/*
 * Tool for testing PCX run-length encoding.
 * Copyright © 2012, 2022 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 <https://www.gnu.org/licenses/>.
 */

#include <config.h>
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <getopt.h>
#include <errno.h>
#include <assert.h>

#include <engine/pcx.h>
#include "common.h"

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

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

static void print_help(void)
{
	print_usage(stdout);
	test_print_options(lopts);
}

static void rle_error(const unsigned char *raw, size_t n, const char *str)
{
	fprintf(stderr, "%s: %s\n", progname, str);
	fprintf(stderr, "%s: raw input was:\n", progname);

	fprintf(stderr, "%*s", 4, "");
	for (size_t i = 0; i < n; i++)
		printf("%.2hhx", raw[i]);
	putchar('\n');
}

static int compare_rle(const unsigned char *rle_buf, size_t rle_len,
                       const unsigned char *raw_buf, size_t raw_len)
{
	unsigned char tmp[raw_len];
	size_t offset = 0;

	for (size_t i = 0; i < rle_len; i++) {
		size_t count = 1;

		if ((rle_buf[i] & 0xc0) == 0xc0) {
			count = rle_buf[i] & 0x3f;
			if (++i >= rle_len) {
				rle_error(raw_buf, raw_len, "invalid RLE encoding");
				return -1;
			}
		}

		if (offset + count > raw_len) {
			rle_error(raw_buf, raw_len, "RLE expansion exceeds raw size");
			return -1;
		}

		memset(tmp+offset, rle_buf[i], count);
		offset += count;
	}

	if (offset < raw_len) {
		rle_error(raw_buf, raw_len, "RLE expansion falls short of raw size");
		return -1;
	}

	if (memcmp(raw_buf, tmp, raw_len) != 0) {
		rle_error(raw_buf, raw_len, "RLE expansion does not match raw data");
		return -1;
	}

	return 0;
}

static int encode_rle(FILE *tmp, const char *hex)
{
	unsigned char buf[256], rle_buf[sizeof buf*2];
	struct pcx_head head;
	int rc, ret = -1;
	long offset;
	size_t n;

	n = test_decode_hex(hex, buf, sizeof buf);
	if (n == -1) {
		fprintf(stderr, "%s: invalid hex sequence: %s\n",
		                progname, hex);
		return -1;
	} else if (n == 0) {
		fprintf(stderr, "%s: empty argument\n", progname);
		return -1;
	} else if (n > sizeof buf) {
		fprintf(stderr, "%s: hex sequence too long: %s\n",
		                progname, hex);
		return -1;
	}

	rewind(tmp);
	head.width = head.height = n;
	rc = pcx_write_scanline(&head, buf, tmp);
	if (rc != 0) {
		fprintf(stderr, "%s: failed to encode data: %s\n",
		                progname, strerror(errno));
		return -1;
	}

	offset = ftell(tmp);
	if (offset < 0) {
		fprintf(stderr, "%s: failed to get file offset: %s\n",
		                progname, strerror(errno));
		return -1;
	}
	rewind(tmp);

	if (fread(rle_buf, offset, 1, tmp) != 1) {
		fprintf(stderr, "%s: failed to read RLE data: %s\n",
		                progname, strerror(errno));
		return -1;
	}

	ret = compare_rle(rle_buf, offset, buf, n);
	for (long i = 0; i < offset; i++)
		printf("%.2hhx", rle_buf[i]);
	putchar('\n');
	return ret;
}

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

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

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

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

	tmp = tmpfile();
	if (!tmp) {
		fprintf(stderr, "%s: failed to create temporary file: %s\n",
		                progname, strerror(errno));
		return EXIT_FAILURE;
	}

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

	return ret;
}