/******************************************************************************
 *
 * Project:  OpenGIS Simple Features Reference Implementation
 * Purpose:  Implements OGRPGResultLayer class, access the resultset from
 *           a particular select query done via ExecuteSQL().
 * Author:   Frank Warmerdam, warmerdam@pobox.com
 *
 ******************************************************************************
 * Copyright (c) 2002, Frank Warmerdam
 * Copyright (c) 2008-2013, Even Rouault <even dot rouault at spatialys.com>
 *
 * SPDX-License-Identifier: MIT
 ****************************************************************************/

#include "cpl_conv.h"
#include "ogr_pg.h"

#define PQexec this_is_an_error

/************************************************************************/
/*                          OGRPGResultLayer()                          */
/************************************************************************/

OGRPGResultLayer::OGRPGResultLayer(OGRPGDataSource *poDSIn,
                                   const char *pszRawQueryIn,
                                   PGresult *hInitialResultIn)
    : pszRawStatement(CPLStrdup(pszRawQueryIn))
{
    poDS = poDSIn;

    iNextShapeId = 0;

    BuildFullQueryStatement();

    ReadResultDefinition(hInitialResultIn);

    /* Find at which index the geometry column is */
    /* and prepare a request to identify not-nullable fields */
    int iGeomCol = -1;
    CPLString osRequest;
    std::map<std::pair<int, int>, int> oMapAttributeToFieldIndex;

    for (int iRawField = 0; iRawField < PQnfields(hInitialResultIn);
         iRawField++)
    {
        if (poFeatureDefn->GetGeomFieldCount() == 1 &&
            strcmp(PQfname(hInitialResultIn, iRawField),
                   poFeatureDefn->GetGeomFieldDefn(0)->GetNameRef()) == 0)
        {
            iGeomCol = iRawField;
        }

        Oid tableOID = PQftable(hInitialResultIn, iRawField);
        int tableCol = PQftablecol(hInitialResultIn, iRawField);
        if (tableOID != InvalidOid && tableCol > 0)
        {
            if (!osRequest.empty())
                osRequest += " OR ";
            osRequest += "(attrelid = ";
            osRequest += CPLSPrintf("%d", tableOID);
            osRequest += " AND attnum = ";
            osRequest += CPLSPrintf("%d)", tableCol);
            oMapAttributeToFieldIndex[std::pair<int, int>(tableOID, tableCol)] =
                iRawField;
        }
    }

    CPLString osQuery(pszRawQueryIn);
    // Only a INNER JOIN can guarantee that the non-nullability of source
    // columns will be valid for the result of the join.
    if (!osRequest.empty() && osQuery.ifind("LEFT JOIN") == std::string::npos &&
        osQuery.ifind("RIGHT JOIN") == std::string::npos &&
        osQuery.ifind("OUTER JOIN") == std::string::npos)
    {
        osRequest = "SELECT attnum, attrelid FROM pg_attribute WHERE "
                    "attnotnull = 't' AND (" +
                    osRequest + ")";
        PGresult *hResult = OGRPG_PQexec(poDS->GetPGConn(), osRequest);
        if (hResult && PQresultStatus(hResult) == PGRES_TUPLES_OK)
        {
            for (int iCol = 0; iCol < PQntuples(hResult); iCol++)
            {
                const char *pszAttNum = PQgetvalue(hResult, iCol, 0);
                const char *pszAttRelid = PQgetvalue(hResult, iCol, 1);
                int iRawField = oMapAttributeToFieldIndex[std::pair<int, int>(
                    atoi(pszAttRelid), atoi(pszAttNum))];
                const char *pszFieldname = PQfname(hInitialResultIn, iRawField);
                int iFieldIdx = poFeatureDefn->GetFieldIndex(pszFieldname);
                if (iFieldIdx >= 0)
                    poFeatureDefn->GetFieldDefn(iFieldIdx)->SetNullable(FALSE);
                else
                {
                    iFieldIdx = poFeatureDefn->GetGeomFieldIndex(pszFieldname);
                    if (iFieldIdx >= 0)
                        poFeatureDefn->GetGeomFieldDefn(iFieldIdx)->SetNullable(
                            FALSE);
                }
            }
        }
        OGRPGClearResult(hResult);
    }

