/*
   This file is part of TALER
   Copyright (C) 2023 Taler Systems SA

   TALER is free software; you can redistribute it and/or modify it under the
   terms of the GNU General Public License as published by the Free Software
   Foundation; either version 3, or (at your option) any later version.

   TALER is distributed in the hope that it will be useful, but WITHOUT ANY
   WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
   A PARTICULAR PURPOSE.  See the GNU General Public License for more details.

   You should have received a copy of the GNU General Public License along with
   TALER; see the file COPYING.  If not, see <http://www.gnu.org/licenses/>
 */
/**
 * @file pg_helper.c
 * @brief shared internal definitions for postgres DB plugin
 * @author Christian Grothoff
 */
#include "platform.h"
#include "pg_helper.h"
#include <gnunet/gnunet_util_lib.h>
#include <gnunet/gnunet_pq_lib.h>
#include <taler/taler_util.h>
#include <taler/taler_pq_lib.h>
#include <taler/taler_json_lib.h>
#include <taler/taler_mhd_lib.h>


enum GNUNET_GenericReturnValue
TMH_PG_start (void *cls,
              const char *name)
{
  struct PostgresClosure *pg = cls;
  struct GNUNET_PQ_ExecuteStatement es[] = {
    GNUNET_PQ_make_execute ("START TRANSACTION ISOLATION LEVEL SERIALIZABLE"),
    GNUNET_PQ_EXECUTE_STATEMENT_END
  };

  GNUNET_assert (NULL != name);
  check_connection (pg);
  postgres_preflight (pg);
  GNUNET_log (GNUNET_ERROR_TYPE_INFO,
              "Starting merchant DB transaction `%s'\n",
              name);
  if (GNUNET_OK !=
      GNUNET_PQ_exec_statements (pg->conn,
                                 es))
  {
    TALER_LOG_ERROR ("Failed to start transaction\n");
    GNUNET_break (0);
    return GNUNET_SYSERR;
  }
  pg->transaction_name = name;
  return GNUNET_OK;
}


enum GNUNET_GenericReturnValue
TMH_PG_start_read_committed (void *cls,
                             const char *name)
{
  struct PostgresClosure *pg = cls;
  struct GNUNET_PQ_ExecuteStatement es[] = {
    GNUNET_PQ_make_execute ("START TRANSACTION ISOLATION LEVEL READ COMMITTED"),
    GNUNET_PQ_EXECUTE_STATEMENT_END
  };

  GNUNET_assert (NULL != name);
  check_connection (pg);
  postgres_preflight (pg);
  GNUNET_log (GNUNET_ERROR_TYPE_INFO,
              "Starting merchant DB transaction %s (READ COMMITTED)\n",
              name);
  if (GNUNET_OK !=
      GNUNET_PQ_exec_statements (pg->conn,
                                 es))
  {
    TALER_LOG_ERROR ("Failed to start transaction\n");
    GNUNET_break (0);
    return GNUNET_SYSERR;
  }
  pg->transaction_name = name;
  return GNUNET_OK;
}


void
TMH_PG_rollback (void *cls)
{
  struct PostgresClosure *pg = cls;
  struct GNUNET_PQ_ExecuteStatement es[] = {
    GNUNET_PQ_make_execute ("ROLLBACK"),
    GNUNET_PQ_EXECUTE_STATEMENT_END
  };

  if (NULL == pg->transaction_name)
    return;
  GNUNET_log (GNUNET_ERROR_TYPE_INFO,
              "Rolling back merchant DB transaction `%s'\n",
              pg->transaction_name);
  GNUNET_break (GNUNET_OK ==
                GNUNET_PQ_exec_statements (pg->conn,
                                           es));
  pg->transaction_name = NULL;
}


enum GNUNET_DB_QueryStatus
TMH_PG_commit (void *cls)
{
  struct PostgresClosure *pg = cls;
  struct GNUNET_PQ_QueryParam params[] = {
    GNUNET_PQ_query_param_end
  };
  enum GNUNET_DB_QueryStatus qs;

  GNUNET_log (GNUNET_ERROR_TYPE_INFO,
              "Committing merchant DB transaction %s\n",
              pg->transaction_name);
  check_connection (pg);
  PREPARE (pg,
           "merchant_commit",
           "COMMIT");
  qs = GNUNET_PQ_eval_prepared_non_select (pg->conn,
                                           "merchant_commit",
                                           params);
  if (qs < 0)
  {
    GNUNET_log (GNUNET_ERROR_TYPE_WARNING,
                "Failed to commit transaction\n");
    TMH_PG_rollback (pg);
    return qs;
  }
  pg->transaction_name = NULL;
  return qs;
}