/******************************************************************************
 *
 * Project:  GDAL
 * Purpose:  STACIT (Spatio-Temporal Asset Catalog ITems) driver
 * Author:   Even Rouault, <even dot rouault at spatialys.com>
 *
 ******************************************************************************
 * Copyright (c) 2021, Even Rouault <even dot rouault at spatialys.com>
 *
 * SPDX-License-Identifier: MIT
 ****************************************************************************/

#include "cpl_json.h"
#include "cpl_http.h"
#include "gdal_frmts.h"
#include "gdal_driver.h"
#include "gdal_drivermanager.h"
#include "gdal_openinfo.h"
#include "gdal_cpp_functions.h"
#include "vrtdataset.h"
#include "ogr_spatialref.h"

#include <algorithm>
#include <limits>
#include <map>
#include <string>

namespace
{

struct AssetItem
{
    std::string osFilename{};
    std::string osDateTime{};
    int nXSize = 0;
    int nYSize = 0;
    double dfXMin = 0;
    double dfYMin = 0;
    double dfXMax = 0;
    double dfYMax = 0;
};

struct AssetSetByProjection
{
    std::string osProjUserString{};
    std::vector<AssetItem> assets{};
};

struct Asset
{
    std::string osName{};
    CPLJSONArray bands{};
    std::map<std::string, AssetSetByProjection> assets{};
};

struct Collection
{
    std::string osName{};
    std::map<std::string, Asset> assets{};
};
}  // namespace

/************************************************************************/
/*                            STACITDataset                             */
/************************************************************************/

class STACITDataset final : public VRTDataset
{
    bool Open(GDALOpenInfo *poOpenInfo);
    bool SetupDataset(GDALOpenInfo *poOpenInfo,
                      const std::string &osSTACITFilename,
                      std::map<std::string, Collection> &oMapCollection);
    void
    SetSubdatasets(const std::string &osFilename,
                   const std::map<std::string, Collection> &oMapCollection);

  public:
    STACITDataset();
    ~STACITDataset() override;

    static int Identify(GDALOpenInfo *poOpenInfo);
    static GDALDataset *OpenStatic(GDALOpenInfo *poOpenInfo);
};

/************************************************************************/
/*                          STACITDataset()                             */
/************************************************************************/

STACITDataset::STACITDataset() : VRTDataset(0, 0)
{
    poDriver = nullptr;  // cancel what the VRTDataset did
    SetWritable(false);
}

STACITDataset::~STACITDataset() = default;

/************************************************************************/
/*                             Identify()                               */
/************************************************************************/

int STACITDataset::Identify(GDALOpenInfo *poOpenInfo)
{
    if (STARTS_WITH(poOpenInfo->pszFilename, "STACIT:"))
    {
        return true;
    }

    const bool bIsSingleDriver = poOpenInfo->IsSingleAllowedDriver("STACIT");
    if (bIsSingleDriver && (STARTS_WITH(poOpenInfo->pszFilename, "http://") ||
                            STARTS_WITH(poOpenInfo->pszFilename, "https://")))
    {
        return true;
    }

    if (poOpenInfo->nHeaderBytes == 0)
    {
        return false;
    }

    if (poOpenInfo->IsExtensionEqualToCI("zarr"))
        return false;

    for (int i = 0; i < 2; i++)
    {
        // TryToIngest() may reallocate pabyHeader, so do not move this
        // before the loop.
        const char *pszHeader =
            reinterpret_cast<const char *>(poOpenInfo->pabyHeader);
        while (*pszHeader != 0 &&
               std::isspace(static_cast<unsigned char>(*pszHeader)))
            ++pszHeader;
        if (bIsSingleDriver)
        {
            return pszHeader[0] == '{';
        }

        if (strstr(pszHeader, "\"stac_version\"") != nullptr)
        {
            int nTransformBBOXShapeCount = 0;
            for (const char *pszItem :
                 {"\"proj:transform\"", "\"proj:bbox\"", "\"proj:shape\""})
            {
                if (strstr(pszHeader, pszItem))
                    nTransformBBOXShapeCount++;
            }
            if (nTransformBBOXShapeCount >= 2)
            {
                return true;
            }
        }

        if (i == 0)
        {
            // Should be enough for a STACIT .json file
            poOpenInfo->TryToIngest(32768);
        }
    }

    return false;
}

/************************************************************************/
/*                        SanitizeCRSValue()                            */
/************************************************************************/

static std::string SanitizeCRSValue(const std::string &v)
{
    std::string ret;
    bool lastWasAlphaNum = true;
    for (char ch : v)
    {
        if (!isalnum(static_cast<unsigned char>(ch)))
        {
            if (lastWasAlphaNum)
                ret += '_';
            lastWasAlphaNum = false;
        }
        else
        {
            ret += ch;
            lastWasAlphaNum = true;
        }
    }
    if (!ret.empty() && ret.back() == '_')
        ret.pop_back();
    return ret;
}

