/*
 * Tool for decoding compact index values for testing.
 * Copyright © 2012 Nick Bowler
 *
 * 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, see <http://www.gnu.org/licenses/>.
 */

#include <config.h>
#include <stdio.h>
#include <stdlib.h>
#include <ctype.h>
#include <getopt.h>

#include <upkg.h>

#define PROGNAME "decodeindex"
static const char *progname = PROGNAME;
static const unsigned char sopts[] = "VH";
static const struct option lopts[] = {
	{ "version", 0, NULL, 'V' },
	{ "help",    0, NULL, 'H' },
	{ 0 }
};

/*
 * Decode a hexadecimal string into a sequence of bytes.  If there are an
 * odd number of nibbles, treat the first character as the least significant
 * nibble of the first byte.  The result is written to the buffer specified by
 * buf.  At most n bytes are written to the buffer.
 *
 * Returns the number of bytes that would be written provided that n was large
 * enough, or (size_t)-1 if the input is not valid.
 */
static size_t decode_hex(const char *hex, unsigned char *buf, size_t n)
{
	size_t len, count = 0;
	char tmp[] = "00";

	for (len = 0; hex[len]; len++) {
		if (!isxdigit(hex[len]))
			return -1;
	}

	if (!len)
		return 0;

	switch (len % 2) {
		while (len > 0) {
			case 0: tmp[0] = *hex++; len--;
			case 1: tmp[1] = *hex++; len--;

			if (count < n)
				buf[count] = strtoul(tmp, NULL, 16);
			count++;
		}
	}

	return count;
}

static void print_usage(FILE *f)
{
	fprintf(f, "Usage: %s [options] index [index ...]\n", progname);
}

static void print_version(void)
{
	printf("%s (%s) %s\n", PROGNAME, PACKAGE_NAME, PACKAGE_VERSION);
	puts("Copyright (C) 2012 Nick Bowler.");
	puts("License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>.");
	puts("This is free software: you are free to change and redistribute it.");
	puts("There is NO WARRANTY, to the extent permitted by law.");
}

static void print_bytes(FILE *f, int indent, void *buf, size_t n)
{
	fprintf(f, "%*s", indent, "");
	for (size_t i = 0; i < n; i++)
		fprintf(f, "%*s%.2hhx", i != 0, "", ((unsigned char *)buf)[i]);
	putc('\n', f);
}

static int print_index(const char *hex)
{
	unsigned char buf[32];
	long index = 0;
	size_t n, rc;
	int ret = -1;

	n = decode_hex(hex, buf, sizeof buf);
	if (n == -1) {
		fprintf(stderr, "%s: invalid hex sequence: %s\n",
		                progname, hex);
		goto out;
	} else if (n == 0) {
		fprintf(stderr, "%s: empty argument\n", progname);
		goto out;
	} else if (n > sizeof buf) {
		fprintf(stderr, "%s: hex sequence too long: %s\n",
		                progname, hex);
		goto out;
	}
		
	rc = upkg_decode_index(&index, buf, n);
	if (rc == 0) {
		fprintf(stderr, "%s: invalid index encoding:\n", progname);
		print_bytes(stderr, 4, buf, n);
		goto out;
	} else if (rc < n) {
		fprintf(stderr, "%s: trailing bytes in argument:\n", progname);
		print_bytes(stderr, 4, buf+rc, n-rc);
		/* Non-fatal */
	}

	ret = 0;
out:
	printf("%ld\n", index);
	return ret;
}

int main(int argc, char **argv)
{
	int opt, ret = EXIT_SUCCESS;

	if (argc > 0)
		progname = argv[0];

	while ((opt = getopt_long(argc, argv, sopts, lopts, NULL)) != -1) {
		switch (opt) {
		case 'V':
			print_version();
			return EXIT_SUCCESS;
		case 'H':
			print_usage(stdout);
			return EXIT_SUCCESS;
		default:
			print_usage(stderr);
			return EXIT_FAILURE;
		}
	}

	if (!argv[optind]) {
		print_usage(stderr);
		return EXIT_FAILURE;
	}

	for (int i = optind; i < argc; i++) {
		if (print_index(argv[i]) != 0) {
			ret = EXIT_FAILURE;
		}
	}

	return ret;
}