/*
 * This file is part of libsamsung-ipc.
 *
 * Copyright (C) 2023 Denis 'GNUtoo' Carikli <GNUtoo@cyberdimension.org>
 *
 * libsamsung-ipc 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.
 *
 * libsamsung-ipc 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 libsamsung-ipc.  If not, see <http://www.gnu.org/licenses/>.
 */

#include <errno.h>
#include <fcntl.h>
#include <libgen.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sysexits.h>
#include <unistd.h>

void usage(char *progname)
{
	printf("Usage:\n");
	printf("\t%s FILE command <index>    # %s\n",
	       basename(progname),
	       "Get bruteforce command.");
	printf("\t%s FILE bruteforce <index> # %s\n",
	       basename(progname),
	       "Get bruteforce command.");
	printf("\t%s list-supported          # %s\n",
	       basename(progname),
	       "List supported devices/EFS.");
	printf("\t%s --help                  # %s\n",
	       basename(progname),
	       "Print this help.");
}

int print_byte(int fd, off_t base, uint8_t offset)
{
	off_t file_offset;
	ssize_t rd;
	char buf[1];
	int rc;

	bzero(&buf, sizeof(buf));

	file_offset = lseek(fd, base + offset, SEEK_SET);
	if (file_offset == -1) {
		int err = errno;
		printf("%s: lseek: %s\n", __func__, strerror(err));
		return EX_OSERR;
	}

	do {
		rd = read(fd, &buf, 1);
		if (rd == -1) {
			int err = errno;
			printf("%s: read: %s\n", __func__, strerror(err));
			return EX_OSERR;
		}
	} while (rd != 1);

	rc = printf("%02x", buf[0] & 0xff);
	if (rc < 0) {
		int err = errno;
		printf("%s: printf: %s\n", __func__, strerror(err));
		return EX_OSERR;
	}

	return 0;
}

off_t field_offset(unsigned field_nr)
{
	if (field_nr == 0)
		return 0x18146e;
	else if (field_nr == 1)
		return 0x18148e;
	else if (field_nr == 2)
		return 0x1814ce;
	else if (field_nr == 3)
		return 0x1814fe;
	else
		return 0;
}

int cmd_list_supported(void)
{

	printf("Supported devices:\n\t%s\n",
	       "Galaxy S II (GT-I9100)");

	return 0;
}


int cmd_command(char* nv_data_path, int field_nr)
{
	int fd;
	int rc;
	int i;
	off_t base;

	base = field_offset(field_nr);
	if (base == 0) {
		printf("%s: invalid field_offset: 0\n", __func__);
		return EX_SOFTWARE;
	}

	fd = open(nv_data_path, O_RDONLY);
	if (fd == -1) {
		printf("%s: open: %s\n", __func__, strerror(errno));
		return EX_NOINPUT;
	}

	printf("hashcat -m 110 --hex-salt -a 3 ");
	for (i=0; i<20 ; i++) {
		rc = print_byte(fd, base, i);
		if (rc)
			return rc;
	}

	rc = printf(":0000000000000000 ?d?d?d?d?d?d?d?d --show"
		    " | "
		    "cut -d : -f 3\n");
	if (rc == -1) {
		printf("%s: printf: %s\n", __func__, strerror(errno));
		return EX_OSERR;
	}

	rc = close (fd);
	if (fd == -1) {
		printf("%s: close: %s\n", __func__, strerror(errno));
		return EX_OSERR;
	}

	return 0;
}

int cmd_bruteforce()
{
	return 0;
}

int main(int argc, char * const argv[])
{
	if (argc == 4 && !strcmp(argv[2], "command")) {
		char *endptr;
		int field_nr = 0;

		field_nr = strtol(argv[3], &endptr, 10);
		if (errno != 0) {
			usage(argv[0]);
			return EX_USAGE;
		}

		if (!(argv[3][0] != '\0' && *endptr == '\0')) {
			usage(argv[0]);
			return EX_USAGE;
		}

		return cmd_command(argv[1], field_nr);
	} else if (argc == 4 && !strcmp(argv[2], "bruteforce")) {
		char *endptr;
		int field_nr = 0;

		field_nr = strtol(argv[3], &endptr, 10);
		if (errno != 0) {
			usage(argv[0]);
			return EX_USAGE;
		}

		if (!(argv[3][0] != '\0' && *endptr == '\0')) {
			usage(argv[0]);
			return EX_USAGE;
		}

		return cmd_bruteforce(argv[1], field_nr);
	} else if (argc == 2 && !strcmp(argv[1], "list-supported")) {
		return cmd_list_supported();
	} else if (argc == 2 && !strcmp(argv[1], "--help")) {
		usage(argv[0]);
		return 0;
	} else {
		usage(argv[0]);
		return EX_USAGE;
	}

}