/******************************************************************************
 *
 * Project:  Earth Engine Data API Images driver
 * Purpose:  Earth Engine Data API Images driver
 * Author:   Even Rouault, even dot rouault at spatialys.com
 *
 ******************************************************************************
 * Copyright (c) 2017-2018, Planet Labs
 *
 * SPDX-License-Identifier: MIT
 ****************************************************************************/

#include "cpl_http.h"
#include "cpl_multiproc.h"  // CPLSleep
#include "eeda.h"
#include "ogrlibjsonutils.h"

#include <stdlib.h>
#include <limits>

std::vector<EEDAIBandDesc>
BuildBandDescArray(json_object *poBands,
                   std::map<CPLString, CPLString> &oMapCodeToWKT)
{
    const auto nBandCount = json_object_array_length(poBands);
    std::vector<EEDAIBandDesc> aoBandDesc;

    for (auto i = decltype(nBandCount){0}; i < nBandCount; i++)
    {
        json_object *poBand = json_object_array_get_idx(poBands, i);
        if (poBand == nullptr ||
            json_object_get_type(poBand) != json_type_object)
            continue;

        json_object *poId = CPL_json_object_object_get(poBand, "id");
        const char *pszBandId = json_object_get_string(poId);
        if (pszBandId == nullptr)
            continue;

        json_object *poDataType =
            CPL_json_object_object_get(poBand, "dataType");
        if (poDataType == nullptr ||
            json_object_get_type(poDataType) != json_type_object)
        {
            continue;
        }

        json_object *poPrecision =
            CPL_json_object_object_get(poDataType, "precision");
        const char *pszPrecision = json_object_get_string(poPrecision);
        if (pszPrecision == nullptr)
            continue;
        GDALDataType eDT = GDT_Byte;
        if (EQUAL(pszPrecision, "INT"))
        {
            json_object *poRange =
                CPL_json_object_object_get(poDataType, "range");
            if (poRange && json_object_get_type(poRange) == json_type_object)
            {
                int nMin = 0;
                int nMax = 0;
                json_object *poMin = CPL_json_object_object_get(poRange, "min");
                if (poMin)
                {
                    nMin = json_object_get_int(poMin);
                }
                json_object *poMax = CPL_json_object_object_get(poRange, "max");
                if (poMax)
                {
                    nMax = json_object_get_int(poMax);
                }

                if (nMin == -128 && nMax == 127)
                {
                    eDT = GDT_Int8;
                }
                else if (nMin < std::numeric_limits<GInt16>::min())
                {
                    eDT = GDT_Int32;
                }
                else if (nMax > std::numeric_limits<GUInt16>::max())
                {
                    eDT = GDT_UInt32;
                }
                else if (nMin < 0)
                {
                    eDT = GDT_Int16;
                }
                else if (nMax > std::numeric_limits<GByte>::max())
                {
                    eDT = GDT_UInt16;
                }
            }
        }
        else if (EQUAL(pszPrecision, "FLOAT"))
        {
            eDT = GDT_Float32;
        }
        else if (EQUAL(pszPrecision, "DOUBLE"))
        {
            eDT = GDT_Float64;
        }
        else
        {
            CPLError(CE_Warning, CPLE_NotSupported,
                     "Unhandled dataType %s for band %s", pszPrecision,
                     pszBandId);
            continue;
        }

        json_object *poGrid = CPL_json_object_object_get(poBand, "grid");
        if (poGrid == nullptr ||
            json_object_get_type(poGrid) != json_type_object)
        {
            continue;
        }

        CPLString osWKT;
        // Cf https://developers.google.com/earth-engine/reference/rest/v1alpha/PixelGrid
        json_object *poCrs = CPL_json_object_object_get(poGrid, "crsCode");
        if (poCrs == nullptr)
            poCrs = CPL_json_object_object_get(poGrid, "crsWkt");
        if (poCrs ==
            nullptr)  // "wkt" must come from a preliminary version of the API
            poCrs = CPL_json_object_object_get(poGrid, "wkt");
        OGRSpatialReference oSRS;
        if (poCrs)
        {
            const char *pszStr = json_object_get_string(poCrs);
            if (pszStr == nullptr)
                continue;
            if (STARTS_WITH(pszStr, "SR-ORG:"))
            {
                // For EEDA:MCD12Q1 for example
                pszStr =
                    CPLSPrintf("http://spatialreference.org/ref/sr-org/%s/",
                               pszStr + strlen("SR-ORG:"));
            }

