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

int contains_7_or_is_multiple_of_7(int nr) {
    if(nr % 7 == 0) {
        return 1;
    }
    while(nr > 0) {
        if(nr % 10 == 7) {
            return 1;
        }
        nr = nr / 10;
    }
    return 0;
}

void play(int pipes[][2], int index, int n) {
    int nr = 1, i;
    int read_idx = index % n;
    int write_idx = (index+1) % n;
    for (i = 0; i < n; i++) {
        if(i == read_idx) {
            close(pipes[i][1]);
        } else if (i == write_idx) {
            close(pipes[i][0]);
        } else {
            close(pipes[i][0]);
            close(pipes[i][1]);
        }
    }
    if(index == 0) {
        printf("%d - start\n", nr);
        if(0 > write(pipes[write_idx][1], &nr, sizeof(int))) {
            perror("Error on writing number");
        }
    }
    while(nr >= 1) {
        if(0 > read(pipes[read_idx][0], &nr, sizeof(int))) {
            perror("Error on reading number");
        }
        if(nr != 0) {
            nr++;
            int success = random() % 3;
            if(contains_7_or_is_multiple_of_7(nr)) {
                if(!success) {
                    printf("%d - fail\n", nr);
                    nr = 0;
                } else {
                    printf("Boltz!\n");
                }
            } else {
                printf("%d\n", nr);
            }

            if(0 > write(pipes[write_idx][1], &nr, sizeof(int))) {
                perror("Error on writing number");
            }
        } else {
            if(0 > write(pipes[write_idx][1], &nr, sizeof(int))) {
                perror("Error on writing number");
            }
            break;
        }
    }
    wait(0);
    close(pipes[read_idx][0]);
    close(pipes[write_idx][1]);
}

int main(int argc, char *argv[]) {
    if (argc < 2) {
        printf("Provide an integer argument!\n");
        exit(1);
    }
    int n = atoi(argv[1]), i;
    int pipes[n][2];
    for (i = 0; i < n; i++) {
        if (0 > pipe(pipes[i])) {
            perror("Error on opening pipe");
            exit(1);
        }
    }
    srandom(time(NULL));
    for(i = 0; i < n; i++) {
        int f = fork();
        if(f < 0) {
            perror("Oh no my child!");
        } else if (f > 0) {
            //break in the parent so we don't create more processes;
            break;
        } else {
        // let the child run one for cycle so it creates another child
        // after it creates the child, it will also break from the for
        }
    }
    if(i < n)
        play(pipes, i, n);
    return 0;
}