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

void kill_process() {
    printf("\nZamykanie programu...\n");
    exit(0);
}

int main(void) {
    int pp1 = 0, pp2 = 0, pipe1[2], pipe2[2], pipe3[2], pipe4[2];
    char buf, end = 8;
    _Bool receiving = 0;
    pipe(pipe1);
    pipe(pipe2);
    pipe(pipe3);
    pipe(pipe4);

    if ((pp1 = fork())) {
        if ((pp2 = fork())) {
            signal(SIGTERM, kill_process);
            // parent
            close(pipe1[1]);
            close(pipe2[0]);
            close(pipe3[1]);
            close(pipe4[0]);
            while (read(pipe1[0], &buf, 1) > 0) {
                if (!receiving)
                    printf("1. PM:%i\n", getpid());
                receiving = 1;
                write(pipe2[1], &buf, 1);
                if (buf == end) {
                    receiving = 0;
                    while (read(pipe3[0], &buf, 1) > 0) {
                        if (!receiving)
                            printf("3. PM:%i\n", getpid());
                        receiving = 1;
                        write(pipe4[1], &buf, 1);
                        if (buf == end) {
                            receiving = 0;
                            break;
                        }
                    }
                }
            }
            close(pipe1[0]);
            wait(NULL);
            exit(EXIT_SUCCESS);
        } else {
            // pp2
            close(pipe2[1]);
            close(pipe3[0]);
            while (read(pipe2[0], &buf, 1) > 0) {
                if (!receiving)
                    printf("2. PP2:%i\n", getpid());
                receiving = 1;
                buf = tolower(buf);
                write(pipe3[1], &buf, 1);
                if (buf == end)
                    receiving = 0;
            }
        }
    } else {
        // pp1
        close(pipe1[0]);
        close(pipe4[1]);
        char str[100] = "";
        while (1) {
            scanf("%s", str);
            if (strcmp("q", str) == 0) {
                kill(getppid(), SIGTERM);
                break;
            };
            write(pipe1[1], str, strlen(str));
            write(pipe1[1], &end, 1);
            while (read(pipe4[0], &buf, 1) > 0) {
                if (!receiving)
                    printf("4. PP1:%i\n", getpid());
                receiving = 1;
                write(STDOUT_FILENO, &buf, 1);
                if (buf == end) {
                    receiving = 0;
                    write(STDOUT_FILENO, "\n", 1);
                    break;
                }
            }
        }
        close(pipe1[1]);
        close(pipe4[0]);
        exit(0);
    }

    return 0;
}