            std::map<CPLString, CPLString>::const_iterator oIter =
                oMapCodeToWKT.find(pszStr);
            if (oIter != oMapCodeToWKT.end())
            {
                osWKT = oIter->second;
            }
            else if (oSRS.SetFromUserInput(pszStr) != OGRERR_NONE)
            {
                CPLError(CE_Warning, CPLE_AppDefined, "Unrecognized crs: %s",
                         pszStr);
                oMapCodeToWKT[pszStr] = "";
            }
            else
            {
                char *pszWKT = nullptr;
                oSRS.exportToWkt(&pszWKT);
                if (pszWKT != nullptr)
                    osWKT = pszWKT;
                CPLFree(pszWKT);
                oMapCodeToWKT[pszStr] = osWKT;
            }
        }

        json_object *poAT =
            CPL_json_object_object_get(poGrid, "affineTransform");
        if (poAT == nullptr || json_object_get_type(poAT) != json_type_object)
        {
            continue;
        }
        GDALGeoTransform gt{
            json_object_get_double(
                CPL_json_object_object_get(poAT, "translateX")),
            json_object_get_double(CPL_json_object_object_get(poAT, "scaleX")),
            json_object_get_double(CPL_json_object_object_get(poAT, "shearX")),
            json_object_get_double(
                CPL_json_object_object_get(poAT, "translateY")),
            json_object_get_double(CPL_json_object_object_get(poAT, "shearY")),
            json_object_get_double(CPL_json_object_object_get(poAT, "scaleY")),
        };

        json_object *poDimensions =
            CPL_json_object_object_get(poGrid, "dimensions");
        if (poDimensions == nullptr ||
            json_object_get_type(poDimensions) != json_type_object)
        {
            continue;
        }
        json_object *poWidth =
            CPL_json_object_object_get(poDimensions, "width");
        int nWidth = json_object_get_int(poWidth);
        json_object *poHeight =
            CPL_json_object_object_get(poDimensions, "height");
        int nHeight = json_object_get_int(poHeight);

#if 0
        if( poWidth == nullptr && poHeight == nullptr && poX == nullptr && poY == nullptr &&
            dfResX == 1.0 && dfResY == 1.0 )
        {
            // e.g. EEDAI:LT5_L1T_8DAY_EVI/19840109
            const char* pszAuthorityName = oSRS.GetAuthorityName(nullptr);
            const char* pszAuthorityCode = oSRS.GetAuthorityCode(nullptr);
            if( pszAuthorityName && pszAuthorityCode &&
                EQUAL(pszAuthorityName, "EPSG") &&
                EQUAL(pszAuthorityCode, "4326") )
            {
                dfX = -180;
                dfY = 90;
                nWidth = 1 << 30;
                nHeight = 1 << 29;
                dfResX = 360.0 / nWidth;
                dfResY = -dfResX;
            }
        }
#endif

        if (nWidth <= 0 || nHeight <= 0)
        {
            CPLError(CE_Warning, CPLE_AppDefined,
                     "Invalid width/height for band %s", pszBandId);
            continue;
        }

        EEDAIBandDesc oDesc;
        oDesc.osName = pszBandId;
        oDesc.osWKT = std::move(osWKT);
        oDesc.eDT = eDT;
        oDesc.gt = std::move(gt);
        oDesc.nWidth = nWidth;
        oDesc.nHeight = nHeight;
        aoBandDesc.emplace_back(std::move(oDesc));
    }
    return aoBandDesc;
}

/************************************************************************/
/*                      GDALEEDABaseDataset()                           */
/************************************************************************/

GDALEEDABaseDataset::GDALEEDABaseDataset()
    : m_bMustCleanPersistent(false), m_nExpirationTime(0)
{
}

/************************************************************************/
/*                     ~GDALEEDABaseDataset()                           */
/************************************************************************/

GDALEEDABaseDataset::~GDALEEDABaseDataset()
{
    if (m_bMustCleanPersistent)
    {
        char **papszOptions = CSLSetNameValue(nullptr, "CLOSE_PERSISTENT",
                                              CPLSPrintf("EEDAI:%p", this));
        CPLHTTPDestroyResult(CPLHTTPFetch(m_osBaseURL, papszOptions));
        CSLDestroy(papszOptions);
    }
}

/************************************************************************/
/*                          ConvertPathToName()                        */
/************************************************************************/

CPLString GDALEEDABaseDataset::ConvertPathToName(const CPLString &path)
{
    size_t end = path.find('/');
    CPLString folder = path.substr(0, end);

    if (folder == "users")
    {
        return "projects/earthengine-legacy/assets/" + path;
    }
    else if (folder != "projects")
    {
        return "projects/earthengine-public/assets/" + path;
    }

