/******************************************************************************
 *
 * Project:  CPL - Common Portability Library
 * Purpose:  Implement VSI large file api for WebHDFS REST API
 * Author:   Even Rouault, even.rouault at spatialys.com
 *
 ******************************************************************************
 * Copyright (c) 2018, Even Rouault <even.rouault at spatialys.com>
 *
 * Permission is hereby granted, free of charge, to any person obtaining a
 * copy of this software and associated documentation files (the "Software"),
 * to deal in the Software without restriction, including without limitation
 * the rights to use, copy, modify, merge, publish, distribute, sublicense,
 * and/or sell copies of the Software, and to permit persons to whom the
 * Software is furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included
 * in all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
 * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
 * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
 * DEALINGS IN THE SOFTWARE.
 ****************************************************************************/

#include "cpl_port.h"
#include "cpl_http.h"
#include "cpl_json.h"
#include "cpl_vsil_curl_priv.h"
#include "cpl_vsil_curl_class.h"

#include <algorithm>
#include <set>
#include <map>
#include <memory>

#include "cpl_alibaba_oss.h"

CPL_CVSID("$Id: cpl_vsil_webhdfs.cpp beade9d55838ac41f7a798dceb5fce56213a0336 2018-11-08 11:23:07 +0100 Even Rouault $")

#ifndef HAVE_CURL

void VSIInstallWebHdfsHandler( void )
{
    // Not supported
}


#else

//! @cond Doxygen_Suppress
#ifndef DOXYGEN_SKIP

#define ENABLE_DEBUG 0

namespace cpl {



/************************************************************************/
/*                         VSIWebHDFSFSHandler                          */
/************************************************************************/

class VSIWebHDFSFSHandler final : public VSICurlFilesystemHandler
{
    CPL_DISALLOW_COPY_ASSIGN(VSIWebHDFSFSHandler)

protected:
        VSICurlHandle* CreateFileHandle( const char* pszFilename ) override;

        int HasOptimizedReadMultiRange( const char* /* pszPath */ )
            override { return false; }

        char** GetFileList(const char *pszFilename,
                               int nMaxFiles,
                               bool* pbGotFileList) override;

        CPLString GetURLFromFilename( const CPLString& osFilename ) override;

public:
        VSIWebHDFSFSHandler() = default;
        ~VSIWebHDFSFSHandler() override = default;

        VSIVirtualHandle *Open( const char *pszFilename,
                                const char *pszAccess,
                                bool bSetError ) override;
        int Unlink( const char *pszFilename ) override;
        int Rmdir( const char *pszFilename ) override;
        int Mkdir( const char *pszDirname, long nMode ) override;

        CPLString GetFSPrefix() override { return "/vsiwebhdfs/"; }

        const char* GetOptions() override;
};

/************************************************************************/
/*                            VSIWebHDFSHandle                          */
/************************************************************************/

class VSIWebHDFSHandle final : public VSICurlHandle
{
    CPL_DISALLOW_COPY_ASSIGN(VSIWebHDFSHandle)

    CPLString       m_osDataNodeHost{};
    CPLString       m_osUsernameParam{};
    CPLString       m_osDelegationParam{};

    bool            DownloadRegion(vsi_l_offset startOffset, int nBlocks) override;

  public:
    VSIWebHDFSHandle( VSIWebHDFSFSHandler* poFS,
                      const char* pszFilename, const char* pszURL );
    ~VSIWebHDFSHandle() override = default;

    int ReadMultiRange( int nRanges, void ** ppData,
                        const vsi_l_offset* panOffsets,
                        const size_t* panSizes ) override {
        return VSIVirtualHandle::ReadMultiRange( nRanges,  ppData,
                                                 panOffsets, panSizes );
    }

    vsi_l_offset GetFileSize( bool bSetError ) override;
};

/************************************************************************/
/*                           PatchWebHDFSUrl()                          */
/************************************************************************/

#ifdef HAVE_CURLINFO_REDIRECT_URL
static CPLString PatchWebHDFSUrl(const CPLString& osURLIn,
                                 const CPLString& osNewHost)
{
    CPLString osURL(osURLIn);
    size_t nStart = 0;
    if( osURL.find("http://") == 0 )
        nStart = strlen("http://");
    else if( osURL.find("https://") == 0 )
        nStart = strlen("https://");
    if( nStart )
    {
        size_t nHostEnd = osURL.find(':', nStart);
        if( nHostEnd != std::string::npos )
        {
            osURL = osURL.substr(0, nStart) + osNewHost +
                    osURL.substr(nHostEnd);
        }
    }
    return osURL;
}
#endif

/************************************************************************/
/*                       GetWebHDFSDataNodeHost()                       */
/************************************************************************/

static CPLString GetWebHDFSDataNodeHost()
{
    CPLString osDataNodeHost = CPLGetConfigOption("WEBHDFS_DATANODE_HOST", "");
#ifndef HAVE_CURLINFO_REDIRECT_URL
    if( !osDataNodeHost.empty() )
    {
        static bool bFirstTime = true;
        if( bFirstTime )
        {
            CPLError(CE_Warning, CPLE_AppDefined,
                 "WEBHDFS_DATANODE_HOST not honored due to too old libcurl");
            bFirstTime = false;
        }
    }
#endif
    return osDataNodeHost;
}

#ifdef HAVE_CURLINFO_REDIRECT_URL

/************************************************************************/
/*                         VSIWebHDFSWriteHandle                        */
/************************************************************************/

class VSIWebHDFSWriteHandle final : public VSIAppendWriteHandle
{
    CPL_DISALLOW_COPY_ASSIGN(VSIWebHDFSWriteHandle)

