#include <ctype.h> /* isdigit(3) */
#include <errno.h> /* errno */
#include <stdio.h> /* fprintf(3), stderr, NULL */
#include <stdlib.h> /* srand(3), strtol(3) */
#include <time.h> /* time(3) */

#if !defined EX_SOFTWARE || !defined EX_USAGE
#	include <sysexits.h>
#endif

static char *program_name = "roll";

int main(int argc, char *argv[]){
	char *argv0;
	char *argvc;
	char *ep;
	int r; /* rolls */
	int s; /* sides */

	argv0 = argv[0];

	if(argc < 2){
		fprintf(stderr,
			"Usage: %s [dice...]\n"
				"\tDice should be formatted [rolls]d[sides],"
		       		" e.g. 1d3, 5d6...\n",
			argv0 == NULL ? program_name : argv0
		);
		return EX_USAGE;
	}

	srand(time(NULL));

	while(--argc > 0){
		argvc = *++argv;

		/* Parse out [rolls]d[sides] */
		if(**argv >= 0x80 || !isdigit(**argv))
			goto error;

		errno = 0;
		r = strtol(*argv, &ep, 10);

		if(errno != 0)
			goto range;

		if(*(*argv = ep) != 'd'
				|| **argv >= 0x80
				|| !isdigit(*(++*argv)))
			goto error;

		s = strtol(*argv, &ep, 10);
		if(errno != 0)
			goto range;
		if(*ep != '\0')
			goto error;

		while(r --> 0)
			fprintf(stdout, "%d\n", rand() % s + 1);
	}

	return EX_OK;

error:	fprintf(stderr,
		"%s: %s: Improperly formatted die"
		" (should be [rolls]d[sides]).\n",
		argv0, argvc
	);
	return EX_USAGE;

range:	fprintf(stderr,
		"%s: %s: Number out of working range for this program.\n",
		argv0, argvc
		
	);
	return EX_SOFTWARE;
}