#include	<stdio.h>
#include	<time.h>
#include	<signal.h>

#define	A_MINUTE	60
#define	MAXLINE		512

#define	MINUTES	59
#define	HOURS	23
#define	DOMS	31
#define	MOYS	12
#define	DOWS	7

#define	ANY	'*'
#define	NFSEP	','

int		too_long = 0;

char		*crontab = {"crontab"};

FILE		*cronfile = 0;

char		cronline[MAXLINE] = {0};
char		*command = 0;
char		*input = 0;

long		now = 0;
struct time	*tm = {0};

int		minute[MINUTES+1] = {0};
int		hour[HOURS+1] = {0};
int		dom[DOMS+2] = {0};
int		moy[MOYS+2] = {0};
int		dow[DOWS+2] = {0};

int		debug = 0;

main (argc, argv)
int	argc;
char	**argv;
{
	int	nada ();
	int	pid;

	if (fork () != 0)
		exit (0);

	signal (SIGINT, SIG_IGN);
	signal (SIGQUIT, SIG_IGN);

	if (argc > 1)
		++debug;

	if ((cronfile = fopen (crontab, "r")) == NULL)
	{
		fprintf (stderr, "%s: can't access %s\n",
			argv[0], crontab);
		exit (1);
	}

	signal (SIGALRM, nada);

        for (;;)
        {
		rewind (cronfile);

		too_long = 0;
		alarm (A_MINUTE);

		get_time ();

		while (get_cron_line () != NULL)
			if (parse () && nows_the_time ())
				do_the_command ();

		while (wait (&pid) != -1)
			;

		if (!too_long)
			pause ();
	}
}

nada ()
{
	++too_long;
	signal (SIGALRM, nada);
}

get_time ()
{
	time (&now);
	tm = localtime (&tm);
}

get_cron_line ()
{
	return (fgets (cronline, MAXLINE, cronfile));
}
			
parse ()
{
	register char	*p;

	if (debug)
		printf ("parsing: %s", cronline);

	p = cronline;

	if ((p = get_n_field (p, 0, MINUTES, minute)) == NULL)
	{
		p_field_error ("minutes");
		return (NULL);
	}

	if ((p = get_n_field (p, 0, HOURS, hour)) == NULL)
	{
		p_field_error ("hours");
		return (NULL);
	}

	if ((p = get_n_field (p, 1, DOMS, dom)) == NULL)
	{
		p_field_error ("day of month");
		return (NULL);
	}

	if ((p = get_n_field (p, 1, MOYS, moy)) == NULL)
	{
		p_field_error ("month of year");
		return (NULL);
	}

	if ((p = get_n_field (p, 1, DOWS, dow)) == NULL)
	{
		p_field_error ("day of week");
		return (NULL);
	}

	while (*p == ' ' || *p == '\t')
		++p;

	if (*p == '\n' || *p == '\0')
	{
		p_field_error ("command");
		return (NULL);
	}

	command = p;

	input = 0;

	while (*p)
	{
		if (*p == '%')
		{
			if (input == 0)
			{
				*p = '\0';
				input = p + 1;
			}
			else
				*p = '\n';
		}
		else if (*p == '\n' && input == 0)
			*p = '\0';
		++p;
	}


	if (debug)
	{
		printf ("successful parse: %s", ctime (&now));
		p_n_field ("minutes       ", 0, MINUTES, minute);
		p_n_field ("hours         ", 0, HOURS, hour);
		p_n_field ("days of month ", 1, DOMS, dom);
		p_n_field ("months of year", 1, MOYS, moy);
		p_n_field ("days of week  ", 1, DOWS, dow);
		printf ("command:       %s\n", command);
		printf ("input:         %s",
			(input) ? input : "--> NONE <--\n");
	}
}

p_n_field (s, low, high, fa)
char	*s;
int	low, high;
int	fa[];
{
	register int	i;
	register int	all;

	printf ("%s:", s);

	for (i = low, all = 1; i <= high && all; ++i)
		if (fa[i] == 0)
			all = 0;

	if (all)
	{
		printf (" ALL\n");
		return;
	}

	printf ("\n");

	for (i = 0; low <= high; ++low)
		if (fa[low])
		{
			printf (" %2d", low);
			if (++i > 30)
			{
				printf ("\n");
				i = 0;
			}
		}

	if (i)
		printf ("\n");
	printf ("\n");
}

get_n_field (p, low, high, fa)
char	*p;
int	low, high;
int	fa[];
{
	register int	i;

	for (i = low; i <= high; ++i)
		fa[i] = 0;

	while (*p == ' ' || *p == '\t')
		++p;

	do
	{
		if ((p = get_pat (p, low, high, fa)) == NULL)
			return (NULL);
	} while (*p++ == NFSEP);

	if (*--p != ' ' && *p != '\t')
		return (NULL);

	return (p);
}

get_pat (p, low, high, fa)
char	*p;
int	low, high;
int	fa[];
{
	register int	i;
	int		first;
	int		last;

	if (*p == ANY)
	{
		first = low;
		last = high;
		++p;
	}
	else if (isdigit (*p))
	{
		first = last = atoi (p);
		while (isdigit (*p))
			++p;
		if (*p == '-' && isdigit (p[1]))
		{
			last = atoi (++p);
			while (isdigit (*p))
				++p;
		}
		if (first > last)
		{
			i = first;
			first = last;
			last = first;
		}
	}
	else
		return (NULL);

	if (first < low || high < last)
		return (NULL);

	for (i = first; i <= last; ++i)
		fa[i] = 1;

	return (p);
}

atoi (p)
register char	*p;
{
	register int	i;

	for (i = 0; isdigit (*p); ++p)
		i = i * 10 + *p - '0';

	return (i);
}

p_field_error (s)
char	*s;
{
	if (debug)
		fprintf (stderr, "invalid %s field: %s", s, cronline);
}

/*
**	crontab thinks sunday is day 7, whereas
**	localtime thinks sunday is day 0
**	so map it!
*/

int	dow_map[7] = {7, 1, 2, 3, 4, 5, 6};

nows_the_time ()
{
	return (minute [tm->minutes          ] &&
		hour   [tm->hours            ] &&
		dom    [tm->day_month + 1    ] &&
		moy    [tm->month     + 1    ] &&
		dow    [dow_map[tm->day_week]]
	       );
}

do_the_command ()
{
	register FILE	*f;
	register int	pid;

	if ((pid = fork ()) == 0)
	{
		if ((f = popen (command, "w")) != NULL)
		{
			fwrite (input, strlen (input), 1, f);
			fflush (f);
			pclose (f);
		}
		exit (0);
	}
}