    CPLString           m_osURL{};
    CPLString           m_osDataNodeHost{};
    CPLString           m_osUsernameParam{};
    CPLString           m_osDelegationParam{};

    bool                Send(bool bIsLastBlock) override;
    bool                CreateFile();
    bool                Append();

    void                InvalidateParentDirectory();

    public:
        VSIWebHDFSWriteHandle( VSIWebHDFSFSHandler* poFS,
                               const char* pszFilename );
        virtual ~VSIWebHDFSWriteHandle();
};

/************************************************************************/
/*                        GetWebHDFSBufferSize()                        */
/************************************************************************/

static int GetWebHDFSBufferSize()
{
    int nBufferSize;
    int nChunkSizeMB = atoi(CPLGetConfigOption("VSIWEBHDFS_SIZE", "4"));
    if( nChunkSizeMB <= 0 || nChunkSizeMB > 1000 )
        nBufferSize = 4 * 1024 * 1024;
    else
        nBufferSize = nChunkSizeMB * 1024 * 1024;

    // For testing only !
    const char* pszChunkSizeBytes =
        CPLGetConfigOption("VSIWEBHDFS_SIZE_BYTES", nullptr);
    if( pszChunkSizeBytes )
        nBufferSize = atoi(pszChunkSizeBytes);
    if( nBufferSize <= 0 || nBufferSize > 1000 * 1024 * 1024 )
        nBufferSize = 4 * 1024 * 1024;
    return nBufferSize;
}

/************************************************************************/
/*                      VSIWebHDFSWriteHandle()                         */
/************************************************************************/

VSIWebHDFSWriteHandle::VSIWebHDFSWriteHandle( VSIWebHDFSFSHandler* poFS,
                                              const char* pszFilename) :
        VSIAppendWriteHandle(poFS, poFS->GetFSPrefix(), pszFilename,
                             GetWebHDFSBufferSize()),
        m_osURL( pszFilename + poFS->GetFSPrefix().size() )
{
    m_osDataNodeHost = GetWebHDFSDataNodeHost();
    m_osUsernameParam = CPLGetConfigOption("WEBHDFS_USERNAME", "");
    if( !m_osUsernameParam.empty() )
        m_osUsernameParam = "&user.name=" + m_osUsernameParam;
    m_osDelegationParam = CPLGetConfigOption("WEBHDFS_DELEGATION", "");
    if( !m_osDelegationParam.empty() )
        m_osDelegationParam = "&delegation=" + m_osDelegationParam;

    if( m_pabyBuffer != nullptr && !CreateFile() )
    {
        CPLFree(m_pabyBuffer);
        m_pabyBuffer = nullptr;
    }
}

/************************************************************************/
/*                     ~VSIWebHDFSWriteHandle()                         */
/************************************************************************/

VSIWebHDFSWriteHandle::~VSIWebHDFSWriteHandle()
{
    Close();
}

/************************************************************************/
/*                    InvalidateParentDirectory()                       */
/************************************************************************/

void VSIWebHDFSWriteHandle::InvalidateParentDirectory()
{
    m_poFS->InvalidateCachedData(m_osURL);

    CPLString osFilenameWithoutSlash(m_osFilename);
    if( !osFilenameWithoutSlash.empty() && osFilenameWithoutSlash.back() == '/' )
        osFilenameWithoutSlash.resize( osFilenameWithoutSlash.size() - 1 );
    m_poFS->InvalidateDirContent( CPLGetDirname(osFilenameWithoutSlash) );
}

/************************************************************************/
/*                             Send()                                   */
/************************************************************************/

bool VSIWebHDFSWriteHandle::Send(bool /* bIsLastBlock */)
{
    if( m_nCurOffset > 0 )
        return Append();
    return true;
}

/************************************************************************/
/*                           CreateFile()                               */
/************************************************************************/

bool VSIWebHDFSWriteHandle::CreateFile()
{
    if( m_osUsernameParam.empty() && m_osDelegationParam.empty() )
    {
        CPLError(CE_Failure, CPLE_AppDefined,
                 "Configuration option WEBHDFS_USERNAME or WEBHDFS_DELEGATION "
                 "should be defined");
        return false;
    }

    CPLString osURL = m_osURL + "?op=CREATE&overwrite=true" +
        m_osUsernameParam + m_osDelegationParam;

    CPLString osPermission = CPLGetConfigOption("WEBHDFS_PERMISSION", "");
    if( !osPermission.empty() )
        osURL += "&permission=" + osPermission;

    CPLString osReplication = CPLGetConfigOption("WEBHDFS_REPLICATION", "");
    if( !osReplication.empty() )
        osURL += "&replication=" + osReplication;

    bool bInRedirect = false;

retry:
    CURL* hCurlHandle = curl_easy_init();

    struct curl_slist* headers = static_cast<struct curl_slist*>(
        CPLHTTPSetOptions(hCurlHandle, osURL.c_str(), nullptr));

    curl_easy_setopt(hCurlHandle, CURLOPT_CUSTOMREQUEST, "PUT");
    curl_easy_setopt(hCurlHandle, CURLOPT_INFILESIZE, 0);

    if( !m_osDataNodeHost.empty() )
    {
        curl_easy_setopt(hCurlHandle, CURLOPT_FOLLOWLOCATION, 0);
    }

    curl_easy_setopt(hCurlHandle, CURLOPT_HTTPHEADER, headers);

