/******************************************************************************
 *
 * Project:  GeoRSS Translator
 * Purpose:  Implements OGRGeoRSSDataSource class
 * Author:   Even Rouault, even dot rouault at spatialys.com
 *
 ******************************************************************************
 * Copyright (c) 2008-2011, Even Rouault <even dot rouault at spatialys.com>
 *
 * SPDX-License-Identifier: MIT
 ****************************************************************************/

#include "cpl_port.h"
#include "ogr_georss.h"

#include <cstdio>
#include <cstring>

#include "cpl_conv.h"
#include "cpl_csv.h"
#include "cpl_error.h"
#include "cpl_string.h"
#include "cpl_vsi.h"
#ifdef HAVE_EXPAT
#include "expat.h"
#endif
#include "ogr_core.h"
#include "ogr_expat.h"
#include "ogr_spatialref.h"
#include "ogrsf_frmts.h"

/************************************************************************/
/*                          OGRGeoRSSDataSource()                          */
/************************************************************************/

OGRGeoRSSDataSource::OGRGeoRSSDataSource()
    : papoLayers(nullptr), nLayers(0), fpOutput(nullptr),
#ifdef HAVE_EXPAT
      validity(GEORSS_VALIDITY_UNKNOWN),
#endif
      eFormat(GEORSS_RSS), eGeomDialect(GEORSS_SIMPLE), bUseExtensions(false),
      bWriteHeaderAndFooter(true)
#ifdef HAVE_EXPAT
      ,
      oCurrentParser(nullptr), nDataHandlerCounter(0)
#endif
{
}

/************************************************************************/
/*                         ~OGRGeoRSSDataSource()                          */
/************************************************************************/

OGRGeoRSSDataSource::~OGRGeoRSSDataSource()

{
    if (fpOutput != nullptr)
    {
        if (bWriteHeaderAndFooter)
        {
            if (eFormat == GEORSS_RSS)
            {
                VSIFPrintfL(fpOutput, "  </channel>\n");
                VSIFPrintfL(fpOutput, "</rss>\n");
            }
            else
            {
                VSIFPrintfL(fpOutput, "</feed>\n");
            }
        }
        VSIFCloseL(fpOutput);
    }

    for (int i = 0; i < nLayers; i++)
        delete papoLayers[i];
    CPLFree(papoLayers);
}

/************************************************************************/
/*                           TestCapability()                           */
/************************************************************************/

int OGRGeoRSSDataSource::TestCapability(const char *pszCap)

{
    if (EQUAL(pszCap, ODsCCreateLayer))
        return TRUE;
    // else if( EQUAL(pszCap,ODsCDeleteLayer) )
    //    return FALSE;
    else if (EQUAL(pszCap, ODsCZGeometries))
        return TRUE;

    return FALSE;
}

/************************************************************************/
/*                              GetLayer()                              */
/************************************************************************/

OGRLayer *OGRGeoRSSDataSource::GetLayer(int iLayer)

{
    if (iLayer < 0 || iLayer >= nLayers)
        return nullptr;

    return papoLayers[iLayer];
}

/************************************************************************/
/*                           ICreateLayer()                             */
/************************************************************************/

OGRLayer *
OGRGeoRSSDataSource::ICreateLayer(const char *pszLayerName,
                                  const OGRGeomFieldDefn *poGeomFieldDefn,
                                  CSLConstList /*papszOptions*/)
{
    if (fpOutput == nullptr)
        return nullptr;

    const auto poSRS =
        poGeomFieldDefn ? poGeomFieldDefn->GetSpatialRef() : nullptr;
    if (poSRS != nullptr && eGeomDialect != GEORSS_GML)
    {
        OGRSpatialReference oSRS;
        oSRS.SetWellKnownGeogCS("WGS84");
        oSRS.SetAxisMappingStrategy(OAMS_TRADITIONAL_GIS_ORDER);
        const char *const apszOptions[] = {
            "IGNORE_DATA_AXIS_TO_SRS_AXIS_MAPPING=YES", nullptr};
        if (!poSRS->IsSame(&oSRS, apszOptions))
        {
            CPLError(CE_Failure, CPLE_NotSupported,
                     "For a non GML dialect, only WGS84 SRS is supported");
            return nullptr;
        }
    }

    nLayers++;
    papoLayers = static_cast<OGRGeoRSSLayer **>(
        CPLRealloc(papoLayers, nLayers * sizeof(OGRGeoRSSLayer *)));
    OGRSpatialReference *poSRSClone = nullptr;
    if (poSRS)
    {
        poSRSClone = poSRS->Clone();
        poSRSClone->SetAxisMappingStrategy(OAMS_TRADITIONAL_GIS_ORDER);
    }
    papoLayers[nLayers - 1] = new OGRGeoRSSLayer(GetDescription(), pszLayerName,
                                                 this, poSRSClone, TRUE);
    if (poSRSClone)
        poSRSClone->Release();

