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#ifndef QT3DRENDER_RENDER_BUFFERVISITOR_P_H
#define QT3DRENDER_RENDER_BUFFERVISITOR_P_H

//
//  W A R N I N G
//  -------------
//
// This file is not part of the Qt API.  It exists for the convenience
// of other Qt classes.  This header file may change from version to
// version without notice, or even be removed.
//
// We mean it.
//

#include <Qt3DCore/qnodeid.h>
#include <Qt3DRender/QAttribute>
#include <Qt3DRender/private/trianglesvisitor_p.h>
#include <Qt3DRender/private/attribute_p.h>
#include <Qt3DRender/private/buffer_p.h>
#include <Qt3DRender/private/bufferutils_p.h>
#include <Qt3DRender/private/geometryrenderer_p.h>
#include <Qt3DRender/private/geometry_p.h>
#include <Qt3DRender/private/managers_p.h>
#include <Qt3DRender/private/nodemanagers_p.h>

QT_BEGIN_NAMESPACE

namespace Qt3DCore {
class QEntity;
}

namespace Qt3DRender {
namespace Render {


template <typename ValueType, QAttribute::VertexBaseType VertexBaseType, uint dataSize>
class Q_AUTOTEST_EXPORT BufferVisitor
{
public:
    explicit BufferVisitor(NodeManagers *manager)
        : m_manager(manager)
    {
    }
    virtual ~BufferVisitor() { }

    virtual void visit(uint ndx, ValueType x) {
        Q_UNUSED(ndx); Q_UNUSED(x);
    }
    virtual void visit(uint ndx, ValueType x, ValueType y) {
        Q_UNUSED(ndx); Q_UNUSED(x); Q_UNUSED(y);
    }
    virtual void visit(uint ndx, ValueType x, ValueType y, ValueType z) {
        Q_UNUSED(ndx); Q_UNUSED(x); Q_UNUSED(y); Q_UNUSED(z);
    }
    virtual void visit(uint ndx, ValueType x, ValueType y, ValueType z, ValueType w) {
        Q_UNUSED(ndx); Q_UNUSED(x); Q_UNUSED(y); Q_UNUSED(z); Q_UNUSED(w);
    }

    bool apply(const GeometryRenderer *renderer, const QString &attributeName)
    {
        if (renderer == nullptr || renderer->instanceCount() != 1) {
            return false;
        }

        Geometry *geom = m_manager->lookupResource<Geometry, GeometryManager>(renderer->geometryId());

        if (!geom)
            return false;

        Attribute *attribute = nullptr;

        const auto attrIds = geom->attributes();
        for (const Qt3DCore::QNodeId attrId : attrIds) {
            attribute = m_manager->lookupResource<Attribute, AttributeManager>(attrId);
            if (attribute){
                if (attribute->name() == attributeName
                        || (attributeName == QStringLiteral("default")
                            && attribute->name() == QAttribute::defaultTextureCoordinateAttributeName())) {
                    break;
                }
            }
            attribute = nullptr;
        }

        if (!attribute)
            return false;

        return apply(attribute);
    }

    bool apply(Qt3DRender::Render::Attribute *attribute)
    {
        if (attribute->vertexBaseType() != VertexBaseType)
            return false;
        if (attribute->vertexSize() < dataSize)
            return false;

        auto data = m_manager->lookupResource<Buffer, BufferManager>(attribute->bufferId())->data();
        auto buffer = BufferTypeInfo::castToType<VertexBaseType>(data, attribute->byteOffset());
        switch (dataSize) {
        case 1: traverseCoordinates1(buffer, attribute->byteStride(), attribute->count()); break;
        case 2: traverseCoordinates2(buffer, attribute->byteStride(), attribute->count()); break;
        case 3: traverseCoordinates3(buffer, attribute->byteStride(), attribute->count()); break;
        case 4: traverseCoordinates4(buffer, attribute->byteStride(), attribute->count()); break;
        default: Q_UNREACHABLE();
        }

        return true;
    }

protected:

    template <typename Coordinate>
    void traverseCoordinates1(Coordinate *coordinates,
                              const uint byteStride,
                              const uint count)
    {
        const uint stride = byteStride / sizeof(Coordinate);
        for (uint ndx = 0; ndx < count; ++ndx) {
            visit(ndx, coordinates[0]);
            coordinates += stride;
        }
    }

    template <typename Coordinate>
    void traverseCoordinates2(Coordinate *coordinates,
                              const uint byteStride,
                              const uint count)
    {
        const uint stride = byteStride / sizeof(Coordinate);
        for (uint ndx = 0; ndx < count; ++ndx) {
            visit(ndx, coordinates[0], coordinates[1]);
            coordinates += stride;
        }
    }

    template <typename Coordinate>
    void traverseCoordinates3(Coordinate *coordinates,
                              const uint byteStride,
                              const uint count)
    {
        const uint stride = byteStride / sizeof(Coordinate);
        for (uint ndx = 0; ndx < count; ++ndx) {
            visit(ndx, coordinates[0], coordinates[1], coordinates[2]);
            coordinates += stride;
        }
    }

    template <typename Coordinate>
    void traverseCoordinates4(Coordinate *coordinates,
                              const uint byteStride,
                              const uint count)
    {
        const uint stride = byteStride / sizeof(Coordinate);
        for (uint ndx = 0; ndx < count; ++ndx) {
            visit(ndx, coordinates[0], coordinates[1], coordinates[2], coordinates[3]);
            coordinates += stride;
        }
    }

    NodeManagers *m_manager;
};

typedef BufferVisitor<float, QAttribute::Float, 3> Buffer3fVisitor;

} // namespace Render

} // namespace Qt3DRender

QT_END_NAMESPACE


#endif // QT3DRENDER_RENDER_BUFFERVISITOR_P_H