/*
 * Copyright (C) 2023  Patrick McDermott
 *
 * This file is part of opkg-opk.
 *
 * opkg-opk 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.
 *
 * opkg-opk 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 opkg-opk.  If not, see <https://www.gnu.org/licenses/>.
 */

#include "config.h"

#include <errno.h>
#include <fcntl.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/stat.h>
#include <unistd.h>

#ifdef ENABLE_NLS
#include <locale.h>
#include <libintl.h>
#define _(msgid) gettext(msgid)
#else
#define _(msgid) (msgid)
#endif

#ifdef HAVE_GETOPT_LONG
#include <getopt.h>
#endif

static const char *_OPTSTRING = "m:";
#ifdef HAVE_GETOPT_LONG
static const struct option _LONGOPTS[] = {
	{
		.name    = "mode",
		.has_arg = 1,
		.flag    = NULL,
		.val     = 'm',
	},
};
#endif

static const unsigned int _TIMEOUT = 10U;

int
main(int argc, char *argv[])
{
	char          *program_name;
	char          *work_area;
	char         **exec_argv;
	int            arg;
	mode_t         mode;
	int            opt;
	char          *name;
	char           type;
	char          *end;
	long int       major;
	long int       minor;
	char          *specials_file_name;
	char          *specials_lock_name;
	int            fd;
	unsigned int   timeout;
	int            specials_fd;
	FILE          *specials_file;
	struct stat    stat_buf;

#ifdef ENABLE_NLS
	bindtextdomain(GETTEXT_PACKAGE, LOCALEDIR);
#ifdef HAVE_BIND_TEXTDOMAIN_CODESET
	bind_textdomain_codeset(PACKAGE, "UTF-8");
#endif
	textdomain(PACKAGE);
	setlocale(LC_ALL, "");
#endif

	program_name = argv[0];

	work_area = getenv("OPK_WORK_AREA");
	if (work_area == NULL || work_area[0] == '\0') {
		fprintf(stderr, _("%s: OPK_WORK_AREA environment variable not "
					"set\n"), program_name);
		fprintf(stderr, _("%s: Possibly building package dependent on "
					"opkg-opk with opkbuild too old to use "
					"it\n"), program_name);
		fprintf(stderr, _("%s: Executing system mknod instead\n"),
			program_name);
		exec_argv = calloc(argc + 1, sizeof(*exec_argv));
		if (exec_argv == NULL) {
			fprintf(stderr, _("%s: Failed to allocate memory\n"),
					program_name);
			return EXIT_FAILURE;
		}
		exec_argv[0] = malloc(strlen(MKNOD) + 1);
		if (exec_argv[0] == NULL) {
			fprintf(stderr, _("%s: Failed to allocate memory\n"),
					program_name);
			free(exec_argv);
			return EXIT_FAILURE;
		}
		strcpy(exec_argv[0], MKNOD);
		for (arg = 1; arg < argc; ++arg) {
			exec_argv[arg] = argv[arg];
		}
		exec_argv[argc] = NULL;
		execve(MKNOD, exec_argv, NULL);  /* Shouldn't return */
		fprintf(stderr, _("%s: Failed to execute system mknod\n"),
				program_name);
		free(exec_argv[0]);
		free(exec_argv);
		return EXIT_FAILURE;
	}

	mode = 0;
#ifdef HAVE_GETOPT_LONG
	while ((opt = getopt_long(argc, argv, _OPTSTRING, _LONGOPTS, NULL))
			!= -1) {
#else
	while ((opt = getopt(argc, argv, _OPTSTRING)) != -1) {
#endif
		switch(opt) {
			case 'm':
				/* TODO: Parse mode. */
				break;
			default:
				fprintf(stderr, _("%s: Warning: Unknown option:"
							" \"%c\"\n"),
						program_name, optopt);
				return EXIT_FAILURE;
		}
	}
	argc -= optind;
	argv += optind;

	if (argc < 2) {
		fprintf(stderr, _("%s: Wrong number of operands\n"),
				program_name);
		return EXIT_FAILURE;
	}
	name = argv[0];
	switch (argv[1][0]) {
		case 'c':
		case 'u':
			type = 'c';
			break;
		case 'b':
			type = 'b';
			break;
		case 'p':
			if (argc != 2) {
				fprintf(stderr, _("%s: Wrong number of "
							"operands\n"),
						program_name);
				return EXIT_FAILURE;
			}
			if (mkfifo(name, mode) != 0) {
				fprintf(stderr, _("%s: Failed to create link "
							"\"%s\"\n"),
						program_name, name);
				return EXIT_FAILURE;
			}
			return EXIT_SUCCESS;
		default:
			fprintf(stderr, _("%s: Invalid node type \"%c\"\n"),
						program_name, argv[1][0]);
			return EXIT_FAILURE;
	}