    return papoLayers[nLayers - 1];
}

#ifdef HAVE_EXPAT
/************************************************************************/
/*                startElementValidateCbk()                             */
/************************************************************************/

void OGRGeoRSSDataSource::startElementValidateCbk(const char *pszNameIn,
                                                  const char **ppszAttr)
{
    if (validity == GEORSS_VALIDITY_UNKNOWN)
    {
        if (strcmp(pszNameIn, "rss") == 0)
        {
            validity = GEORSS_VALIDITY_VALID;
            eFormat = GEORSS_RSS;
        }
        else if (strcmp(pszNameIn, "feed") == 0 ||
                 strcmp(pszNameIn, "atom:feed") == 0)
        {
            validity = GEORSS_VALIDITY_VALID;
            eFormat = GEORSS_ATOM;
        }
        else if (strcmp(pszNameIn, "rdf:RDF") == 0)
        {
            const char **ppszIter = ppszAttr;
            while (*ppszIter)
            {
                if (strcmp(*ppszIter, "xmlns:georss") == 0)
                {
                    validity = GEORSS_VALIDITY_VALID;
                    eFormat = GEORSS_RSS_RDF;
                }
                ppszIter += 2;
            }
        }
        else
        {
            validity = GEORSS_VALIDITY_INVALID;
        }
    }
}

/************************************************************************/
/*                      dataHandlerValidateCbk()                        */
/************************************************************************/

void OGRGeoRSSDataSource::dataHandlerValidateCbk(const char * /* data */,
                                                 int /* nLen */)
{
    nDataHandlerCounter++;
    if (nDataHandlerCounter >= PARSER_BUF_SIZE)
    {
        CPLError(CE_Failure, CPLE_AppDefined,
                 "File probably corrupted (million laugh pattern)");
        XML_StopParser(oCurrentParser, XML_FALSE);
    }
}

static void XMLCALL startElementValidateCbk(void *pUserData,
                                            const char *pszName,
                                            const char **ppszAttr)
{
    OGRGeoRSSDataSource *poDS = static_cast<OGRGeoRSSDataSource *>(pUserData);
    poDS->startElementValidateCbk(pszName, ppszAttr);
}

static void XMLCALL dataHandlerValidateCbk(void *pUserData, const char *data,
                                           int nLen)
{
    OGRGeoRSSDataSource *poDS = static_cast<OGRGeoRSSDataSource *>(pUserData);
    poDS->dataHandlerValidateCbk(data, nLen);
}
#endif

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

int OGRGeoRSSDataSource::Open(const char *pszFilename, int bUpdateIn)

{
    if (bUpdateIn)
    {
        CPLError(CE_Failure, CPLE_NotSupported,
                 "OGR/GeoRSS driver does not support opening a file "
                 "in update mode");
        return FALSE;
    }
#ifdef HAVE_EXPAT

    // Try to open the file.
    VSILFILE *fp = VSIFOpenL(pszFilename, "r");
    if (fp == nullptr)
        return FALSE;

    validity = GEORSS_VALIDITY_UNKNOWN;

    XML_Parser oParser = OGRCreateExpatXMLParser();
    XML_SetUserData(oParser, this);
    XML_SetElementHandler(oParser, ::startElementValidateCbk, nullptr);
    XML_SetCharacterDataHandler(oParser, ::dataHandlerValidateCbk);
    oCurrentParser = oParser;

    std::vector<char> aBuf(PARSER_BUF_SIZE);
    int nDone = 0;
    unsigned int nLen = 0;
    int nCount = 0;

    // Begin to parse the file and look for the <rss> or <feed> element.
    // It *MUST* be the first element of an XML file.
    // Once we have read the first element, we know if we can
    // handle the file or not with that driver.
    do
    {
        nDataHandlerCounter = 0;
        nLen = static_cast<unsigned int>(
            VSIFReadL(aBuf.data(), 1, aBuf.size(), fp));
        nDone = nLen < aBuf.size();
        if (XML_Parse(oParser, aBuf.data(), nLen, nDone) == XML_STATUS_ERROR)
        {
            if (nLen <= PARSER_BUF_SIZE - 1)
                aBuf[nLen] = 0;
            else
                aBuf[PARSER_BUF_SIZE - 1] = 0;