    // Find the start and end positions of the third segment, if it exists.
    int segment = 1;
    size_t start = 0;
    while (end != std::string::npos && segment < 3)
    {
        segment++;
        start = end + 1;
        end = path.find('/', start);
    }

    end = (end == std::string::npos) ? path.size() : end;
    // segment is 3 if path has at least 3 segments.
    if (folder == "projects" && segment == 3)
    {
        // If the first segment is "projects" and the third segment is "assets",
        // path is a name, so return as-is.
        if (path.substr(start, end - start) == "assets")
        {
            return path;
        }
    }
    return "projects/earthengine-legacy/assets/" + path;
}

/************************************************************************/
/*                          GetBaseHTTPOptions()                        */
/************************************************************************/

char **GDALEEDABaseDataset::GetBaseHTTPOptions()
{
    m_bMustCleanPersistent = true;

    char **papszOptions = nullptr;
    papszOptions =
        CSLAddString(papszOptions, CPLSPrintf("PERSISTENT=EEDAI:%p", this));

    // Strategy to get the Bearer Authorization value:
    // - if it is specified in the EEDA_BEARER config option, use it
    // - otherwise if EEDA_BEARER_FILE is specified, read it and use its content
    // - otherwise if GOOGLE_APPLICATION_CREDENTIALS is specified, read the
    //   corresponding file to get the private key and client_email, to get a
    //   bearer using OAuth2ServiceAccount method
    // - otherwise if EEDA_PRIVATE_KEY and EEDA_CLIENT_EMAIL are set, use them
    //   to get a bearer using OAuth2ServiceAccount method
    // - otherwise if EEDA_PRIVATE_KEY_FILE and EEDA_CLIENT_EMAIL are set, use
    //   them to get a bearer

    CPLString osBearer(CPLGetConfigOption("EEDA_BEARER", m_osBearer));
    if (osBearer.empty() ||
        (!m_osBearer.empty() && time(nullptr) > m_nExpirationTime))
    {
        CPLString osBearerFile(CPLGetConfigOption("EEDA_BEARER_FILE", ""));
        if (!osBearerFile.empty())
        {
            VSILFILE *fp = VSIFOpenL(osBearerFile, "rb");
            if (fp == nullptr)
            {
                CPLError(CE_Failure, CPLE_FileIO, "Cannot open %s",
                         osBearerFile.c_str());
            }
            else
            {
                char abyBuffer[512];
                size_t nRead = VSIFReadL(abyBuffer, 1, sizeof(abyBuffer), fp);
                osBearer.assign(abyBuffer, nRead);
                VSIFCloseL(fp);
            }
        }
        else
        {
            CPLString osPrivateKey(CPLGetConfigOption("EEDA_PRIVATE_KEY", ""));
            CPLString osClientEmail(
                CPLGetConfigOption("EEDA_CLIENT_EMAIL", ""));

            if (osPrivateKey.empty())
            {
                CPLString osPrivateKeyFile(
                    CPLGetConfigOption("EEDA_PRIVATE_KEY_FILE", ""));
                if (!osPrivateKeyFile.empty())
                {
                    VSILFILE *fp = VSIFOpenL(osPrivateKeyFile, "rb");
                    if (fp == nullptr)
                    {
                        CPLError(CE_Failure, CPLE_FileIO, "Cannot open %s",
                                 osPrivateKeyFile.c_str());
                    }
                    else
                    {
                        char *pabyBuffer =
                            static_cast<char *>(CPLMalloc(32768));
                        size_t nRead = VSIFReadL(pabyBuffer, 1, 32768, fp);
                        osPrivateKey.assign(pabyBuffer, nRead);
                        VSIFCloseL(fp);
                        CPLFree(pabyBuffer);
                    }
                }
            }

            CPLString osServiceAccountJson;
            const char *pszVSIPath =
                CSLFetchNameValue(papszOpenOptions, "VSI_PATH_FOR_AUTH");
            if (pszVSIPath)
                osServiceAccountJson = VSIGetPathSpecificOption(
                    pszVSIPath, "GOOGLE_APPLICATION_CREDENTIALS", "");
            if (osServiceAccountJson.empty())
                osServiceAccountJson =
                    CPLGetConfigOption("GOOGLE_APPLICATION_CREDENTIALS", "");
            if (!osServiceAccountJson.empty())
            {
                CPLJSONDocument oDoc;
                if (!oDoc.Load(osServiceAccountJson))
                {
                    CSLDestroy(papszOptions);
                    return nullptr;
                }

                osPrivateKey = oDoc.GetRoot().GetString("private_key");
                osPrivateKey.replaceAll("\\n", "\n");
                osClientEmail = oDoc.GetRoot().GetString("client_email");
            }

