/**
 * @file supervisor.c
 * @date 2018-05-21
 *
 * @brief Server program which reads solutions and orders them.
 */

#include "common.h"

static const char *pname;

struct circ_buf *shared;

struct sigaction sa;

static volatile sig_atomic_t quit = 0;

static void sig_handler(int signum)
{
	quit = 1;
}

void usage(void)
{
	fprintf(stderr, "SYNOPSIS\n"
			"\tsupervisor\n");
	exit(EXIT_FAILURE);
}

void initCircBuf()
{
	shared->quit = 0;
	for (int i = 0; i < MAX_ITEMS; i++) {
		shared->data[i] = 0;
	}
	return;
}

int getSolution(sem_t sUsedSpace, sem_t sFreeSpace, int *solution)
{
	sem_wait(&sUsedSpace);

	int value;

	value = shared->data[shared->head];
	shared->head = (shared->head + 1) % MAX_ITEMS;

	sem_post(&sFreeSpace);

	return value;
}

int main(int argc, char *argv[])
{
	if (argc != 1)
		usage();
	pname = argv[0];

	struct sigaction sa;
	memset(&sa, 0, sizeof(sa));
	sa.sa_handler = &sig_handler;
	sigaction(SIGINT, &sa, NULL);
	sigaction(SIGTERM, &sa, NULL);

	int shmfd = shm_open(SHM_NAME, O_RDWR | O_CREAT, PERMISSION);
	if (shmfd == -1) {
		perror(pname);
		exit(EXIT_FAILURE);
	}
	if (ftruncate(shmfd, sizeof(*shared)) == -1) {
		perror(pname);
		exit(EXIT_FAILURE);
	}

	shared = mmap(NULL, sizeof(*shared), PROT_READ | PROT_WRITE, MAP_SHARED, shmfd, 0);
	if (shared == MAP_FAILED) {
		perror(pname);
		exit(EXIT_FAILURE);
	}

	sem_t *sFreeSpace = sem_open(SEM_FREE_SPACE, O_CREAT | O_EXCL, PERMISSION, MAX_ITEMS);
	sem_t *sUsedSpace = sem_open(SEM_USED_SPACE, O_CREAT | O_EXCL, PERMISSION, 0);

	initCircBuf();

	while (quit == 0) {
		int solution[MAX_ITEMS] = {-1};
		getSolution(*sUsedSpace, *sFreeSpace, solution);

	}

	return 0;
}