/*
 * Copyright (c) 2005, 2007, 2013 Kamo Hiroyasu
 *
 * Permission to use, copy, modify, and distribute this software for any
 * purpose with or without fee is hereby granted, provided that the above
 * copyright notice and this permission notice appear in all copies.
 *
 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 */

/*
 *  Hello
 *  Author: Kamo Hiroyasu <wd@ics.nara-wu.ac.jp>
 */

#include <errno.h>
#include <limits.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>

#define DEFAULT_GREETING	"Hello"

static int
number_of_times(const char *s)
{
	long	n;
	char	*ep;

	errno = 0;
	n = strtol(s, &ep, 10);
	if ((n == LONG_MIN || n == LONG_MAX) && errno == ERANGE) {
		perror(s);
		exit(1);
	} else if (*ep != '\0' || n < 0 || n > INT_MAX) {
		fprintf(stderr, "%s: illegal number of times\n", s);
		exit(1);
	}
	return (int)n;
}

static inline void
hello(const char *s)
{
	printf("%s!\n", s);
}

int
main(int argc, char *argv[])
{
	const char	*greeting = NULL;
	const char	*number_arg = NULL;
	int		ch;

	while ((ch = getopt(argc, argv, "g:l:")) != -1) {
		switch (ch) {
		case 'g':
			greeting = optarg;
			break;
		case 'l':
			number_arg = optarg;
			break;
		default:
			exit(1);
		}
	}
	if (optind < argc) {
		fprintf(stderr, "%s: too many arguments\n", argv[0]);
		return 1;
	}

	if (greeting == NULL) {
		greeting = getenv("HELLO");
	}
	if (number_arg == NULL) {
		number_arg = getenv("HELLOLINES");
	}

	if (greeting == NULL) {
		greeting = DEFAULT_GREETING;
	}

	{
		int	n = number_arg ? number_of_times(number_arg) : 1;

		for (; n > 0; n --) {
			hello(greeting);
		}
	}
	return 0;
}