// Copyright (C) 2008-2012 NVIDIA Corporation.
// Copyright (C) 2019 The Qt Company Ltd.
// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR GPL-3.0-only

#ifndef QSSG_RENDER_SHADOW_MAP_H
#define QSSG_RENDER_SHADOW_MAP_H

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

#include <QtQuick3DRuntimeRender/private/qtquick3druntimerenderglobal_p.h>
#include <QtGui/QMatrix4x4>
#include <QtGui/QVector3D>
#include <QtQuick3DUtils/private/qssgrenderbasetypes_p.h>
#include <QtQuick3DRuntimeRender/private/qssgrenderableobjects_p.h>

QT_BEGIN_NAMESPACE

class QSSGRhiContext;
class QSSGRenderContextInterface;

class QRhiRenderBuffer;
class QRhiTextureRenderTarget;
class QRhiRenderPassDescriptor;
class QRhiTexture;

enum class ShadowMapModes
{
    VSM, ///< variance shadow mapping
    CUBE, ///< cubemap omnidirectional shadows
};

struct QSSGShadowMapEntry
{
    QSSGShadowMapEntry();

    static QSSGShadowMapEntry withRhiDepthMap(quint32 lightIdx, ShadowMapModes mode, QRhiTexture *textureArray);

    static QSSGShadowMapEntry withRhiDepthCubeMap(quint32 lightIdx, ShadowMapModes mode, QRhiTexture *depthCube, QRhiRenderBuffer *depthStencil);
    bool isCompatible(QSize mapSize, quint32 layerIndex, quint32 csmNumSplits, ShadowMapModes mapMode, QRhiTexture::Format textureFormat);
    void destroyRhiResources();

    quint32 m_lightIndex; ///< the light index it belongs to
    ShadowMapModes m_shadowMapMode; ///< shadow map method
    quint32 m_depthArrayIndex; ///< shadow map texture array index

    // RHI resources
    QRhiTexture *m_rhiDepthTextureArray = nullptr; // for shadow map (VSM) (not owned)
    QRhiTexture *m_rhiDepthCube = nullptr; // shadow cube map (CUBE)
    std::array<QRhiRenderBuffer *, 4> m_rhiDepthStencil = {}; // depth/stencil
    std::array<QRhiTextureRenderTarget *, 6> m_rhiRenderTargets = {}; // texture RT
    std::array<QRhiRenderPassDescriptor *, 4> m_rhiRenderPassDesc = {}; // texture RT renderpass descriptor

    QMatrix4x4 m_lightViewProjection[4]; ///< light view projection matrix
    QMatrix4x4 m_lightCubeView[6]; ///< light cubemap view matrices
    QMatrix4x4 m_lightView; ///< light view transform
    quint32 m_csmNumSplits = 0;
    float m_csmSplits[4] = {};
    float m_csmActive[4] = {};
    float m_shadowMapFar = 0.f;
};

class Q_QUICK3DRUNTIMERENDER_EXPORT QSSGRenderShadowMap
{
    Q_DISABLE_COPY(QSSGRenderShadowMap)

public:
    const QSSGRenderContextInterface &m_context;

    explicit QSSGRenderShadowMap(const QSSGRenderContextInterface &inContext);
    ~QSSGRenderShadowMap();
    void releaseCachedResources();
    void addShadowMaps(const QSSGShaderLightList &renderableLights);

    QSSGShadowMapEntry *shadowMapEntry(int lightIdx);

    qsizetype shadowMapEntryCount() { return m_shadowMapList.size(); }

private:
    QSSGShadowMapEntry *addDirectionalShadowMap(qint32 lightIdx,
                                                QSize size,
                                                bool use32bit,
                                                quint32 layerStartIndex,
                                                quint32 csmNumSplits,
                                                const QString &renderNodeObjName);
    QSSGShadowMapEntry *addCubeShadowMap(qint32 lightIdx, QSize size, bool use32bit, const QString &renderNodeObjName);

    QVector<QSSGShadowMapEntry> m_shadowMapList;
    std::array<QHash<QSize, QRhiTexture *>, 2> m_depthTextureArrays; // 0: 16 bit, 1: 32 bit
};

using QSSGRenderShadowMapPtr = std::shared_ptr<QSSGRenderShadowMap>;

QT_END_NAMESPACE

#endif