/************************************************************************/
/*                            ParseAsset()                              */
/************************************************************************/

static void ParseAsset(const CPLJSONObject &jAsset,
                       const CPLJSONObject &oProperties,
                       const std::string &osCollection,
                       const std::string &osFilteredCRS,
                       std::map<std::string, Collection> &oMapCollection)
{
    // Skip assets that are obviously not images
    const auto osType = jAsset["type"].ToString();
    if (osType == "application/json" || osType == "application/xml" ||
        osType == "text/plain")
    {
        return;
    }

    // Skip assets whose role is obviously non georeferenced
    const auto oRoles = jAsset.GetArray("roles");
    if (oRoles.IsValid())
    {
        for (const auto &oRole : oRoles)
        {
            const auto osRole = oRole.ToString();
            if (osRole == "thumbnail" || osRole == "info" ||
                osRole == "metadata")
            {
                return;
            }
        }
    }

    const auto osAssetName = jAsset.GetName();

    std::string osHref = jAsset["href"].ToString();
    if (osHref.empty())
    {
        CPLError(CE_Warning, CPLE_AppDefined, "Missing href on asset %s",
                 osAssetName.c_str());
        return;
    }

    const auto GetAssetOrFeatureProperty =
        [&oProperties, &jAsset](const char *pszName)
    {
        auto obj = jAsset[pszName];
        if (obj.IsValid())
            return obj;
        return oProperties[pszName];
    };

    std::string osProjUserString;
    const auto oProjCode = GetAssetOrFeatureProperty("proj:code");
    if (oProjCode.IsValid() && oProjCode.GetType() != CPLJSONObject::Type::Null)
    {
        osProjUserString = oProjCode.ToString();
    }
    else
    {
        const auto oProjEPSG = GetAssetOrFeatureProperty("proj:epsg");
        if (oProjEPSG.IsValid() &&
            oProjEPSG.GetType() != CPLJSONObject::Type::Null)
        {
            osProjUserString = "EPSG:" + oProjEPSG.ToString();
        }
        else
        {
            const auto oProjWKT2 = GetAssetOrFeatureProperty("proj:wkt2");
            if (oProjWKT2.IsValid() &&
                oProjWKT2.GetType() == CPLJSONObject::Type::String)
            {
                osProjUserString = oProjWKT2.ToString();
            }
            else
            {
                const auto oProjPROJJSON =
                    GetAssetOrFeatureProperty("proj:projjson");
                if (oProjPROJJSON.IsValid() &&
                    oProjPROJJSON.GetType() == CPLJSONObject::Type::Object)
                {
                    osProjUserString = oProjPROJJSON.ToString();
                }
                else
                {
                    CPLDebug("STACIT",
                             "Skipping asset %s that lacks a valid CRS member",
                             osAssetName.c_str());
                    return;
                }
            }
        }
    }

    if (!osFilteredCRS.empty() &&
        osFilteredCRS != SanitizeCRSValue(osProjUserString))
    {
        return;
    }

    AssetItem item;
    item.osFilename = std::move(osHref);
    item.osDateTime = oProperties["datetime"].ToString();

    // Figure out item bounds and width/height
    auto oProjBBOX = GetAssetOrFeatureProperty("proj:bbox").ToArray();
    auto oProjShape = GetAssetOrFeatureProperty("proj:shape").ToArray();
    auto oProjTransform = GetAssetOrFeatureProperty("proj:transform").ToArray();
    const bool bIsBBOXValid = oProjBBOX.IsValid() && oProjBBOX.Size() == 4;
    const bool bIsShapeValid = oProjShape.IsValid() && oProjShape.Size() == 2;
    const bool bIsTransformValid =
        oProjTransform.IsValid() &&
        (oProjTransform.Size() == 6 || oProjTransform.Size() == 9);
    std::vector<double> bbox;
    if (bIsBBOXValid)
    {
        for (const auto &oItem : oProjBBOX)
            bbox.push_back(oItem.ToDouble());
        CPLAssert(bbox.size() == 4);
    }
    std::vector<int> shape;
    if (bIsShapeValid)
    {
        for (const auto &oItem : oProjShape)
            shape.push_back(oItem.ToInteger());
        CPLAssert(shape.size() == 2);
    }
    std::vector<double> transform;
    if (bIsTransformValid)
    {
        for (const auto &oItem : oProjTransform)
            transform.push_back(oItem.ToDouble());
        CPLAssert(transform.size() == 6 || transform.size() == 9);
#if defined(__GNUC__)
#pragma GCC diagnostic push
#pragma GCC diagnostic ignored "-Wnull-dereference"
#endif
        if (transform[0] <= 0 || transform[1] != 0 || transform[3] != 0 ||
            transform[4] >= 0 ||
            (transform.size() == 9 &&
             (transform[6] != 0 || transform[7] != 0 || transform[8] != 1)))
        {
            CPLError(
                CE_Warning, CPLE_AppDefined,
                "Skipping asset %s because its proj:transform is "
                "not of the form [xres,0,xoffset,0,yres<0,yoffset[,0,0,1]]",
                osAssetName.c_str());
            return;
        }
#if defined(__GNUC__)
#pragma GCC diagnostic pop
#endif
    }

