/******************************************************************************
 *
 * Project:  Virtual GDAL Datasets
 * Purpose:  Declaration of virtual gdal dataset classes.
 * Author:   Frank Warmerdam, warmerdam@pobox.com
 *
 ******************************************************************************
 * Copyright (c) 2001, Frank Warmerdam <warmerdam@pobox.com>
 * Copyright (c) 2007-2013, Even Rouault <even dot rouault at spatialys.com>
 *
 * SPDX-License-Identifier: MIT
 ****************************************************************************/

#ifndef VIRTUALDATASET_H_INCLUDED
#define VIRTUALDATASET_H_INCLUDED

#ifndef DOXYGEN_SKIP

#include "cpl_hash_set.h"
#include "cpl_minixml.h"
#include "gdal_pam.h"
#include "gdal_priv.h"
#include "gdal_rat.h"
#include "gdal_vrt.h"
#include "gdal_rat.h"

#include <atomic>
#include <deque>
#include <functional>
#include <map>
#include <memory>
#include <mutex>
#include <vector>

CPLErr GDALRegisterDefaultPixelFunc();
void GDALVRTRegisterDefaultProcessedDatasetFuncs();
CPLString CPL_DLL VRTSerializeNoData(double dfVal, GDALDataType eDataType,
                                     int nPrecision);

#if 0
int VRTWarpedOverviewTransform( void *pTransformArg, int bDstToSrc,
                                int nPointCount,
                                double *padfX, double *padfY, double *padfZ,
                                int *panSuccess );
void* VRTDeserializeWarpedOverviewTransformer( CPLXMLNode *psTree );
#endif

/************************************************************************/
/*                          VRTOverviewInfo()                           */
/************************************************************************/
class VRTOverviewInfo
{
    CPL_DISALLOW_COPY_ASSIGN(VRTOverviewInfo)

  public:
    CPLString osFilename{};
    int nBand = 0;
    GDALRasterBand *poBand = nullptr;
    int bTriedToOpen = FALSE;

    VRTOverviewInfo() = default;

    VRTOverviewInfo(VRTOverviewInfo &&oOther) noexcept
        : osFilename(std::move(oOther.osFilename)), nBand(oOther.nBand),
          poBand(oOther.poBand), bTriedToOpen(oOther.bTriedToOpen)
    {
        oOther.poBand = nullptr;
    }

    ~VRTOverviewInfo()
    {
        CloseDataset();
    }

    bool CloseDataset()
    {
        if (poBand == nullptr)
            return false;

        GDALDataset *poDS = poBand->GetDataset();
        // Nullify now, to prevent recursion in some cases !
        poBand = nullptr;
        if (poDS->GetShared())
            GDALClose(/* (GDALDatasetH) */ poDS);
        else
            poDS->Dereference();

        return true;
    }
};

/************************************************************************/
/*                            VRTMapSharedResources                     */
/************************************************************************/

/** Map of shared datasets */
class CPL_DLL VRTMapSharedResources
{
  public:
    VRTMapSharedResources() = default;

    /** Return a dataset from its key */
    GDALDataset *Get(const std::string &osKey) const;

    /** Inserts a dataset. It must be kept alive while this
     * VRTMapSharedResources is alive.
     */
    void Insert(const std::string &osKey, GDALDataset *poDS);

    /** To be called before any attempt at using this instance in a
     * multi-threaded context.
     */
    void InitMutex();

  private:
    std::mutex oMutex{};
    std::mutex *poMutex = nullptr;
    std::map<std::string, GDALDataset *> oMap{};

    CPL_DISALLOW_COPY_ASSIGN(VRTMapSharedResources)
};

/************************************************************************/
/*                              VRTSource                               */
/************************************************************************/

class CPL_DLL VRTSource
{
  public:
    struct CPL_DLL WorkingState
    {
        // GByte whose initialization constructor does nothing
#ifdef __GNUC__
#pragma GCC diagnostic push
#pragma GCC diagnostic ignored "-Weffc++"
#endif
        struct NoInitByte
        {
            GByte value;

            // cppcheck-suppress uninitMemberVar
            NoInitByte()
            {
                // do nothing
                /* coverity[uninit_member] */
            }

            inline operator GByte() const
            {
                return value;
            }
        };
#ifdef __GNUC__
#pragma GCC diagnostic pop
#endif

        std::vector<NoInitByte> m_abyWrkBuffer{};
        std::vector<NoInitByte> m_abyWrkBufferMask{};
    };

    virtual ~VRTSource();

    virtual CPLErr RasterIO(GDALDataType eVRTBandDataType, int nXOff, int nYOff,
                            int nXSize, int nYSize, void *pData, int nBufXSize,
                            int nBufYSize, GDALDataType eBufType,
                            GSpacing nPixelSpace, GSpacing nLineSpace,
                            GDALRasterIOExtraArg *psExtraArg,
                            WorkingState &oWorkingState) = 0;

    virtual double GetMinimum(int nXSize, int nYSize, int *pbSuccess) = 0;
    virtual double GetMaximum(int nXSize, int nYSize, int *pbSuccess) = 0;
    virtual CPLErr GetHistogram(int nXSize, int nYSize, double dfMin,
                                double dfMax, int nBuckets,
                                GUIntBig *panHistogram, int bIncludeOutOfRange,
                                int bApproxOK, GDALProgressFunc pfnProgress,
                                void *pProgressData) = 0;

    virtual CPLErr XMLInit(const CPLXMLNode *psTree, const char *,
                           VRTMapSharedResources &) = 0;
    virtual CPLXMLNode *SerializeToXML(const char *pszVRTPath) = 0;

    virtual void GetFileList(char ***ppapszFileList, int *pnSize,
                             int *pnMaxSize, CPLHashSet *hSetFiles);

    /** Returns whether this instance can be cast to a VRTSimpleSource
     * (and its subclasses).
     */
    virtual bool IsSimpleSource() const
    {
        return false;
    }

    virtual const CPLString &GetName() const
    {
        return m_osName;
    }

    /** Returns a string with the VRTSource class type.
     * This method must be implemented in all subclasses
     */
    virtual const char *GetType() const = 0;

    virtual CPLErr FlushCache(bool /*bAtClosing*/)
    {
        return CE_None;
    }

  protected:
    CPLString m_osName{};
};

typedef VRTSource *(*VRTSourceParser)(const CPLXMLNode *, const char *,
                                      VRTMapSharedResources &oMapSharedSources);

VRTSource *VRTParseCoreSources(const CPLXMLNode *psTree, const char *,
                               VRTMapSharedResources &oMapSharedSources);
VRTSource *VRTParseFilterSources(const CPLXMLNode *psTree, const char *,
                                 VRTMapSharedResources &oMapSharedSources);
VRTSource *VRTParseArraySource(const CPLXMLNode *psTree, const char *,
                               VRTMapSharedResources &oMapSharedSources);

/************************************************************************/
/*                              VRTDataset                              */
/************************************************************************/

class VRTRasterBand;

template <class T> struct VRTFlushCacheStruct
{
    static CPLErr FlushCache(T &obj, bool bAtClosing);
};

class VRTWarpedDataset;
class VRTPansharpenedDataset;
class VRTProcessedDataset;
class VRTGroup;
class VRTSimpleSource;

class CPL_DLL VRTDataset CPL_NON_FINAL : public GDALDataset
{
    friend class VRTRasterBand;
    friend struct VRTFlushCacheStruct<VRTDataset>;
    friend struct VRTFlushCacheStruct<VRTWarpedDataset>;
    friend struct VRTFlushCacheStruct<VRTPansharpenedDataset>;
    friend struct VRTFlushCacheStruct<VRTProcessedDataset>;
    friend class VRTSourcedRasterBand;
    friend class VRTSimpleSource;
    friend struct VRTSourcedRasterBandRasterIOJob;
    friend VRTDatasetH CPL_STDCALL VRTCreate(int nXSize, int nYSize);

    std::vector<gdal::GCP> m_asGCPs{};
    std::unique_ptr<OGRSpatialReference, OGRSpatialReferenceReleaser>
        m_poGCP_SRS{};

    bool m_bNeedsFlush = false;
    bool m_bWritable = true;
    bool m_bCanTakeRef = true;

    char *m_pszVRTPath = nullptr;

    VRTRasterBand *m_poMaskBand = nullptr;

    mutable int m_nCompatibleForDatasetIO = -1;
    bool CheckCompatibleForDatasetIO() const;

    // Virtual (ie not materialized) overviews, created either implicitly
    // when it is cheap to do it, or explicitly.
    std::vector<GDALDataset *> m_apoOverviews{};
    std::vector<GDALDataset *> m_apoOverviewsBak{};
    CPLStringList m_aosOverviewList{};  // only temporarily set during Open()
    CPLString m_osOverviewResampling{};
    std::vector<int> m_anOverviewFactors{};

    char **m_papszXMLVRTMetadata = nullptr;

    VRTMapSharedResources m_oMapSharedSources{};
    std::shared_ptr<VRTGroup> m_poRootGroup{};

    // Used by VRTSourcedRasterBand::IRasterIO() in single-threaded situations
    VRTSource::WorkingState m_oWorkingState{};

    // Used by VRTSourcedRasterBand::IRasterIO() when using multi-threading
    struct QueueWorkingStates
    {
        std::mutex oMutex{};
        std::vector<std::unique_ptr<VRTSource::WorkingState>> oStates{};
    };

    QueueWorkingStates m_oQueueWorkingStates{};

    bool m_bMultiThreadedRasterIOLastUsed = false;

    VRTRasterBand *InitBand(const char *pszSubclass, int nBand,
                            bool bAllowPansharpenedOrProcessed);
    static GDALDataset *OpenVRTProtocol(const char *pszSpec);
    bool AddVirtualOverview(int nOvFactor, const char *pszResampling);

    bool GetShiftedDataset(int nXOff, int nYOff, int nXSize, int nYSize,
                           GDALDataset *&poSrcDataset, int &nSrcXOff,
                           int &nSrcYOff);

    static bool IsDefaultBlockSize(int nBlockSize, int nDimension);

    CPL_DISALLOW_COPY_ASSIGN(VRTDataset)

  protected:
    bool m_bBlockSizeSpecified = false;
    int m_nBlockXSize = 0;
    int m_nBlockYSize = 0;

    std::unique_ptr<OGRSpatialReference, OGRSpatialReferenceReleaser> m_poSRS{};

    int m_bGeoTransformSet = false;
    double m_adfGeoTransform[6];

    virtual int CloseDependentDatasets() override;

  public:
    VRTDataset(int nXSize, int nYSize, int nBlockXSize = 0,
               int nBlockYSize = 0);
    virtual ~VRTDataset();

    void SetNeedsFlush()
    {
        m_bNeedsFlush = true;
    }

    virtual CPLErr FlushCache(bool bAtClosing) override;

    void SetWritable(int bWritableIn)
    {
        m_bWritable = CPL_TO_BOOL(bWritableIn);
    }

    virtual CPLErr CreateMaskBand(int nFlags) override;
    void SetMaskBand(VRTRasterBand *poMaskBand);

    const OGRSpatialReference *GetSpatialRef() const override
    {
        return m_poSRS.get();
    }

