#include <unistd.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <grass/gis.h>
#include "cseg.h"

int cseg_open (CSEG *cseg, int srows, int scols, int nsegs_in_memory)
{
	char	*filename;
	int	errflag;
	int 	fd;

	cseg->filename = NULL;
	cseg->fd       = -1;
	cseg->name     = NULL;
	cseg->mapset   = NULL;

	filename = G_tempfile ();
	if (-1 == (fd = creat (filename, 0666)))
	{
		G_warning ("cseg_open(): unable to create segment file");
		return -2;
	}
	if (0 > (errflag = segment_format (fd, G_window_rows(), G_window_cols(), srows, scols, sizeof(CELL))))
	{
		close (fd);
		unlink (filename);
		if (errflag == -1)
		{
			G_warning ("cseg_open(): could not write segment file");
			return -1;
		}
		else
		{
			G_warning ("cseg_open(): illegal configuration parameter(s)");
			return -3;
		}
	}
	close (fd);
	if (-1 == (fd = open(filename, 2)))
	{
		unlink (filename);
		G_warning ("cseg_open(): unable to re-open segment file");
		return -4;
	}
	if (0 > (errflag = segment_init (&(cseg->seg), fd, nsegs_in_memory)))
	{
		close (fd);
		unlink (filename);
		if (errflag == -1)
		{
			G_warning ("cseg_open(): could not read segment file");
			return -5;
		}
		else
		{
			G_warning ("cseg_open(): out of memory");
			return -6;
		}
	}
	cseg->filename = filename;
	cseg->fd       = fd;
	return 0;
}