    if (bIsBBOXValid && bIsShapeValid)
    {
        item.nXSize = shape[1];
        item.nYSize = shape[0];
        item.dfXMin = bbox[0];
        item.dfYMin = bbox[1];
        item.dfXMax = bbox[2];
        item.dfYMax = bbox[3];
    }
    else if (bIsBBOXValid && bIsTransformValid)
    {
        item.dfXMin = bbox[0];
        item.dfYMin = bbox[1];
        item.dfXMax = bbox[2];
        item.dfYMax = bbox[3];
        if (item.dfXMin != transform[2] || item.dfYMax != transform[5])
        {
            CPLError(CE_Warning, CPLE_AppDefined,
                     "Skipping asset %s because the origin of "
                     "proj:transform and proj:bbox are not consistent",
                     osAssetName.c_str());
            return;
        }
        double dfXSize = (item.dfXMax - item.dfXMin) / transform[0];
        double dfYSize = (item.dfYMax - item.dfYMin) / -transform[4];
        if (!(dfXSize < INT_MAX && dfYSize < INT_MAX))
            return;
        item.nXSize = static_cast<int>(dfXSize);
        item.nYSize = static_cast<int>(dfYSize);
    }
    else if (bIsShapeValid && bIsTransformValid)
    {
        item.nXSize = shape[1];
        item.nYSize = shape[0];
        item.dfXMin = transform[2];
        item.dfYMax = transform[5];
        item.dfXMax = item.dfXMin + item.nXSize * transform[0];
        item.dfYMin = item.dfYMax + item.nYSize * transform[4];
    }
    else
    {
        CPLDebug("STACIT",
                 "Skipping asset %s that lacks at least 2 members among "
                 "proj:bbox, proj:shape and proj:transform",
                 osAssetName.c_str());
        return;
    }

    if (item.nXSize <= 0 || item.nYSize <= 0)
    {
        CPLError(CE_Warning, CPLE_AppDefined,
                 "Skipping asset %s because the size is invalid",
                 osAssetName.c_str());
        return;
    }

    // Create/fetch collection
    if (oMapCollection.find(osCollection) == oMapCollection.end())
    {
        Collection collection;
        collection.osName = osCollection;
        oMapCollection[osCollection] = std::move(collection);
    }
    auto &collection = oMapCollection[osCollection];

    // Create/fetch asset in collection
    if (collection.assets.find(osAssetName) == collection.assets.end())
    {
        Asset asset;
        asset.osName = osAssetName;
        asset.bands = jAsset.GetArray("bands");
        if (!asset.bands.IsValid())
            asset.bands = jAsset.GetArray("eo:bands");

        collection.assets[osAssetName] = std::move(asset);
    }
    auto &asset = collection.assets[osAssetName];

    // Create/fetch projection in asset
    if (asset.assets.find(osProjUserString) == asset.assets.end())
    {
        AssetSetByProjection assetByProj;
        assetByProj.osProjUserString = osProjUserString;
        asset.assets[osProjUserString] = std::move(assetByProj);
    }
    auto &assets = asset.assets[osProjUserString];

    // Add item
    assets.assets.emplace_back(std::move(item));
}

/************************************************************************/
/*                           SetupDataset()                             */
/************************************************************************/

bool STACITDataset::SetupDataset(
    GDALOpenInfo *poOpenInfo, const std::string &osSTACITFilename,
    std::map<std::string, Collection> &oMapCollection)
{
    auto &collection = oMapCollection.begin()->second;
    auto &asset = collection.assets.begin()->second;
    auto &assetByProj = asset.assets.begin()->second;
    auto &items = assetByProj.assets;