    CPLErr SetSpatialRef(const OGRSpatialReference *poSRS) override;

    virtual CPLErr GetGeoTransform(double *) override;
    virtual CPLErr SetGeoTransform(double *) override;

    virtual CPLErr SetMetadata(char **papszMetadata,
                               const char *pszDomain = "") override;
    virtual CPLErr SetMetadataItem(const char *pszName, const char *pszValue,
                                   const char *pszDomain = "") override;

    virtual char **GetMetadata(const char *pszDomain = "") override;
    virtual const char *GetMetadataItem(const char *pszName,
                                        const char *pszDomain = "") override;

    virtual int GetGCPCount() override;

    const OGRSpatialReference *GetGCPSpatialRef() const override
    {
        return m_poGCP_SRS.get();
    }

    virtual const GDAL_GCP *GetGCPs() override;
    using GDALDataset::SetGCPs;
    CPLErr SetGCPs(int nGCPCount, const GDAL_GCP *pasGCPList,
                   const OGRSpatialReference *poSRS) override;

    virtual CPLErr AddBand(GDALDataType eType,
                           char **papszOptions = nullptr) override;

    virtual char **GetFileList() override;

    virtual CPLErr IRasterIO(GDALRWFlag eRWFlag, int nXOff, int nYOff,
                             int nXSize, int nYSize, void *pData, int nBufXSize,
                             int nBufYSize, GDALDataType eBufType,
                             int nBandCount, BANDMAP_TYPE panBandMap,
                             GSpacing nPixelSpace, GSpacing nLineSpace,
                             GSpacing nBandSpace,
                             GDALRasterIOExtraArg *psExtraArg) override;

    virtual CPLStringList
    GetCompressionFormats(int nXOff, int nYOff, int nXSize, int nYSize,
                          int nBandCount, const int *panBandList) override;
    virtual CPLErr ReadCompressedData(const char *pszFormat, int nXOff,
                                      int nYOff, int nXSize, int nYSize,
                                      int nBandCount, const int *panBandList,
                                      void **ppBuffer, size_t *pnBufferSize,
                                      char **ppszDetailedFormat) override;

    virtual CPLErr AdviseRead(int nXOff, int nYOff, int nXSize, int nYSize,
                              int nBufXSize, int nBufYSize, GDALDataType eDT,
                              int nBandCount, int *panBandList,
                              char **papszOptions) override;

    virtual CPLXMLNode *SerializeToXML(const char *pszVRTPath);
    virtual CPLErr XMLInit(const CPLXMLNode *, const char *);

    virtual CPLErr IBuildOverviews(const char *, int, const int *, int,
                                   const int *, GDALProgressFunc, void *,
                                   CSLConstList papszOptions) override;

    std::shared_ptr<GDALGroup> GetRootGroup() const override;

    void ClearStatistics() override;

    /** To be called when a new source is added, to invalidate cached states. */
    void SourceAdded()
    {
        m_nCompatibleForDatasetIO = -1;
    }

    /* Used by PDF driver for example */
    GDALDataset *GetSingleSimpleSource();
    void BuildVirtualOverviews();

    void UnsetPreservedRelativeFilenames();

    bool IsBlockSizeSpecified() const
    {
        return m_bBlockSizeSpecified;
    }

    int GetBlockXSize() const
    {
        return m_nBlockXSize;
    }

    int GetBlockYSize() const
    {
        return m_nBlockYSize;
    }

    static int Identify(GDALOpenInfo *);
    static GDALDataset *Open(GDALOpenInfo *);
    static VRTDataset *OpenXML(const char *, const char * = nullptr,
                               GDALAccess eAccess = GA_ReadOnly);
    static GDALDataset *Create(const char *pszName, int nXSize, int nYSize,
                               int nBands, GDALDataType eType,
                               char **papszOptions);
    static GDALDataset *
    CreateMultiDimensional(const char *pszFilename,
                           CSLConstList papszRootGroupOptions,
                           CSLConstList papszOptions);
    static CPLErr Delete(const char *pszFilename);

    static int GetNumThreads(GDALDataset *poDS);
};

/************************************************************************/
/*                           VRTWarpedDataset                           */
/************************************************************************/

class GDALWarpOperation;
class VRTWarpedRasterBand;

class CPL_DLL VRTWarpedDataset final : public VRTDataset
{
    GDALWarpOperation *m_poWarper;

    bool m_bIsOverview = false;
    std::vector<VRTWarpedDataset *> m_apoOverviews{};
    int m_nSrcOvrLevel;

    bool GetOverviewSize(GDALDataset *poSrcDS, int iOvr, int iSrcOvr,
                         int &nOvrXSize, int &nOvrYSize, double &dfSrcRatioX,
                         double &dfSrcRatioY) const;
    int GetOverviewCount() const;
    int GetSrcOverviewLevel(int iOvr, bool &bThisLevelOnlyOut) const;
    VRTWarpedDataset *CreateImplicitOverview(int iOvr) const;
    void CreateImplicitOverviews();

    friend class VRTWarpedRasterBand;

    CPL_DISALLOW_COPY_ASSIGN(VRTWarpedDataset)

  protected:
    virtual int CloseDependentDatasets() override;

  public:
    VRTWarpedDataset(int nXSize, int nYSize, int nBlockXSize = 0,
                     int nBlockYSize = 0);
    virtual ~VRTWarpedDataset();

    virtual CPLErr FlushCache(bool bAtClosing) override;

    CPLErr Initialize(/* GDALWarpOptions */ void *);

    virtual CPLErr IBuildOverviews(const char *, int, const int *, int,
                                   const int *, GDALProgressFunc, void *,
                                   CSLConstList papszOptions) override;

    virtual CPLErr SetMetadataItem(const char *pszName, const char *pszValue,
                                   const char *pszDomain = "") override;

    virtual CPLXMLNode *SerializeToXML(const char *pszVRTPath) override;
    virtual CPLErr XMLInit(const CPLXMLNode *, const char *) override;

    virtual CPLErr AddBand(GDALDataType eType,
                           char **papszOptions = nullptr) override;

    virtual char **GetFileList() override;

    virtual CPLErr IRasterIO(GDALRWFlag eRWFlag, int nXOff, int nYOff,
                             int nXSize, int nYSize, void *pData, int nBufXSize,
                             int nBufYSize, GDALDataType eBufType,
                             int nBandCount, BANDMAP_TYPE panBandMap,
                             GSpacing nPixelSpace, GSpacing nLineSpace,
                             GSpacing nBandSpace,
                             GDALRasterIOExtraArg *psExtraArg) override;

    CPLErr ProcessBlock(int iBlockX, int iBlockY);

    void GetBlockSize(int *, int *) const;
};

/************************************************************************/
/*                        VRTPansharpenedDataset                        */
/************************************************************************/

class GDALPansharpenOperation;

typedef enum
{
    GTAdjust_Union,
    GTAdjust_Intersection,
    GTAdjust_None,
    GTAdjust_NoneWithoutWarning
} GTAdjustment;

class VRTPansharpenedDataset final : public VRTDataset
{
    friend class VRTPansharpenedRasterBand;

    GDALPansharpenOperation *m_poPansharpener;
    VRTPansharpenedDataset *m_poMainDataset;
    std::vector<VRTPansharpenedDataset *> m_apoOverviewDatasets{};
    // Map from absolute to relative.
    std::map<CPLString, CPLString> m_oMapToRelativeFilenames{};

    int m_bLoadingOtherBands;

    GByte *m_pabyLastBufferBandRasterIO;
    int m_nLastBandRasterIOXOff;
    int m_nLastBandRasterIOYOff;
    int m_nLastBandRasterIOXSize;
    int m_nLastBandRasterIOYSize;
    GDALDataType m_eLastBandRasterIODataType;

    GTAdjustment m_eGTAdjustment;
    int m_bNoDataDisabled;

    std::vector<GDALDataset *> m_apoDatasetsToClose{};

    CPL_DISALLOW_COPY_ASSIGN(VRTPansharpenedDataset)

  protected:
    virtual int CloseDependentDatasets() override;

  public:
    VRTPansharpenedDataset(int nXSize, int nYSize, int nBlockXSize = 0,
                           int nBlockYSize = 0);
    virtual ~VRTPansharpenedDataset();

    virtual CPLErr FlushCache(bool bAtClosing) override;

    virtual CPLErr XMLInit(const CPLXMLNode *, const char *) override;
    virtual CPLXMLNode *SerializeToXML(const char *pszVRTPath) override;

    CPLErr XMLInit(const CPLXMLNode *psTree, const char *pszVRTPath,
                   GDALRasterBandH hPanchroBandIn, int nInputSpectralBandsIn,
                   GDALRasterBandH *pahInputSpectralBandsIn);

    virtual CPLErr AddBand(GDALDataType eType,
                           char **papszOptions = nullptr) override;

    virtual char **GetFileList() override;

    virtual CPLErr IRasterIO(GDALRWFlag eRWFlag, int nXOff, int nYOff,
                             int nXSize, int nYSize, void *pData, int nBufXSize,
                             int nBufYSize, GDALDataType eBufType,
                             int nBandCount, BANDMAP_TYPE panBandMap,
                             GSpacing nPixelSpace, GSpacing nLineSpace,
                             GSpacing nBandSpace,
                             GDALRasterIOExtraArg *psExtraArg) override;

    void GetBlockSize(int *, int *) const;

    GDALPansharpenOperation *GetPansharpener()
    {
        return m_poPansharpener;
    }
};

/************************************************************************/
/*                        VRTPansharpenedDataset                        */
/************************************************************************/

/** Specialized implementation of VRTDataset that chains several processing
 * steps applied on all bands at a time.
 *
 * @since 3.9
 */
class VRTProcessedDataset final : public VRTDataset
{
  public:
    VRTProcessedDataset(int nXSize, int nYSize);
    ~VRTProcessedDataset() override;

    virtual CPLErr FlushCache(bool bAtClosing) override;

    virtual CPLErr XMLInit(const CPLXMLNode *, const char *) override;
    virtual CPLXMLNode *SerializeToXML(const char *pszVRTPath) override;

    void GetBlockSize(int *, int *) const;

    // GByte whose initialization constructor does nothing
#ifdef __GNUC__
#pragma GCC diagnostic push
#pragma GCC diagnostic ignored "-Weffc++"
#endif
    struct NoInitByte
    {
        GByte value;

        // cppcheck-suppress uninitMemberVar
        NoInitByte()
        {
            // do nothing
            /* coverity[uninit_member] */
        }

        inline operator GByte() const
        {
            return value;
        }
    };
#ifdef __GNUC__
#pragma GCC diagnostic pop
#endif

  protected:
    virtual CPLErr IRasterIO(GDALRWFlag eRWFlag, int nXOff, int nYOff,
                             int nXSize, int nYSize, void *pData, int nBufXSize,
                             int nBufYSize, GDALDataType eBufType,
                             int nBandCount, BANDMAP_TYPE panBandMap,
                             GSpacing nPixelSpace, GSpacing nLineSpace,
                             GSpacing nBandSpace,
                             GDALRasterIOExtraArg *psExtraArg) override;

  private:
    friend class VRTProcessedRasterBand;

    //! Data for a processing step.
    struct Step
    {
        //! Algorithm name
        std::string osAlgorithm{};

        //! Arguments to pass to the processing function.
        CPLStringList aosArguments{};

        //! Data type of the input buffer.
        GDALDataType eInDT = GDT_Unknown;

        //! Data type of the output buffer.
        GDALDataType eOutDT = GDT_Unknown;

        //! Number of input bands.
        int nInBands = 0;

        //! Number of output bands.
        int nOutBands = 0;

        //! Nodata values (nInBands) of the input bands.
        std::vector<double> adfInNoData{};

        //! Nodata values (nOutBands) of the output bands.
        std::vector<double> adfOutNoData{};

        //! Working data structure (private data of the implementation of the function)
        VRTPDWorkingDataPtr pWorkingData = nullptr;

        // NOTE: if adding a new member, edit the move constructor and
        // assignment operators!

