/******************************************************************************
 *
 * Project:  OpenGIS Simple Features Reference Implementation
 * Purpose:  Implements OGRMySQLLayer class.
 * Author:   Frank Warmerdam, warmerdam@pobox.com
 * Author:   Howard Butler, hobu@hobu.net
 *
 ******************************************************************************
 * Copyright (c) 2004, Frank Warmerdam <warmerdam@pobox.com>
 *
 * SPDX-License-Identifier: MIT
 ****************************************************************************/

#include "ogr_mysql.h"
#include "cpl_conv.h"
#include "cpl_string.h"

/************************************************************************/
/*                           OGRMySQLLayer()                            */
/************************************************************************/

OGRMySQLLayer::OGRMySQLLayer(OGRMySQLDataSource *poDSIn) : poDS(poDSIn)
{
}

/************************************************************************/
/*                           ~OGRMySQLLayer()                           */
/************************************************************************/

OGRMySQLLayer::~OGRMySQLLayer()

{
    if (m_nFeaturesRead > 0 && poFeatureDefn != nullptr)
    {
        CPLDebug("MySQL", "%d features read on layer '%s'.",
                 (int)m_nFeaturesRead, poFeatureDefn->GetName());
    }

    if (poFeatureDefn && poFeatureDefn->GetGeomFieldCount() > 0)
    {
        auto poGeomFieldDefn = dynamic_cast<OGRMySQLGeomFieldDefn *>(
            poFeatureDefn->GetGeomFieldDefn(0));
        if (poGeomFieldDefn)
            poGeomFieldDefn->UnsetDataSource();
    }

    OGRMySQLLayer::ResetReading();

    CPLFree(pszGeomColumn);
    CPLFree(pszGeomColumnTable);
    CPLFree(pszFIDColumn);
    CPLFree(pszQueryStatement);

    if (poFeatureDefn)
        poFeatureDefn->Release();
}

/************************************************************************/
/*                            ResetReading()                            */
/************************************************************************/

void OGRMySQLLayer::ResetReading()

{
    iNextShapeId = 0;

    if (hResultSet != nullptr)
    {
        mysql_free_result(hResultSet);
        hResultSet = nullptr;

        poDS->InterruptLongResult();
    }
    m_bEOF = false;
}

/************************************************************************/
/*                           GetNextFeature()                           */
/************************************************************************/

OGRFeature *OGRMySQLLayer::GetNextFeature()

{
    if (m_bEOF)
        return nullptr;

    while (true)
    {
        OGRFeature *poFeature;

        poFeature = GetNextRawFeature();
        if (poFeature == nullptr)
        {
            m_bEOF = true;
            return nullptr;
        }

        if ((m_poFilterGeom == nullptr ||
             FilterGeometry(poFeature->GetGeometryRef())) &&
            (m_poAttrQuery == nullptr || m_poAttrQuery->Evaluate(poFeature)))
            return poFeature;

        delete poFeature;
    }
}

/************************************************************************/
/*                          RecordToFeature()                           */
/*                                                                      */
/*      Convert the indicated record of the current result set into     */
/*      a feature.                                                      */
/************************************************************************/

OGRFeature *OGRMySQLLayer::RecordToFeature(char **papszRow,
                                           unsigned long *panLengths)

{
    mysql_field_seek(hResultSet, 0);

    /* -------------------------------------------------------------------- */
    /*      Create a feature from the current result.                       */
    /* -------------------------------------------------------------------- */
    OGRFeature *poFeature = new OGRFeature(poFeatureDefn);

    poFeature->SetFID(iNextShapeId);
    m_nFeaturesRead++;

    /* ==================================================================== */
    /*      Transfer all result fields we can.                              */
    /* ==================================================================== */
    for (int iField = 0; iField < (int)mysql_num_fields(hResultSet); iField++)
    {
        MYSQL_FIELD *psMSField = mysql_fetch_field(hResultSet);

        /* --------------------------------------------------------------------
         */
        /*      Handle FID. */
        /* --------------------------------------------------------------------
         */
        if (bHasFid && EQUAL(psMSField->name, pszFIDColumn))
        {
            if (papszRow[iField] == nullptr)
            {
                CPLError(CE_Failure, CPLE_AppDefined,
                         "NULL primary key in RecordToFeature()");
                return nullptr;
            }

            poFeature->SetFID(CPLAtoGIntBig(papszRow[iField]));
        }

        if (papszRow[iField] == nullptr)
        {
            const int iOGRField = poFeatureDefn->GetFieldIndex(psMSField->name);
            if (iOGRField >= 0)
                poFeature->SetFieldNull(iOGRField);

            continue;
        }

        /* --------------------------------------------------------------------
         */
        /*      Handle MySQL geometry */
        /* --------------------------------------------------------------------
         */
        if (pszGeomColumn && EQUAL(psMSField->name, pszGeomColumn))
        {
            OGRGeometry *poGeometry = nullptr;

