/*----------------------------------------------------------------------------*/
/**
   @file    flipx.c
   @author  N. Devillard
   @date    July 2001
   @version	$Revision: 1.5 $
   @brief   flip x axis in a FITS image
*/
/*----------------------------------------------------------------------------*/

/*
	$Id: flipx.c,v 1.5 2002/12/04 13:28:25 yjung Exp $
	$Author: yjung $
	$Date: 2002/12/04 13:28:25 $
	$Revision: 1.5 $
*/

/*-----------------------------------------------------------------------------
   								Includes
 -----------------------------------------------------------------------------*/

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <sys/mman.h>
#include <fcntl.h>
#include "qfits.h"

/*-----------------------------------------------------------------------------
							Private functions
 -----------------------------------------------------------------------------*/

/*
 * Swap pixels between position p1 and p2, regardless of the pixel
 * type and endian-ness of the local host.
 */
static void
swap_pix (char *buf, int p1, int p2, int psize)
{
  int i;
  char c;

  for (i = 0; i < psize; i++)
    {
      c = buf[p1 + i];
      buf[p1 + i] = buf[p2 + i];
      buf[p2 + i] = c;
    }
}

/*
 * Main processing function. It expects one only file name
 * and will flip pixels on the input frame.
 */
static int
fits_flip (char *pname, char *filename)
{
  char *sval;
  int dstart;
  int lx, ly;
  int bpp;
  int i, j;
  char *buf;
  char *fbuf;
  int psize;
  struct stat fileinfo;
  int fd;

  printf ("%s: processing %s\n", pname, filename);

  if (stat (filename, &fileinfo) != 0)
    {
      return -1;
    }
  if (fileinfo.st_size < 1)
    {
      printf ("cannot stat file\n");
      return -1;
    }

  /* Retrieve image attributes */
  if (is_fits_file (filename) != 1)
    {
      printf ("not a FITS file\n");
      return -1;
    }

  sval = qfits_query_hdr (filename, "NAXIS1");
  if (sval == NULL)
    {
      printf ("cannot read NAXIS1\n");
      return -1;
    }
  lx = atoi (sval);
  sval = qfits_query_hdr (filename, "NAXIS2");
  if (sval == NULL)
    {
      printf ("cannot read NAXIS2\n");
      return -1;
    }
  ly = atoi (sval);
  sval = qfits_query_hdr (filename, "BITPIX");
  if (sval == NULL)
    {
      printf ("cannot read BITPIX\n");
      return -1;
    }
  bpp = atoi (sval);

  psize = bpp / 8;
  if (psize < 0)
    psize = -psize;

  /* Retrieve start of first data section */
  if (qfits_get_hdrinfo (filename, 0, &dstart, NULL) != 0)
    {
      printf ("reading header information\n");
      return -1;
    }

  /* Map the input file in read/write mode (input file is modified) */
  if ((fd = open (filename, O_RDWR)) == -1)
    {
      perror ("open");
      printf ("reading file\n");
      return -1;
    }
  fbuf = (char *) mmap (0,
			fileinfo.st_size,
			PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0);
  if (fbuf == (char *) -1)
    {
      perror ("mmap");
      printf ("mapping file\n");
      return -1;
    }
  buf = fbuf + dstart;

  /* Double loop */
  for (j = 0; j < ly; j++)
    {
      for (i = 0; i < lx / 2; i++)
	{
	  /* Swap bytes */
	  swap_pix (buf, i * psize, (lx - i - 1) * psize, psize);
	}
      buf += lx * psize;
    }
  if (munmap (fbuf, fileinfo.st_size) != 0)
    {
      printf ("unmapping file\n");
      return -1;
    }
  return 0;
}

/*-----------------------------------------------------------------------------
								Main
 -----------------------------------------------------------------------------*/
int
main (int argc, char *argv[])
{
  int i;
  int err;

  if (argc < 2)
    {
      printf ("use: %s <list of FITS files...>\n", argv[0]);
      return 1;
    }
  err = 0;
  for (i = 1; i < argc; i++)
    {
      err += fits_flip (argv[0], argv[i]);
    }
  if (err > 0)
    {
      fprintf (stderr, "%s: %d error(s) occurred\n", argv[0], err);
      return -1;
    }
  return 0;
}