    WriteFuncStruct sWriteFuncData;
    VSICURLInitWriteFuncStruct(&sWriteFuncData, nullptr, nullptr, nullptr);
    curl_easy_setopt(hCurlHandle, CURLOPT_WRITEDATA, &sWriteFuncData);
    curl_easy_setopt(hCurlHandle, CURLOPT_WRITEFUNCTION,
                        VSICurlHandleWriteFunc);

    MultiPerform(m_poFS->GetCurlMultiHandleFor(m_osURL), hCurlHandle);

    curl_slist_free_all(headers);

    long response_code = 0;
    curl_easy_getinfo(hCurlHandle, CURLINFO_HTTP_CODE, &response_code);

    if( !bInRedirect )
    {
        char *pszRedirectURL = nullptr;
        curl_easy_getinfo(hCurlHandle, CURLINFO_REDIRECT_URL, &pszRedirectURL);
        if( pszRedirectURL &&
            strstr(pszRedirectURL, osURL.c_str()) == nullptr )
        {
            CPLDebug("WEBHDFS", "Redirect URL: %s", pszRedirectURL);

            bInRedirect = true;
            osURL = pszRedirectURL;
            if( !m_osDataNodeHost.empty() )
            {
                osURL = PatchWebHDFSUrl(osURL, m_osDataNodeHost);
            }

            curl_easy_cleanup(hCurlHandle);
            CPLFree(sWriteFuncData.pBuffer);

            goto retry;
        }
    }

    curl_easy_cleanup(hCurlHandle);

    if( response_code == 201 )
    {
        InvalidateParentDirectory();
    }
    else
    {
        CPLDebug("WEBHDFS",
                    "%s",
                    sWriteFuncData.pBuffer
                    ? sWriteFuncData.pBuffer
                    : "(null)");
        CPLError(CE_Failure, CPLE_AppDefined,
                    "PUT of %s failed",
                    m_osURL.c_str());
    }
    CPLFree(sWriteFuncData.pBuffer);

    return response_code == 201;
}

/************************************************************************/
/*                             Append()                                 */
/************************************************************************/

bool VSIWebHDFSWriteHandle::Append()
{
    CPLString osURL = m_osURL + "?op=APPEND" +
                      m_osUsernameParam + m_osDelegationParam;

    CURL* hCurlHandle = curl_easy_init();

    struct curl_slist* headers = static_cast<struct curl_slist*>(
        CPLHTTPSetOptions(hCurlHandle, osURL.c_str(), nullptr));

    curl_easy_setopt(hCurlHandle, CURLOPT_CUSTOMREQUEST, "POST");
    curl_easy_setopt(hCurlHandle, CURLOPT_FOLLOWLOCATION, 0);
    curl_easy_setopt(hCurlHandle, CURLOPT_HTTPHEADER, headers);

    WriteFuncStruct sWriteFuncData;
    VSICURLInitWriteFuncStruct(&sWriteFuncData, nullptr, nullptr, nullptr);
    curl_easy_setopt(hCurlHandle, CURLOPT_WRITEDATA, &sWriteFuncData);
    curl_easy_setopt(hCurlHandle, CURLOPT_WRITEFUNCTION,
                        VSICurlHandleWriteFunc);

    MultiPerform(m_poFS->GetCurlMultiHandleFor(m_osURL), hCurlHandle);

    curl_slist_free_all(headers);

    long response_code = 0;
    curl_easy_getinfo(hCurlHandle, CURLINFO_HTTP_CODE, &response_code);

    if( response_code != 307 )
    {
        CPLDebug("WEBHDFS",
                    "%s",
                    sWriteFuncData.pBuffer
                    ? sWriteFuncData.pBuffer
                    : "(null)");
        CPLError(CE_Failure, CPLE_AppDefined,
                    "POST of %s failed",
                    m_osURL.c_str());
        curl_easy_cleanup(hCurlHandle);
        CPLFree(sWriteFuncData.pBuffer);
        return false;
    }

    char *pszRedirectURL = nullptr;
    curl_easy_getinfo(hCurlHandle, CURLINFO_REDIRECT_URL, &pszRedirectURL);
    if( pszRedirectURL == nullptr )
    {
        curl_easy_cleanup(hCurlHandle);
        CPLFree(sWriteFuncData.pBuffer);
        return false;
    }
    CPLDebug("WEBHDFS", "Redirect URL: %s", pszRedirectURL);

    osURL = pszRedirectURL;
    if( !m_osDataNodeHost.empty() )
    {
        osURL = PatchWebHDFSUrl(osURL, m_osDataNodeHost);
    }

    curl_easy_cleanup(hCurlHandle);
    CPLFree(sWriteFuncData.pBuffer);


    // After redirection

    hCurlHandle = curl_easy_init();

    headers = static_cast<struct curl_slist*>(
        CPLHTTPSetOptions(hCurlHandle, osURL.c_str(), nullptr));
    headers = curl_slist_append(headers, "Content-Type: application/octet-stream");

    curl_easy_setopt(hCurlHandle, CURLOPT_POSTFIELDS, m_pabyBuffer);
    curl_easy_setopt(hCurlHandle, CURLOPT_POSTFIELDSIZE , m_nBufferOff);
    curl_easy_setopt(hCurlHandle, CURLOPT_FOLLOWLOCATION, 0);
    curl_easy_setopt(hCurlHandle, CURLOPT_HTTPHEADER, headers);

