#include "kernel/types.h"
#include "user/user.h"

void redirect(int n, int pd[]) {
    close(n);
    dup(pd[n]);
    close(pd[0]);
    close(pd[1]);
}

void primes() {
    int previous, next;
    int fd[2];

    while (read(0, &previous, sizeof(int))) {
        printf("prime %d\n", previous);

        if (pipe(fd) < 0) {
            fprintf(2, "pipe failed\n");
            exit(1);
        }

        if (fork() == 0) {
            redirect(1, fd);
            while (read(0, &next, sizeof(int))) {
                if (next % previous != 0) {
                    write(1, &next, sizeof(int));
                }
            }
            exit(0);
        } else {
            close(fd[1]);
            redirect(0, fd);
        }
    }
}

int main(int argc, char *argv[]) {
    int fd[2];

    if (pipe(fd) < 0) {
        fprintf(2, "pipe failed\n");
        exit(1);
    }

    if (fork() == 0) {
        redirect(1, fd);
        for (int i = 2; i < 36; i++) {
            write(1, &i, sizeof(int));
        }
        exit(0);
    } else {
        close(fd[1]);
        redirect(0, fd);
        primes();
    }

    exit(0);
}