/*----------------------------------------------------------------------------
   
   File name    :   replacekey.c
   Author       :   N. Devillard
   Created on   :   July 14th, 1998
   Description  :   Search & Replace operations in FITS headers

 ---------------------------------------------------------------------------*/

/*
	$Id: replacekey.c,v 1.1 2001/12/14 09:15:19 ndevilla Exp $
	$Author: ndevilla $
	$Date: 2001/12/14 09:15:19 $
	$Revision: 1.1 $
 */

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

#include <stdio.h>
#include <stdlib.h>
#include <fcntl.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/mman.h>
#include <string.h>
#include <ctype.h>


/*----------------------------------------------------------------------------
                                Defines
 ---------------------------------------------------------------------------*/

#define NM_SIZ  				512
#define DEFAULT_PLACEHOLDER		"COMMENT PLACEHOLDER"

/*----------------------------------------------------------------------------
                   Private functions and module variables 
 ---------------------------------------------------------------------------*/

static char prog_desc[] = "replace keyholder in a FITS header" ;
 
static void             usage(char *) ;
static int              replace_placeholder(char *, char *, char*) ;
static int				get_FITS_header_size(char *) ;


/*----------------------------------------------------------------------------
                            main() 
 ---------------------------------------------------------------------------*/

int main(int argc, char *argv[])
{
    char            name_in[NM_SIZ] ;
	char			placeholder[NM_SIZ] ;
	char			card[NM_SIZ] ;

    if (argc<3) usage(argv[0]) ;
    strncpy(name_in, argv[1], NM_SIZ) ;
    strncpy(card, argv[2], NM_SIZ) ;
	if (argc==4) {
		strncpy(placeholder, argv[3], NM_SIZ) ;
	} else {
		strncpy(placeholder, DEFAULT_PLACEHOLDER, NM_SIZ);
	}

	/*
	 * Sanity tests
	 */
	if (strlen(card)>80) {
		fprintf(stderr, "requested card is too long: %d chars\n",strlen(card));
		return -1;
	}

    if (replace_placeholder(name_in, card, placeholder) != 0) {
        fprintf(stderr, "error during placeholder replacement: aborting\n") ;
    }
    return 0 ;
}


/*
 * This function only gives the usage for the program
 */

static void usage(char *pname)
{
    printf("%s : %s\n", pname, prog_desc) ;
    printf("use : %s <in> <card> [placeholder]\n", pname) ;
    printf("\n\n") ;
    exit(0) ;
}


/*---------------------------------------------------------------------------
   Function :   replace_placeholder()
   In       :   name of the FITS file to modify, card to insert,
			    name of the placeholder
   Out      :   int 0 if Ok, anything else otherwise
   Job      :   replaces a placeholder by a given FITS card
   Notice   :   modifies the input FITS file
   				Does not check the validity of the given FITS card
 ---------------------------------------------------------------------------*/


static int replace_placeholder(
	char * name_in,
	char * card,
	char * placeholder)
{
    int         fd ;
    char    *   buf ;
	char    *   where ;
    int			hs ;

    /*
     * mmap the FITS header of the input file 
     */

    hs = get_FITS_header_size(name_in) ; 
    if (hs < 1) {
        fprintf(stderr, "error getting FITS header size for %s\n", name_in);
        return -1 ;
    }
    fd = open(name_in, O_RDWR) ;
    if (fd == -1) {
        fprintf(stderr, "cannot open %s: aborting\n", name_in) ;
        return -1 ;
    }
    buf = (char*)mmap(0,
                      hs,
                      PROT_READ | PROT_WRITE,
                      MAP_SHARED,
                      fd,
                      0) ;
    if (buf == (char*)-1) {
        perror("mmap") ;
        fprintf(stderr, "cannot mmap file: %s\n", name_in) ;
        close(fd) ;
        return -1 ;
    }

    /*
     * Apply search and replace for the input keyword lists
     */

	where = buf ;
	do {
		where = strstr(where, placeholder);
		if (where == NULL) {
			fprintf(stderr, "not found in input: [%s]\n", placeholder) ;
			close(fd);
			munmap(buf,hs);
			return -1 ;
		}
	} while ((where-buf)%80) ;

	/* Replace current placeholder by blanks */
	memset(where, ' ', 80);
	/* Copy card into placeholder */
	memcpy(where, card, strlen(card));

    close(fd) ;
    munmap(buf, hs) ;
    return 0 ;
}


/*---------------------------------------------------------------------------
   Function :   get_FITS_header_size()
   In       :   FITS file name
   Out      :   unsigned long
   Job      :   compute the size (in bytes) of a FITS header
   Notice   :   should always be a multiple of 2880. This implementation
               assumes only that 80 characters are found per line.
 ---------------------------------------------------------------------------*/

#define FITS_BLSZ 2880
static int get_FITS_header_size(char * name)
{
    FILE    *   in ;
    char        line[81] ;
    int         found = 0 ;
    int         count ;
    int         hs ;

    if ((in = fopen(name, "r")) == NULL) {
        fprintf(stderr, "cannot open %s: aborting\n", name) ;
        return 0 ;
    }
    count = 0 ;
    while (!found) {
        if (fread(line, 1, 80, in)!=80) {
            break ;
        }
        count ++ ;
        if (!strncmp(line, "END ", 4)) {
            found = 1 ;
        }
    }
    fclose(in);

    if (!found) return 0 ;
    /*
     * The size is the number of found cards times 80,
     * rounded to the closest higher multiple of 2880.
     */
    hs = count * 80 ;
    if ((hs % FITS_BLSZ) != 0) {
        hs = (1+(hs/FITS_BLSZ)) * FITS_BLSZ ;
    }
    return hs ;
}
#undef FITS_BLSZ

/*------------------------------ end of file ------------------------------*/