    VSICURLInitWriteFuncStruct(&sWriteFuncData, nullptr, nullptr, nullptr);
    curl_easy_setopt(hCurlHandle, CURLOPT_WRITEDATA, &sWriteFuncData);
    curl_easy_setopt(hCurlHandle, CURLOPT_WRITEFUNCTION,
                        VSICurlHandleWriteFunc);

    MultiPerform(m_poFS->GetCurlMultiHandleFor(m_osURL), hCurlHandle);

    curl_slist_free_all(headers);

    response_code = 0;
    curl_easy_getinfo(hCurlHandle, CURLINFO_HTTP_CODE, &response_code);

    curl_easy_cleanup(hCurlHandle);

    if( response_code != 200 )
    {
        CPLDebug("WEBHDFS",
                    "%s",
                    sWriteFuncData.pBuffer
                    ? sWriteFuncData.pBuffer
                    : "(null)");
        CPLError(CE_Failure, CPLE_AppDefined,
                    "POST of %s failed",
                    m_osURL.c_str());
    }
    CPLFree(sWriteFuncData.pBuffer);

    return response_code == 200;
}

#endif // #ifdef HAVE_CURLINFO_REDIRECT_URL


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

VSIVirtualHandle* VSIWebHDFSFSHandler::Open( const char *pszFilename,
                                        const char *pszAccess,
                                        bool bSetError)
{
    if( !STARTS_WITH_CI(pszFilename, GetFSPrefix()) )
        return nullptr;

    if( strchr(pszAccess, 'w') != nullptr || strchr(pszAccess, 'a') != nullptr )
    {
#ifdef HAVE_CURLINFO_REDIRECT_URL
        VSIWebHDFSWriteHandle* poHandle =
            new VSIWebHDFSWriteHandle(this, pszFilename);
        if( !poHandle->IsOK() )
        {
            delete poHandle;
            poHandle = nullptr;
        }
        return poHandle;
#else
        CPLError(CE_Failure, CPLE_AppDefined,
                 "libcurl >= 7.18.1 for /vsiwebhdfs support");
        return nullptr;
#endif
    }

    return
        VSICurlFilesystemHandler::Open(pszFilename, pszAccess, bSetError);
}

/************************************************************************/
/*                           GetOptions()                               */
/************************************************************************/

const char* VSIWebHDFSFSHandler::GetOptions()
{
    static CPLString osOptions(
        CPLString("<Options>") +
    "  <Option name='WEBHDFS_USERNAME' type='string' "
        "description='username (when security is off)'/>"
    "  <Option name='WEBHDFS_DELEGATION' type='string' "
        "description='Hadoop delegation token (when security is on)'/>"
    "  <Option name='WEBHDFS_DATANODE_HOST' type='string' "
        "description='For APIs using redirect, substitute the redirection "
        "hostname with the one provided by this option (normally resolvable "
        "hostname should be rewritten by a proxy)'/>"
    "  <Option name='WEBHDFS_REPLICATION' type='integer' "
        "description='Replication value used when creating a file'/>"
    "  <Option name='WEBHDFS_PERMISSION' type='integer' "
        "description='Permission mask (to provide as decimal number) when "
        "creating a file or directory'/>" +
        VSICurlFilesystemHandler::GetOptionsStatic() +
        "</Options>");
    return osOptions.c_str();
}

/************************************************************************/
/*                          CreateFileHandle()                          */
/************************************************************************/

VSICurlHandle* VSIWebHDFSFSHandler::CreateFileHandle(const char* pszFilename)
{
    return new VSIWebHDFSHandle(this, pszFilename,
                                pszFilename + GetFSPrefix().size());
}

/************************************************************************/
/*                          GetURLFromFilename()                         */
/************************************************************************/

CPLString VSIWebHDFSFSHandler::GetURLFromFilename( const CPLString& osFilename )
{
    return osFilename.substr(GetFSPrefix().size());
}
/************************************************************************/
/*                           GetFileList()                              */
/************************************************************************/

char** VSIWebHDFSFSHandler::GetFileList( const char *pszDirname,
                                         int /*nMaxFiles*/,
                                         bool* pbGotFileList )
{
    if( ENABLE_DEBUG )
        CPLDebug("WEBHDFS", "GetFileList(%s)" , pszDirname);
    *pbGotFileList = false;

    CPLAssert( strlen(pszDirname) >= GetFSPrefix().size() );
    CPLString osDirnameWithoutPrefix = pszDirname + GetFSPrefix().size();

    CPLString osBaseURL = osDirnameWithoutPrefix;
    if( !osBaseURL.empty() && osBaseURL.back() != '/' )
        osBaseURL += '/';

    CURLM* hCurlMultiHandle = GetCurlMultiHandleFor(osBaseURL);

    CPLString osUsernameParam = CPLGetConfigOption("WEBHDFS_USERNAME", "");
    if( !osUsernameParam.empty() )
        osUsernameParam = "&user.name=" + osUsernameParam;
    CPLString osDelegationParam = CPLGetConfigOption("WEBHDFS_DELEGATION", "");
    if( !osDelegationParam.empty() )
        osDelegationParam = "&delegation=" + osDelegationParam;
    CPLString osURL = osBaseURL + "?op=LISTSTATUS" + osUsernameParam + osDelegationParam;

    CURL* hCurlHandle = curl_easy_init();

    struct curl_slist* headers =
            VSICurlSetOptions(hCurlHandle, osURL, nullptr);

    WriteFuncStruct sWriteFuncData;
    VSICURLInitWriteFuncStruct(&sWriteFuncData, nullptr, nullptr, nullptr);
    curl_easy_setopt(hCurlHandle, CURLOPT_WRITEDATA, &sWriteFuncData);
    curl_easy_setopt(hCurlHandle, CURLOPT_WRITEFUNCTION,
                     VSICurlHandleWriteFunc);

    curl_easy_setopt(hCurlHandle, CURLOPT_HTTPHEADER, headers);

