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

// program dla danego zapytania SQL printuje je w postaci JSON na ekran
// przyklad uzycia:
// ./zadanie "select * from kurs1.kurs;"

// funkcja drukujaca na ekran rezultat polecania w formie JSON
void printJSON(PGresult *result) {

    int row, field;
    int nrows   = PQntuples(result);
    int nfields = PQnfields(result);
    printf("[");
    for(row = 0; row < nrows; ++row) {
            printf("{");
        for(field = 0; field < nfields; field++) {
                printf("\"%s\":\"%s\"", PQfname(result, field), PQgetvalue(result, row, field), PQgetlength(result, row, field));
        if (field != nfields -1)
            printf(", ");
    }
        printf(row != nrows - 1 ? "},\n" : "}");
    }
    printf("]\n");

    return;
}



void doSQL(PGconn *conn, char *command){
    PGresult *result;
    printf("------------------------------\n");
    printf("%s\n", command);
    result = PQexec(conn, command);
    printf("status is : %s\n", PQresStatus(PQresultStatus(result)));
    printf("#rows affected: %s\n", PQcmdTuples(result));
    printf("JSON: %s\n", PQresultErrorMessage(result));
    if (PQresultStatus(result) == PGRES_TUPLES_OK)
        printJSON(result);
    PQclear(result);
}

int main(int argc, char * argv[] ){
    PGresult *result;
    PGconn *conn;
    const char *connection_str = "host=localhost port=5432 dbname=u6podsiadlo user=u6podsiadlo  password=6podsiadlo";
    conn = PQconnectdb(connection_str);
    if (PQstatus(conn) == CONNECTION_BAD) {
            fprintf(stderr, "Connection to %s failed, %s", connection_str, PQerrorMessage(conn));
    }
    else {
            printf("Connected OK\n");
            doSQL(conn, argv[1]);
    }
    PQfinish(conn);
    return EXIT_SUCCESS;
}