/***************************************************************************
                       msi.cpp  -  description
                           -------------------
  begin                : Mie Jun 18 2003
  copyright            : (C) 2003 by InfoSiAL, S.L.
  email                : mail@infosial.com
***************************************************************************/ 
/***************************************************************************
 *                                                                         *
 *   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.                                   *
 *                                                                         *
 ***************************************************************************/

/*
 * msi.c -- encoding for MSI-Plessey
 *
 * Copyright (c) 2000 Leonid A. Broukhis (leob@mailcom.com)
 *
 *   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.
 */

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

#include "barcode.h"


/* Patterns */
static char *patterns[] = { "13", "31" };

static char *fillers[] = { "031", "131" };

static int width = 16 /* each character uses 4 patterns */ ,
                   startpos = 6 /* length of the first filler */ ;

/*
 * Check that the text can be encoded. Returns 0 or -1.
 */
int Barcode_msi_verify( char *text ) {
	int i;

	if ( !strlen( text ) )
		return -1;
	for ( i = 0; text[ i ]; i++ ) {
		if ( !isdigit( text[ i ] ) )
			return -1;
	}
	return 0;
}

static int add_one( char *ptr, int code ) {
	sprintf( ptr, "%s%s%s%s",
	         patterns[ ( code >> 3 ) & 1 ],
	         patterns[ ( code >> 2 ) & 1 ],
	         patterns[ ( code >> 1 ) & 1 ], patterns[ code & 1 ] );
	return 0;
}

/*
 * The encoding functions fills the "partial" and "textinfo" fields.
 * Lowercase chars are converted to uppercase
 */
int Barcode_msi_encode( struct Barcode_Item *bc ) {
	static char *text;
	static char *partial;				/* dynamic */
	static char *textinfo;			/* dynamic */
	char *ptr, *textptr;
	int i, code, textpos, usesum, checksum = 0;

	if ( bc->partial )
		free( bc->partial );
	if ( bc->textinfo )
		free( bc->textinfo );
	bc->partial = bc->textinfo = NULL;	/* safe */

	if ( !bc->encoding )
		bc->encoding = strdup( "msi" );

	if ( ( bc->flags & BARCODE_NO_CHECKSUM ) )
		usesum = 0;
	else
		usesum = 1;

	text = bc->ascii;

	/* the partial code is head + 8 * (text + check) + tail + margin + term. */
	partial = ( char * ) malloc( 3 + 8 * ( strlen( text ) + 1 ) + 3 + 2 );
	if ( !partial ) {
		bc->error = errno;
		return -1;
	}

	/* the text information is at most "nnn:fff:c " * strlen +term */
	textinfo = ( char * ) malloc( 10 * strlen( text ) + 2 );
	if ( !textinfo ) {
		bc->error = errno;
		free( partial );
		return -1;
	}

	strcpy( partial, fillers[ 0 ] );
	ptr = partial + strlen( partial );
	textptr = textinfo;
	textpos = startpos;

	for ( i = 0; i < strlen( text ); i++ ) {
		code = text[ i ] - '0';
		add_one( ptr, code );
		sprintf( textptr, "%i:12:%c ", textpos, text[ i ] );

		textpos += width;				/* width of each code */
		textptr += strlen( textptr );
		ptr += strlen( ptr );
		if ( usesum ) {
			/* For a code ...FEDCBA the checksum is computed
			 * as the sum of digits of the number ...FDB plus
			 * the sum of digits of the number ...ECA * 2.
			 * Which is equivalent to the sum of each digit of ...ECA doubled
			 * plus carry.
			 */
			if ( ( i ^ strlen( text ) ) & 1 ) {
				/* a last digit, 2 away from last, etc. */
				checksum += 2 * code + ( 2 * code ) / 10;
			} else {
				checksum += code;
			}
		}
	}
	/* Some implementations use a double checksum. Currently the only way
	 * to print a barcode with double checksum is to put the checksum
	 * digit printed below at the end of a code in the command line
	 * and re-run the program.
	 */
	if ( usesum ) {
		/* the check digit is the complement of the checksum
		 * to a multiple of 10.
		 */
		checksum = ( checksum + 9 ) / 10 * 10 - checksum;
		/* fprintf(stderr, "Checksum: %d\n", checksum); */
		add_one( ptr, checksum );
		ptr += strlen( ptr );
	}

	strcpy( ptr, fillers[ 1 ] );
	bc->partial = partial;
	bc->textinfo = textinfo;

	return 0;
}