    MultiPerform(hCurlMultiHandle, hCurlHandle);

    VSICURLResetHeaderAndWriterFunctions(hCurlHandle);

    curl_slist_free_all(headers);

    long response_code = 0;
    curl_easy_getinfo(hCurlHandle, CURLINFO_HTTP_CODE, &response_code);

    CPLStringList aosList;
    bool bOK = false;
    if( response_code == 200 && sWriteFuncData.pBuffer )
    {
        CPLJSONDocument oDoc;
        if( oDoc.LoadMemory(reinterpret_cast<const GByte*>(sWriteFuncData.pBuffer )) )
        {
            CPLJSONArray oFileStatus = oDoc.GetRoot().GetArray("FileStatuses/FileStatus");
            bOK = oFileStatus.IsValid();
            for( int i = 0; i < oFileStatus.Size(); i++ )
            {
                CPLJSONObject oItem = oFileStatus[i];
                vsi_l_offset fileSize = oItem.GetLong("length");
                size_t mTime = static_cast<size_t>(
                    oItem.GetLong("modificationTime") / 1000);
                bool bIsDirectory = oItem.GetString("type") == "DIRECTORY";
                CPLString osName = oItem.GetString("pathSuffix");
                // can be empty if we for example ask to list a file: in that
                // case the file entry is reported but with an empty pathSuffix
                if( !osName.empty() )
                {
                    aosList.AddString(osName);

                    FileProp prop;
                    prop.eExists = EXIST_YES;
                    prop.bIsDirectory = bIsDirectory;
                    prop.bHasComputedFileSize = true;
                    prop.fileSize = fileSize;
                    prop.mTime = mTime;
                    CPLString osCachedFilename(osBaseURL + osName);
#if DEBUG_VERBOSE
                    CPLDebug("WEBHDFS", "Cache %s", osCachedFilename.c_str());
#endif
                    SetCachedFileProp(osCachedFilename, prop);
                }
            }
        }
    }
    if( pbGotFileList )
        *pbGotFileList = bOK;

    CPLFree(sWriteFuncData.pBuffer);
    curl_easy_cleanup(hCurlHandle);

    if( bOK )
        return aosList.StealList();
    else
        return nullptr;
}

/************************************************************************/
/*                               Unlink()                               */
/************************************************************************/

int VSIWebHDFSFSHandler::Unlink( const char *pszFilename )
{
    if( !STARTS_WITH_CI(pszFilename, GetFSPrefix()) )
        return -1;

    CPLString osBaseURL = GetURLFromFilename(pszFilename);

    CURLM* hCurlMultiHandle = GetCurlMultiHandleFor(osBaseURL);

    CPLString osUsernameParam = CPLGetConfigOption("WEBHDFS_USERNAME", "");
    if( !osUsernameParam.empty() )
        osUsernameParam = "&user.name=" + osUsernameParam;
    CPLString osDelegationParam = CPLGetConfigOption("WEBHDFS_DELEGATION", "");
    if( !osDelegationParam.empty() )
        osDelegationParam = "&delegation=" + osDelegationParam;
    CPLString osURL = osBaseURL + "?op=DELETE" + osUsernameParam + osDelegationParam;

    CURL* hCurlHandle = curl_easy_init();

    curl_easy_setopt(hCurlHandle, CURLOPT_CUSTOMREQUEST, "DELETE");

    struct curl_slist* headers =
            VSICurlSetOptions(hCurlHandle, osURL, nullptr);

    WriteFuncStruct sWriteFuncData;
    VSICURLInitWriteFuncStruct(&sWriteFuncData, nullptr, nullptr, nullptr);
    curl_easy_setopt(hCurlHandle, CURLOPT_WRITEDATA, &sWriteFuncData);
    curl_easy_setopt(hCurlHandle, CURLOPT_WRITEFUNCTION,
                     VSICurlHandleWriteFunc);

    curl_easy_setopt(hCurlHandle, CURLOPT_HTTPHEADER, headers);

    MultiPerform(hCurlMultiHandle, hCurlHandle);

    VSICURLResetHeaderAndWriterFunctions(hCurlHandle);

    curl_slist_free_all(headers);

    long response_code = 0;
    curl_easy_getinfo(hCurlHandle, CURLINFO_HTTP_CODE, &response_code);

    CPLStringList aosList;
    bool bOK = false;
    if( response_code == 200 && sWriteFuncData.pBuffer )
    {
        CPLJSONDocument oDoc;
        if( oDoc.LoadMemory(reinterpret_cast<const GByte*>(sWriteFuncData.pBuffer )) )
        {
            bOK = oDoc.GetRoot().GetBool("boolean");
        }
    }
    if( bOK )
    {
        InvalidateCachedData(osBaseURL);

        CPLString osFilenameWithoutSlash(pszFilename);
        if( !osFilenameWithoutSlash.empty() && osFilenameWithoutSlash.back() == '/' )
            osFilenameWithoutSlash.resize( osFilenameWithoutSlash.size() - 1 );

        InvalidateDirContent( CPLGetDirname(osFilenameWithoutSlash) );
    }
    else
    {
        CPLDebug("WEBHDFS",
                    "%s",
                    sWriteFuncData.pBuffer
                    ? sWriteFuncData.pBuffer
                    : "(null)");
    }

