#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#include <getopt.h>

#include <image.h>
#include <macros.h>
#include <option.h>
#include <unpack.h>

enum {
	OPTION_HELP = 'h',
	OPTION_IMAGE = 'i',
	OPTION_OUTPUT = 'o',
};

struct args {
	const char *image, *output;
};

static struct opt_desc opt_descs[] = {
	{ "-i", "--image=PATH", "the image in ROTS format to unpack" },
	{ "-o", "--output=PATH", "the file to contain the payload" },
	{ "-h", "--help", "display this help and exit" },
	{ NULL, NULL, NULL },
};

static int parse_args(struct args *args, int argc, char *argv[])
{
	struct option options[] = {
		{ "help", no_argument, NULL, OPTION_HELP },
		{ "image", required_argument, NULL, OPTION_IMAGE },
		{ "output", required_argument, NULL, OPTION_OUTPUT },
		{ NULL, 0, 0, 0 },
	};
	int ret;

	while ((ret = getopt_long(argc, (char * const *)argv, "hi:o:", options,
		NULL)) >= 0) {
		switch (ret) {
		case OPTION_HELP: return -1;
		case OPTION_IMAGE: args->image = optarg; break;
		case OPTION_OUTPUT: args->output = optarg; break;
		default: return -1;
		}
	}

	if (!args->image || !args->output)
		return -1;

	return 0;
}

void show_unpack_usage(const char *prog_name, const char *cmd)
{
	fprintf(stderr, "usage: %s %s [option]...\n\n"
		"unpack the payload of an image\n\n", prog_name, cmd);
	format_options(opt_descs);
}

int do_unpack(int argc, char *argv[])
{
	char data[512];
	struct rots_hdr hdr;
	FILE *in, *out;
	struct args args;
	size_t nbytes, size;

	memset(&args, 0, sizeof args);

	if (parse_args(&args, argc, argv) < 0) {
		show_unpack_usage(argv[0], argv[1]);
		return -1;
	}

	if (!(in = fopen(args.image, "rb"))) {
		fprintf(stderr, "error: file '%s' not found.\n", args.image);
		return -1;
	}

	if (!(out = fopen(args.output, "wb"))) {
		fprintf(stderr, "error: cannot open '%s' for writing.\n", args.output);
		goto err_close_in;
	}

	if (rots_read_hdr(in, &hdr) < 0) {
		fprintf(stderr, "error: file '%s' is not a ROTS-image.\n", args.image);
		goto err_close_out;
	}

	size = hdr.size;

	while (size) {
		nbytes = fread(data, sizeof *data, min(size, sizeof data), in);

		if (nbytes == 0) {
			fprintf(stderr, "error: cannot read the next chunk.\n");
			goto err_close_out;
		}

		if (fwrite(data, sizeof *data, nbytes, out) < nbytes) {
			fprintf(stderr, "error: cannot write the current chunk.\n");
			goto err_close_out;
		}

		size -= nbytes;
	}

	fclose(out);
	fclose(in);

	return 0;

err_close_out:
	fclose(out);
err_close_in:
	fclose(in);
	return -1;
}