/*
 * This program is based on
 * src/test/examples/testlibpq.c (example 33.1)
 * from section 33.21 of the PostgreSQL documentation
 * (https://www.postgresql.org/docs/13/libpq-example.html)
 *
 */
#include <stdio.h>
#include <stdlib.h>
#include <time.h>
#include "libpq-fe.h"

static void
exit_nicely(PGconn *conn)
{
    PQfinish(conn);
    exit(1);
}

int
main(int argc, char **argv)
{
    const char *conninfo;
    PGconn     *conn;
    PGresult   *res;
    int         nFields;
    int         i,
                j;
    struct timespec ts0, ts1, ts2, ts3, ts4;

    /*
     * If the user supplies a parameter on the command line, use it as the
     * conninfo string; otherwise default to setting dbname=postgres and using
     * environment variables or defaults for all other connection parameters.
     */
    if (argc > 1)
        conninfo = argv[1];
    else
        conninfo = "";

    clock_gettime(CLOCK_MONOTONIC, &ts0);

    /* Make a connection to the database */
    conn = PQconnectdb(conninfo);

    /* Check to see that the backend connection was successfully made */
    if (PQstatus(conn) != CONNECTION_OK)
    {
        fprintf(stderr, "Connection to database failed: %s",
                PQerrorMessage(conn));
        exit_nicely(conn);
    }
    clock_gettime(CLOCK_MONOTONIC, &ts1);

    res = PQexec(conn, "select current_timestamp");
    if (PQresultStatus(res) != PGRES_TUPLES_OK)
    {
        fprintf(stderr, "Select command failed: %s", PQerrorMessage(conn));
        PQclear(res);
        exit_nicely(conn);
    }

    /* first, print out the attribute names */
    nFields = PQnfields(res);
    for (i = 0; i < nFields; i++)
        printf("%-15s", PQfname(res, i));
    printf("\n\n");

    /* next, print out the rows */
    for (i = 0; i < PQntuples(res); i++)
    {
        for (j = 0; j < nFields; j++)
            printf("%-15s", PQgetvalue(res, i, j));
        printf("\n");
    }

    PQclear(res);
    clock_gettime(CLOCK_MONOTONIC, &ts2);

    /* close the connection to the database and cleanup */
    PQfinish(conn);
    clock_gettime(CLOCK_MONOTONIC, &ts3);
    printf("%f connect\n", (ts1.tv_sec - ts0.tv_sec) + (ts1.tv_nsec - ts0.tv_nsec) * 1E-9);
    printf("%f session\n", (ts3.tv_sec - ts0.tv_sec) + (ts3.tv_nsec - ts0.tv_nsec) * 1E-9);

    return 0;
}