#include <getopt.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>

static void usage(const char *progname)
{
	static const int width = 24;

	printf("usage: %s -h\n", progname);
	printf("       %s -bo[ABC] [files...]\n\n", progname);
	printf("\t%-*s%s\n", width, "-h",                   "Show this help text");
	printf("\t%-*s%s\n", width, "-b bootsector",        "Bootsector image");
	printf("\t%-*s%s\n", width, "-o output",            "Output isofs file");
	printf("\t%-*s%s\n", width, "-A abstract_path",     "Path in isofs of abstract file");
	printf("\t%-*s%s\n", width, "-B bibliography_path", "Path in isofs of bibliography file");
	printf("\t%-*s%s\n", width, "-C copyright_path",    "Path in isofs of copyright file");
	printf("\t%-*s%s\n", width, "files...",             "Files to include in the isofs image");

	printf("\nFor -A/B/C, the path must refer to a file which exists within the isofs image.\n");
}

#define FLAG_o (1U << 1)
#define FLAG_b (1U << 3)
#define FLAG_A (1U << 5)
#define FLAG_B (1U << 7)
#define FLAG_C (1U << 9)

int main(int argc, char **argv)
{
	static const char *optpat   = "ho:b:A:B:C:";
	static const char *fileopts = "boABC";
	char *specialfiles[5] = {
		0, 0, "DUMMY.TXT", "DUMMY.TXT", "DUMMY.TXT",
	};

#define SPECIALFILE(c) specialfiles[strchr(fileopts, (c)) - fileopts]

	uint32_t seen = 0;
	int opt, fail = 0;

#define SEEN(flags) ((seen | (flags)) == seen)
#define FLAG(c)     (1U << (strchr(optpat, (c)) - optpat))

	extern char *optarg;
	extern int optind, optopt;
	while ((opt = getopt(argc, argv, optpat)) != -1) {
		uint32_t flag = opt == '?' ? 0 : FLAG(opt);
		if (SEEN(flag)) {
			fprintf(stderr, "%s: Duplicate option -%c\n", argv[0], opt);
			fail = 1;
			continue;
		}
		seen |= flag;

		switch (opt) {
		case 'h':
			usage(argv[0]);
			return 0;

		case 'b':
		case 'o':
		case 'A':
		case 'B':
		case 'C':
			SPECIALFILE(opt) = optarg;
			break;

		default:
			fail = 1;
		}
	}

	for (const char *c = "bo"; *c; c++) {
		if (!SEEN(FLAG(*c))) {
			fprintf(stderr, "%s: Missing required option -%c\n", argv[0], *c);
			fail = 1;
		}
	}
	if (fail) {
		fprintf(stderr, "\nUse -h option for help on correct usage.\n");
		return 1;
	}

	char *argprefix[] = {
		"mkisofs", "-graft-points", "-full-iso9660-filenames",
		"-G",         SPECIALFILE('b'),
		"-o",         SPECIALFILE('o'),
		"-abstract",  SPECIALFILE('A'),
		"-biblio",    SPECIALFILE('B'),
		"-copyright", SPECIALFILE('C'),
	};

#define ARRAYLEN(a) (sizeof(a) / sizeof *(a))

	char **args = calloc(argc - optind + ARRAYLEN(argprefix) + 2, sizeof *args);
	if (!args) {
		perror("malloc");
		return 1;
	}

	size_t argidx;
	for (argidx = 0; argidx < ARRAYLEN(argprefix); argidx++)
		args[argidx] = argprefix[argidx];
	while (argv[optind])
		args[argidx++] = argv[optind++];
	if (!SEEN(FLAG_A | FLAG_B | FLAG_C))
		args[argidx++] = "DUMMY.TXT=/dev/null";

	execvp("mkisofs", args);
	perror("exec");
	return 1;
}