    // Compute global bounds and resolution
    double dfXMin = std::numeric_limits<double>::max();
    double dfYMin = std::numeric_limits<double>::max();
    double dfXMax = -std::numeric_limits<double>::max();
    double dfYMax = -std::numeric_limits<double>::max();
    double dfXRes = 0;
    double dfYRes = 0;
    const char *pszResolution = CSLFetchNameValueDef(
        poOpenInfo->papszOpenOptions, "RESOLUTION", "AVERAGE");
    for (const auto &assetItem : items)
    {
        dfXMin = std::min(dfXMin, assetItem.dfXMin);
        dfYMin = std::min(dfYMin, assetItem.dfYMin);
        dfXMax = std::max(dfXMax, assetItem.dfXMax);
        dfYMax = std::max(dfYMax, assetItem.dfYMax);
        const double dfThisXRes =
            (assetItem.dfXMax - assetItem.dfXMin) / assetItem.nXSize;
        const double dfThisYRes =
            (assetItem.dfYMax - assetItem.dfYMin) / assetItem.nYSize;
#ifdef DEBUG_VERBOSE
        CPLDebug("STACIT", "%s -> resx=%f resy=%f",
                 assetItem.osFilename.c_str(), dfThisXRes, dfThisYRes);
#endif
        if (dfXRes != 0 && EQUAL(pszResolution, "HIGHEST"))
        {
            dfXRes = std::min(dfXRes, dfThisXRes);
            dfYRes = std::min(dfYRes, dfThisYRes);
        }
        else if (dfXRes != 0 && EQUAL(pszResolution, "LOWEST"))
        {
            dfXRes = std::max(dfXRes, dfThisXRes);
            dfYRes = std::max(dfYRes, dfThisYRes);
        }
        else
        {
            dfXRes += dfThisXRes;
            dfYRes += dfThisYRes;
        }
    }
    if (EQUAL(pszResolution, "AVERAGE"))
    {
        dfXRes /= static_cast<int>(items.size());
        dfYRes /= static_cast<int>(items.size());
    }

    // Set raster size
    if (dfXRes == 0 || dfYRes == 0)
    {
        CPLError(CE_Failure, CPLE_AppDefined,
                 "Invalid computed dataset dimensions");
        return false;
    }
    double dfXSize = std::round((dfXMax - dfXMin) / dfXRes);
    double dfYSize = std::round((dfYMax - dfYMin) / dfYRes);
    if (dfXSize <= 0 || dfYSize <= 0 || dfXSize > INT_MAX || dfYSize > INT_MAX)
    {
        CPLError(CE_Failure, CPLE_AppDefined,
                 "Invalid computed dataset dimensions");
        return false;
    }
    nRasterXSize = static_cast<int>(dfXSize);
    nRasterYSize = static_cast<int>(dfYSize);

    // Set geotransform
    GDALGeoTransform gt{dfXMin, dfXRes, 0, dfYMax, 0, -dfYRes};
    SetGeoTransform(gt);

    // Set SRS
    OGRSpatialReference oSRS;
    if (oSRS.SetFromUserInput(
            assetByProj.osProjUserString.c_str(),
            OGRSpatialReference::SET_FROM_USER_INPUT_LIMITATIONS_get()) ==
        OGRERR_NONE)
    {
        oSRS.SetAxisMappingStrategy(OAMS_TRADITIONAL_GIS_ORDER);
        SetSpatialRef(&oSRS);
    }

    // Open of the items to find the number of bands, their data type
    // and nodata.
    const auto BuildVSICurlFilename =
        [&osSTACITFilename, &collection](const std::string &osFilename)
    {
        std::string osRet;
        if (STARTS_WITH(osFilename.c_str(), "http"))
        {
            if (STARTS_WITH(osSTACITFilename.c_str(),
                            "https://planetarycomputer.microsoft.com/api/"))
            {
                osRet = "/vsicurl?pc_url_signing=yes&pc_collection=";
                osRet += collection.osName;
                osRet += "&url=";
                char *pszEncoded =
                    CPLEscapeString(osFilename.c_str(), -1, CPLES_URL);
                CPLString osEncoded(pszEncoded);
                CPLFree(pszEncoded);
                // something is confused if the whole URL appears as
                // /vsicurl...blabla_without_slash.tif" so transform back %2F to
                // /
                osEncoded.replaceAll("%2F", '/');
                osRet += osEncoded;
            }
            else
            {
                osRet = "/vsicurl/";
                osRet += osFilename;
            }
        }
        else
        {
            osRet = VSIURIToVSIPath(osFilename);
        }
        return osRet;
    };

    const auto osFirstItemName(BuildVSICurlFilename(items.front().osFilename));
    auto poItemDS = std::unique_ptr<GDALDataset>(
        GDALDataset::Open(osFirstItemName.c_str()));
    if (!poItemDS)
    {
        CPLError(CE_Failure, CPLE_AppDefined,
                 "Cannot open %s to retrieve band characteristics",
                 osFirstItemName.c_str());
        return false;
    }

