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

#define N 5
#define LEFT ((i+N-1)%N)
#define RIGHT ((i+1)%N)
#define THINKING 0
#define HUNGRY 1
#define EATING 2

int state[N];
int phil[N] = {0,1,2,3,4};
pthread_mutex_t the_mutex;
pthread_mutex_t s[N];

void eat(int i)
{
    if ( state[i] == EATING )
        printf("Philosopher %d is eating with fork %d and %d\n", i, LEFT, RIGHT);
    //usleep(100000);
}

void think(int i)
{
    if ( state[i] == THINKING )
        printf("Philosopher %d is thinking\n", i);
    //usleep(10000);
}

void hungry(int i)
{
    if ( state[i] == HUNGRY )
        printf("Philosopher %d is hungry\n", i);
}

void test(int i)
{
    if (state[i] == HUNGRY && state[LEFT] != EATING
        && state[RIGHT] != EATING)
    {
        state[i] = EATING;
        eat(i);
        pthread_mutex_unlock(&s[i]);
    }
}

void takefork(int i)
{
    pthread_mutex_lock(&the_mutex);
    state[i] = HUNGRY;
    hungry(i);
    test(i);
    pthread_mutex_unlock(&the_mutex);
    pthread_mutex_lock(&s[i]);
}

void putfork(int i)
{
    pthread_mutex_lock(&the_mutex);
    state[i] = THINKING;
    test(LEFT);
    test(RIGHT);
    pthread_mutex_unlock(&the_mutex);
}

void *philosopher(void * num)
{
    int i = (int)num;
    while (1)
    {
        think(i);
        takefork(i); //critical region start
        eat(i);
        putfork(i); //critical region end
    }
}

int main()
{
    int i;
    pthread_t phil_id[N];
    pthread_mutex_init(&the_mutex, 0);

    for (i= 0; i < N; i++)
    {
        pthread_mutex_init(&s[i], 0);
    }

    for (i= 0; i < N; i++)
    {
        pthread_create(&phil_id[i], 0, philosopher, (void*)phil[i]);
    }

    for (i = 0; i > -1; i--)
    {
        pthread_join(phil[i], NULL);
    }

    pthread_mutex_destroy(&the_mutex);
    for (i = 0; i < N; i++)
    {
        pthread_mutex_destroy(&s[i]);
    }


}