/*
    qureje is a database managment tool.
    Copyright (C) 2022  Alessandro Iezzi <aiezzi AT alessandroiezzi PERIOD it>

    This program 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 of the License, or
    (at your option) any later version.

    This program 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 this program.  If not, see <https://www.gnu.org/licenses/>.
 */

#include <libpq-fe.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#include "database.h"
#include "utils.h"

static char *
parameter(const char *key, char *value)
{
  int vsize = 0;
  char *param = NULL;

  if (value == NULL || (vsize = strlen(value)) <= 0) return NULL;

  param = strcrt(strlen(key) + vsize + 2);
  strcat(param, key);
  strcat(param, "=");
  strcat(param, value);
  strcat(param, " ");

  return param;
}

static void
prmcat(char *conninfo, char *prm)
{
  if (prm != NULL) {
    strcat(conninfo, prm);
    free(prm);
  }
}

static char *
create_connection_info(qureje_conn *conn)
{
  int strsize = 0;
  char *conninfo,
    *prmusr = NULL,
    *prmdb  = NULL;

  if ((prmusr = parameter("user", conn->user)) != NULL) {
    strsize += strlen(prmusr);
  }

  if ((prmdb = parameter("dbname", conn->dbname)) != NULL) {
    strsize += strlen(prmdb);
  }

  conninfo = strcrt(strsize + 1);

  prmcat(conninfo, prmusr);
  prmcat(conninfo, prmdb );

  return conninfo;
}

int
qureje_psql_connect(qureje_conn *conn)
{
  char *conninfo = NULL;
  PGconn *pgconn;

  if (conn == NULL) return 1;

  conninfo = create_connection_info(conn);
  /*
   * Using an empty connectstring will use default values for everything.
   * If set, the environment variables PGHOST, PGDATABASE, PGPORT and
   * PGUSER will be used.
   */
  pgconn = PQconnectdb(conninfo);

  free(conninfo);

  /*
   * This can only happen if there is not enough memory
   * to allocate the PGconn structure.
   */
  if (pgconn == NULL) {
    fprintf(stderr, "Out of memory connecting to PostgreSQL.\n");

    return 1;
  }

  /* check if the connection attempt worked */
  if (PQstatus(pgconn) != CONNECTION_OK) {
      fprintf(stderr, "%s\n", PQerrorMessage(pgconn));
      /*
       * Even if the connection failed, the PGconn structure has been
       * allocated and must be freed.
       */
      PQfinish(pgconn);

      return 1;
  }

  /* this program expects the database to return data in UTF-8 */
  PQsetClientEncoding(pgconn, "UTF8");

  conn->conn = pgconn;

  return 0;
}