    CPLFree(sWriteFuncData.pBuffer);
    curl_easy_cleanup(hCurlHandle);

    return bOK ? 0 : -1;
}

/************************************************************************/
/*                               Rmdir()                                */
/************************************************************************/

int VSIWebHDFSFSHandler::Rmdir( const char *pszFilename )
{
    return Unlink(pszFilename);
}

/************************************************************************/
/*                               Mkdir()                                */
/************************************************************************/

int VSIWebHDFSFSHandler::Mkdir( const char *pszDirname, long nMode )
{
    if( !STARTS_WITH_CI(pszDirname, GetFSPrefix()) )
        return -1;

    CPLString osDirnameWithoutEndSlash(pszDirname);
    if( !osDirnameWithoutEndSlash.empty() &&
        osDirnameWithoutEndSlash.back() == '/' )
    {
        osDirnameWithoutEndSlash.resize( osDirnameWithoutEndSlash.size() - 1 );
    }

    if( osDirnameWithoutEndSlash.find("/webhdfs/v1") ==
        osDirnameWithoutEndSlash.size() - strlen("/webhdfs/v1") &&
        std::count(osDirnameWithoutEndSlash.begin(),
                   osDirnameWithoutEndSlash.end(),'/') == 6 )
    {
        // The server does weird things (creating a webhdfs/v1 subfolder)
        // if we provide the root directory like
        // /vsiwebhdfs/http://localhost:50070/webhdfs/v1
        return -1;
    }

    CPLString osBaseURL = GetURLFromFilename(osDirnameWithoutEndSlash);

    CURLM* hCurlMultiHandle = GetCurlMultiHandleFor(osBaseURL);

    CPLString osUsernameParam = CPLGetConfigOption("WEBHDFS_USERNAME", "");
    if( !osUsernameParam.empty() )
        osUsernameParam = "&user.name=" + osUsernameParam;
    CPLString osDelegationParam = CPLGetConfigOption("WEBHDFS_DELEGATION", "");
    if( !osDelegationParam.empty() )
        osDelegationParam = "&delegation=" + osDelegationParam;
    CPLString osURL = osBaseURL + "?op=MKDIRS" + osUsernameParam + osDelegationParam;
    if( nMode )
    {
        osURL += "&permission=";
        osURL += CPLSPrintf("%o", static_cast<int>(nMode));
    }

    CURL* hCurlHandle = curl_easy_init();

    curl_easy_setopt(hCurlHandle, CURLOPT_CUSTOMREQUEST, "PUT");

    struct curl_slist* headers =
            VSICurlSetOptions(hCurlHandle, osURL, nullptr);

    WriteFuncStruct sWriteFuncData;
    VSICURLInitWriteFuncStruct(&sWriteFuncData, nullptr, nullptr, nullptr);
    curl_easy_setopt(hCurlHandle, CURLOPT_WRITEDATA, &sWriteFuncData);
    curl_easy_setopt(hCurlHandle, CURLOPT_WRITEFUNCTION,
                     VSICurlHandleWriteFunc);

    curl_easy_setopt(hCurlHandle, CURLOPT_HTTPHEADER, headers);

    MultiPerform(hCurlMultiHandle, hCurlHandle);

    VSICURLResetHeaderAndWriterFunctions(hCurlHandle);

    curl_slist_free_all(headers);

    long response_code = 0;
    curl_easy_getinfo(hCurlHandle, CURLINFO_HTTP_CODE, &response_code);

    CPLStringList aosList;
    bool bOK = false;
    if( response_code == 200 && sWriteFuncData.pBuffer )
    {
        CPLJSONDocument oDoc;
        if( oDoc.LoadMemory(reinterpret_cast<const GByte*>(sWriteFuncData.pBuffer )) )
        {
            bOK = oDoc.GetRoot().GetBool("boolean");
        }
    }
    if( bOK )
    {
        InvalidateDirContent( CPLGetDirname(osDirnameWithoutEndSlash) );

        FileProp cachedFileProp;
        cachedFileProp.eExists = EXIST_YES;
        cachedFileProp.bIsDirectory = true;
        cachedFileProp.bHasComputedFileSize = true;
        SetCachedFileProp(GetURLFromFilename(osDirnameWithoutEndSlash), cachedFileProp);

        RegisterEmptyDir(osDirnameWithoutEndSlash);
    }
    else
    {
        CPLDebug("WEBHDFS",
                    "%s",
                    sWriteFuncData.pBuffer
                    ? sWriteFuncData.pBuffer
                    : "(null)");
    }

    CPLFree(sWriteFuncData.pBuffer);
    curl_easy_cleanup(hCurlHandle);

    return bOK ? 0 : -1;
}

/************************************************************************/
/*                            VSIWebHDFSHandle()                        */
/************************************************************************/

VSIWebHDFSHandle::VSIWebHDFSHandle( VSIWebHDFSFSHandler* poFSIn,
                          const char* pszFilename, const char* pszURL ) :
        VSICurlHandle(poFSIn, pszFilename, pszURL)
{
    m_osDataNodeHost = GetWebHDFSDataNodeHost();
    m_osUsernameParam = CPLGetConfigOption("WEBHDFS_USERNAME", "");
    if( !m_osUsernameParam.empty() )
        m_osUsernameParam = "&user.name=" + m_osUsernameParam;
    m_osDelegationParam = CPLGetConfigOption("WEBHDFS_DELEGATION", "");
    if( !m_osDelegationParam.empty() )
        m_osDelegationParam = "&delegation=" + m_osDelegationParam;

