//
// Written for Computer Networks and Systems lab classes
// AUTHOR : Sergiusz Warga

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

void echo(int parent_to_child, int child_to_parent) {
    while(1) {
        char buff[8000] = {0};
        int read_bytes = read(parent_to_child, &buff, sizeof(buff));
        write(child_to_parent, &buff, read_bytes);
    }
}

int main() {
    int parent_to_child[2], child_to_parent[2];
    if (pipe(parent_to_child) < 0 || pipe(child_to_parent) < 0 ){
    	fprintf(stderr,"Something went wrong!\n");
    	return -1;
    }
	 
	int status;
	pid_t pid;
    pid = fork();

    if (pid == -1) {    // If something went wrong.
        perror("Fork: ");
        exit(EXIT_FAILURE);
    }

    if (pid == 0) {     // If this is a child process.
        echo(parent_to_child[0], child_to_parent[1]);
        exit(EXIT_SUCCESS);
    }

    char buff[8000];
    char messages[3][32] = {"Hello there!", "Second message.", "Bye!"};

    for (int i = 0; i < 3; ++i) {
        write(parent_to_child[1], &messages[i], sizeof(messages[i]));
        read(child_to_parent[0], buff, sizeof(buff));
        printf("%s\n", buff);
    }
	
	wait(&status);
	close(parent_to_child[1]);
    close(child_to_parent[0]);
	
	return 0;
}