        Step() = default;
        ~Step();
        Step(Step &&);
        Step &operator=(Step &&);

      private:
        Step(const Step &) = delete;
        Step &operator=(const Step &) = delete;
        void deinit();
    };

    //! Directory of the VRT
    std::string m_osVRTPath{};

    //! Source of source dataset generated with GDALTranslate
    std::unique_ptr<GDALDataset> m_poVRTSrcDS{};

    //! Source dataset
    std::unique_ptr<GDALDataset> m_poSrcDS{};

    //! Processing steps.
    std::vector<Step> m_aoSteps{};

    //! Backup XML tree passed to XMLInit()
    CPLXMLTreeCloser m_oXMLTree{nullptr};

    //! Overview datasets (dynamically generated from the ones of m_poSrcDS)
    std::vector<std::unique_ptr<GDALDataset>> m_apoOverviewDatasets{};

    //! Input buffer of a processing step
    std::vector<NoInitByte> m_abyInput{};

    //! Output buffer of a processing step
    std::vector<NoInitByte> m_abyOutput{};

    //! Provenance of OutputBands.count and OutputBands.dataType
    enum class ValueProvenance
    {
        FROM_VRTRASTERBAND,
        FROM_SOURCE,
        FROM_LAST_STEP,
        USER_PROVIDED,
    };

    //! Provenance of OutputBands.count attribute
    ValueProvenance m_outputBandCountProvenance = ValueProvenance::FROM_SOURCE;

    //! Value of OutputBands.count attribute if m_outputBandCountProvenance = USER_PROVIDED
    int m_outputBandCountValue = 0;

    //! Provenance of OutputBands.dataType attribute
    ValueProvenance m_outputBandDataTypeProvenance =
        ValueProvenance::FROM_SOURCE;

    //! Value of OutputBands.dataType attribute if m_outputBandDataTypeProvenance = USER_PROVIDED
    GDALDataType m_outputBandDataTypeValue = GDT_Unknown;

    //! Number of temporary bytes we need per output pixel.
    int m_nWorkingBytesPerPixel = 1;

    //! Value of CPLGetUsablePhysicalRAM() / 10 * 4
    GIntBig m_nAllowedRAMUsage = 0;

    CPLErr Init(const CPLXMLNode *, const char *,
                const VRTProcessedDataset *poParentDS,
                GDALDataset *poParentSrcDS, int iOvrLevel);

    bool ParseStep(const CPLXMLNode *psStep, bool bIsFinalStep,
                   GDALDataType &eCurrentDT, int &nCurrentBandCount,
                   std::vector<double> &adfInNoData,
                   std::vector<double> &adfOutNoData);
    bool ProcessRegion(int nXOff, int nYOff, int nBufXSize, int nBufYSize,
                       GDALProgressFunc pfnProgress, void *pProgressData);
};

/************************************************************************/
/*                            VRTRasterBand                             */
/*                                                                      */
/*      Provides support for all the various kinds of metadata but      */
/*      no raster access.  That is handled by derived classes.          */
/************************************************************************/

constexpr double VRT_DEFAULT_NODATA_VALUE = -10000.0;

class CPL_DLL VRTRasterBand CPL_NON_FINAL : public GDALRasterBand
{
  private:
    void ResetNoDataValues();

  protected:
    friend class VRTDataset;

    int m_bIsMaskBand = FALSE;

    int m_bNoDataValueSet = FALSE;
    // If set to true, will not report the existence of nodata.
    int m_bHideNoDataValue = FALSE;
    double m_dfNoDataValue = VRT_DEFAULT_NODATA_VALUE;

    bool m_bNoDataSetAsInt64 = false;
    int64_t m_nNoDataValueInt64 = GDAL_PAM_DEFAULT_NODATA_VALUE_INT64;

    bool m_bNoDataSetAsUInt64 = false;
    uint64_t m_nNoDataValueUInt64 = GDAL_PAM_DEFAULT_NODATA_VALUE_UINT64;

    std::unique_ptr<GDALColorTable> m_poColorTable{};

    GDALColorInterp m_eColorInterp = GCI_Undefined;

    char *m_pszUnitType = nullptr;
    CPLStringList m_aosCategoryNames{};

    double m_dfOffset = 0.0;
    double m_dfScale = 1.0;

    CPLXMLNode *m_psSavedHistograms = nullptr;

    void Initialize(int nXSize, int nYSize);

    std::vector<VRTOverviewInfo> m_aoOverviewInfos{};

    VRTRasterBand *m_poMaskBand = nullptr;

    std::unique_ptr<GDALRasterAttributeTable> m_poRAT{};

    CPL_DISALLOW_COPY_ASSIGN(VRTRasterBand)

    bool IsNoDataValueInDataTypeRange() const;

  public:
    VRTRasterBand();
    virtual ~VRTRasterBand();

    virtual CPLErr XMLInit(const CPLXMLNode *, const char *,
                           VRTMapSharedResources &);
    virtual CPLXMLNode *SerializeToXML(const char *pszVRTPath,
                                       bool &bHasWarnedAboutRAMUsage,
                                       size_t &nAccRAMUsage);

    CPLErr SetNoDataValue(double) override;
    CPLErr SetNoDataValueAsInt64(int64_t nNoData) override;
    CPLErr SetNoDataValueAsUInt64(uint64_t nNoData) override;
    double GetNoDataValue(int *pbSuccess = nullptr) override;
    int64_t GetNoDataValueAsInt64(int *pbSuccess = nullptr) override;
    uint64_t GetNoDataValueAsUInt64(int *pbSuccess = nullptr) override;
    CPLErr DeleteNoDataValue() override;

    virtual CPLErr SetColorTable(GDALColorTable *) override;
    virtual GDALColorTable *GetColorTable() override;

    virtual GDALRasterAttributeTable *GetDefaultRAT() override;
    virtual CPLErr
    SetDefaultRAT(const GDALRasterAttributeTable *poRAT) override;

    virtual CPLErr SetColorInterpretation(GDALColorInterp) override;
    virtual GDALColorInterp GetColorInterpretation() override;

    virtual const char *GetUnitType() override;
    CPLErr SetUnitType(const char *) override;

    virtual char **GetCategoryNames() override;
    virtual CPLErr SetCategoryNames(char **) override;

    virtual CPLErr SetMetadata(char **papszMD,
                               const char *pszDomain = "") override;
    virtual CPLErr SetMetadataItem(const char *pszName, const char *pszValue,
                                   const char *pszDomain = "") override;

    virtual double GetOffset(int *pbSuccess = nullptr) override;
    CPLErr SetOffset(double) override;
    virtual double GetScale(int *pbSuccess = nullptr) override;
    CPLErr SetScale(double) override;

    virtual int GetOverviewCount() override;
    virtual GDALRasterBand *GetOverview(int) override;

    virtual CPLErr GetHistogram(double dfMin, double dfMax, int nBuckets,
                                GUIntBig *panHistogram, int bIncludeOutOfRange,
                                int bApproxOK, GDALProgressFunc,
                                void *pProgressData) override;

    virtual CPLErr GetDefaultHistogram(double *pdfMin, double *pdfMax,
                                       int *pnBuckets, GUIntBig **ppanHistogram,
                                       int bForce, GDALProgressFunc,
                                       void *pProgressData) override;

    virtual CPLErr SetDefaultHistogram(double dfMin, double dfMax, int nBuckets,
                                       GUIntBig *panHistogram) override;

    CPLErr CopyCommonInfoFrom(GDALRasterBand *);

    virtual void GetFileList(char ***ppapszFileList, int *pnSize,
                             int *pnMaxSize, CPLHashSet *hSetFiles);

    virtual void SetDescription(const char *) override;

    virtual GDALRasterBand *GetMaskBand() override;
    virtual int GetMaskFlags() override;

    virtual CPLErr CreateMaskBand(int nFlagsIn) override;

    void SetMaskBand(VRTRasterBand *poMaskBand);

    void SetIsMaskBand();

    virtual bool IsMaskBand() const override;

    CPLErr UnsetNoDataValue();

    virtual int CloseDependentDatasets();

    virtual int IsSourcedRasterBand()
    {
        return FALSE;
    }

    virtual int IsPansharpenRasterBand()
    {
        return FALSE;
    }
};

/************************************************************************/
/*                         VRTSourcedRasterBand                         */
/************************************************************************/

class VRTSimpleSource;

class CPL_DLL VRTSourcedRasterBand CPL_NON_FINAL : public VRTRasterBand
{
  private:
    CPLString m_osLastLocationInfo{};
    char **m_papszSourceList = nullptr;
    int m_nSkipBufferInitialization = -1;

    bool CanUseSourcesMinMaxImplementations();

    bool IsMosaicOfNonOverlappingSimpleSourcesOfFullRasterNoResAndTypeChange(
        bool bAllowMaxValAdjustment) const;

    CPL_DISALLOW_COPY_ASSIGN(VRTSourcedRasterBand)

  protected:
    bool SkipBufferInitialization();

  public:
    int nSources = 0;
    VRTSource **papoSources = nullptr;

    VRTSourcedRasterBand(GDALDataset *poDS, int nBand);
    VRTSourcedRasterBand(GDALDataType eType, int nXSize, int nYSize);
    VRTSourcedRasterBand(GDALDataset *poDS, int nBand, GDALDataType eType,
                         int nXSize, int nYSize);
    VRTSourcedRasterBand(GDALDataset *poDS, int nBand, GDALDataType eType,
                         int nXSize, int nYSize, int nBlockXSizeIn,
                         int nBlockYSizeIn);
    virtual ~VRTSourcedRasterBand();

    virtual CPLErr IRasterIO(GDALRWFlag, int, int, int, int, void *, int, int,
                             GDALDataType, GSpacing nPixelSpace,
                             GSpacing nLineSpace,
                             GDALRasterIOExtraArg *psExtraArg) override;

    virtual int IGetDataCoverageStatus(int nXOff, int nYOff, int nXSize,
                                       int nYSize, int nMaskFlagStop,
                                       double *pdfDataPct) override;

    virtual char **GetMetadataDomainList() override;
    virtual const char *GetMetadataItem(const char *pszName,
                                        const char *pszDomain = "") override;
    virtual char **GetMetadata(const char *pszDomain = "") override;
    virtual CPLErr SetMetadata(char **papszMetadata,
                               const char *pszDomain = "") override;
    virtual CPLErr SetMetadataItem(const char *pszName, const char *pszValue,
                                   const char *pszDomain = "") override;

    virtual CPLErr XMLInit(const CPLXMLNode *, const char *,
                           VRTMapSharedResources &) override;
    virtual CPLXMLNode *SerializeToXML(const char *pszVRTPath,
                                       bool &bHasWarnedAboutRAMUsage,
                                       size_t &nAccRAMUsage) override;

    virtual double GetMinimum(int *pbSuccess = nullptr) override;
    virtual double GetMaximum(int *pbSuccess = nullptr) override;
    virtual CPLErr ComputeRasterMinMax(int bApproxOK,
                                       double *adfMinMax) override;
    virtual CPLErr ComputeStatistics(int bApproxOK, double *pdfMin,
                                     double *pdfMax, double *pdfMean,
                                     double *pdfStdDev,
                                     GDALProgressFunc pfnProgress,
                                     void *pProgressData) override;
    virtual CPLErr GetHistogram(double dfMin, double dfMax, int nBuckets,
                                GUIntBig *panHistogram, int bIncludeOutOfRange,
                                int bApproxOK, GDALProgressFunc pfnProgress,
                                void *pProgressData) override;

