/* file: edf-anonymize.c	G. Moody	28 April 2010

-------------------------------------------------------------------------------
edf-anonymize: Make an anonymized copy of an EDF/EDF+ file
Copyright (C) 2010 George B. Moody

This program is free software; you can redistribute it and/or modify it under
the terms of the GNU General Public License as published by the Free Software
Foundation; either version 2 of the License, or (at your option) any later
version.

This program is distributed in the hope that it will be useful, but WITHOUT ANY
WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A
PARTICULAR PURPOSE.  See the GNU General Public License for more details.

You should have received a copy of the GNU General Public License along with
this program; if not, write to the Free Software Foundation, Inc., 59 Temple
Place - Suite 330, Boston, MA 02111-1307, USA.

You may contact the author by e-mail (george@mit.edu) or postal mail
(MIT Room E25-505A, Cambridge, MA 02139 USA).  For updates to this software,
please visit PhysioNet (http://www.physionet.org/).
_______________________________________________________________________________
*/

#include <stdio.h>
#include <stdlib.h>
#include <string.h>

main(int argc, char **argv)
{
    static char buf[1024];
    FILE *ifile, *ofile;
    int i, n;

    if (argc < 3 || strcmp(argv[1], argv[2]) == 0) {
	fprintf(stderr, "usage: %s INPUT OUTPUT [SNAME [SID [SDM]]]\n"
  " where INPUT is the name of the EDF file to be anonymized,\n"
  " OUTPUT is the name of the anonymized EDF file to be written,\n"
  " SNAME and SID are the surrogate name and ID to be written into OUTPUT,\n"
  " and SDM is the surrogate day and month to be written, in the form DD.MM\n"
  " SNAME and SID are optional and empty by default; SDM is optional and is\n"
  " '01.01' (1 January) by default\n", argv[0]);
	exit(1);
    }
    if ((ifile = fopen(argv[1], "rb")) == NULL) {
	fprintf(stderr, "%s: can't open %s\n", argv[0], argv[1]);
	exit(2);
    }
    /* All EDF/EDF+ files begin with a 256-byte fixed-format header */
    n = fread(buf, 1, sizeof(buf), ifile);
    if (n < 256) {
	fprintf(stderr, "%s: %s is too short for an EDF/EDF+ file\n"
		" No output written\n",
		argv[0], argv[1]);
	fclose(ifile);
	exit(3);
    }

    /* Replace name with surrogate name. */
    i = 0;
    if (argc > 3)
	for (i = 0; i < 80 && argv[3][i]; i++)
	    buf[i+8] = argv[3][i];
    for ( ; i < 80; i++)
	buf[i+8] = ' ';

    /* Replace id with surrogate id. */
    i = 0;
    if (argc > 4)
	for (i = 0; i < 80 && argv[4][i]; i++)
	    buf[i+88] = argv[4][i];
    for ( ; i < 80; i++)
	buf[i+88] = ' ';

    /* Replace date with surrogate date. */
    if (argc > 5) {
	if (strlen(argv[5]) == 5 && argv[5][2] == '.')
	    strncpy(buf+168, argv[5], 5);
	else {
	    fprintf(stderr, "%s: improper format for surrogate day and month\n"
		    " Correct format is DD.MM (e.g. 05.09 is 5 September)\n",
		    argv[0]);
	    fclose(ifile);
	    exit(4);
	}
    }
    else
	strncpy(buf+168, "01.01", 5);  /* 01.01 is 1 January */

    if ((ofile = fopen(argv[2], "wb")) == NULL) {
	fprintf(stderr, "%s: can't open %s\n", argv[0], argv[2]);
	fclose(ifile);
	exit(5);
    }

    /* Check the format and warn if the reserved area is not empty. */
    if (strncmp("EDF+C", buf+192, 5) == 0) {
	fprintf(stderr, "Format: EDF+C\n");
	i = 5;
    }
    else if (strncmp("EDF+D", buf+192, 5) == 0) {
	fprintf(stderr, "Format: EDF+D\n");
	i = 5;
    }
    else {
	fprintf(stderr, "Format: EDF\n");
	i = 0;
    }
    for ( ; i < 44; i++) {
	if (buf[i+192] != ' ') {
	    fprintf(stderr, "%s: WARNING\n"
		    " Reserved area of header is not empty as expected\n"
		    " Check for possible PHI in bytes %d-236 of %s\n",
		    argv[0], i+192, argv[2]);
	    break;
	}
    }

    /* Write the output, beginning with the anonymized header and copying
       the remainder of the input. */
    do 
	fwrite(buf, 1, n, ofile);
    while (n = fread(buf, 1, 1024, ifile));

    fclose(ofile);
    fclose(ifile);
    exit(0);
}