add forgotten file

/*******************************************************************************

 * Copyright (c) 2023, Jan Koester jan.koester@gmx.net

 * All rights reserved.

 *

 * Redistribution and use in source and binary forms, with or without

 * modification, are permitted provided that the following conditions are met:

 * Redistributions of source code must retain the above copyright

 *      notice, this list of conditions and the following disclaimer.

 * Redistributions in binary form must reproduce the above copyright

 *      notice, this list of conditions and the following disclaimer in the

 *      documentation and/or other materials provided with the distribution.

 * Neither the name of the <organization> nor the

 *      names of its contributors may be used to endorse or promote products

 *      derived from this software without specific prior written permission.

 *

 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND

 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED

 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE

 * DISCLAIMED. IN NO EVENT SHALL <COPYRIGHT HOLDER> BE LIABLE FOR ANY

 * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES

 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;

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 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

 *******************************************************************************/

#include <mutex>

#include <httppp/exception.h>

#include <libpq-fe.h>

#include <database.h>

namespace dbpp {

    std::mutex g_lock_mutex;

    class Postgresql : public DatabaseApi{

    public:

        Postgresql(const char *constr) {

            _dbconn = PQconnectdb(constr);

            if (PQstatus(_dbconn) != CONNECTION_OK){

                libhttppp::HTTPException exp;

                exp[libhttppp::HTTPException::Critical] << PQerrorMessage(_dbconn);

                PQfinish(_dbconn);

                throw exp;

            }

        }

        ~Postgresql(){

            PQfinish(_dbconn);

        }

        int exec(const SQL &sql,DBResult &res) override{

            PGresult *pres = PQexec(_dbconn,sql.c_str());

            int pstate=PQresultStatus(pres);

            if(pstate==PGRES_FATAL_ERROR || pstate==PGRES_BAD_RESPONSE) {

                 libhttppp::HTTPException exp;

                 exp[libhttppp::HTTPException::Critical] << PQerrorMessage(_dbconn);

                 PQclear(pres);

                 throw exp;

            }

            res.clear();

            DBResult::Data *lastdat=nullptr;

            int rcount=PQntuples(pres);

            for(int i = 0; i < rcount; ++i ){

                for(int ii=0; ii < PQnfields(pres); ++ii){

                    if(!res.firstRow){

                       res.firstRow = new DBResult::Data(i,ii,PQgetvalue(pres,i,ii),PQgetlength(pres,i,ii));

                       lastdat=res.firstRow;

                    }else{

                       lastdat->nextData=new DBResult::Data(i,ii,PQgetvalue(pres,i,ii),PQgetlength(pres,i,ii));

                       lastdat=lastdat->nextData;

                    }

                }

            }

            PQclear(pres);

            return rcount;

        };

        const char *getDriverName() override{

            return "pgsql";

        };

        const SQL &autoincrement(SQL &sql) override{

            return (sql << "GENERATED BY DEFAULT AS IDENTITY");

        }

        const SQL &getUUIDType(SQL &sql) override {

            return (sql << "UUID");

        }

        bool isConnected() override{

            const std::lock_guard<std::mutex> lock(g_lock_mutex);

            if(PQstatus(_dbconn)==CONNECTION_OK)

                return true;

            return false;

        }

        void reset() override{

            const std::lock_guard<std::mutex> lock(g_lock_mutex);

            PQreset(_dbconn);

        }

    private:

        PGconn      *_dbconn;

    };

}