    CPLErr AddSource(VRTSource *);

    CPLErr AddSimpleSource(const char *pszFilename, int nBand,
                           double dfSrcXOff = -1, double dfSrcYOff = -1,
                           double dfSrcXSize = -1, double dfSrcYSize = -1,
                           double dfDstXOff = -1, double dfDstYOff = -1,
                           double dfDstXSize = -1, double dfDstYSize = -1,
                           const char *pszResampling = "near",
                           double dfNoDataValue = VRT_NODATA_UNSET);

    CPLErr AddSimpleSource(GDALRasterBand *poSrcBand, double dfSrcXOff = -1,
                           double dfSrcYOff = -1, double dfSrcXSize = -1,
                           double dfSrcYSize = -1, double dfDstXOff = -1,
                           double dfDstYOff = -1, double dfDstXSize = -1,
                           double dfDstYSize = -1,
                           const char *pszResampling = "near",
                           double dfNoDataValue = VRT_NODATA_UNSET);

    CPLErr AddComplexSource(const char *pszFilename, int nBand,
                            double dfSrcXOff = -1, double dfSrcYOff = -1,
                            double dfSrcXSize = -1, double dfSrcYSize = -1,
                            double dfDstXOff = -1, double dfDstYOff = -1,
                            double dfDstXSize = -1, double dfDstYSize = -1,
                            double dfScaleOff = 0.0, double dfScaleRatio = 1.0,
                            double dfNoDataValue = VRT_NODATA_UNSET,
                            int nColorTableComponent = 0);

    CPLErr AddComplexSource(GDALRasterBand *poSrcBand, double dfSrcXOff = -1,
                            double dfSrcYOff = -1, double dfSrcXSize = -1,
                            double dfSrcYSize = -1, double dfDstXOff = -1,
                            double dfDstYOff = -1, double dfDstXSize = -1,
                            double dfDstYSize = -1, double dfScaleOff = 0.0,
                            double dfScaleRatio = 1.0,
                            double dfNoDataValue = VRT_NODATA_UNSET,
                            int nColorTableComponent = 0);

    CPLErr AddMaskBandSource(GDALRasterBand *poSrcBand, double dfSrcXOff = -1,
                             double dfSrcYOff = -1, double dfSrcXSize = -1,
                             double dfSrcYSize = -1, double dfDstXOff = -1,
                             double dfDstYOff = -1, double dfDstXSize = -1,
                             double dfDstYSize = -1);

    CPLErr AddFuncSource(VRTImageReadFunc pfnReadFunc, void *hCBData,
                         double dfNoDataValue = VRT_NODATA_UNSET);

    void ConfigureSource(VRTSimpleSource *poSimpleSource,
                         GDALRasterBand *poSrcBand, int bAddAsMaskBand,
                         double dfSrcXOff, double dfSrcYOff, double dfSrcXSize,
                         double dfSrcYSize, double dfDstXOff, double dfDstYOff,
                         double dfDstXSize, double dfDstYSize);

    void RemoveCoveredSources(CSLConstList papszOptions = nullptr);

    bool CanIRasterIOBeForwardedToEachSource(
        GDALRWFlag eRWFlag, int nXOff, int nYOff, int nXSize, int nYSize,
        int nBufXSize, int nBufYSize, GDALRasterIOExtraArg *psExtraArg) const;

    bool CanMultiThreadRasterIO(double dfXOff, double dfYOff, double dfXSize,
                                double dfYSize,
                                int &nContributingSources) const;

    virtual CPLErr IReadBlock(int, int, void *) override;

    virtual void GetFileList(char ***ppapszFileList, int *pnSize,
                             int *pnMaxSize, CPLHashSet *hSetFiles) override;

    virtual int CloseDependentDatasets() override;

    virtual int IsSourcedRasterBand() override
    {
        return TRUE;
    }

    virtual CPLErr FlushCache(bool bAtClosing) override;
};

/************************************************************************/
/*                         VRTWarpedRasterBand                          */
/************************************************************************/

class CPL_DLL VRTWarpedRasterBand final : public VRTRasterBand
{
  public:
    VRTWarpedRasterBand(GDALDataset *poDS, int nBand,
                        GDALDataType eType = GDT_Unknown);
    virtual ~VRTWarpedRasterBand();

    virtual CPLXMLNode *SerializeToXML(const char *pszVRTPath,
                                       bool &bHasWarnedAboutRAMUsage,
                                       size_t &nAccRAMUsage) override;

    virtual CPLErr IReadBlock(int, int, void *) override;
    virtual CPLErr IWriteBlock(int, int, void *) override;

    virtual CPLErr IRasterIO(GDALRWFlag eRWFlag, int nXOff, int nYOff,
                             int nXSize, int nYSize, void *pData, int nBufXSize,
                             int nBufYSize, GDALDataType eBufType,
                             GSpacing nPixelSpace, GSpacing nLineSpace,
                             GDALRasterIOExtraArg *psExtraArg) override;

    virtual int GetOverviewCount() override;
    virtual GDALRasterBand *GetOverview(int) override;

    bool
    EmitErrorMessageIfWriteNotSupported(const char *pszCaller) const override;

  private:
    int m_nIRasterIOCounter =
        0;  //! Protects against infinite recursion inside IRasterIO()

    int GetBestOverviewLevel(int &nXOff, int &nYOff, int &nXSize, int &nYSize,
                             int nBufXSize, int nBufYSize,
                             GDALRasterIOExtraArg *psExtraArg) const;
};

/************************************************************************/
/*                        VRTPansharpenedRasterBand                     */
/************************************************************************/

class VRTPansharpenedRasterBand final : public VRTRasterBand
{
    int m_nIndexAsPansharpenedBand;

  public:
    VRTPansharpenedRasterBand(GDALDataset *poDS, int nBand,
                              GDALDataType eDataType = GDT_Unknown);
    virtual ~VRTPansharpenedRasterBand();

    virtual CPLXMLNode *SerializeToXML(const char *pszVRTPath,
                                       bool &bHasWarnedAboutRAMUsage,
                                       size_t &nAccRAMUsage) override;

    virtual CPLErr IReadBlock(int, int, void *) override;

    virtual CPLErr IRasterIO(GDALRWFlag eRWFlag, int nXOff, int nYOff,
                             int nXSize, int nYSize, void *pData, int nBufXSize,
                             int nBufYSize, GDALDataType eBufType,
                             GSpacing nPixelSpace, GSpacing nLineSpace,
                             GDALRasterIOExtraArg *psExtraArg) override;

    virtual int GetOverviewCount() override;
    virtual GDALRasterBand *GetOverview(int) override;

    virtual int IsPansharpenRasterBand() override
    {
        return TRUE;
    }

    void SetIndexAsPansharpenedBand(int nIdx)
    {
        m_nIndexAsPansharpenedBand = nIdx;
    }

    int GetIndexAsPansharpenedBand() const
    {
        return m_nIndexAsPansharpenedBand;
    }
};

/************************************************************************/
/*                        VRTProcessedRasterBand                        */
/************************************************************************/

class VRTProcessedRasterBand final : public VRTRasterBand
{
  public:
    VRTProcessedRasterBand(VRTProcessedDataset *poDS, int nBand,
                           GDALDataType eDataType = GDT_Unknown);

    virtual CPLErr IReadBlock(int, int, void *) override;

    virtual int GetOverviewCount() override;
    virtual GDALRasterBand *GetOverview(int) override;

    virtual CPLXMLNode *SerializeToXML(const char *pszVRTPath,
                                       bool &bHasWarnedAboutRAMUsage,
                                       size_t &nAccRAMUsage) override;
};

/************************************************************************/
/*                         VRTDerivedRasterBand                         */
/************************************************************************/

class VRTDerivedRasterBandPrivateData;

class CPL_DLL VRTDerivedRasterBand CPL_NON_FINAL : public VRTSourcedRasterBand
{
    VRTDerivedRasterBandPrivateData *m_poPrivate;
    bool InitializePython();
    CPLErr
    GetPixelFunctionArguments(const CPLString &,
                              std::vector<std::pair<CPLString, CPLString>> &);

    CPL_DISALLOW_COPY_ASSIGN(VRTDerivedRasterBand)

  public:
    char *pszFuncName;
    GDALDataType eSourceTransferType;

    using PixelFunc =
        std::function<CPLErr(void **, int, void *, int, int, GDALDataType,
                             GDALDataType, int, int, CSLConstList)>;

    VRTDerivedRasterBand(GDALDataset *poDS, int nBand);
    VRTDerivedRasterBand(GDALDataset *poDS, int nBand, GDALDataType eType,
                         int nXSize, int nYSize);
    virtual ~VRTDerivedRasterBand();

    virtual CPLErr IRasterIO(GDALRWFlag, int, int, int, int, void *, int, int,
                             GDALDataType, GSpacing nPixelSpace,
                             GSpacing nLineSpace,
                             GDALRasterIOExtraArg *psExtraArg) override;

    virtual int IGetDataCoverageStatus(int nXOff, int nYOff, int nXSize,
                                       int nYSize, int nMaskFlagStop,
                                       double *pdfDataPct) override;

    static CPLErr AddPixelFunction(const char *pszFuncNameIn,
                                   GDALDerivedPixelFunc pfnPixelFunc);
    static CPLErr AddPixelFunction(const char *pszFuncNameIn,
                                   GDALDerivedPixelFuncWithArgs pfnPixelFunc,
                                   const char *pszMetadata);

    static const std::pair<PixelFunc, std::string> *
    GetPixelFunction(const char *pszFuncNameIn);

    void SetPixelFunctionName(const char *pszFuncNameIn);
    void SetSourceTransferType(GDALDataType eDataType);
    void SetPixelFunctionLanguage(const char *pszLanguage);

    virtual CPLErr XMLInit(const CPLXMLNode *, const char *,
                           VRTMapSharedResources &) override;
    virtual CPLXMLNode *SerializeToXML(const char *pszVRTPath,
                                       bool &bHasWarnedAboutRAMUsage,
                                       size_t &nAccRAMUsage) override;

    virtual double GetMinimum(int *pbSuccess = nullptr) override;
    virtual double GetMaximum(int *pbSuccess = nullptr) override;
    virtual CPLErr ComputeRasterMinMax(int bApproxOK,
                                       double *adfMinMax) override;
    virtual CPLErr ComputeStatistics(int bApproxOK, double *pdfMin,
                                     double *pdfMax, double *pdfMean,
                                     double *pdfStdDev,
                                     GDALProgressFunc pfnProgress,
                                     void *pProgressData) override;
    virtual CPLErr GetHistogram(double dfMin, double dfMax, int nBuckets,
                                GUIntBig *panHistogram, int bIncludeOutOfRange,
                                int bApproxOK, GDALProgressFunc pfnProgress,
                                void *pProgressData) override;

    static void Cleanup();
};

