#include <iostream>
#include <string>
#include <cstdlib>
#include <pthread.h>
#include <unistd.h>
#include <semaphore.h>
#include <ctime>
#include "rollercoaster.h"
using namespace std;

int main (int argc, char **argv) {

    srand (time (nullptr));
    sem_init (&admin,false,1);  //The false is a boolean that indicates whether this semaphore is visible to other processes
    sem_init (&board,false,0);
    sem_init (&unboard,false,0);
    sem_init (&car,false,0);
    id = new int[R];
    for (int i=0; i < R; i++) id[i] = i+1;
    RiderThread = new pthread_t [R];
    for (int i=0; i < R; i++)
     pthread_create (&RiderThread[i],nullptr,rider,&id[i]);
    pthread_create (&CarThread,nullptr,rollercoaster,nullptr);
    for (int i=0; i < R; i++)
     pthread_join (RiderThread[i],nullptr);
    pthread_join (CarThread,nullptr);
    delete[] id;
    delete[] RiderThread;
    return 0;
}

void *rollercoaster (void *a) {

 while (true) {
    sem_wait (&car); //sem_wait is like P.
    cout << "Car:  driving\n";
    sleep (30);
    cout << "Car:  ride over\n";
    sem_wait (&admin);
    sem_post (&unboard); //sem_post is like V.
 }
 return nullptr;
}

void *rider (void *a) {

 int idnum = *(int *)a;
 while (true) {
    sleep (10+rand()%21); //sleep 10-30 seconds
    sem_wait (&admin);
    if (nr==C) {nrw++; sem_post (&admin); cout << "Rider "+to_string(idnum)+":  Waiting to board\n";sem_wait (&board);}
    nr++;
    cout << "Rider "+to_string(idnum)+":  Boarding\n";
    if (nr==C) {sem_post (&car); sem_post (&admin);}
    else if (nrw > 0) {nrw--; sem_post (&board);}
    else sem_post (&admin);
    sem_wait (&unboard);
    cout << "Rider "+to_string(idnum)+":  Unboarding\n";
    nr--;
    if (nr > 0) sem_post (&unboard);
    else if (nrw > 0) {nrw--; sem_post (&board);}
    else sem_post (&admin);
 }
 return nullptr;
}