    /* Determine the table from which the geometry column is extracted */
    if (iGeomCol != -1)
    {
        Oid tableOID = PQftable(hInitialResultIn, iGeomCol);
        if (tableOID != InvalidOid)
        {
            CPLString osGetTableName;
            osGetTableName.Printf(
                "SELECT c.relname, n.nspname FROM pg_class c "
                "JOIN pg_namespace n ON c.relnamespace=n.oid WHERE c.oid = %d ",
                tableOID);
            PGresult *hTableNameResult =
                OGRPG_PQexec(poDS->GetPGConn(), osGetTableName);
            if (hTableNameResult &&
                PQresultStatus(hTableNameResult) == PGRES_TUPLES_OK)
            {
                if (PQntuples(hTableNameResult) > 0)
                {
                    pszGeomTableName =
                        CPLStrdup(PQgetvalue(hTableNameResult, 0, 0));
                    pszGeomTableSchemaName =
                        CPLStrdup(PQgetvalue(hTableNameResult, 0, 1));
                }
            }
            OGRPGClearResult(hTableNameResult);
        }
    }
}

/************************************************************************/
/*                          ~OGRPGResultLayer()                          */
/************************************************************************/

OGRPGResultLayer::~OGRPGResultLayer()

{
    CPLFree(pszRawStatement);
    CPLFree(pszGeomTableName);
    CPLFree(pszGeomTableSchemaName);
}

/************************************************************************/
/*                      BuildFullQueryStatement()                       */
/************************************************************************/

void OGRPGResultLayer::BuildFullQueryStatement()

{
    if (pszQueryStatement != nullptr)
    {
        CPLFree(pszQueryStatement);
        pszQueryStatement = nullptr;
    }

    const size_t nLen = strlen(pszRawStatement) + osWHERE.size() + 40;
    pszQueryStatement = static_cast<char *>(CPLMalloc(nLen));

    if (osWHERE.empty())
        strcpy(pszQueryStatement, pszRawStatement);
    else
        snprintf(pszQueryStatement, nLen,
                 "SELECT * FROM (%s) AS ogrpgsubquery %s", pszRawStatement,
                 osWHERE.c_str());
}

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

void OGRPGResultLayer::ResetReading()

{
    OGRPGLayer::ResetReading();
}

/************************************************************************/
/*                          GetFeatureCount()                           */
/************************************************************************/

GIntBig OGRPGResultLayer::GetFeatureCount(int bForce)

{
    if (TestCapability(OLCFastFeatureCount) == FALSE)
        return OGRPGLayer::GetFeatureCount(bForce);

    PGconn *hPGConn = poDS->GetPGConn();
    CPLString osCommand;
    int nCount = 0;

    osCommand.Printf("SELECT count(*) FROM (%s) AS ogrpgcount",
                     pszQueryStatement);

    PGresult *hResult = OGRPG_PQexec(hPGConn, osCommand);
    if (hResult != nullptr && PQresultStatus(hResult) == PGRES_TUPLES_OK)
        nCount = atoi(PQgetvalue(hResult, 0, 0));
    else
        CPLDebug("PG", "%s; failed.", osCommand.c_str());
    OGRPGClearResult(hResult);

    return nCount;
}

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

int OGRPGResultLayer::TestCapability(const char *pszCap)

{
    GetLayerDefn();

    if (EQUAL(pszCap, OLCFastFeatureCount) ||
        EQUAL(pszCap, OLCFastSetNextByIndex))
    {
        OGRPGGeomFieldDefn *poGeomFieldDefn = nullptr;
        if (poFeatureDefn->GetGeomFieldCount() > 0)
            poGeomFieldDefn =
                poFeatureDefn->GetGeomFieldDefn(m_iGeomFieldFilter);
        return (m_poFilterGeom == nullptr || poGeomFieldDefn == nullptr ||
                poGeomFieldDefn->ePostgisType == GEOM_TYPE_GEOMETRY ||
                poGeomFieldDefn->ePostgisType == GEOM_TYPE_GEOGRAPHY) &&
               m_poAttrQuery == nullptr;
    }
    else if (EQUAL(pszCap, OLCFastSpatialFilter))
    {
        OGRPGGeomFieldDefn *poGeomFieldDefn = nullptr;
        if (poFeatureDefn->GetGeomFieldCount() > 0)
            poGeomFieldDefn =
                poFeatureDefn->GetGeomFieldDefn(m_iGeomFieldFilter);
        return (poGeomFieldDefn == nullptr ||
                poGeomFieldDefn->ePostgisType == GEOM_TYPE_GEOMETRY ||
                poGeomFieldDefn->ePostgisType == GEOM_TYPE_GEOGRAPHY) &&
               m_poAttrQuery == nullptr;
    }