/************************************************************************/
/*                           VRTRawRasterBand                           */
/************************************************************************/

class RawRasterBand;

class CPL_DLL VRTRawRasterBand CPL_NON_FINAL : public VRTRasterBand
{
    RawRasterBand *m_poRawRaster;

    char *m_pszSourceFilename;
    int m_bRelativeToVRT;

    CPL_DISALLOW_COPY_ASSIGN(VRTRawRasterBand)

  public:
    VRTRawRasterBand(GDALDataset *poDS, int nBand,
                     GDALDataType eType = GDT_Unknown);
    virtual ~VRTRawRasterBand();

    virtual CPLErr XMLInit(const CPLXMLNode *, const char *,
                           VRTMapSharedResources &) override;
    virtual CPLXMLNode *SerializeToXML(const char *pszVRTPath,
                                       bool &bHasWarnedAboutRAMUsage,
                                       size_t &nAccRAMUsage) override;

    virtual CPLErr IRasterIO(GDALRWFlag, int, int, int, int, void *, int, int,
                             GDALDataType, GSpacing nPixelSpace,
                             GSpacing nLineSpace,
                             GDALRasterIOExtraArg *psExtraArg) override;

    virtual CPLErr IReadBlock(int, int, void *) override;
    virtual CPLErr IWriteBlock(int, int, void *) override;

    CPLErr SetRawLink(const char *pszFilename, const char *pszVRTPath,
                      int bRelativeToVRT, vsi_l_offset nImageOffset,
                      int nPixelOffset, int nLineOffset,
                      const char *pszByteOrder);

    void ClearRawLink();

    CPLVirtualMem *GetVirtualMemAuto(GDALRWFlag eRWFlag, int *pnPixelSpace,
                                     GIntBig *pnLineSpace,
                                     char **papszOptions) override;

    virtual void GetFileList(char ***ppapszFileList, int *pnSize,
                             int *pnMaxSize, CPLHashSet *hSetFiles) override;
};

/************************************************************************/
/*                              VRTDriver                               */
/************************************************************************/

class VRTDriver final : public GDALDriver
{
    CPL_DISALLOW_COPY_ASSIGN(VRTDriver)

    std::mutex m_oMutex{};
    std::map<std::string, VRTSourceParser> m_oMapSourceParser{};

  public:
    VRTDriver();
    virtual ~VRTDriver();

    char **papszSourceParsers;

    virtual char **GetMetadataDomainList() override;
    virtual char **GetMetadata(const char *pszDomain = "") override;
    virtual CPLErr SetMetadata(char **papszMetadata,
                               const char *pszDomain = "") override;

    VRTSource *ParseSource(const CPLXMLNode *psSrc, const char *pszVRTPath,
                           VRTMapSharedResources &oMapSharedSources);
    void AddSourceParser(const char *pszElementName, VRTSourceParser pfnParser);
};

/************************************************************************/
/*                           VRTSimpleSource                            */
/************************************************************************/

class CPL_DLL VRTSimpleSource CPL_NON_FINAL : public VRTSource
{
    CPL_DISALLOW_COPY_ASSIGN(VRTSimpleSource)

  private:
    // Owned by the VRTDataset
    VRTMapSharedResources *m_poMapSharedSources = nullptr;

    mutable GDALRasterBand *m_poRasterBand = nullptr;

    // When poRasterBand is a mask band, poMaskBandMainBand is the band
    // from which the mask band is taken.
    mutable GDALRasterBand *m_poMaskBandMainBand = nullptr;

    CPLStringList m_aosOpenOptionsOri{};  // as read in the original source XML
    CPLStringList
        m_aosOpenOptions{};  // same as above, but potentially augmented with ROOT_PATH
    bool m_bSrcDSNameFromVRT =
        false;  // whereas content in m_osSrcDSName is a <VRTDataset> XML node

    void OpenSource() const;

  protected:
    friend class VRTSourcedRasterBand;
    friend class VRTDataset;
    friend class GDALTileIndexDataset;
    friend class GDALTileIndexBand;

    int m_nBand = 0;
    bool m_bGetMaskBand = false;

    /* Value for uninitialized source or destination window. It is chosen such
     * that SrcToDst() and DstToSrc() are no-ops if both source and destination
     * windows are unset.
     */
    static constexpr double UNINIT_WINDOW = -1.0;

    double m_dfSrcXOff = UNINIT_WINDOW;
    double m_dfSrcYOff = UNINIT_WINDOW;
    double m_dfSrcXSize = UNINIT_WINDOW;
    double m_dfSrcYSize = UNINIT_WINDOW;

    double m_dfDstXOff = UNINIT_WINDOW;
    double m_dfDstYOff = UNINIT_WINDOW;
    double m_dfDstXSize = UNINIT_WINDOW;
    double m_dfDstYSize = UNINIT_WINDOW;

    CPLString m_osResampling{};

    int m_nMaxValue = 0;

    int m_bRelativeToVRTOri = -1;
    CPLString m_osSourceFileNameOri{};
    int m_nExplicitSharedStatus = -1;  // -1 unknown, 0 = unshared, 1 = shared
    CPLString m_osSrcDSName{};

    bool m_bDropRefOnSrcBand = true;

    int NeedMaxValAdjustment() const;

    GDALRasterBand *GetRasterBandNoOpen() const
    {
        return m_poRasterBand;
    }

    void SetRasterBand(GDALRasterBand *poBand, bool bDropRef)
    {
        m_poRasterBand = poBand;
        m_bDropRefOnSrcBand = bDropRef;
    }

    virtual bool ValidateOpenedBand(GDALRasterBand * /*poBand*/) const
    {
        return true;
    }

    /** Returns whether the source window is set */
    bool IsSrcWinSet() const
    {
        return m_dfSrcXOff != UNINIT_WINDOW || m_dfSrcYOff != UNINIT_WINDOW ||
               m_dfSrcXSize != UNINIT_WINDOW || m_dfSrcYSize != UNINIT_WINDOW;
    }

    /** Returns whether the destination window is set */
    bool IsDstWinSet() const
    {
        return m_dfDstXOff != UNINIT_WINDOW || m_dfDstYOff != UNINIT_WINDOW ||
               m_dfDstXSize != UNINIT_WINDOW || m_dfDstYSize != UNINIT_WINDOW;
    }

    void AddSourceFilenameNode(const char *pszVRTPath, CPLXMLNode *psSrc);

  public:
    VRTSimpleSource();
    VRTSimpleSource(const VRTSimpleSource *poSrcSource, double dfXDstRatio,
                    double dfYDstRatio);
    virtual ~VRTSimpleSource();

    virtual CPLErr XMLInit(const CPLXMLNode *psTree, const char *,
                           VRTMapSharedResources &) override;
    virtual CPLXMLNode *SerializeToXML(const char *pszVRTPath) override;

    CPLErr ParseSrcRectAndDstRect(const CPLXMLNode *psSrc);

    void SetSrcBand(const char *pszFilename, int nBand);
    void SetSrcBand(GDALRasterBand *);
    void SetSrcMaskBand(GDALRasterBand *);
    void SetSrcWindow(double, double, double, double);
    void SetDstWindow(double, double, double, double);
    void GetDstWindow(double &, double &, double &, double &) const;
    bool DstWindowIntersects(double dfXOff, double dfYOff, double dfXSize,
                             double dfYSize) const;

    const std::string &GetSourceDatasetName() const
    {
        return m_osSrcDSName;
    }

    const CPLString &GetResampling() const
    {
        return m_osResampling;
    }

    void SetResampling(const char *pszResampling);

    int GetSrcDstWindow(double, double, double, double, int, int,
                        double *pdfReqXOff, double *pdfReqYOff,
                        double *pdfReqXSize, double *pdfReqYSize, int *, int *,
                        int *, int *, int *, int *, int *, int *,
                        bool &bErrorOut);

    virtual CPLErr RasterIO(GDALDataType eVRTBandDataType, int nXOff, int nYOff,
                            int nXSize, int nYSize, void *pData, int nBufXSize,
                            int nBufYSize, GDALDataType eBufType,
                            GSpacing nPixelSpace, GSpacing nLineSpace,
                            GDALRasterIOExtraArg *psExtraArgIn,
                            WorkingState &oWorkingState) override;

    virtual double GetMinimum(int nXSize, int nYSize, int *pbSuccess) override;
    virtual double GetMaximum(int nXSize, int nYSize, int *pbSuccess) override;
    virtual CPLErr GetHistogram(int nXSize, int nYSize, double dfMin,
                                double dfMax, int nBuckets,
                                GUIntBig *panHistogram, int bIncludeOutOfRange,
                                int bApproxOK, GDALProgressFunc pfnProgress,
                                void *pProgressData) override;

    void DstToSrc(double dfX, double dfY, double &dfXOut, double &dfYOut) const;
    void SrcToDst(double dfX, double dfY, double &dfXOut, double &dfYOut) const;

    virtual void GetFileList(char ***ppapszFileList, int *pnSize,
                             int *pnMaxSize, CPLHashSet *hSetFiles) override;

    bool IsSimpleSource() const override
    {
        return true;
    }

    /** Returns the same value as GetType() called on objects that are exactly
     * instances of VRTSimpleSource.
     */
    static const char *GetTypeStatic();

    const char *GetType() const override;

    virtual CPLErr FlushCache(bool bAtClosing) override;

    GDALRasterBand *GetRasterBand() const;
    GDALRasterBand *GetMaskBandMainBand();
    bool IsSameExceptBandNumber(const VRTSimpleSource *poOtherSource) const;
    CPLErr DatasetRasterIO(GDALDataType eVRTBandDataType, int nXOff, int nYOff,
                           int nXSize, int nYSize, void *pData, int nBufXSize,
                           int nBufYSize, GDALDataType eBufType, int nBandCount,
                           const int *panBandMap, GSpacing nPixelSpace,
                           GSpacing nLineSpace, GSpacing nBandSpace,
                           GDALRasterIOExtraArg *psExtraArg);

    void UnsetPreservedRelativeFilenames();

    void SetMaxValue(int nVal)
    {
        m_nMaxValue = nVal;
    }
};