    // Sort by ascending datetime
    std::sort(items.begin(), items.end(),
              [](const AssetItem &a, const AssetItem &b)
              {
                  if (!a.osDateTime.empty() && !b.osDateTime.empty())
                      return a.osDateTime < b.osDateTime;
                  return &a < &b;
              });

    // Create VRT bands and add sources
    bool bAtLeastOneBandHasNoData = false;
    for (int i = 0; i < poItemDS->GetRasterCount(); i++)
    {
        auto poItemBand = poItemDS->GetRasterBand(i + 1);
        AddBand(poItemBand->GetRasterDataType(), nullptr);
        auto poVRTBand =
            cpl::down_cast<VRTSourcedRasterBand *>(GetRasterBand(i + 1));
        int bHasNoData = FALSE;
        const double dfNoData = poItemBand->GetNoDataValue(&bHasNoData);
        if (bHasNoData)
        {
            bAtLeastOneBandHasNoData = true;
            poVRTBand->SetNoDataValue(dfNoData);
        }

        const auto eInterp = poItemBand->GetColorInterpretation();
        if (eInterp != GCI_Undefined)
            poVRTBand->SetColorInterpretation(eInterp);

        // Set band properties
        if (asset.bands.IsValid() &&
            asset.bands.Size() == poItemDS->GetRasterCount())
        {
            const auto &band = asset.bands[i];
            const auto osBandName = band["name"].ToString();
            if (!osBandName.empty())
                poVRTBand->SetDescription(osBandName.c_str());

            auto osCommonName = band["eo:common_name"].ToString();
            if (osCommonName.empty())
                osCommonName = band["common_name"].ToString();
            if (!osCommonName.empty())
            {
                const auto eInterpFromCommonName =
                    GDALGetColorInterpFromSTACCommonName(osCommonName.c_str());
                if (eInterpFromCommonName != GCI_Undefined)
                    poVRTBand->SetColorInterpretation(eInterpFromCommonName);
            }

            for (const auto &bandChild : band.GetChildren())
            {
                const auto osChildName = bandChild.GetName();
                if (osChildName != "name" && osChildName != "common_name" &&
                    osChildName != "eo:common_name")
                {
                    poVRTBand->SetMetadataItem(osChildName.c_str(),
                                               bandChild.ToString().c_str());
                }
            }
        }

        // Add items as VRT sources
        for (const auto &assetItem : items)
        {
            const auto osItemName(BuildVSICurlFilename(assetItem.osFilename));
            const double dfDstXOff = (assetItem.dfXMin - dfXMin) / dfXRes;
            const double dfDstXSize =
                (assetItem.dfXMax - assetItem.dfXMin) / dfXRes;
            const double dfDstYOff = (dfYMax - assetItem.dfYMax) / dfYRes;
            const double dfDstYSize =
                (assetItem.dfYMax - assetItem.dfYMin) / dfYRes;
            if (!bHasNoData)
            {
                poVRTBand->AddSimpleSource(osItemName.c_str(), i + 1, 0, 0,
                                           assetItem.nXSize, assetItem.nYSize,
                                           dfDstXOff, dfDstYOff, dfDstXSize,
                                           dfDstYSize);
            }
            else
            {
                poVRTBand->AddComplexSource(osItemName.c_str(), i + 1, 0, 0,
                                            assetItem.nXSize, assetItem.nYSize,
                                            dfDstXOff, dfDstYOff, dfDstXSize,
                                            dfDstYSize,
                                            0.0,  // offset
                                            1.0,  // scale
                                            dfNoData);
            }
        }

        const char *pszOverlapStrategy =
            CSLFetchNameValueDef(poOpenInfo->papszOpenOptions,
                                 "OVERLAP_STRATEGY", "REMOVE_IF_NO_NODATA");
        if ((EQUAL(pszOverlapStrategy, "REMOVE_IF_NO_NODATA") &&
             !bAtLeastOneBandHasNoData) ||
            EQUAL(pszOverlapStrategy, "USE_MOST_RECENT"))
        {
            const char *const apszOptions[] = {
                "EMIT_ERROR_IF_GEOS_NOT_AVAILABLE=NO", nullptr};
            poVRTBand->RemoveCoveredSources(apszOptions);
        }
    }
    return true;
}