            char **papszMD = nullptr;
            if (!osPrivateKey.empty() && !osClientEmail.empty())
            {
                CPLDebug("EEDA", "Requesting Bearer token");
                osPrivateKey.replaceAll("\\n", "\n");
                // CPLDebug("EEDA", "Private key: %s", osPrivateKey.c_str());
                papszMD = GOA2GetAccessTokenFromServiceAccount(
                    osPrivateKey, osClientEmail,
                    "https://www.googleapis.com/auth/earthengine.readonly",
                    nullptr, nullptr);
                if (papszMD == nullptr)
                {
                    CSLDestroy(papszOptions);
                    return nullptr;
                }
            }
            // Some Travis-CI workers are GCE machines, and for some tests, we
            // don't want this code path to be taken. And on AppVeyor/Window, we
            // would also attempt a network access
            else if (!CPLTestBool(CPLGetConfigOption("CPL_GCE_SKIP", "NO")) &&
                     CPLIsMachinePotentiallyGCEInstance())
            {
                papszMD = GOA2GetAccessTokenFromCloudEngineVM(nullptr);
            }

            if (papszMD)
            {
                osBearer = CSLFetchNameValueDef(papszMD, "access_token", "");
                m_osBearer = osBearer;
                m_nExpirationTime = CPLAtoGIntBig(
                    CSLFetchNameValueDef(papszMD, "expires_in", "0"));
                if (m_nExpirationTime != 0)
                    m_nExpirationTime += time(nullptr) - 10;
                CSLDestroy(papszMD);
            }
            else
            {
                CPLError(CE_Failure, CPLE_AppDefined,
                         "Missing EEDA_BEARER, EEDA_BEARER_FILE or "
                         "GOOGLE_APPLICATION_CREDENTIALS or "
                         "EEDA_PRIVATE_KEY/EEDA_PRIVATE_KEY_FILE + "
                         "EEDA_CLIENT_EMAIL config option or "
                         "VSI_PATH_FOR_AUTH open option");
                CSLDestroy(papszOptions);
                return nullptr;
            }
        }
    }
    papszOptions = CSLAddString(
        papszOptions,
        CPLSPrintf("HEADERS=Authorization: Bearer %s", osBearer.c_str()));

    return papszOptions;
}

/* Add a small amount of random jitter to avoid cyclic server stampedes */
static double EEDABackoffFactor(double base)
{
    // We don't need cryptographic quality randomness...
    return base
#ifndef __COVERITY__
           + rand() * 0.5 / RAND_MAX
#endif
        ;
}

/************************************************************************/
/*                           EEDAHTTPFetch()                            */
/************************************************************************/

CPLHTTPResult *EEDAHTTPFetch(const char *pszURL, char **papszOptions)
{
    CPLHTTPResult *psResult;
    const int RETRY_COUNT = 4;
    double dfRetryDelay = 1.0;
    for (int i = 0; i <= RETRY_COUNT; i++)
    {
        psResult = CPLHTTPFetch(pszURL, papszOptions);

        if (psResult == nullptr)
            break;
        if (psResult->nDataLen != 0 && psResult->nStatus == 0 &&
            psResult->pszErrBuf == nullptr)
        {
            /* got a valid response */
            CPLErrorReset();
            break;
        }
        else
        {
            const char *pszErrorText =
                psResult->pszErrBuf ? psResult->pszErrBuf : "(null)";

            /* Get HTTP status code */
            int nHTTPStatus = -1;
            if (psResult->pszErrBuf != nullptr &&
                EQUALN(psResult->pszErrBuf,
                       "HTTP error code : ", strlen("HTTP error code : ")))
            {
                nHTTPStatus =
                    atoi(psResult->pszErrBuf + strlen("HTTP error code : "));
                if (psResult->pabyData)
                    pszErrorText =
                        reinterpret_cast<const char *>(psResult->pabyData);
            }

            if ((nHTTPStatus == 429 || nHTTPStatus == 500 ||
                 (nHTTPStatus >= 502 && nHTTPStatus <= 504)) &&
                i < RETRY_COUNT)
            {
                CPLError(CE_Warning, CPLE_FileIO,
                         "GET error when downloading %s, HTTP status=%d, "
                         "retrying in %.2fs : %s",
                         pszURL, nHTTPStatus, dfRetryDelay, pszErrorText);
                CPLHTTPDestroyResult(psResult);
                psResult = nullptr;

                CPLSleep(dfRetryDelay);
                dfRetryDelay *= EEDABackoffFactor(4);
            }
            else
            {
                break;
            }
        }
    }

    return psResult;
}