            if (strstr(aBuf.data(), "<?xml") &&
                (strstr(aBuf.data(), "<rss") || strstr(aBuf.data(), "<feed") ||
                 strstr(aBuf.data(), "<atom:feed")))
            {
                CPLError(CE_Failure, CPLE_AppDefined,
                         "XML parsing of GeoRSS file failed: "
                         "%s at line %d, column %d",
                         XML_ErrorString(XML_GetErrorCode(oParser)),
                         static_cast<int>(XML_GetCurrentLineNumber(oParser)),
                         static_cast<int>(XML_GetCurrentColumnNumber(oParser)));
            }
            validity = GEORSS_VALIDITY_INVALID;
            break;
        }
        if (validity == GEORSS_VALIDITY_INVALID)
        {
            break;
        }
        else if (validity == GEORSS_VALIDITY_VALID)
        {
            break;
        }
        else
        {
            // After reading 50 * PARSER_BUF_SIZE bytes, and not finding whether the file
            // is GeoRSS or not, we give up and fail silently.
            nCount++;
            if (nCount == 50)
                break;
        }
    } while (!nDone && nLen > 0);

    XML_ParserFree(oParser);

    VSIFCloseL(fp);

    if (validity == GEORSS_VALIDITY_VALID)
    {
        CPLDebug("GeoRSS", "%s seems to be a GeoRSS file.", pszFilename);

        nLayers = 1;
        papoLayers = static_cast<OGRGeoRSSLayer **>(
            CPLRealloc(papoLayers, nLayers * sizeof(OGRGeoRSSLayer *)));
        papoLayers[0] =
            new OGRGeoRSSLayer(pszFilename, "georss", this, nullptr, FALSE);
    }

    return validity == GEORSS_VALIDITY_VALID;
#else
    VSILFILE *fp = VSIFOpenL(pszFilename, "r");
    if (fp)
    {
        char aBuf[256];
        const unsigned int nLen =
            static_cast<unsigned int>(VSIFReadL(aBuf, 1, 255, fp));
        aBuf[nLen] = '\0';
        if (strstr(aBuf, "<?xml") &&
            (strstr(aBuf, "<rss") || strstr(aBuf, "<atom:feed") ||
             strstr(aBuf, "<feed")))
        {
            CPLError(CE_Failure, CPLE_NotSupported,
                     "OGR/GeoRSS driver has not been built with read support. "
                     "Expat library required");
        }
        VSIFCloseL(fp);
    }
    return FALSE;
#endif
}

/************************************************************************/
/*                               Create()                               */
/************************************************************************/

int OGRGeoRSSDataSource::Create(const char *pszFilename, char **papszOptions)
{
    if (fpOutput != nullptr)
    {
        CPLAssert(false);
        return FALSE;
    }

    if (strcmp(pszFilename, "/dev/stdout") == 0)
        pszFilename = "/vsistdout/";

    /* -------------------------------------------------------------------- */
    /*     Do not override exiting file.                                    */
    /* -------------------------------------------------------------------- */
    VSIStatBufL sStatBuf;

    if (VSIStatL(pszFilename, &sStatBuf) == 0)
    {
        CPLError(CE_Failure, CPLE_NotSupported,
                 "You have to delete %s before being able to create it "
                 "with the GeoRSS driver",
                 pszFilename);
        return FALSE;
    }

    /* -------------------------------------------------------------------- */
    /*      Create the output file.                                         */
    /* -------------------------------------------------------------------- */
    fpOutput = VSIFOpenL(pszFilename, "w");
    if (fpOutput == nullptr)
    {
        CPLError(CE_Failure, CPLE_OpenFailed,
                 "Failed to create GeoRSS file %s.", pszFilename);
        return FALSE;
    }

    const char *pszFormat = CSLFetchNameValue(papszOptions, "FORMAT");
    if (pszFormat)
    {
        if (EQUAL(pszFormat, "RSS"))
            eFormat = GEORSS_RSS;
        else if (EQUAL(pszFormat, "ATOM"))
            eFormat = GEORSS_ATOM;
        else
            CPLError(CE_Warning, CPLE_NotSupported,
                     "Unsupported value for %s : %s", "FORMAT", pszFormat);
    }

    const char *pszGeomDialect =
        CSLFetchNameValue(papszOptions, "GEOM_DIALECT");
    if (pszGeomDialect)
    {
        if (EQUAL(pszGeomDialect, "GML"))
            eGeomDialect = GEORSS_GML;
        else if (EQUAL(pszGeomDialect, "SIMPLE"))
            eGeomDialect = GEORSS_SIMPLE;
        else if (EQUAL(pszGeomDialect, "W3C_GEO"))
            eGeomDialect = GEORSS_W3C_GEO;
        else
            CPLError(CE_Warning, CPLE_NotSupported,
                     "Unsupported value for %s : %s", "GEOM_DIALECT",
                     pszGeomDialect);
    }

