/*
 * testlibpq.c
 * 	Test the C version of LIBPQ, the POSTGRES frontend library.
 *
 *
 */
#include <stdio.h>
#include "libpq-fe.h"

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

main()
{
  char *pghost, *pgport, *pgoptions, *pgtty;
  char* dbName;
  int nFields;
  int i,j;

#ifdef DEBUG
 FILE *debug; 
#endif /* DEBUG */

  PGconn* conn;
  PGresult* res;

  /* begin, by setting the parameters for a backend connection
     if the parameters are null, then the system will try to use
     reasonable defaults by looking up environment variables 
     or, failing that, using hardwired constants */
  pghost = NULL;  /* host name of the backend server */
  pgport = NULL;  /* port of the backend server */
  pgoptions = NULL; /* special options to start up the backend server */
  pgtty = NULL;     /* debugging tty for the backend server */
  dbName = "template1";

  /* make a connection to the database */
  conn = PQsetdb(pghost, pgport, pgoptions, pgtty, dbName);

  /* check to see that the backend connection was successfully made */
  if (PQstatus(conn) == CONNECTION_BAD) {
    fprintf(stderr,"Connection to database '%s' failed.\n", dbName);
    fprintf(stderr,"%s",PQerrorMessage(conn));
    exit_nicely(conn);
  }

#ifdef DEBUG
  debug = fopen("/tmp/trace.out","w");  
  PQtrace(conn, debug);  
#endif /* DEBUG */

  /* start a transaction block */
  res = PQexec(conn,"BEGIN"); 
  if (PQresultStatus(res) != PGRES_COMMAND_OK) {
    fprintf(stderr,"BEGIN command failed\n");
    PQclear(res);
    exit_nicely(conn);
  }
  /* should PQclear PGresult whenever it is no longer needed to avoid
     memory leaks */
  PQclear(res); 

  /* fetch instances from the pg_database, the system catalog of databases*/
  res = PQexec(conn,"DECLARE myportal CURSOR FOR select * from pg_database");
  if (PQresultStatus(res) != PGRES_COMMAND_OK) {
    fprintf(stderr,"DECLARE CURSOR command failed\n");
    PQclear(res);
    exit_nicely(conn);
  }
  PQclear(res);

  res = PQexec(conn,"FETCH ALL in myportal");
  if (PQresultStatus(res) != PGRES_TUPLES_OK) {
    fprintf(stderr,"FETCH ALL command didn't return tuples properly\n");
    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 instances */
  for (i=0; i < PQntuples(res); i++) {
    for (j=0  ; j < nFields; j++) {
      printf("%-15s", PQgetvalue(res,i,j));
    }
    printf("\n");
  }

  PQclear(res);
  
  /* close the portal */
  res = PQexec(conn, "CLOSE myportal");
  PQclear(res);

  /* end the transaction */
  res = PQexec(conn, "END");
  PQclear(res);

  /* close the connection to the database and cleanup */
  PQfinish(conn);

#ifdef DEBUG
  fclose(debug); 
#endif /* DEBUG */

  exit(0);
}
  