/************************************************************************/
/*                          VRTAveragedSource                           */
/************************************************************************/

class VRTAveragedSource final : public VRTSimpleSource
{
    CPL_DISALLOW_COPY_ASSIGN(VRTAveragedSource)

    int m_bNoDataSet = false;
    double m_dfNoDataValue = VRT_NODATA_UNSET;

  public:
    VRTAveragedSource();
    virtual CPLErr RasterIO(GDALDataType eVRTBandDataType, int nXOff, int nYOff,
                            int nXSize, int nYSize, void *pData, int nBufXSize,
                            int nBufYSize, GDALDataType eBufType,
                            GSpacing nPixelSpace, GSpacing nLineSpace,
                            GDALRasterIOExtraArg *psExtraArgIn,
                            WorkingState &oWorkingState) override;

    virtual double GetMinimum(int nXSize, int nYSize, int *pbSuccess) override;
    virtual double GetMaximum(int nXSize, int nYSize, int *pbSuccess) override;
    virtual CPLErr GetHistogram(int nXSize, int nYSize, double dfMin,
                                double dfMax, int nBuckets,
                                GUIntBig *panHistogram, int bIncludeOutOfRange,
                                int bApproxOK, GDALProgressFunc pfnProgress,
                                void *pProgressData) override;

    void SetNoDataValue(double dfNoDataValue);

    virtual CPLXMLNode *SerializeToXML(const char *pszVRTPath) override;

    /** Returns the same value as GetType() called on objects that are exactly
     * instances of VRTAveragedSource.
     */
    static const char *GetTypeStatic();

    const char *GetType() const override;
};

/************************************************************************/
/*                       VRTNoDataFromMaskSource                        */
/************************************************************************/

class VRTNoDataFromMaskSource final : public VRTSimpleSource
{
    CPL_DISALLOW_COPY_ASSIGN(VRTNoDataFromMaskSource)

    bool m_bNoDataSet = false;
    double m_dfNoDataValue = 0;
    double m_dfMaskValueThreshold = 0;
    bool m_bHasRemappedValue = false;
    double m_dfRemappedValue = 0;

  public:
    VRTNoDataFromMaskSource();
    virtual CPLErr RasterIO(GDALDataType eVRTBandDataType, int nXOff, int nYOff,
                            int nXSize, int nYSize, void *pData, int nBufXSize,
                            int nBufYSize, GDALDataType eBufType,
                            GSpacing nPixelSpace, GSpacing nLineSpace,
                            GDALRasterIOExtraArg *psExtraArgIn,
                            WorkingState &oWorkingState) override;

    virtual double GetMinimum(int nXSize, int nYSize, int *pbSuccess) override;
    virtual double GetMaximum(int nXSize, int nYSize, int *pbSuccess) override;
    virtual CPLErr GetHistogram(int nXSize, int nYSize, double dfMin,
                                double dfMax, int nBuckets,
                                GUIntBig *panHistogram, int bIncludeOutOfRange,
                                int bApproxOK, GDALProgressFunc pfnProgress,
                                void *pProgressData) override;

    void SetParameters(double dfNoDataValue, double dfMaskValueThreshold);
    void SetParameters(double dfNoDataValue, double dfMaskValueThreshold,
                       double dfRemappedValue);

    virtual CPLErr XMLInit(const CPLXMLNode *psTree, const char *,
                           VRTMapSharedResources &) override;
    virtual CPLXMLNode *SerializeToXML(const char *pszVRTPath) override;

    /** Returns the same value as GetType() called on objects that are exactly
     * instances of VRTNoDataFromMaskSource.
     */
    static const char *GetTypeStatic();

    const char *GetType() const override;
};

/************************************************************************/
/*                           VRTComplexSource                           */
/************************************************************************/

class CPL_DLL VRTComplexSource CPL_NON_FINAL : public VRTSimpleSource
{
    CPL_DISALLOW_COPY_ASSIGN(VRTComplexSource)

  protected:
    static constexpr int PROCESSING_FLAG_NODATA = 1 << 0;
    static constexpr int PROCESSING_FLAG_USE_MASK_BAND =
        1 << 1;  // Mutually exclusive with NODATA
    static constexpr int PROCESSING_FLAG_SCALING_LINEAR = 1 << 2;
    static constexpr int PROCESSING_FLAG_SCALING_EXPONENTIAL =
        1 << 3;  // Mutually exclusive with SCALING_LINEAR
    static constexpr int PROCESSING_FLAG_COLOR_TABLE_EXPANSION = 1 << 4;
    static constexpr int PROCESSING_FLAG_LUT = 1 << 5;

    int m_nProcessingFlags = 0;

    // adjusted value should be read with GetAdjustedNoDataValue()
    double m_dfNoDataValue = VRT_NODATA_UNSET;
    std::string
        m_osNoDataValueOri{};  // string value read in XML deserialization

    double m_dfScaleOff = 0;    // For linear scaling.
    double m_dfScaleRatio = 1;  // For linear scaling.

    // For non-linear scaling with a power function.
    bool m_bSrcMinMaxDefined = false;
    double m_dfSrcMin = 0;
    double m_dfSrcMax = 0;
    double m_dfDstMin = 0;
    double m_dfDstMax = 0;
    double m_dfExponent = 1;
    bool m_bClip = true;  // Only taken into account for non-linear scaling

    int m_nColorTableComponent = 0;

    std::vector<double> m_adfLUTInputs{};
    std::vector<double> m_adfLUTOutputs{};

    double GetAdjustedNoDataValue() const;

    template <class WorkingDT>
    CPLErr
    RasterIOInternal(GDALRasterBand *poSourceBand,
                     GDALDataType eVRTBandDataType, int nReqXOff, int nReqYOff,
                     int nReqXSize, int nReqYSize, void *pData, int nOutXSize,
                     int nOutYSize, GDALDataType eBufType, GSpacing nPixelSpace,
                     GSpacing nLineSpace, GDALRasterIOExtraArg *psExtraArg,
                     GDALDataType eWrkDataType, WorkingState &oWorkingState);

    template <class SourceDT, GDALDataType eSourceType>
    CPLErr RasterIOProcessNoData(GDALRasterBand *poSourceBand,
                                 GDALDataType eVRTBandDataType, int nReqXOff,
                                 int nReqYOff, int nReqXSize, int nReqYSize,
                                 void *pData, int nOutXSize, int nOutYSize,
                                 GDALDataType eBufType, GSpacing nPixelSpace,
                                 GSpacing nLineSpace,
                                 GDALRasterIOExtraArg *psExtraArg,
                                 WorkingState &oWorkingState);

  public:
    VRTComplexSource() = default;
    VRTComplexSource(const VRTComplexSource *poSrcSource, double dfXDstRatio,
                     double dfYDstRatio);

    virtual CPLErr RasterIO(GDALDataType eVRTBandDataType, int nXOff, int nYOff,
                            int nXSize, int nYSize, void *pData, int nBufXSize,
                            int nBufYSize, GDALDataType eBufType,
                            GSpacing nPixelSpace, GSpacing nLineSpace,
                            GDALRasterIOExtraArg *psExtraArgIn,
                            WorkingState &oWorkingState) override;

    virtual double GetMinimum(int nXSize, int nYSize, int *pbSuccess) override;
    virtual double GetMaximum(int nXSize, int nYSize, int *pbSuccess) override;
    virtual CPLErr GetHistogram(int nXSize, int nYSize, double dfMin,
                                double dfMax, int nBuckets,
                                GUIntBig *panHistogram, int bIncludeOutOfRange,
                                int bApproxOK, GDALProgressFunc pfnProgress,
                                void *pProgressData) override;

    virtual CPLXMLNode *SerializeToXML(const char *pszVRTPath) override;
    virtual CPLErr XMLInit(const CPLXMLNode *, const char *,
                           VRTMapSharedResources &) override;

    /** Returns the same value as GetType() called on objects that are exactly
     * instances of VRTComplexSource.
     */
    static const char *GetTypeStatic();

    const char *GetType() const override;

    bool AreValuesUnchanged() const;

    double LookupValue(double dfInput);

    void SetNoDataValue(double dfNoDataValue);

    void SetUseMaskBand(bool bUseMaskBand)
    {
        if (bUseMaskBand)
            m_nProcessingFlags |= PROCESSING_FLAG_USE_MASK_BAND;
        else
            m_nProcessingFlags &= ~PROCESSING_FLAG_USE_MASK_BAND;
    }

    void SetLinearScaling(double dfOffset, double dfScale);
    void SetPowerScaling(double dfExponent, double dfSrcMin, double dfSrcMax,
                         double dfDstMin, double dfDstMax, bool bClip = true);
    void SetColorTableComponent(int nComponent);
};

/************************************************************************/
/*                           VRTFilteredSource                          */
/************************************************************************/

class VRTFilteredSource CPL_NON_FINAL : public VRTComplexSource
{
  private:
    int IsTypeSupported(GDALDataType eTestType) const;

    CPL_DISALLOW_COPY_ASSIGN(VRTFilteredSource)

  protected:
    int m_nSupportedTypesCount;
    GDALDataType m_aeSupportedTypes[20];

    int m_nExtraEdgePixels;

  public:
    VRTFilteredSource();
    virtual ~VRTFilteredSource();

    const char *GetType() const override = 0;

    void SetExtraEdgePixels(int);
    void SetFilteringDataTypesSupported(int, GDALDataType *);

    virtual CPLErr FilterData(int nXSize, int nYSize, GDALDataType eType,
                              GByte *pabySrcData, GByte *pabyDstData) = 0;

    virtual CPLErr RasterIO(GDALDataType eVRTBandDataType, int nXOff, int nYOff,
                            int nXSize, int nYSize, void *pData, int nBufXSize,
                            int nBufYSize, GDALDataType eBufType,
                            GSpacing nPixelSpace, GSpacing nLineSpace,
                            GDALRasterIOExtraArg *psExtraArg,
                            WorkingState &oWorkingState) override;
};

/************************************************************************/
/*                       VRTKernelFilteredSource                        */
/************************************************************************/

class VRTKernelFilteredSource CPL_NON_FINAL : public VRTFilteredSource
{
    CPL_DISALLOW_COPY_ASSIGN(VRTKernelFilteredSource)

  protected:
    int m_nKernelSize = 0;
    bool m_bSeparable = false;
    // m_nKernelSize elements if m_bSeparable, m_nKernelSize * m_nKernelSize otherwise
    std::vector<double> m_adfKernelCoefs{};
    bool m_bNormalized = false;

  public:
    VRTKernelFilteredSource();

    const char *GetType() const override;

    virtual CPLErr XMLInit(const CPLXMLNode *psTree, const char *,
                           VRTMapSharedResources &) override;
    virtual CPLXMLNode *SerializeToXML(const char *pszVRTPath) override;

    virtual CPLErr FilterData(int nXSize, int nYSize, GDALDataType eType,
                              GByte *pabySrcData, GByte *pabyDstData) override;

    CPLErr SetKernel(int nKernelSize, bool bSeparable,
                     const std::vector<double> &adfNewCoefs);
    void SetNormalized(bool);
};

/************************************************************************/
/*                       VRTAverageFilteredSource                       */
/************************************************************************/

class VRTAverageFilteredSource final : public VRTKernelFilteredSource
{
    CPL_DISALLOW_COPY_ASSIGN(VRTAverageFilteredSource)

  public:
    explicit VRTAverageFilteredSource(int nKernelSize);
    virtual ~VRTAverageFilteredSource();

    const char *GetType() const override;

    virtual CPLErr XMLInit(const CPLXMLNode *psTree, const char *,
                           VRTMapSharedResources &) override;
    virtual CPLXMLNode *SerializeToXML(const char *pszVRTPath) override;
};