	if (argc != 4) {
		fprintf(stderr, _("%s: Wrong number of operands\n"),
				program_name);
		return EXIT_FAILURE;
	}
	major = strtol(argv[2], &end, 10);
	if (*end != '\0') {
		fprintf(stderr, _("%s: Invalid number \"%s\"\n"),
				program_name, argv[2]);
		return EXIT_FAILURE;
	}
	minor = strtol(argv[3], &end, 10);
	if (*end != '\0') {
		fprintf(stderr, _("%s: Invalid number \"%s\"\n"),
				program_name, argv[3]);
		return EXIT_FAILURE;
	}

	specials_file_name = malloc(strlen(work_area) + strlen("/specials")
			+ 1 /* "\0" */);
	if (specials_file_name == NULL) {
		fprintf(stderr, _("%s: Failed to allocate memory\n"),
				program_name);
		return EXIT_FAILURE;
	}
	specials_lock_name = malloc(strlen(work_area) + strlen("/specials~")
			+ 1 /* "\0" */);
	if (specials_lock_name == NULL) {
		fprintf(stderr, _("%s: Failed to allocate memory\n"),
				program_name);
		free(specials_file_name);
		return EXIT_FAILURE;
	}
	sprintf(specials_file_name, "%s/specials",  work_area);
	sprintf(specials_lock_name, "%s/specials~", work_area);

	/* Create the named node.  This should be done before appending to the
	 * specials file, in case a file by the specified name already exists.
	 */
	fd = open(name, O_CREAT | O_EXCL, mode);
	if (fd < 0 || close(fd) < 0) {
		fprintf(stderr, _("%s: Failed to create node\n"), program_name);
		free(specials_file_name);
		free(specials_lock_name);
		return EXIT_FAILURE;
	}

	/* Acquire lock ("specials~"). */
	for (timeout = _TIMEOUT; timeout > 0; --timeout) {
		specials_fd = open(specials_lock_name, O_CREAT | O_EXCL, 0644);
		if (specials_fd >= 0) {
			goto opened;
		}
	}
	fprintf(stderr, _("%s: Failed to lock specials file\n"), program_name);
	free(specials_file_name);
	free(specials_lock_name);
	unlink(name);
	return EXIT_FAILURE;

 opened:
	specials_file = fdopen(specials_fd, "a");
	if (specials_file == NULL) {
		fprintf(stderr, _("%s: Failed to open specials file stream\n"),
				program_name);
		close(specials_fd);
		free(specials_file_name);
		free(specials_lock_name);
		unlink(name);
		return EXIT_FAILURE;
	}

	/* If "specials" doesn't exist, write header. */
	if (stat(specials_file_name, &stat_buf) != 0) {
		if (errno != ENOENT) {
			fprintf(stderr, _("%s: Failed to stat specials file\n"),
					program_name);
			fclose(specials_file);
			free(specials_file_name);
			free(specials_lock_name);
			unlink(name);
			return EXIT_FAILURE;
		}
		if (fputs("version=1\n", specials_file) < 0 ||
				fputs("type     major     minor  name\n",
					specials_file) < 0) {
			fprintf(stderr, _("%s: Failed to write specials file\n")
					, program_name);
			fclose(specials_file);
			free(specials_file_name);
			free(specials_lock_name);
			unlink(name);
			return EXIT_FAILURE;
		}
	}
	if (fprintf(specials_file, "%c  %8ld  %8ld  %s\n", type, major, minor,
				name) < 0) {
		fprintf(stderr, _("%s: Failed to write specials file\n"),
				program_name);
		fclose(specials_file);
		free(specials_file_name);
		free(specials_lock_name);
		unlink(name);
		return EXIT_FAILURE;
	}
	fclose(specials_file);

	if (rename(specials_lock_name, specials_file_name) != 0) {
		fprintf(stderr, _("%s: Failed to move specials file\n"),
				program_name);
		free(specials_file_name);
		free(specials_lock_name);
		unlink(name);
		return EXIT_FAILURE;
	}

	free(specials_file_name);
	free(specials_lock_name);

	return EXIT_SUCCESS;
}