    else if (EQUAL(pszCap, OLCFastGetExtent))
    {
        OGRPGGeomFieldDefn *poGeomFieldDefn = nullptr;
        if (poFeatureDefn->GetGeomFieldCount() > 0)
            poGeomFieldDefn = poFeatureDefn->GetGeomFieldDefn(0);
        return (poGeomFieldDefn == nullptr ||
                poGeomFieldDefn->ePostgisType == GEOM_TYPE_GEOMETRY) &&
               m_poAttrQuery == nullptr;
    }
    else if (EQUAL(pszCap, OLCStringsAsUTF8))
        return TRUE;
    else if (EQUAL(pszCap, OLCZGeometries))
        return TRUE;
    else
        return FALSE;
}

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

OGRFeature *OGRPGResultLayer::GetNextFeature()

{
    OGRPGGeomFieldDefn *poGeomFieldDefn = nullptr;
    if (poFeatureDefn->GetGeomFieldCount() != 0)
        poGeomFieldDefn = poFeatureDefn->GetGeomFieldDefn(m_iGeomFieldFilter);

    while (true)
    {
        OGRFeature *poFeature = GetNextRawFeature();
        if (poFeature == nullptr)
            return nullptr;

        if ((m_poFilterGeom == nullptr || poGeomFieldDefn == nullptr ||
             poGeomFieldDefn->ePostgisType == GEOM_TYPE_GEOMETRY ||
             poGeomFieldDefn->ePostgisType == GEOM_TYPE_GEOGRAPHY ||
             FilterGeometry(poFeature->GetGeomFieldRef(m_iGeomFieldFilter))) &&
            (m_poAttrQuery == nullptr || m_poAttrQuery->Evaluate(poFeature)))
            return poFeature;

        delete poFeature;
    }
}

/************************************************************************/
/*                         ISetSpatialFilter()                          */
/************************************************************************/

OGRErr OGRPGResultLayer::ISetSpatialFilter(int iGeomField,
                                           const OGRGeometry *poGeomIn)

{
    m_iGeomFieldFilter = iGeomField;

    OGRPGGeomFieldDefn *poGeomFieldDefn =
        poFeatureDefn->GetGeomFieldDefn(m_iGeomFieldFilter);
    if (InstallFilter(poGeomIn))
    {
        if (poGeomFieldDefn->ePostgisType == GEOM_TYPE_GEOMETRY ||
            poGeomFieldDefn->ePostgisType == GEOM_TYPE_GEOGRAPHY)
        {
            if (m_poFilterGeom != nullptr)
            {
                char szBox3D_1[128];
                char szBox3D_2[128];
                OGREnvelope sEnvelope;

                m_poFilterGeom->getEnvelope(&sEnvelope);
                if (poGeomFieldDefn->ePostgisType == GEOM_TYPE_GEOGRAPHY)
                {
                    if (sEnvelope.MinX < -180.0)
                        sEnvelope.MinX = -180.0;
                    if (sEnvelope.MinY < -90.0)
                        sEnvelope.MinY = -90.0;
                    if (sEnvelope.MaxX > 180.0)
                        sEnvelope.MaxX = 180.0;
                    if (sEnvelope.MaxY > 90.0)
                        sEnvelope.MaxY = 90.0;
                }
                CPLsnprintf(szBox3D_1, sizeof(szBox3D_1), "%.17g %.17g",
                            sEnvelope.MinX, sEnvelope.MinY);
                CPLsnprintf(szBox3D_2, sizeof(szBox3D_2), "%.17g %.17g",
                            sEnvelope.MaxX, sEnvelope.MaxY);
                osWHERE.Printf(
                    "WHERE %s && %s('BOX3D(%s, %s)'::box3d,%d) ",
                    OGRPGEscapeColumnName(poGeomFieldDefn->GetNameRef())
                        .c_str(),
                    (poDS->sPostGISVersion.nMajor >= 2) ? "ST_SetSRID"
                                                        : "SetSRID",
                    szBox3D_1, szBox3D_2, poGeomFieldDefn->nSRSId);
            }
            else
            {
                osWHERE = "";
            }