/************************************************************************/
/*                         SetSubdatasets()                             */
/************************************************************************/

void STACITDataset::SetSubdatasets(
    const std::string &osFilename,
    const std::map<std::string, Collection> &oMapCollection)
{
    CPLStringList aosSubdatasets;
    int nCount = 1;
    for (const auto &collectionKV : oMapCollection)
    {
        for (const auto &assetKV : collectionKV.second.assets)
        {
            std::string osCollectionAssetArg;
            if (oMapCollection.size() > 1)
                osCollectionAssetArg +=
                    "collection=" + collectionKV.first + ",";
            osCollectionAssetArg += "asset=" + assetKV.first;

            std::string osCollectionAssetText;
            if (oMapCollection.size() > 1)
                osCollectionAssetText +=
                    "Collection " + collectionKV.first + ", ";
            osCollectionAssetText += "Asset " + assetKV.first;

            if (assetKV.second.assets.size() == 1)
            {
                aosSubdatasets.AddString(CPLSPrintf(
                    "SUBDATASET_%d_NAME=STACIT:\"%s\":%s", nCount,
                    osFilename.c_str(), osCollectionAssetArg.c_str()));
                aosSubdatasets.AddString(CPLSPrintf(
                    "SUBDATASET_%d_DESC=%s of %s", nCount,
                    osCollectionAssetText.c_str(), osFilename.c_str()));
                nCount++;
            }
            else
            {
                for (const auto &assetsByProjKV : assetKV.second.assets)
                {
                    aosSubdatasets.AddString(CPLSPrintf(
                        "SUBDATASET_%d_NAME=STACIT:\"%s\":%s,crs=%s", nCount,
                        osFilename.c_str(), osCollectionAssetArg.c_str(),
                        SanitizeCRSValue(assetsByProjKV.first).c_str()));
                    aosSubdatasets.AddString(CPLSPrintf(
                        "SUBDATASET_%d_DESC=%s of %s in CRS %s", nCount,
                        osCollectionAssetText.c_str(), osFilename.c_str(),
                        assetsByProjKV.first.c_str()));
                    nCount++;
                }
            }
        }
    }
    GDALDataset::SetMetadata(aosSubdatasets.List(), "SUBDATASETS");
}

/************************************************************************/
/*                               Open()                                 */
/************************************************************************/

bool STACITDataset::Open(GDALOpenInfo *poOpenInfo)
{
    CPLString osFilename(poOpenInfo->pszFilename);
    std::string osFilteredCollection =
        CSLFetchNameValueDef(poOpenInfo->papszOpenOptions, "COLLECTION", "");
    std::string osFilteredAsset =
        CSLFetchNameValueDef(poOpenInfo->papszOpenOptions, "ASSET", "");
    std::string osFilteredCRS = SanitizeCRSValue(
        CSLFetchNameValueDef(poOpenInfo->papszOpenOptions, "CRS", ""));
    if (STARTS_WITH(poOpenInfo->pszFilename, "STACIT:"))
    {
        const CPLStringList aosTokens(CSLTokenizeString2(
            poOpenInfo->pszFilename, ":", CSLT_HONOURSTRINGS));
        if (aosTokens.size() != 2 && aosTokens.size() != 3)
            return false;
        osFilename = aosTokens[1];
        if (aosTokens.size() >= 3)
        {
            const CPLStringList aosFilters(
                CSLTokenizeString2(aosTokens[2], ",", 0));
            osFilteredCollection = aosFilters.FetchNameValueDef(
                "collection", osFilteredCollection.c_str());
            osFilteredAsset =
                aosFilters.FetchNameValueDef("asset", osFilteredAsset.c_str());
            osFilteredCRS =
                aosFilters.FetchNameValueDef("crs", osFilteredCRS.c_str());
        }
    }

    std::map<std::string, Collection> oMapCollection;
    GIntBig nItemIter = 0;
    GIntBig nMaxItems = CPLAtoGIntBig(CSLFetchNameValueDef(
        poOpenInfo->papszOpenOptions, "MAX_ITEMS", "1000"));

    const bool bMaxItemsSpecified =
        CSLFetchNameValue(poOpenInfo->papszOpenOptions, "MAX_ITEMS") != nullptr;
    if (!bMaxItemsSpecified)
    {
        // If the URL includes a limit parameter, and it's larger than our
        // default MAX_ITEMS value, then increase the later to the former.
        const auto nPos = osFilename.ifind("&limit=");
        if (nPos != std::string::npos)
        {
            const auto nLimit = CPLAtoGIntBig(
                osFilename.substr(nPos + strlen("&limit=")).c_str());
            nMaxItems = std::max(nMaxItems, nLimit);
        }
    }

    auto osCurFilename = osFilename;
    std::string osMethod = "GET";
    CPLJSONObject oHeaders;
    CPLJSONObject oBody;
    bool bMerge = false;
    int nLoops = 0;
    oBody.Deinit();
    do
    {
        ++nLoops;
        if (nMaxItems > 0 && nLoops > nMaxItems)
        {
            break;
        }

