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#ifndef QT3D_RENDER_RENDERSTATE_H
#define QT3D_RENDER_RENDERSTATE_H

#include <QList>
#include <QSet>

QT_BEGIN_NAMESPACE

namespace Qt3D {

class QRenderState;

namespace Render {

class QGraphicsContext;

enum StateMask
{
    BlendStateMask          = 1 << 0,
    StencilWriteStateMask   = 1 << 1,
    StencilTestStateMask    = 1 << 2,
    ScissorStateMask        = 1 << 3,
    DepthTestStateMask      = 1 << 4,
    DepthWriteStateMask     = 1 << 5,
    CullFaceStateMask       = 1 << 6,
    AlphaTestMask           = 1 << 7,
    FrontFaceStateMask      = 1 << 8,
    DitheringStateMask      = 1 << 9,
    AlphaCoverageStateMask  = 1 << 10,
    PolygonOffsetStateMask  = 1 << 11,
    ColorStateMask          = 1 << 12
};

typedef quint64 StateMaskSet;

class Q_AUTOTEST_EXPORT RenderState
{
public:
    virtual ~RenderState() {}

    virtual void apply(QGraphicsContext* gc) const = 0;

    virtual StateMaskSet mask() const = 0;

    static RenderState *getOrCreateBackendState(QRenderState *renderState);
protected:
};

class RenderStateSet
{
public:
    RenderStateSet();

    void addState(RenderState* ds);

    /**
     * @brief changeCost - metric of cost to change to this state-set from
     * a candidate previous state-set. This is used to find an optimal
     * ordering of state-sets when sending draw commands.
     * @param previousState
     * @return
     */
    int changeCost(RenderStateSet* previousState);

    void apply(QGraphicsContext* gc);

    StateMaskSet stateMask() const;

    void resetMasked(StateMaskSet maskOfStatesToReset, QGraphicsContext* gc);
private:
    /**
     * @brief contains - check if this set contains a matching piece of state
     * @param ds
     * @return
     */
    bool contains(RenderState* ds) const;

    QSet<RenderState*> m_states;

    StateMaskSet m_stateMask;

    RenderStateSet* m_cachedPrevious;
    QList<RenderState*> m_cachedDeltaStates;

};

} // Render
} // namespace Qt3D

QT_END_NAMESPACE

#endif // QT3D_RENDER_RENDERSTATE_H