/*
 * otpcli - CLI utility for generating OTPs
 *
 * Written in 2020 by Lucas
 *
 * To the extent possible under law, the author(s) have dedicated all
 * copyright and related and neighboring rights to this software to the
 * public domain worldwide. This software is distributed without any
 * warranty.
 *
 * You should have received a copy of the CC0 Public Domain Dedication
 * along with this software. If not, see
 * <http://creativecommons.org/publicdomain/zero/1.0/>.
 */

#include <errno.h>
#include <inttypes.h>
#include <limits.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>

#include "err.h"
#include "mystrtonum.h"
#include "otp.h"

extern const char *__progname;

static void
usage(void)
{
	fprintf(stderr, "Usage: %s [-H counter] SECRET\n", __progname);
	exit(1);
}

int
main(int argc, char *argv[])
{
	const char *errstr;
	uint64_t counter;
	int32_t r;
	int ch, do_hotp;

	counter = 0;
	do_hotp = 0;
	while ((ch = getopt(argc, argv, "H:")) != -1) {
		switch (ch) {
		case 'H':
			counter = mystrtonum(optarg, 0, LLONG_MAX, &errstr);
			if (errstr != NULL)
				errx(1, "counter is %s: %s", errstr, optarg);
			do_hotp = 1;
			break;
		default:
			usage();
		}
	}
	argc -= optind;
	argv += optind;

	if (argc != 1)
		usage();

	if (do_hotp) {
		r = hotp(OTP_HMAC_SHA1, argv[0], strlen(argv[0]), counter, 6);
		if (r == -1)
			errx(1, "couldn't calculate HOTP");
		printf("%" PRId32 "\n", r);
	} else
		errx(1, "TOTP unimplemented");

	return 0;
}