        CPLJSONDocument oDoc;

        if (STARTS_WITH(osCurFilename, "http://") ||
            STARTS_WITH(osCurFilename, "https://"))
        {
            // Cf https://github.com/radiantearth/stac-api-spec/tree/release/v1.0.0/item-search#pagination
            CPLStringList aosOptions;
            if (oBody.IsValid() &&
                oBody.GetType() == CPLJSONObject::Type::Object)
            {
                if (bMerge)
                    CPLDebug("STACIT",
                             "Ignoring 'merge' attribute from next link");
                const std::string osPostContent =
                    oBody.Format(CPLJSONObject::PrettyFormat::Pretty);
                aosOptions.SetNameValue("POSTFIELDS", osPostContent.c_str());
            }
            aosOptions.SetNameValue("CUSTOMREQUEST", osMethod.c_str());
            CPLString osHeaders;
            if (!oHeaders.IsValid() ||
                oHeaders.GetType() != CPLJSONObject::Type::Object ||
                oHeaders["Content-Type"].ToString().empty())
            {
                osHeaders = "Content-Type: application/json";
            }
            if (oHeaders.IsValid() &&
                oHeaders.GetType() == CPLJSONObject::Type::Object)
            {
                for (const auto &obj : oHeaders.GetChildren())
                {
                    osHeaders += "\r\n";
                    osHeaders += obj.GetName();
                    osHeaders += ": ";
                    osHeaders += obj.ToString();
                }
            }
            aosOptions.SetNameValue("HEADERS", osHeaders.c_str());
            CPLHTTPResult *psResult =
                CPLHTTPFetch(osCurFilename.c_str(), aosOptions.List());
            if (!psResult)
                return false;
            if (!psResult->pabyData)
            {
                CPLHTTPDestroyResult(psResult);
                return false;
            }
            const bool bOK = oDoc.LoadMemory(
                reinterpret_cast<const char *>(psResult->pabyData));
            // CPLDebug("STACIT", "Response: %s", reinterpret_cast<const char*>(psResult->pabyData));
            CPLHTTPDestroyResult(psResult);
            if (!bOK)
                return false;
        }
        else
        {
            if (!oDoc.Load(osCurFilename))
                return false;
        }
        const auto oRoot = oDoc.GetRoot();
        auto oFeatures = oRoot.GetArray("features");
        if (!oFeatures.IsValid())
        {
            if (oRoot.GetString("type") == "Feature")
            {
                oFeatures = CPLJSONArray();
                oFeatures.Add(oRoot);
            }
            else
            {
                CPLError(CE_Failure, CPLE_AppDefined, "Missing features");
                return false;
            }
        }
        for (const auto &oFeature : oFeatures)
        {
            nItemIter++;
            if (nMaxItems > 0 && nItemIter > nMaxItems)
            {
                break;
            }

            auto oStacExtensions = oFeature.GetArray("stac_extensions");
            if (!oStacExtensions.IsValid())
            {
                CPLDebug("STACIT",
                         "Skipping Feature that lacks stac_extensions");
                continue;
            }
            bool bProjExtensionFound = false;
            for (const auto &oStacExtension : oStacExtensions)
            {
                if (oStacExtension.ToString() == "proj" ||
                    oStacExtension.ToString().find(
                        "https://stac-extensions.github.io/projection/") == 0)
                {
                    bProjExtensionFound = true;
                    break;
                }
            }
            if (!bProjExtensionFound)
            {
                CPLDebug(
                    "STACIT",
                    "Skipping Feature that lacks the 'proj' STAC extension");
                continue;
            }

            auto jAssets = oFeature["assets"];
            if (!jAssets.IsValid() ||
                jAssets.GetType() != CPLJSONObject::Type::Object)
            {
                CPLError(CE_Warning, CPLE_AppDefined,
                         "Missing assets on a Feature");
                continue;
            }

            auto oProperties = oFeature["properties"];
            if (!oProperties.IsValid() ||
                oProperties.GetType() != CPLJSONObject::Type::Object)
            {
                CPLError(CE_Warning, CPLE_AppDefined,
                         "Missing properties on a Feature");
                continue;
            }

            const auto osCollection = oFeature["collection"].ToString();
            if (!osFilteredCollection.empty() &&
                osFilteredCollection != osCollection)
                continue;

            for (const auto &jAsset : jAssets.GetChildren())
            {
                const auto osAssetName = jAsset.GetName();
                if (!osFilteredAsset.empty() && osFilteredAsset != osAssetName)
                    continue;

                ParseAsset(jAsset, oProperties, osCollection, osFilteredCRS,
                           oMapCollection);
            }
        }
        if (nMaxItems > 0 && nItemIter >= nMaxItems)
        {
            if (!bMaxItemsSpecified)
            {
                CPLError(CE_Warning, CPLE_AppDefined,
                         "Maximum number of items (" CPL_FRMT_GIB
                         ") allowed to be retrieved has been hit",
                         nMaxItems);
            }
            else
            {
                CPLDebug("STACIT",
                         "Maximum number of items (" CPL_FRMT_GIB
                         ") allowed to be retrieved has been hit",
                         nMaxItems);
            }
            break;
        }