}

/************************************************************************/
/*                           GetFileSize()                              */
/************************************************************************/

vsi_l_offset VSIWebHDFSHandle::GetFileSize( bool bSetError )
{
    if( oFileProp.bHasComputedFileSize )
        return oFileProp.fileSize;

    oFileProp.bHasComputedFileSize = true;

    CURLM* hCurlMultiHandle = poFS->GetCurlMultiHandleFor(m_pszURL);

    CPLString osURL(m_pszURL);

    if( osURL.find("/webhdfs/v1") ==
        osURL.size() - strlen("/webhdfs/v1") &&
        std::count(osURL.begin(),
                   osURL.end(),'/') == 4 )
    {
        // If this is the root directory, add a trailing slash
        osURL += "/";
    }

    osURL += "?op=GETFILESTATUS" + m_osUsernameParam + m_osDelegationParam;

    CURL* hCurlHandle = curl_easy_init();

    struct curl_slist* headers =
            VSICurlSetOptions(hCurlHandle, osURL, m_papszHTTPOptions);

    WriteFuncStruct sWriteFuncData;
    VSICURLInitWriteFuncStruct(&sWriteFuncData, nullptr, nullptr, nullptr);
    curl_easy_setopt(hCurlHandle, CURLOPT_WRITEDATA, &sWriteFuncData);
    curl_easy_setopt(hCurlHandle, CURLOPT_WRITEFUNCTION,
                     VSICurlHandleWriteFunc);

    curl_easy_setopt(hCurlHandle, CURLOPT_HTTPHEADER, headers);

    char szCurlErrBuf[CURL_ERROR_SIZE+1] = {};
    szCurlErrBuf[0] = '\0';
    curl_easy_setopt(hCurlHandle, CURLOPT_ERRORBUFFER, szCurlErrBuf );

    MultiPerform(hCurlMultiHandle, hCurlHandle);

    VSICURLResetHeaderAndWriterFunctions(hCurlHandle);

    curl_slist_free_all(headers);

    long response_code = 0;
    curl_easy_getinfo(hCurlHandle, CURLINFO_HTTP_CODE, &response_code);

    oFileProp.eExists = EXIST_NO;
    if( response_code == 200 && sWriteFuncData.pBuffer )
    {
        CPLJSONDocument oDoc;
        if( oDoc.LoadMemory(reinterpret_cast<const GByte*>(sWriteFuncData.pBuffer )) )
        {
            CPLJSONObject oFileStatus = oDoc.GetRoot().GetObj("FileStatus");
            oFileProp.fileSize = oFileStatus.GetLong("length");
            oFileProp.mTime = static_cast<size_t>(
                oFileStatus.GetLong("modificationTime") / 1000);
            oFileProp.bIsDirectory = oFileStatus.GetString("type") == "DIRECTORY";
            oFileProp.eExists = EXIST_YES;
        }
    }

    // If there was no VSI error thrown in the process,
    // fail by reporting the HTTP response code.
    if( response_code != 200 && bSetError && VSIGetLastErrorNo() == 0 )
    {
        if( strlen(szCurlErrBuf) > 0 )
        {
            if( response_code == 0 )
            {
                VSIError(VSIE_HttpError,
                            "CURL error: %s", szCurlErrBuf);
            }
            else
            {
                VSIError(VSIE_HttpError,
                            "HTTP response code: %d - %s",
                            static_cast<int>(response_code), szCurlErrBuf);
            }
        }
        else
        {
            VSIError(VSIE_HttpError, "HTTP response code: %d",
                        static_cast<int>(response_code));
        }
    }

    if( ENABLE_DEBUG )
        CPLDebug("WEBHDFS", "GetFileSize(%s)=" CPL_FRMT_GUIB
                    "  response_code=%d",
                    osURL.c_str(), oFileProp.fileSize,
                    static_cast<int>(response_code));

    CPLFree(sWriteFuncData.pBuffer);
    curl_easy_cleanup(hCurlHandle);

    oFileProp.bHasComputedFileSize = true;
    poFS->SetCachedFileProp(m_pszURL, oFileProp);

    return oFileProp.fileSize;
}

/************************************************************************/
/*                          DownloadRegion()                            */
/************************************************************************/

bool VSIWebHDFSHandle::DownloadRegion( const vsi_l_offset startOffset,
                                       const int nBlocks )
{
    if( bInterrupted && bStopOnInterruptUntilUninstall )
        return false;

    poFS->GetCachedFileProp(m_pszURL, oFileProp);
    if( oFileProp.eExists == EXIST_NO )
        return false;

    CURLM* hCurlMultiHandle = poFS->GetCurlMultiHandleFor(m_pszURL);

    CPLString osURL(m_pszURL);

    WriteFuncStruct sWriteFuncData;
    int nRetryCount = 0;
    double dfRetryDelay = m_dfRetryDelay;

#ifdef HAVE_CURLINFO_REDIRECT_URL
    bool bInRedirect = false;
#endif

    const vsi_l_offset nEndOffset =
        startOffset + nBlocks * VSICURLGetDownloadChunkSize() - 1;

retry:
    CURL* hCurlHandle = curl_easy_init();

    VSICURLInitWriteFuncStruct(&sWriteFuncData,
                               reinterpret_cast<VSILFILE *>(this),
                               pfnReadCbk, pReadCbkUserData);
    curl_easy_setopt(hCurlHandle, CURLOPT_WRITEDATA, &sWriteFuncData);
    curl_easy_setopt(hCurlHandle, CURLOPT_WRITEFUNCTION,
                     VSICurlHandleWriteFunc);


