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

/*
Ordre des pipes:
AB 0
AC 1
AD 2
BI 3
CE 4
CF 5
DH 6
EG 7
FG 8
GI 9
HI 10
IA 11
*/

int main() {
    int* fds[12];

    for (int i=0; i < 12; i++) {
        fds[i] = malloc(sizeof(int)*2);
        pipe(fds[i]);
    }

    int i=0;
    for (; i < 9; i++) {
        if (fork()) { break; } // Generate 9 processes
        if (i == 8) { return 0; }
    }

    int input[3] = {-1, -1, -1};
    int output[3] = {-1, -1, -1};

    char id = 'A'+i;
    switch (id) {
        case 'A': {// A
            input[0] = 11;
            output[0] = 0;
            output[1] = 1;
            output[2] = 2;
        } break;
        case 'B': {// B
            input[0] = 0;
            output[0] = 3;
        } break;
        case 'C': {// C
            input[0] = 1;
            output[0] = 4;
            output[1] = 5;
        } break;
        case 'D': {// D
            input[0] = 2;
            output[0] = 6;
        } break;
        case 'E': {// E
            input[0] = 4;
            output[0] = 7;
        } break;
        case 'F': {// F
            input[0] = 5;
            output[0] = 8;
        } break;
        case 'G': {// G
            input[0] = 7;
            input[1] = 8;
            output[0] = 9;
        } break;
        case 'H': {// H
            input[0] = 6;
            output[0] = 10;
        } break;
        case 'I': {// I
            input[0] = 3;
            input[1] = 9;
            input[2] = 10;
            output[0] = 11;
        } break;
        default:
            return -1;
    }

    FILE* in_stream[3];
    FILE* out_stream[3];

    for (int j=0; j < 3; j++) {
        if (input[j] != -1) {
            in_stream[j] = fdopen(fds[input[j]][0], "r");
        }
        if (output[j] != -1) {
            out_stream[j] = fdopen(fds[output[j]][1], "w");
        }
    }


    printf("%c: got %d %d %d > %d %d %d\n", id, input[0], input[1], input[2], output[0], output[1], output[2]);
    sleep(1);

    if (id == 'I') {
        int c;
        while (1) { // Get things from stdin
            c = getchar();
            for (int j=0; j < 3; j++) {
                if (output[j] != -1) {
                    fputc(c, out_stream[j]);
                }
            }
        }
        return 0;
    }
    while (1) {
        printf("%c listening...\n", id);

        int c, d;
        d = -1;
        for (int j=0; j < 3; j++) {
            if (input[j] != -1) {
                c = fgetc(in_stream[j]);
                if (d != -1 && c != d) {
                    fprintf(stderr, "%c got two different chars: %c vs %c\n", id, c, d);
                }
                d = c;
            }
        }
        printf("%c received %c\n", id, c);
        for (int j=0; j < 3; j++) {
            if (output[j] != -1) {
                printf("%c transmits %c to %d\n", id, c, output[j]);
                fputc(c, out_stream[j]);
            }
        }
    }

    for (int j=0; j < 3; j++) {
        if (input[j] != -1) {
            fclose(in_stream[j]);
        }
        if (output[j] != -1) {
            fclose(out_stream[j]);
        }
    }
}