM;
    if (!hasCompose && hasMask && useGlobalOpacity)
        mainFragShaderName = MainFragmentShader_MO;
    if (!hasCompose && hasMask && !useGlobalOpacity)
        mainFragShaderName = MainFragmentShader_M;
    if (hasCompose && !hasMask && useGlobalOpacity)
        mainFragShaderName = MainFragmentShader_CO;
    if (hasCompose && !hasMask && !useGlobalOpacity)
        mainFragShaderName = MainFragmentShader_C;
    if (!hasCompose && !hasMask && useGlobalOpacity)
        mainFragShaderName = MainFragmentShader_O;
    if (!hasCompose && !hasMask && !useGlobalOpacity)
        mainFragShaderName = MainFragmentShader;

    compileNamedShader(mainFragShaderName, QGLShader::PartialFragmentShader);
    requiredProgram.mainFragShader = compiledShaders[mainFragShaderName];

    if (hasMask) {
        QGLEngineShaderManager::ShaderName maskShaderName = QGLEngineShaderManager::InvalidShaderName;
        if (maskType == PixelMask)
            maskShaderName = MaskFragmentShader;
        else if (maskType == SubPixelMask)
            maskShaderName = RgbMaskFragmentShader;
        else if (maskType == SubPixelWithGammaMask)
            maskShaderName = RgbMaskWithGammaFragmentShader;
        else
            qCritical("QGLEngineShaderManager::useCorrectShaderProg() - Unknown mask type");

        compileNamedShader(maskShaderName, QGLShader::PartialFragmentShader);
        requiredProgram.maskFragShader = compiledShaders[maskShaderName];
    }
    else
        requiredProgram.maskFragShader = 0;

    if (hasCompose) {
        QGLEngineShaderManager::ShaderName compositionShaderName = QGLEngineShaderManager::InvalidShaderName;
        switch (compositionMode) {
            case QPainter::CompositionMode_Multiply:
                compositionShaderName = MultiplyCompositionModeFragmentShader;
                break;
            case QPainter::CompositionMode_Screen:
                compositionShaderName = ScreenCompositionModeFragmentShader;
                break;
            case QPainter::CompositionMode_Overlay:
                compositionShaderName = OverlayCompositionModeFragmentShader;
                break;
            case QPainter::CompositionMode_Darken:
                compositionShaderName = DarkenCompositionModeFragmentShader;
                break;
            case QPainter::CompositionMode_Lighten:
                compositionShaderName = LightenCompositionModeFragmentShader;
                break;
            case QPainter::CompositionMode_ColorDodge:
                compositionShaderName = ColorDodgeCompositionModeFragmentShader;
                break;
            case QPainter::CompositionMode_ColorBurn:
                compositionShaderName = ColorBurnCompositionModeFragmentShader;
                break;
            case QPainter::CompositionMode_HardLight:
                compositionShaderName = HardLightCompositionModeFragmentShader;
                break;
            case QPainter::CompositionMode_SoftLight:
                compositionShaderName = SoftLightCompositionModeFragmentShader;
                break;
            case QPainter::CompositionMode_Difference:
                compositionShaderName = DifferenceCompositionModeFragmentShader;
                break;
            case QPainter::CompositionMode_Exclusion:
                compositionShaderName = ExclusionCompositionModeFragmentShader;
                break;
            default:
                qWarning("QGLEngineShaderManager::useCorrectShaderProg() - Unsupported composition mode");
        }
        compileNamedShader(compositionShaderName, QGLShader::PartialFragmentShader);
        requiredProgram.compositionFragShader = compiledShaders[compositionShaderName];
    }
    else
        requiredProgram.compositionFragShader = 0;


    // At this point, requiredProgram is fully populated so try to find the program in the cache
    foreach (const QGLEngineShaderProg &prog, cachedPrograms) {
        if (    (prog.mainVertexShader == requiredProgram.mainVertexShader)
             && (prog.positionVertexShader == requiredProgram.positionVertexShader)
             && (prog.mainFragShader == requiredProgram.mainFragShader)
             && (prog.srcPixelFragShader == requiredProgram.srcPixelFragShader)
             && (prog.compositionFragShader == requiredProgram.compositionFragShader) )
        {
            currentShaderProg = prog.program;
            currentShaderProg->enable();
            shaderProgNeedsChanging = false;
            return true;
        }
    }

    // Shader program not found in cache, create it now.
    requiredProgram.program = new QGLShaderProgram(ctx, this);
    requiredProgram.program->addShader(requiredProgram.mainVertexShader);
    requiredProgram.program->addShader(requiredProgram.positionVertexShader);
    requiredProgram.program->addShader(requiredProgram.mainFragShader);
    requiredProgram.program->addShader(requiredProgram.srcPixelFragShader);
    requiredProgram.program->addShader(requiredProgram.maskFragShader);
    requiredProgram.program->addShader(requiredProgram.compositionFragShader);

    // We have to bind the vertex attribute names before the program is linked:
    requiredProgram.program->bindAttributeLocation("inputVertex", QT_VERTEX_COORDS_ATTR);
    if (useTextureCoords)
        requiredProgram.program->bindAttributeLocation("textureCoordArray", QT_TEXTURE_COORDS_ATTR);

    requiredProgram.program->link();
    if (!requiredProgram.program->isLinked()) {
        QString error;
        qWarning() <<  "Shader program failed to link,"
#if defined(QT_DEBUG)
              << '\n'
              << "  Shaders Used:" << '\n'
              << "    mainVertexShader = "     << requiredProgram.mainVertexShader->objectName()  << '\n'
              << "    positionVertexShader = " << requiredProgram.positionVertexShader->objectName() << '\n'
              << "    mainFragShader = "       << requiredProgram.mainFragShader->objectName() << '\n'
              << "    srcPixelFragShader = "   << requiredProgram.srcPixelFragShader->objectName() << '\n'
              << "    maskFragShader = "       << requiredProgram.maskFragShader->objectName() << '\n'
              << "    compositionFragShader = "<< requiredProgram.compositionFragShader->objectName() << '\n'
#endif
              << "  Error Log:" << '\n'
              << "    " << requiredProgram.program->log();
        qWarning() << error;
    }
    else {
        cachedPrograms.append(requiredProgram);
        currentShaderProg = requiredProgram.program;
        currentShaderProg->enable();
    }
    shaderProgNeedsChanging = false;
    return true;
}

void QGLEngineShaderManager::compileNamedShader(QGLEngineShaderManager::ShaderName name, QGLShader::ShaderType type)
{
    if (compiledShaders[name])
        return;

    QGLShader *newShader = new QGLShader(type, ctx, this);
    newShader->setSourceCode(qglEngineShaderSourceCode[name]);
    // newShader->compile(); ### does not exist?

#if defined(QT_DEBUG)
    // Name the shader for easier debugging
    QMetaEnum m = staticMetaObject.enumerator(staticMetaObject.indexOfEnumerator("ShaderName"));
    newShader->setObjectName(QLatin1String(m.valueToKey(name)));
#endif

    compiledShaders[name] = newShader;
}

QT_END_NAMESPACE