/* SPDX-License-Identifier: GPL-2.0-or-later */
/* SPDX-FileCopyrightText: 2020 Laurent Pinchart <laurent.pinchart@ideasonboard.com> */

#include <errno.h>
#include <fcntl.h>
#include <getopt.h>
#include <stdbool.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <unistd.h>

#include "crc.c"

struct image_rect {
	int left;
	int top;
	unsigned int width;
	unsigned int height;
};

struct image_size {
	unsigned int width;
	unsigned int height;
};

struct options {
	const char *filename;
	struct image_rect crop;
	struct image_size size;
};

/* -----------------------------------------------------------------------------
 * Miscellaneous helpers
 */

static bool rect_is_empty(const struct image_rect *rect)
{
	return !rect->width || !rect->height;
}

static bool rect_is_null(const struct image_rect *rect)
{
	return !rect->left && !rect->top && !rect->width && !rect->height;
}

static bool size_is_null(const struct image_size *size)
{
	return !size->width && !size->height;
}

static int readall(int fd, void *buf, size_t count)
{
	int ret;

	do {
		ret = read(fd, buf, count);
		if (ret == -1)
			return -errno;
		if (ret == 0)
			return -ENODATA;

		count -= ret;
		buf += ret;
	} while (count);

	return 0;
}

/* -----------------------------------------------------------------------------
 * Usage and argument parsing
 */

static void usage(const char *argv0)
{
	printf("Usage: %s [options] <infile>\n\n", argv0);
	printf("Calculate the R-Car DISCOM CRC for the image stored in <infile>\n\n");
	printf("Supported options:\n");
	printf("-c, --crop (X,Y)/WxH		Crop the input image (needs --size)\n");
	printf("-s, --size WxH			Input image size\n");
}

static struct option opts[] = {
	{"crop", 1, 0, 'c'},
	{"size", 1, 0, 's'},
	{0, 0, 0, 0}
};

static int parse_args(struct options *options, int argc, char *argv[])
{
	int ret;
	int c;

	if (argc < 2) {
		usage(argv[0]);
		return 1;
	}

	memset(options, 0, sizeof(*options));

	opterr = 0;
	while ((c = getopt_long(argc, argv, "c:s:", opts, NULL)) != -1) {
		int count;

		switch (c) {
		case 'c':
			ret = sscanf(optarg, "(%d,%d)/%ux%u%n",
				     &options->crop.left, &options->crop.top,
				     &options->crop.width, &options->crop.height,
				     &count);
			if (ret != 4 || count != (int)strlen(optarg)) {
				printf("Invalid crop value '%s'\n", optarg);
				return 1;
			}
			break;

		case 's':
			ret = sscanf(optarg, "%ux%u%n",
				     &options->size.width, &options->size.height,
				     &count);
			if (ret != 2 || count != (int)strlen(optarg)) {
				printf("Invalid size value '%s'\n", optarg);
				return 1;
			}
			break;

		default:
			printf("Invalid option -%c\n", c);
			printf("Run %s -h for help.\n", argv[0]);
			return 1;
		}
	}

	if (optind != argc - 1) {
		usage(argv[0]);
		return 1;
	}

	options->filename = argv[optind];

	return 0;
}

/* -----------------------------------------------------------------------------
 * Main
 */

int main(int argc, char *argv[])
{
	struct options options;
	void *image = NULL;
	uint32_t crc;
	off_t offset;
	off_t size;
	int fd = -1;
	int ret;

	/* Parse and validate options. */
	ret = parse_args(&options, argc, argv);
	if (ret)
		return ret;

	if (!rect_is_null(&options.crop)) {
		if (size_is_null(&options.size)) {
			printf("--crop requires --size\n");
			goto error;
		}

		if (rect_is_empty(&options.crop)) {
			printf("Crop rectangle is empty\n");
			goto error;
		}

		if (options.crop.left < 0 || options.crop.top < 0 ||
		    options.crop.left + options.crop.width > options.size.width ||
		    options.crop.top + options.crop.height > options.size.height) {
			printf("Crop rectangle out of image bounds\n");
			goto error;
		}
	}

	/* Open the file and determine its size. */
	fd = open(options.filename, O_RDONLY);
	if (fd == -1) {
		printf("Failed to open '%s': %s\n", options.filename,
		       strerror(errno));
		goto error;
	}

	size = lseek(fd, 0, SEEK_END);
	if (size == -1) {
		printf("Failed to determine file size: %s\n", strerror(errno));
		goto error;
	}

	if (!size_is_null(&options.size) &&
	    options.size.width * options.size.height * 4 != size) {
		printf("Image size %ux%u doesn't match file size %jd\n",
		       options.size.width, options.size.height, (intmax_t)size);
		goto error;
	}

	/* Read the image data. */
	if (!rect_is_null(&options.crop))
		size = options.crop.width * options.crop.height * 4;

	image = malloc(size);
	if (!image) {
		printf("Unable to allocate memory for image data\n");
		goto error;
	}

	offset = (options.crop.top * options.size.width + options.crop.left) * 4;
	lseek(fd, offset, SEEK_SET);

	if (!options.crop.width || options.crop.width == options.size.width) {
		/*
		 * When the crop rectangle width spans the whole image, read it
		 * in one go.
		 */
		ret = readall(fd, image, size);
		if (ret < 0) {
			printf("Unable to read image: %s\n", strerror(errno));
			goto error;
		}
	} else {
		/* Otherwise, read line by line. */
		void *line = image;
		unsigned int y;

		offset = (options.size.width - options.crop.width) * 4;

		for (y = 0; y < options.crop.height; ++y) {
			ret = readall(fd, line, options.crop.width * 4);
			if (ret < 0) {
				printf("Unable to read line %u: %s\n", y,
				       strerror(errno));
				goto error;
			}

			lseek(fd, offset, SEEK_CUR);
			line += options.crop.width * 4;
		}
	}

	close(fd);
	fd = -1;

	/*
	 * Compute the CRC. The generate CRC code XORs the initial value with
	 * the final XOR value, so we need to pass 0 to get the desired
	 * 0xffffffff initial value.
	 */
	crc = calculate_crc(image, size, 0);

	free(image);
	image = NULL;

	printf("0x%08x\n", crc);

	return 0;

error:
	free(image);
	if (fd != -1)
		close(fd);
	return 1;
}