//Michal Lenort
//Jakub Gil

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/wait.h>

int calculate_factorial(int n) {
    if (n == 0) {
        return 1;
    } else {
        return n * calculate_factorial(n - 1);
    }
}

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

int i =0;

    if (argc != 2) {
        printf("Podaj liczbe procesow potomnych jako argument!\n");
        return 1;
    }
    
    int n = atoi(argv[1]); // Liczba procesow potomnych
    
    int pipe_send[2]; // wysylanie
    int pipe_receive[2]; // odbieranie
    
    if (pipe(pipe_send) == -1 || pipe(pipe_receive) == -1) {
        perror("Blad podczas tworzenia potoków!");
        return 1;
    }
    
    pid_t pid;
    
    for (i = 0; i < n; i++) {
        pid = fork();
        
        if (pid == -1) {
            perror("Blad podczas tworzenia procesu potomnego!");
            return 1;
        } else if (pid == 0) {
            // proces potomny
            
            close(pipe_send[1]); // Zamykamy koncowkw zapisu potoku wysylajacego
            
            int number;
            while (read(pipe_send[0], &number, sizeof(int)) > 0) {
                int factorial = calculate_factorial(number);
                write(pipe_receive[1], &factorial, sizeof(int));
            }
            
            close(pipe_send[0]);
            close(pipe_receive[1]);
	    
            
            return 0;
        }
    }
    
    // proces rodzica
    
    close(pipe_send[0]);
    close(pipe_receive[1]); 
    
    int sum = 0;
    for (i = 1; i <= n; i++) {
        write(pipe_send[1], &i, sizeof(int));
    }
    //close
    close(pipe_send[1]);
    
    int factorial;
    while (read(pipe_receive[0], &factorial, sizeof(int)) > 0) {
        sum += factorial;
    }
    
    //close
    close(pipe_receive[0]);
    
    printf("Suma obliczonych silni: %d\n", sum);
    
    
    for (i = 0; i < n; i++) {
        kill(0, SIGTERM);
    }
    
    
    for (i = 0; i < n; i++) {
        wait(NULL);
    }
    
    return 0;
}