        // Follow next link
        // Cf https://github.com/radiantearth/stac-api-spec/tree/release/v1.0.0/item-search#pagination
        const auto oLinks = oRoot.GetArray("links");
        if (!oLinks.IsValid())
            break;
        std::string osNewFilename;
        for (const auto &oLink : oLinks)
        {
            const auto osType = oLink["type"].ToString();
            if (oLink["rel"].ToString() == "next" &&
                (osType.empty() || osType == "application/geo+json"))
            {
                osMethod = oLink.GetString("method", "GET");
                osNewFilename = oLink["href"].ToString();
                oHeaders = oLink["headers"];
                oBody = oLink["body"];
                bMerge = oLink.GetBool("merge", false);
                if (osType == "application/geo+json")
                {
                    break;
                }
            }
        }
        if (!osNewFilename.empty() &&
            (osNewFilename != osCurFilename ||
             (oBody.IsValid() &&
              oBody.GetType() == CPLJSONObject::Type::Object)))
        {
            osCurFilename = osNewFilename;
        }
        else
            osCurFilename.clear();
    } while (!osCurFilename.empty());

    if (oMapCollection.empty())
    {
        CPLError(CE_Failure, CPLE_AppDefined, "No compatible asset found");
        return false;
    }

    if (oMapCollection.size() > 1 ||
        oMapCollection.begin()->second.assets.size() > 1 ||
        oMapCollection.begin()->second.assets.begin()->second.assets.size() > 1)
    {
        // If there's more than one asset type or more than one SRS, expose
        // subdatasets.
        SetSubdatasets(osFilename, oMapCollection);
        return true;
    }
    else
    {
        return SetupDataset(poOpenInfo, osFilename, oMapCollection);
    }
}

/************************************************************************/
/*                            OpenStatic()                              */
/************************************************************************/

GDALDataset *STACITDataset::OpenStatic(GDALOpenInfo *poOpenInfo)
{
    if (!Identify(poOpenInfo))
        return nullptr;
    auto poDS = std::make_unique<STACITDataset>();
    if (!poDS->Open(poOpenInfo))
        return nullptr;
    return poDS.release();
}

/************************************************************************/
/*                       GDALRegister_STACIT()                          */
/************************************************************************/

void GDALRegister_STACIT()

{
    if (GDALGetDriverByName("STACIT") != nullptr)
        return;

    GDALDriver *poDriver = new GDALDriver();

    poDriver->SetDescription("STACIT");
    poDriver->SetMetadataItem(GDAL_DCAP_RASTER, "YES");
    poDriver->SetMetadataItem(GDAL_DMD_LONGNAME,
                              "Spatio-Temporal Asset Catalog Items");
    poDriver->SetMetadataItem(GDAL_DMD_HELPTOPIC, "drivers/raster/stacit.html");
    poDriver->SetMetadataItem(GDAL_DCAP_VIRTUALIO, "YES");
    poDriver->SetMetadataItem(GDAL_DMD_SUBDATASETS, "YES");
    poDriver->SetMetadataItem(
        GDAL_DMD_OPENOPTIONLIST,
        "<OpenOptionList>"
        "   <Option name='MAX_ITEMS' type='int' default='1000' "
        "description='Maximum number of items fetched. 0=unlimited'/>"
        "   <Option name='COLLECTION' type='string' "
        "description='Name of collection to filter items'/>"
        "   <Option name='ASSET' type='string' "
        "description='Name of asset to filter items'/>"
        "   <Option name='CRS' type='string' "
        "description='Name of CRS to filter items'/>"
        "   <Option name='RESOLUTION' type='string-select' default='AVERAGE' "
        "description='Strategy to use to determine dataset resolution'>"
        "       <Value>AVERAGE</Value>"
        "       <Value>HIGHEST</Value>"
        "       <Value>LOWEST</Value>"
        "   </Option>"
        "   <Option name='OVERLAP_STRATEGY' type='string-select' "
        "default='REMOVE_IF_NO_NODATA' "
        "description='Strategy to use when some sources are fully "
        "covered by others'>"
        "       <Value>REMOVE_IF_NO_NODATA</Value>"
        "       <Value>USE_ALL</Value>"
        "       <Value>USE_MOST_RECENT</Value>"
        "   </Option>"
        "</OpenOptionList>");

    poDriver->pfnOpen = STACITDataset::OpenStatic;
    poDriver->pfnIdentify = STACITDataset::Identify;

    GetGDALDriverManager()->RegisterDriver(poDriver);
}