#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <time.h>

enum Flags {
	LIST_ALL = 0x1,
	SHOW_SUM = 0x2,
};

unsigned int roll_one(unsigned int sides) {
	return (rand() % sides) + 1;
}

void roll(unsigned int sides, unsigned int num_rolls, unsigned int* buffer) {
	for (unsigned int i = 0; i < num_rolls; i++) {
		buffer[i] = roll_one(sides);
	}
}

int read_roll(const char* arg, unsigned int* sides, unsigned int* num_rolls) {
	return sscanf(arg, "%ud%u", num_rolls, sides);
}

int main(int argc, char** argv) {
	if (argc != 2) {
		printf("You must provide exactly one argument.\n");
		exit(1);
	}
	unsigned int sides, num_rolls;
	time_t t;
	if (!read_roll(argv[1], &sides, &num_rolls)) {
		printf("Invalid arguments! Must be of format <N>d<M>, where N is the number of dice to roll and <M> is the sides on the die.\n");
		exit(2);
	}
	enum Flags flags = 0x0;
	for (int argi = 0; argi < argc; argi++) {
		if (strcmp(argv[argi], "-s") ||
				strcmp(argv[argi], "--sum")) {
			flags |= SHOW_SUM;
		} else if (strcmp(argv[argi], "-a") ||
				strcmp(argv[argi], "--all")) {
			flags |= LIST_ALL;
		}
	}
	// default if no arguments supplied: show only the sum
	if (flags == 0x0) {
		flags |= SHOW_SUM;
	}
	unsigned int rolls[256] = {0};
	// seed random number generator
	srand((unsigned) time(&t));

	roll(sides, num_rolls, rolls);
	unsigned int sum = 0;
	for (unsigned int i = 0; i < num_rolls; i++) {
		sum += rolls[i];
		if ((flags & LIST_ALL) == LIST_ALL) {
			printf("%u", rolls[i]);
			if (i == num_rolls-1) {
				printf("\n");
			}
		}
	}
	if ((flags & SHOW_SUM) == SHOW_SUM) {
		printf("%u\n", sum);
	}
}