#include <pthread.h>
#include <stdio.h>
#include <sys/time.h>
#include <time.h>
#include <errno.h>
#include <stdlib.h>

pthread_mutex_t mutex = PTHREAD_MUTEX_INITIALIZER;
pthread_cond_t cond = PTHREAD_COND_INITIALIZER;

int g_ms = -1;
int iterations = 0;

void waitMillis(int ms)
{
    int n;
    struct timeval tv;
    struct timespec ts;

    gettimeofday(&tv, NULL);
    ts.tv_sec = time(NULL) + ms / 1000;
    ts.tv_nsec = tv.tv_usec * 1000 + 1000 * 1000 * (ms % 1000);
    ts.tv_sec += ts.tv_nsec / (1000 * 1000 * 1000);
    ts.tv_nsec %= (1000 * 1000 * 1000);

    pthread_mutex_lock(&mutex);
    n = pthread_cond_timedwait(&cond, &mutex, &ts);
    pthread_mutex_unlock(&mutex);

    if (n == 0) {
        printf("waitMillis: We were signalled!\n");
    } else if (n == ETIMEDOUT) {
        printf("waitMillis: We timed out!\n");
    }
}

void *threadRoutine(void *arg) {
    while (1) {
        waitMillis(g_ms);
        iterations++;
        printf("threadRoutine: Finished (%d)\n", iterations);
    }
}

int main(int argc, const char **argv) {
    pthread_t thread;
    int input, ms;

    if (argc < 2) {
        fprintf(stderr, "Error:  Please pass milliseconds for our timer!\n");
        exit(-1);
    }

    ms = atoi(argv[1]);
    if (ms < 100) {
        fprintf(stderr, "Error:  Pas at least 100ms!\n");
        exit(-1);
    }

    g_ms = ms;
    pthread_create(&thread, NULL, threadRoutine, NULL);

    while (1) {
        printf("Main: Enter a number\n");
        scanf(" %d", &input);
        if (input == 0) {
            printf("Main: Signalling thread...\n");
            pthread_cond_signal(&cond);
        } else {
            printf("Main: Not signalling\n");
        }
    }
}