            // Geometry columns will have the first 4 bytes contain the SRID.
            OGRGeometryFactory::createFromWkb(
                papszRow[iField] + 4, nullptr, &poGeometry,
                static_cast<int>(panLengths[iField] - 4));

            if (poGeometry != nullptr)
            {
                poGeometry->assignSpatialReference(GetSpatialRef());
                poFeature->SetGeometryDirectly(poGeometry);
            }
            continue;
        }

        /* --------------------------------------------------------------------
         */
        /*      Transfer regular data fields. */
        /* --------------------------------------------------------------------
         */
        const int iOGRField = poFeatureDefn->GetFieldIndex(psMSField->name);
        if (iOGRField < 0)
            continue;

        OGRFieldDefn *psFieldDefn = poFeatureDefn->GetFieldDefn(iOGRField);

        if (psFieldDefn->GetType() == OFTBinary)
        {
            poFeature->SetField(iOGRField, static_cast<int>(panLengths[iField]),
                                (GByte *)papszRow[iField]);
        }
        else
        {
            poFeature->SetField(iOGRField, papszRow[iField]);
        }
    }

    return poFeature;
}

/************************************************************************/
/*                         GetNextRawFeature()                          */
/************************************************************************/

OGRFeature *OGRMySQLLayer::GetNextRawFeature()

{
    /* -------------------------------------------------------------------- */
    /*      Do we need to establish an initial query?                       */
    /* -------------------------------------------------------------------- */
    if (iNextShapeId == 0 && hResultSet == nullptr)
    {
        CPLAssert(pszQueryStatement != nullptr);

        poDS->RequestLongResult(this);

        if (mysql_query(poDS->GetConn(), pszQueryStatement))
        {
            poDS->ReportError(pszQueryStatement);
            return nullptr;
        }

        hResultSet = mysql_use_result(poDS->GetConn());
        if (hResultSet == nullptr)
        {
            poDS->ReportError("mysql_use_result() failed on query.");
            return nullptr;
        }
    }

    /* -------------------------------------------------------------------- */
    /*      Fetch next record.                                              */
    /* -------------------------------------------------------------------- */
    char **papszRow;
    unsigned long *panLengths;

    papszRow = mysql_fetch_row(hResultSet);
    if (papszRow == nullptr)
    {
        ResetReading();
        return nullptr;
    }

    panLengths = mysql_fetch_lengths(hResultSet);

    /* -------------------------------------------------------------------- */
    /*      Process record.                                                 */
    /* -------------------------------------------------------------------- */
    OGRFeature *poFeature = RecordToFeature(papszRow, panLengths);

    iNextShapeId++;

    return poFeature;
}

/************************************************************************/
/*                             GetFeature()                             */
/*                                                                      */
/*      Note that we actually override this in OGRMySQLTableLayer.      */
/************************************************************************/

OGRFeature *OGRMySQLLayer::GetFeature(GIntBig nFeatureId)

{
    return OGRLayer::GetFeature(nFeatureId);
}

/************************************************************************/
/*                            GetFIDColumn()                            */
/************************************************************************/

const char *OGRMySQLLayer::GetFIDColumn()

{
    if (pszFIDColumn != nullptr)
        return pszFIDColumn;
    else
        return "";
}

/************************************************************************/
/*                         FetchSRSId()                                 */
/************************************************************************/

int OGRMySQLLayer::FetchSRSId()
{
    CPLString osCommand;
    char **papszRow;

    if (hResultSet != nullptr)
        mysql_free_result(hResultSet);
    hResultSet = nullptr;

    if (poDS->GetMajorVersion() < 8 || poDS->IsMariaDB())
    {
        osCommand.Printf("SELECT srid FROM geometry_columns "
                         "WHERE f_table_name = '%s'",
                         pszGeomColumnTable);
    }
    else
    {
        osCommand.Printf(
            "SELECT SRS_ID FROM INFORMATION_SCHEMA.ST_GEOMETRY_COLUMNS "
            "WHERE TABLE_NAME = '%s'",
            pszGeomColumnTable);
    }

    if (!mysql_query(poDS->GetConn(), osCommand))
        hResultSet = mysql_store_result(poDS->GetConn());

    papszRow = nullptr;
    if (hResultSet != nullptr)
        papszRow = mysql_fetch_row(hResultSet);

    if (papszRow != nullptr && papszRow[0] != nullptr)
    {
        nSRSId = atoi(papszRow[0]);
    }

    // make sure to free our results
    if (hResultSet != nullptr)
        mysql_free_result(hResultSet);
    hResultSet = nullptr;

    return nSRSId;
}

/************************************************************************/
/*                           GetSpatialRef()                            */
/************************************************************************/

const OGRSpatialReference *OGRMySQLGeomFieldDefn::GetSpatialRef() const

{
    if (!poDS)
        return poSRS;

    if (poSRS == nullptr && nSRSId > -1)
    {
        poSRS = poDS->FetchSRS(nSRSId);
        if (poSRS != nullptr)
            const_cast<OGRSpatialReference *>(poSRS)->Reference();
        else
            nSRSId = poDS->GetUnknownSRID();
    }

    return poSRS;
}

/************************************************************************/
/*                             GetDataset()                             */
/************************************************************************/

GDALDataset *OGRMySQLLayer::GetDataset()
{
    return poDS;
}