/************************************************************************/
/*                            VRTFuncSource                             */
/************************************************************************/
class VRTFuncSource final : public VRTSource
{
    CPL_DISALLOW_COPY_ASSIGN(VRTFuncSource)

  public:
    VRTFuncSource();
    virtual ~VRTFuncSource();

    virtual CPLErr XMLInit(const CPLXMLNode *, const char *,
                           VRTMapSharedResources &) override
    {
        return CE_Failure;
    }

    virtual CPLXMLNode *SerializeToXML(const char *pszVRTPath) override;

    virtual CPLErr RasterIO(GDALDataType eVRTBandDataType, int nXOff, int nYOff,
                            int nXSize, int nYSize, void *pData, int nBufXSize,
                            int nBufYSize, GDALDataType eBufType,
                            GSpacing nPixelSpace, GSpacing nLineSpace,
                            GDALRasterIOExtraArg *psExtraArg,
                            WorkingState &oWorkingState) override;

    virtual double GetMinimum(int nXSize, int nYSize, int *pbSuccess) override;
    virtual double GetMaximum(int nXSize, int nYSize, int *pbSuccess) override;
    virtual CPLErr GetHistogram(int nXSize, int nYSize, double dfMin,
                                double dfMax, int nBuckets,
                                GUIntBig *panHistogram, int bIncludeOutOfRange,
                                int bApproxOK, GDALProgressFunc pfnProgress,
                                void *pProgressData) override;

    const char *GetType() const override;

    VRTImageReadFunc pfnReadFunc;
    void *pCBData;
    GDALDataType eType;

    float fNoDataValue;
};

/************************************************************************/
/*                              VRTGroup                                */
/************************************************************************/

#ifdef TMPEXPORT
#define TMP_CPL_DLL CPL_DLL
#else
#define TMP_CPL_DLL
#endif

class VRTMDArray;
class VRTAttribute;
class VRTDimension;

class VRTGroup final : public GDALGroup
{
  public:
    struct Ref
    {
        VRTGroup *m_ptr;

        explicit Ref(VRTGroup *ptr) : m_ptr(ptr)
        {
        }

        Ref(const Ref &) = delete;
        Ref &operator=(const Ref &) = delete;
    };

  private:
    std::shared_ptr<Ref> m_poSharedRefRootGroup{};
    std::weak_ptr<Ref> m_poWeakRefRootGroup{};
    std::shared_ptr<Ref> m_poRefSelf{};

    std::string m_osFilename{};
    mutable bool m_bDirty = false;
    std::string m_osVRTPath{};
    std::map<std::string, std::shared_ptr<VRTGroup>> m_oMapGroups{};
    std::map<std::string, std::shared_ptr<VRTMDArray>> m_oMapMDArrays{};
    std::map<std::string, std::shared_ptr<VRTAttribute>> m_oMapAttributes{};
    std::map<std::string, std::shared_ptr<VRTDimension>> m_oMapDimensions{};

    std::shared_ptr<VRTGroup>
    OpenGroupInternal(const std::string &osName) const;
    void SetRootGroupRef(const std::weak_ptr<Ref> &rgRef);
    std::weak_ptr<Ref> GetRootGroupRef() const;

  protected:
    friend class VRTMDArray;
    friend std::shared_ptr<GDALMDArray>
    VRTDerivedArrayCreate(const char *pszVRTPath, const CPLXMLNode *psTree);

    explicit VRTGroup(const char *pszVRTPath);
    VRTGroup(const std::string &osParentName, const std::string &osName);

  public:
    static std::shared_ptr<VRTGroup> Create(const std::string &osParentName,
                                            const std::string &osName)
    {
        auto poGroup =
            std::shared_ptr<VRTGroup>(new VRTGroup(osParentName, osName));
        poGroup->SetSelf(poGroup);
        return poGroup;
    }

    ~VRTGroup();

    bool XMLInit(const std::shared_ptr<VRTGroup> &poRoot,
                 const std::shared_ptr<VRTGroup> &poThisGroup,
                 const CPLXMLNode *psNode, const char *pszVRTPath);

    std::vector<std::string>
    GetMDArrayNames(CSLConstList papszOptions) const override;
    std::shared_ptr<GDALMDArray>
    OpenMDArray(const std::string &osName,
                CSLConstList papszOptions = nullptr) const override;

    std::vector<std::string>
    GetGroupNames(CSLConstList papszOptions) const override;

    std::shared_ptr<GDALGroup> OpenGroup(const std::string &osName,
                                         CSLConstList) const override
    {
        return OpenGroupInternal(osName);
    }

    std::vector<std::shared_ptr<GDALDimension>>
        GetDimensions(CSLConstList) const override;

    std::vector<std::shared_ptr<GDALAttribute>>
        GetAttributes(CSLConstList) const override;

    std::shared_ptr<VRTDimension> GetDimension(const std::string &name) const
    {
        auto oIter = m_oMapDimensions.find(name);
        return oIter == m_oMapDimensions.end() ? nullptr : oIter->second;
    }

    std::shared_ptr<VRTDimension>
    GetDimensionFromFullName(const std::string &name, bool bEmitError) const;

    std::shared_ptr<GDALGroup>
    CreateGroup(const std::string &osName,
                CSLConstList papszOptions = nullptr) override;

    std::shared_ptr<GDALDimension>
    CreateDimension(const std::string &osName, const std::string &osType,
                    const std::string &osDirection, GUInt64 nSize,
                    CSLConstList papszOptions = nullptr) override;

    std::shared_ptr<GDALAttribute>
    CreateAttribute(const std::string &osName,
                    const std::vector<GUInt64> &anDimensions,
                    const GDALExtendedDataType &oDataType,
                    CSLConstList papszOptions = nullptr) override;

    std::shared_ptr<GDALMDArray> CreateMDArray(
        const std::string &osName,
        const std::vector<std::shared_ptr<GDALDimension>> &aoDimensions,
        const GDALExtendedDataType &oDataType,
        CSLConstList papszOptions) override;

    void SetIsRootGroup();

    const std::shared_ptr<Ref> &GetRef() const
    {
        return m_poRefSelf;
    }

    VRTGroup *GetRootGroup() const;
    std::shared_ptr<GDALGroup> GetRootGroupSharedPtr() const;

    const std::string &GetVRTPath() const
    {
        return m_osVRTPath;
    }

    void SetDirty();

    void SetFilename(const std::string &osFilename)
    {
        m_osFilename = osFilename;
    }

    const std::string &GetFilename() const
    {
        return m_osFilename;
    }

    bool Serialize() const;
    CPLXMLNode *SerializeToXML(const char *pszVRTPathIn) const;
    void Serialize(CPLXMLNode *psParent, const char *pszVRTPathIn) const;
};

/************************************************************************/
/*                            VRTDimension                              */
/************************************************************************/

class VRTDimension final : public GDALDimension
{
    std::weak_ptr<VRTGroup::Ref> m_poGroupRef;
    std::string m_osIndexingVariableName;

  public:
    VRTDimension(const std::shared_ptr<VRTGroup::Ref> &poGroupRef,
                 const std::string &osParentName, const std::string &osName,
                 const std::string &osType, const std::string &osDirection,
                 GUInt64 nSize, const std::string &osIndexingVariableName)
        : GDALDimension(osParentName, osName, osType, osDirection, nSize),
          m_poGroupRef(poGroupRef),
          m_osIndexingVariableName(osIndexingVariableName)
    {
    }

    VRTGroup *GetGroup() const;

    static std::shared_ptr<VRTDimension>
    Create(const std::shared_ptr<VRTGroup> &poThisGroup,
           const std::string &osParentName, const CPLXMLNode *psNode);

    std::shared_ptr<GDALMDArray> GetIndexingVariable() const override;

    bool SetIndexingVariable(
        std::shared_ptr<GDALMDArray> poIndexingVariable) override;

    void Serialize(CPLXMLNode *psParent) const;
};

/************************************************************************/
/*                            VRTAttribute                              */
/************************************************************************/

class VRTAttribute final : public GDALAttribute
{
    GDALExtendedDataType m_dt;
    std::vector<std::string> m_aosList{};
    std::vector<std::shared_ptr<GDALDimension>> m_dims{};

  protected:
    bool IRead(const GUInt64 *arrayStartIdx, const size_t *count,
               const GInt64 *arrayStep, const GPtrDiff_t *bufferStride,
               const GDALExtendedDataType &bufferDataType,
               void *pDstBuffer) const override;

    bool IWrite(const GUInt64 *arrayStartIdx, const size_t *count,
                const GInt64 *arrayStep, const GPtrDiff_t *bufferStride,
                const GDALExtendedDataType &bufferDataType,
                const void *pSrcBuffer) override;

  public:
    VRTAttribute(const std::string &osParentName, const std::string &osName,
                 const GDALExtendedDataType &dt,
                 std::vector<std::string> &&aosList)
        : GDALAbstractMDArray(osParentName, osName),
          GDALAttribute(osParentName, osName), m_dt(dt),
          m_aosList(std::move(aosList))
    {
        if (m_aosList.size() > 1)
        {
            m_dims.emplace_back(std::make_shared<GDALDimension>(
                std::string(), "dim", std::string(), std::string(),
                m_aosList.size()));
        }
    }

    VRTAttribute(const std::string &osParentName, const std::string &osName,
                 GUInt64 nDim, const GDALExtendedDataType &dt)
        : GDALAbstractMDArray(osParentName, osName),
          GDALAttribute(osParentName, osName), m_dt(dt)
    {
        if (nDim != 0)
        {
            m_dims.emplace_back(std::make_shared<GDALDimension>(
                std::string(), "dim", std::string(), std::string(), nDim));
        }
    }

    static bool CreationCommonChecks(
        const std::string &osName, const std::vector<GUInt64> &anDimensions,
        const std::map<std::string, std::shared_ptr<VRTAttribute>>
            &oMapAttributes);

    static std::shared_ptr<VRTAttribute> Create(const std::string &osParentName,
                                                const CPLXMLNode *psNode);

    const std::vector<std::shared_ptr<GDALDimension>> &
    GetDimensions() const override
    {
        return m_dims;
    }

    const GDALExtendedDataType &GetDataType() const override
    {
        return m_dt;
    }

    void Serialize(CPLXMLNode *psParent) const;
};

/************************************************************************/
/*                          VRTMDArraySource                            */
/************************************************************************/

class VRTMDArraySource
{
  public:
    virtual ~VRTMDArraySource() = default;

    virtual bool Read(const GUInt64 *arrayStartIdx, const size_t *count,
                      const GInt64 *arrayStep, const GPtrDiff_t *bufferStride,
                      const GDALExtendedDataType &bufferDataType,
                      void *pDstBuffer) const = 0;

    virtual void Serialize(CPLXMLNode *psParent,
                           const char *pszVRTPath) const = 0;
};

/************************************************************************/
/*                            VRTMDArray                                */
/************************************************************************/

class VRTMDArray final : public GDALMDArray
{
  protected:
    friend class VRTGroup;  // for access to SetSelf()

    std::weak_ptr<VRTGroup::Ref> m_poGroupRef;
    std::string m_osVRTPath{};
    std::shared_ptr<VRTGroup> m_poDummyOwningGroup{};