#ifdef HAVE_CURLINFO_REDIRECT_URL
    if( !bInRedirect )
#endif
    {
        osURL += "?op=OPEN&offset=";
        osURL += CPLSPrintf(CPL_FRMT_GUIB, startOffset);
        osURL += "&length=";
        osURL += CPLSPrintf(CPL_FRMT_GUIB, nEndOffset - startOffset + 1);
        osURL += m_osUsernameParam + m_osDelegationParam;
    }

    struct curl_slist* headers =
        VSICurlSetOptions(hCurlHandle, osURL, m_papszHTTPOptions);

#ifdef HAVE_CURLINFO_REDIRECT_URL
    if( !m_osDataNodeHost.empty() )
    {
        curl_easy_setopt(hCurlHandle, CURLOPT_FOLLOWLOCATION, 0);
    }
#endif

    if( ENABLE_DEBUG )
        CPLDebug("WEBHDFS", "Downloading %s...", osURL.c_str());

    char szCurlErrBuf[CURL_ERROR_SIZE+1] = {};
    szCurlErrBuf[0] = '\0';
    curl_easy_setopt(hCurlHandle, CURLOPT_ERRORBUFFER, szCurlErrBuf );

    curl_easy_setopt(hCurlHandle, CURLOPT_HTTPHEADER, headers);

    MultiPerform(hCurlMultiHandle, hCurlHandle);

    VSICURLResetHeaderAndWriterFunctions(hCurlHandle);

    curl_slist_free_all(headers);

    if( sWriteFuncData.bInterrupted )
    {
        bInterrupted = true;

        CPLFree(sWriteFuncData.pBuffer);
        curl_easy_cleanup(hCurlHandle);

        return false;
    }

    long response_code = 0;
    curl_easy_getinfo(hCurlHandle, CURLINFO_HTTP_CODE, &response_code);

    if( ENABLE_DEBUG )
        CPLDebug("WEBHDFS", "Got response_code=%ld", response_code);

#ifdef HAVE_CURLINFO_REDIRECT_URL
    if( !bInRedirect )
    {
        char *pszRedirectURL = nullptr;
        curl_easy_getinfo(hCurlHandle, CURLINFO_REDIRECT_URL, &pszRedirectURL);
        if( pszRedirectURL &&
            strstr(pszRedirectURL, m_pszURL) == nullptr )
        {
            CPLDebug("WEBHDFS", "Redirect URL: %s", pszRedirectURL);

            bInRedirect = true;
            osURL = pszRedirectURL;
            if( !m_osDataNodeHost.empty() )
            {
                osURL = PatchWebHDFSUrl(osURL, m_osDataNodeHost);
            }

            CPLFree(sWriteFuncData.pBuffer);
            curl_easy_cleanup(hCurlHandle);

            goto retry;
        }
    }
#endif

    if( response_code != 200 )
    {
        // If HTTP 429, 500, 502, 503, 504 error retry after a
        // pause.
        const double dfNewRetryDelay = CPLHTTPGetNewRetryDelay(
            static_cast<int>(response_code), dfRetryDelay,
            nullptr);
        if( dfNewRetryDelay > 0 &&
            nRetryCount < m_nMaxRetry )
        {
            CPLError(CE_Warning, CPLE_AppDefined,
                        "HTTP error code: %d - %s. "
                        "Retrying again in %.1f secs",
                        static_cast<int>(response_code), m_pszURL,
                        dfRetryDelay);
            CPLSleep(dfRetryDelay);
            dfRetryDelay = dfNewRetryDelay;
            nRetryCount++;
            CPLFree(sWriteFuncData.pBuffer);
            curl_easy_cleanup(hCurlHandle);
            goto retry;
        }

        if( response_code >= 400 && szCurlErrBuf[0] != '\0' )
        {
            CPLError(CE_Failure, CPLE_AppDefined, "%d: %s",
                        static_cast<int>(response_code), szCurlErrBuf);
        }
        if( !oFileProp.bHasComputedFileSize && startOffset == 0 )
        {
            oFileProp.bHasComputedFileSize = true;
            oFileProp.fileSize = 0;
            oFileProp.eExists = EXIST_NO;
            poFS->SetCachedFileProp(m_pszURL, oFileProp);
        }
        CPLFree(sWriteFuncData.pBuffer);
        curl_easy_cleanup(hCurlHandle);
        return false;
    }

    oFileProp.eExists = EXIST_YES;
    poFS->SetCachedFileProp(m_pszURL, oFileProp);

    DownloadRegionPostProcess(startOffset, nBlocks,
                              sWriteFuncData.pBuffer,
                              sWriteFuncData.nSize);

    CPLFree(sWriteFuncData.pBuffer);
    curl_easy_cleanup(hCurlHandle);

    return true;
}


} /* end of namespace cpl */


#endif // DOXYGEN_SKIP
//! @endcond

/************************************************************************/
/*                      VSIInstallWebHdfsHandler()                      */
/************************************************************************/

/**
 * \brief Install /vsiwebhdfs/ WebHDFS (Hadoop File System) REST API file
 * system handler (requires libcurl)
 *
 * @see <a href="gdal_virtual_file_systems.html#gdal_virtual_file_systems_vsiwebhdfs">/vsiwebhdfs/ documentation</a>
 *
 * @since GDAL 2.4
 */
void VSIInstallWebHdfsHandler( void )
{
    VSIFileManager::InstallHandler( "/vsiwebhdfs/", new cpl::VSIWebHDFSFSHandler );
}

#endif /* HAVE_CURL */