    const char *pszWriteHeaderAndFooter =
        CSLFetchNameValue(papszOptions, "WRITE_HEADER_AND_FOOTER");
    if (pszWriteHeaderAndFooter && !CPLTestBool(pszWriteHeaderAndFooter))
    {
        bWriteHeaderAndFooter = false;
        return TRUE;
    }

    const char *pszTitle = nullptr;
    const char *pszDescription = nullptr;
    const char *pszLink = nullptr;
    const char *pszUpdated = nullptr;
    const char *pszAuthorName = nullptr;
    const char *pszId = nullptr;

    const char *pszHeader = CSLFetchNameValue(papszOptions, "HEADER");

    if (eFormat == GEORSS_RSS && pszHeader == nullptr)
    {
        pszTitle = CSLFetchNameValue(papszOptions, "TITLE");
        if (pszTitle == nullptr)
            pszTitle = "title";

        pszDescription = CSLFetchNameValue(papszOptions, "DESCRIPTION");
        if (pszDescription == nullptr)
            pszDescription = "channel_description";

        pszLink = CSLFetchNameValue(papszOptions, "LINK");
        if (pszLink == nullptr)
            pszLink = "channel_link";
    }
    else if (eFormat == GEORSS_ATOM && pszHeader == nullptr)
    {
        pszTitle = CSLFetchNameValue(papszOptions, "TITLE");
        if (pszTitle == nullptr)
            pszTitle = "title";

        pszUpdated = CSLFetchNameValue(papszOptions, "UPDATED");
        if (pszUpdated == nullptr)
            pszUpdated = "2009-01-01T00:00:00Z";

        pszAuthorName = CSLFetchNameValue(papszOptions, "AUTHOR_NAME");
        if (pszAuthorName == nullptr)
            pszAuthorName = "author";

        pszId = CSLFetchNameValue(papszOptions, "ID");
        if (pszId == nullptr)
            pszId = "id";
    }

    const char *pszUseExtensions =
        CSLFetchNameValue(papszOptions, "USE_EXTENSIONS");
    bUseExtensions = pszUseExtensions && CPLTestBool(pszUseExtensions);

    /* -------------------------------------------------------------------- */
    /*     Output header of GeoRSS file. */
    /* -------------------------------------------------------------------- */
    VSIFPrintfL(fpOutput, "<?xml version=\"1.0\"?>\n");
    if (eFormat == GEORSS_RSS)
    {
        VSIFPrintfL(fpOutput, "<rss version=\"2.0\" ");
        if (eGeomDialect == GEORSS_GML)
            VSIFPrintfL(fpOutput,
                        "xmlns:georss=\"http://www.georss.org/georss\" "
                        "xmlns:gml=\"http://www.opengis.net/gml\"");
        else if (eGeomDialect == GEORSS_SIMPLE)
            VSIFPrintfL(fpOutput,
                        "xmlns:georss=\"http://www.georss.org/georss\"");
        else
            VSIFPrintfL(
                fpOutput,
                "xmlns:geo=\"http://www.w3.org/2003/01/geo/wgs84_pos#\"");
        VSIFPrintfL(fpOutput, ">\n");
        VSIFPrintfL(fpOutput, "  <channel>\n");
        if (pszHeader)
        {
            VSIFPrintfL(fpOutput, "%s", pszHeader);
        }
        else
        {
            VSIFPrintfL(fpOutput, "    <title>%s</title>\n", pszTitle);
            VSIFPrintfL(fpOutput, "    <description>%s</description>\n",
                        pszDescription);
            VSIFPrintfL(fpOutput, "    <link>%s</link>\n", pszLink);
        }
    }
    else
    {
        VSIFPrintfL(fpOutput, "<feed xmlns=\"http://www.w3.org/2005/Atom\" ");
        if (eGeomDialect == GEORSS_GML)
            VSIFPrintfL(fpOutput, "xmlns:gml=\"http://www.opengis.net/gml\"");
        else if (eGeomDialect == GEORSS_SIMPLE)
            VSIFPrintfL(fpOutput,
                        "xmlns:georss=\"http://www.georss.org/georss\"");
        else
            VSIFPrintfL(
                fpOutput,
                "xmlns:geo=\"http://www.w3.org/2003/01/geo/wgs84_pos#\"");
        VSIFPrintfL(fpOutput, ">\n");
        if (pszHeader)
        {
            VSIFPrintfL(fpOutput, "%s", pszHeader);
        }
        else
        {
            VSIFPrintfL(fpOutput, "  <title>%s</title>\n", pszTitle);
            VSIFPrintfL(fpOutput, "  <updated>%s</updated>\n", pszUpdated);
            VSIFPrintfL(fpOutput, "  <author><name>%s</name></author>\n",
                        pszAuthorName);
            VSIFPrintfL(fpOutput, "  <id>%s</id>\n", pszId);
        }
    }

    return TRUE;
}