    GDALExtendedDataType m_dt;
    std::vector<std::shared_ptr<GDALDimension>> m_dims;
    std::map<std::string, std::shared_ptr<VRTAttribute>> m_oMapAttributes{};
    std::vector<std::unique_ptr<VRTMDArraySource>> m_sources{};
    std::shared_ptr<OGRSpatialReference> m_poSRS{};
    std::vector<GByte> m_abyNoData{};
    std::string m_osUnit{};
    double m_dfScale = 1.0;
    double m_dfOffset = 0.0;
    bool m_bHasScale = false;
    bool m_bHasOffset = false;
    std::string m_osFilename{};

    bool IRead(const GUInt64 *arrayStartIdx, const size_t *count,
               const GInt64 *arrayStep, const GPtrDiff_t *bufferStride,
               const GDALExtendedDataType &bufferDataType,
               void *pDstBuffer) const override;

    void SetDirty();

  public:
    VRTMDArray(
        const std::shared_ptr<VRTGroup::Ref> &poGroupRef,
        const std::string &osParentName, const std::string &osName,
        const GDALExtendedDataType &dt,
        std::vector<std::shared_ptr<GDALDimension>> &&dims,
        std::map<std::string, std::shared_ptr<VRTAttribute>> &&oMapAttributes)
        : GDALAbstractMDArray(osParentName, osName),
          GDALMDArray(osParentName, osName), m_poGroupRef(poGroupRef),
          m_osVRTPath(poGroupRef->m_ptr->GetVRTPath()), m_dt(dt),
          m_dims(std::move(dims)), m_oMapAttributes(std::move(oMapAttributes)),
          m_osFilename(poGroupRef->m_ptr->GetFilename())
    {
    }

    VRTMDArray(const std::shared_ptr<VRTGroup::Ref> &poGroupRef,
               const std::string &osParentName, const std::string &osName,
               const std::vector<std::shared_ptr<GDALDimension>> &dims,
               const GDALExtendedDataType &dt)
        : GDALAbstractMDArray(osParentName, osName),
          GDALMDArray(osParentName, osName), m_poGroupRef(poGroupRef),
          m_osVRTPath(poGroupRef->m_ptr->GetVRTPath()), m_dt(dt), m_dims(dims),
          m_osFilename(poGroupRef->m_ptr->GetFilename())
    {
    }

    bool IsWritable() const override
    {
        return false;
    }

    const std::string &GetFilename() const override
    {
        return m_osFilename;
    }

    static std::shared_ptr<VRTMDArray> Create(const char *pszVRTPath,
                                              const CPLXMLNode *psNode);

    static std::shared_ptr<VRTMDArray>
    Create(const std::shared_ptr<VRTGroup> &poThisGroup,
           const std::string &osParentName, const CPLXMLNode *psNode);

    const std::vector<std::shared_ptr<GDALDimension>> &
    GetDimensions() const override
    {
        return m_dims;
    }

    std::vector<std::shared_ptr<GDALAttribute>>
        GetAttributes(CSLConstList) const override;

    const GDALExtendedDataType &GetDataType() const override
    {
        return m_dt;
    }

    bool SetSpatialRef(const OGRSpatialReference *poSRS) override;

    std::shared_ptr<OGRSpatialReference> GetSpatialRef() const override
    {
        return m_poSRS;
    }

    const void *GetRawNoDataValue() const override;

    bool SetRawNoDataValue(const void *pRawNoData) override;

    const std::string &GetUnit() const override
    {
        return m_osUnit;
    }

    bool SetUnit(const std::string &osUnit) override
    {
        m_osUnit = osUnit;
        return true;
    }

    double GetOffset(bool *pbHasOffset,
                     GDALDataType *peStorageType) const override
    {
        if (pbHasOffset)
            *pbHasOffset = m_bHasOffset;
        if (peStorageType)
            *peStorageType = GDT_Unknown;
        return m_dfOffset;
    }

    double GetScale(bool *pbHasScale,
                    GDALDataType *peStorageType) const override
    {
        if (pbHasScale)
            *pbHasScale = m_bHasScale;
        if (peStorageType)
            *peStorageType = GDT_Unknown;
        return m_dfScale;
    }

    bool SetOffset(double dfOffset,
                   GDALDataType /* eStorageType */ = GDT_Unknown) override
    {
        SetDirty();
        m_bHasOffset = true;
        m_dfOffset = dfOffset;
        return true;
    }

    bool SetScale(double dfScale,
                  GDALDataType /* eStorageType */ = GDT_Unknown) override
    {
        SetDirty();
        m_bHasScale = true;
        m_dfScale = dfScale;
        return true;
    }

    void AddSource(std::unique_ptr<VRTMDArraySource> &&poSource);

    std::shared_ptr<GDALAttribute>
    CreateAttribute(const std::string &osName,
                    const std::vector<GUInt64> &anDimensions,
                    const GDALExtendedDataType &oDataType,
                    CSLConstList papszOptions = nullptr) override;

    bool CopyFrom(GDALDataset *poSrcDS, const GDALMDArray *poSrcArray,
                  bool bStrict, GUInt64 &nCurCost, const GUInt64 nTotalCost,
                  GDALProgressFunc pfnProgress, void *pProgressData) override;

    void Serialize(CPLXMLNode *psParent, const char *pszVRTPathIn) const;

    VRTGroup *GetGroup() const;

    const std::string &GetVRTPath() const
    {
        return m_osVRTPath;
    }

    std::shared_ptr<GDALGroup> GetRootGroup() const override
    {
        auto poGroup = m_poGroupRef.lock();
        if (poGroup)
            return poGroup->m_ptr->GetRootGroupSharedPtr();
        return nullptr;
    }
};

/************************************************************************/
/*                       VRTMDArraySourceInlinedValues                  */
/************************************************************************/

class VRTMDArraySourceInlinedValues final : public VRTMDArraySource
{
    const VRTMDArray *m_poDstArray = nullptr;
    bool m_bIsConstantValue;
    std::vector<GUInt64> m_anOffset{};
    std::vector<size_t> m_anCount{};
    std::vector<GByte> m_abyValues{};
    std::vector<size_t> m_anInlinedArrayStrideInBytes{};
    GDALExtendedDataType m_dt;

    VRTMDArraySourceInlinedValues(const VRTMDArraySourceInlinedValues &) =
        delete;
    VRTMDArraySourceInlinedValues &
    operator=(const VRTMDArraySourceInlinedValues &) = delete;

  public:
    VRTMDArraySourceInlinedValues(const VRTMDArray *poDstArray,
                                  bool bIsConstantValue,
                                  std::vector<GUInt64> &&anOffset,
                                  std::vector<size_t> &&anCount,
                                  std::vector<GByte> &&abyValues)
        : m_poDstArray(poDstArray), m_bIsConstantValue(bIsConstantValue),
          m_anOffset(std::move(anOffset)), m_anCount(std::move(anCount)),
          m_abyValues(std::move(abyValues)), m_dt(poDstArray->GetDataType())
    {
        const auto nDims(poDstArray->GetDimensionCount());
        m_anInlinedArrayStrideInBytes.resize(nDims);
        if (!bIsConstantValue && nDims > 0)
        {
            m_anInlinedArrayStrideInBytes.back() =
                poDstArray->GetDataType().GetSize();
            for (size_t i = nDims - 1; i > 0;)
            {
                --i;
                m_anInlinedArrayStrideInBytes[i] =
                    m_anInlinedArrayStrideInBytes[i + 1] * m_anCount[i + 1];
            }
        }
    }

    ~VRTMDArraySourceInlinedValues();

    static std::unique_ptr<VRTMDArraySourceInlinedValues>
    Create(const VRTMDArray *poDstArray, const CPLXMLNode *psNode);

    bool Read(const GUInt64 *arrayStartIdx, const size_t *count,
              const GInt64 *arrayStep, const GPtrDiff_t *bufferStride,
              const GDALExtendedDataType &bufferDataType,
              void *pDstBuffer) const override;

    void Serialize(CPLXMLNode *psParent, const char *pszVRTPath) const override;
};

/************************************************************************/
/*                     VRTMDArraySourceRegularlySpaced                  */
/************************************************************************/

class VRTMDArraySourceRegularlySpaced final : public VRTMDArraySource
{
    double m_dfStart;
    double m_dfIncrement;

  public:
    VRTMDArraySourceRegularlySpaced(double dfStart, double dfIncrement)
        : m_dfStart(dfStart), m_dfIncrement(dfIncrement)
    {
    }

    bool Read(const GUInt64 *arrayStartIdx, const size_t *count,
              const GInt64 *arrayStep, const GPtrDiff_t *bufferStride,
              const GDALExtendedDataType &bufferDataType,
              void *pDstBuffer) const override;

    void Serialize(CPLXMLNode *psParent, const char *pszVRTPath) const override;
};

/************************************************************************/
/*                       VRTMDArraySourceFromArray                      */
/************************************************************************/

class VRTMDArraySourceFromArray final : public VRTMDArraySource
{
    const VRTMDArray *m_poDstArray = nullptr;
    bool m_bRelativeToVRTSet = false;
    bool m_bRelativeToVRT = false;
    std::string m_osFilename{};
    std::string m_osArray{};
    std::string m_osBand{};
    std::vector<int> m_anTransposedAxis{};
    std::string m_osViewExpr{};
    std::vector<GUInt64> m_anSrcOffset{};
    mutable std::vector<GUInt64> m_anCount{};
    std::vector<GUInt64> m_anStep{};
    std::vector<GUInt64> m_anDstOffset{};

    VRTMDArraySourceFromArray(const VRTMDArraySourceFromArray &) = delete;
    VRTMDArraySourceFromArray &
    operator=(const VRTMDArraySourceFromArray &) = delete;

  public:
    VRTMDArraySourceFromArray(
        const VRTMDArray *poDstArray, bool bRelativeToVRTSet,
        bool bRelativeToVRT, const std::string &osFilename,
        const std::string &osArray, const std::string &osBand,
        std::vector<int> &&anTransposedAxis, const std::string &osViewExpr,
        std::vector<GUInt64> &&anSrcOffset, std::vector<GUInt64> &&anCount,
        std::vector<GUInt64> &&anStep, std::vector<GUInt64> &&anDstOffset)
        : m_poDstArray(poDstArray), m_bRelativeToVRTSet(bRelativeToVRTSet),
          m_bRelativeToVRT(bRelativeToVRT), m_osFilename(osFilename),
          m_osArray(osArray), m_osBand(osBand),
          m_anTransposedAxis(std::move(anTransposedAxis)),
          m_osViewExpr(osViewExpr), m_anSrcOffset(std::move(anSrcOffset)),
          m_anCount(std::move(anCount)), m_anStep(std::move(anStep)),
          m_anDstOffset(std::move(anDstOffset))
    {
    }

    ~VRTMDArraySourceFromArray() override;

    static std::unique_ptr<VRTMDArraySourceFromArray>
    Create(const VRTMDArray *poDstArray, const CPLXMLNode *psNode);

    bool Read(const GUInt64 *arrayStartIdx, const size_t *count,
              const GInt64 *arrayStep, const GPtrDiff_t *bufferStride,
              const GDALExtendedDataType &bufferDataType,
              void *pDstBuffer) const override;

    void Serialize(CPLXMLNode *psParent, const char *pszVRTPath) const override;
};

#endif /* #ifndef DOXYGEN_SKIP */

#endif /* ndef VIRTUALDATASET_H_INCLUDED */