            BuildFullQueryStatement();
        }

        ResetReading();
    }
    return OGRERR_NONE;
}

/************************************************************************/
/*                            ResolveSRID()                             */
/************************************************************************/

void OGRPGResultLayer::ResolveSRID(const OGRPGGeomFieldDefn *poGFldDefn)

{
    /* We have to get the SRID of the geometry column, so to be able */
    /* to do spatial filtering */
    int nSRSId = UNDETERMINED_SRID;

    if (poGFldDefn->ePostgisType == GEOM_TYPE_GEOGRAPHY)
    {
        if (!(poDS->sPostGISVersion.nMajor >= 3 ||
              (poDS->sPostGISVersion.nMajor == 2 &&
               poDS->sPostGISVersion.nMinor >= 2)))
        {
            // EPSG:4326 was a requirement for geography before PostGIS 2.2
            nSRSId = 4326;
        }
    }

    if (nSRSId == UNDETERMINED_SRID &&
        (poGFldDefn->ePostgisType == GEOM_TYPE_GEOMETRY ||
         poGFldDefn->ePostgisType == GEOM_TYPE_GEOGRAPHY))
    {
        if (pszGeomTableName != nullptr)
        {
            CPLString osName(pszGeomTableSchemaName);
            osName += ".";
            osName += pszGeomTableName;
            OGRPGLayer *poBaseLayer =
                cpl::down_cast<OGRPGLayer *>(poDS->GetLayerByName(osName));
            if (poBaseLayer)
            {
                int iBaseIdx = poBaseLayer->GetLayerDefn()->GetGeomFieldIndex(
                    poGFldDefn->GetNameRef());
                if (iBaseIdx >= 0)
                {
                    const OGRPGGeomFieldDefn *poBaseGFldDefn =
                        poBaseLayer->GetLayerDefn()->GetGeomFieldDefn(iBaseIdx);
                    poBaseGFldDefn
                        ->GetSpatialRef(); /* To make sure nSRSId is resolved */
                    nSRSId = poBaseGFldDefn->nSRSId;
                }
            }
        }

        if (nSRSId == UNDETERMINED_SRID)
        {
            CPLString osGetSRID;

            const char *psGetSRIDFct =
                poDS->sPostGISVersion.nMajor >= 2 ? "ST_SRID" : "getsrid";

            osGetSRID += "SELECT ";
            osGetSRID += psGetSRIDFct;
            osGetSRID += "(";
            osGetSRID += OGRPGEscapeColumnName(poGFldDefn->GetNameRef());
            if (poDS->sPostGISVersion.nMajor > 2 ||
                (poDS->sPostGISVersion.nMajor == 2 &&
                 poDS->sPostGISVersion.nMinor >= 2))
                osGetSRID += "::geometry";
            osGetSRID += ") FROM (";
            osGetSRID += pszRawStatement;
            osGetSRID += ") AS ogrpggetsrid WHERE (";
            osGetSRID += OGRPGEscapeColumnName(poGFldDefn->GetNameRef());
            osGetSRID += " IS NOT NULL) LIMIT 1";

            PGresult *hSRSIdResult = OGRPG_PQexec(poDS->GetPGConn(), osGetSRID);

            nSRSId = poDS->GetUndefinedSRID();

            if (hSRSIdResult && PQresultStatus(hSRSIdResult) == PGRES_TUPLES_OK)
            {
                if (PQntuples(hSRSIdResult) > 0)
                    nSRSId = atoi(PQgetvalue(hSRSIdResult, 0, 0));
            }
            else
            {
                CPLError(CE_Failure, CPLE_AppDefined, "%s",
                         PQerrorMessage(poDS->GetPGConn()));
            }

            OGRPGClearResult(hSRSIdResult);
        }
    }

    poGFldDefn->nSRSId = nSRSId;
}
