#include <iostream>
#include <stdio.h>
#include <cmath>
#include <sys/types.h>
#include <sys/wait.h>
#include <unistd.h>
#include <iomanip>
#include <sys/resource.h>
 
using namespace std;
 
void findPrimes(int primes[], int numPrimesToFind);
void sumPrimes(int primes[], int numPrimesToFind);
 
int main(int argc, char **argv)
{
    int numPrimesToFind = atoi(argv[1]);
    int primes[numPrimesToFind];
    int stat_val;
    struct rusage parent_usage;
    struct rusage child_usage;
    double usage = 0.0;
    pid_t childPID;
    pid_t child_pid;
 
 
    findPrimes(primes, numPrimesToFind);
 
    childPID = fork();
 
    if(childPID == -1)
    {
        cout << "No children were forked in the making of this program :(" << endl;
        exit(1);
    }
 
    if(childPID == 0)
    {
        cout << "=======================Child========================\n";
        sumPrimes(primes, numPrimesToFind);
        getrusage(RUSAGE_SELF, &child_usage);
        usage = child_usage.ru_utime.tv_sec + child_usage.ru_stime.tv_sec; //) / pow(10.0, 9);
        cout << "Process ID: " << getpid() << " ..... " << " CPU time " << fixed << showpoint << setprecision(6) << usage << " s\n\n";
        cout << "Ending child process\n\n";
        cout << "====================================================\n\n";
    }
    else
    {
 
        child_pid = wait(0);
 
        cout << "==========================Parent=========================\n\n";
        getrusage(RUSAGE_CHILDREN, &child_usage);
        usage = child_usage.ru_utime.tv_sec + child_usage.ru_stime.tv_sec; //) / pow(10.0, 9); 
        cout << "Child PID = "  << childPID << " Child CPU time = " << fixed << showpoint << setprecision(6) << usage << " s\n";
        getrusage(RUSAGE_SELF, &parent_usage);
        usage = parent_usage.ru_utime.tv_sec + parent_usage.ru_stime.tv_sec; //) / pow(10.0, 9); 
        cout << "Parent PID = " << getpid() << " Parent CPU time = " << fixed << showpoint << setprecision(6) << usage << " s\n";
 
        cout << endl << endl << endl << "List of first " << numPrimesToFind << " prime numbers:\n";
    /*
        for(int index = 0; index < numPrimesToFind; index++)
        {
            cout << primes[index] << endl;
        }
    */
        cout << "=============================================================\n\n";
 
    }
 
    return 0;
}
 
void findPrimes(int primes[], int numPrimesToFind)
{
    int divider = 2;
    int number = 2;
    int index = 0;
    bool prime = true;
 
    /*loop through to find the first numPrimesToFind prime numbers*/
    while(index < numPrimesToFind)
    {
 
            /*A composite integer will have a prime number as a factor that does 
              not exceed the square root of the composite integer. If this prime
              is not found, then the number itself must be prime*/
 
            while (divider <= sqrt(number) && prime)
            {
                /*if number divides evenly into divider, then it is not prime*/
                if(number % divider == 0)
                    prime = false;
 
                divider++;
            }
 
            if(prime)
            {
                primes[index] = number;
                index++;
            }
 
            prime = true;
            divider = 2;
            number++;
 
    }
}
 
void sumPrimes(int primes[], int numPrimesToFind)
{
    int sum = 0;
 
    for(int index = 0; index < numPrimesToFind; index++)
        sum += primes[index];
 
    cout << endl << "The sum of the first " << numPrimesToFind <<  " prime numbers is: " << sum << endl;
}