/* A reverse-engineered implementation of the EasyCard data format */

/* (C) 2010 by Harald Welte <laforge@gnumonks.org>
 * All Rights Reserved
 *
 * 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 3 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.,
 * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 */

/* System includes */
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <stdint.h>
#include <fcntl.h>
#include <string.h>
#include <time.h>
#include <errno.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <sys/mman.h>
#include <netinet/in.h>

/* libnfc includes */
#include <nfc/nfc-types.h>
#include <nfc/mifaretag.h>

#include "mifare_classic.h"

/* Easycard specific includes */
#include "easycard.h"

time_t easy_timestamp2time(const uint8_t *easy_ts)
{
	return (easy_ts[2] << 16 | easy_ts[1] << 8 | easy_ts[0]) << 8;
}

/* apply a telta (positive or negative) to a EasyCard log record */
int easy_update_log_rec(struct easy_log_rec *elr, int16_t delta)
{
	int32_t sum = elr->amount + delta;
	int32_t remaining = elr->remaining = delta;

	if ((sum < 0 || sum > 0xffff) ||
	    (remaining < 0 || remaining > 0xffff))
		return -ERANGE;

	elr->amount = sum;
	elr->remaining = remaining;

	return 0;
}

/* apply a delta to the 'sum of day' record in Sector 15 Block 2 */
int easy_update_sum_of_day(struct easy_sect15blk2 *s15b2, int16_t delta)
{
	int32_t sum = s15b2->sum_of_day + delta;

	if (sum < 0 || sum > 0xffff)
		return -ERANGE;

	s15b2->sum_of_day = sum;

	return 0;
}

static char tsbuf[64];
char *easy_asc_timestamp(const uint8_t *timestamp)
{
	time_t t_time = easy_timestamp2time(timestamp);
	struct tm *t_tm = gmtime(&t_time);
	memset(tsbuf, 0, sizeof(tsbuf));
	snprintf(tsbuf, sizeof(tsbuf), "%4u-%02u-%02u %02u:%02u",
		t_tm->tm_year+1900, t_tm->tm_mon+1, t_tm->tm_mday,
		t_tm->tm_hour, t_tm->tm_min);
	return tsbuf;
}