#include<stdio.h>
#include <stdlib.h>
#include<unistd.h>
#include<pthread.h>
#include <time.h>

#define K 3 
#define N 10
#define JUG 1
#define SEVER 2
#define NEODREDJENO 0

pthread_mutex_t MOST = PTHREAD_MUTEX_INITIALIZER;
pthread_cond_t CONDS = PTHREAD_COND_INITIALIZER;
pthread_cond_t CONDJ = PTHREAD_COND_INITIALIZER;


int smer = NEODREDJENO;

int cekaJUG=0;
int cekaSEVER=0;

int prelaziJUG = 0;
int prelaziSEVER = 0;

int k = 0;


void *autoJUG(void *x)
{
    sleep(rand() % 5);

    long id = (long)x;

    pthread_mutex_lock(&MOST);

    cekaJUG++;
    while(smer == SEVER || (smer==JUG && k >= K && cekaSEVER!=0))
    {        
        pthread_cond_wait(&CONDJ, &MOST);
    }
    cekaJUG--;
    prelaziJUG++;
    k ++;

    smer = JUG;

    pthread_mutex_unlock(&MOST);

    printf("Automobil %ld prelazi most sa juzne strane!\n", id);  
    fflush(stdin);  
    sleep(1);

    pthread_mutex_lock(&MOST);

    prelaziJUG --;

    if(k >= K && cekaSEVER || ( cekaJUG == 0 && prelaziJUG == 0 && cekaSEVER ))
    {      
        k=0;
        smer = SEVER;
        pthread_cond_broadcast(&CONDS);
    }

    pthread_mutex_unlock(&MOST);

    return NULL;
}

void *autoSEVER(void *x)
{
    sleep(rand() % 5);

    long id = (long)x;

    pthread_mutex_lock(&MOST);

    cekaSEVER++;
    while(smer == JUG || (smer==SEVER && k >= K && cekaJUG!=0))
    {        
        pthread_cond_wait(&CONDS, &MOST);
    }
    cekaSEVER--;
    prelaziSEVER++;
    k ++;

    smer = SEVER;

    pthread_mutex_unlock(&MOST);

    printf("Automobil %ld prelazi most sa severne strane!\n", id);  
    sleep(1); 

    pthread_mutex_lock(&MOST);

    prelaziSEVER --;

    if(k >= K && cekaJUG || ( cekaSEVER == 0 && prelaziSEVER == 0 && cekaJUG ))
    {      
        k=0;
        smer = JUG;
        pthread_cond_broadcast(&CONDJ);
    }

    pthread_mutex_unlock(&MOST);

    return NULL;
}

int main()
{
    pthread_t aJUG[N];
    pthread_t aSEVER[N];

    for(long i=0;i<N;i++)
        pthread_create(aJUG+i,NULL,autoJUG,(void*)i);


    for(long i=0;i<N;i++)
        pthread_create(aSEVER+i,NULL,autoSEVER,(void*)i);

    pthread_exit(NULL);
}