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

struct client{
int fd[2];
pid_t pid;
};

int main(){
    fd_set  read_set;
    struct client clients[2];
    struct client servers[2];
    struct timeval tv;
    tv.tv_sec = 2;
    tv.tv_usec = 0;
    int     i = 0;
    int     j = 0;
    int     k = 0;
    int     r = 0;
    int     serverbytes;
    int     clientbytes;
    char    serverbuffer[80];
    char    clientbuffer[80];
    char    message[80];

    for(r;r<2;r++)
    {
    if(pipe(clients[r].fd) < 0)
        printf("pipe %i error n", r);
    else
        printf("client pipe %i created n", r);
    }
    r = 0;
    for(r;r<2;r++)
    {
    if(pipe(servers[r].fd) < 0)
        printf("pipe %i error n", r);
    else
        printf("server pipe %i created n", r);
    }

    clients[0].pid = fork();

    if(clients[0].pid != 0)
    {
    clients[1].pid = fork();
    if(clients[1].pid != 0){
            printf("server works. pid=%i n", getpid());
            while(1){
            int maxfd = clients[1].fd[0];
            FD_ZERO(&read_set);
            FD_SET(clients[0].fd[0], &read_set);
            FD_SET(clients[1].fd[0], &read_set);
            int serverSelect = select(maxfd+1, &read_set, NULL, NULL, &tv);
            if(serverSelect != -1){
                for(k;k<2;k++)
                {
                    if(FD_ISSET(clients[k].fd[0], &read_set)){
                        serverbytes = read(clients[k].fd[0], serverbuffer, sizeof(serverbuffer));
                        printf("server receive: %s from client ID=%d n", serverbuffer, k);
                        for(i;i<2;i++){
                            if(i!=k){
                                close(servers[k].fd[0]);
                                write(servers[k].fd[1], serverbuffer, sizeof(serverbuffer));
                            }
                        }
                    }
                }
            }
            else if(serverSelect == 0)
                printf("select timeout n");
            else
                perror("err");
            sleep(5);
            }
    }
    else
    {
        sprintf(message,"child %d", 1);
        printf("client %i works. pid=%i n", 1, getpid());
        //close(servers[1].fd[1]);
        //open(servers[1].fd[0]);
        //if(read(servers[1].fd[0], clientbuffer, sizeof(clientbuffer)) == -1){
            //printf("client %i read error n",1);
        //}
        //else
           //printf("client %i receive %s n",1,clientbuffer);
        //close(clients[1].fd[0]);
        while(1){
        write(clients[1].fd[1], message, (strlen(message)+1));
        printf("client %i send: %s n", 1, message);
            sleep(3);
    }
        exit(0);
    }
    }
    else
    {
    sprintf(message,"child %d", 0);
    printf("client %i works. pid=%i n", 0, getpid());
    //close(servers[0].fd[1]);
    //open(servers[0].fd[0]);
    //if(read(servers[0].fd[0], clientbuffer, sizeof(clientbuffer)) == -1){
       //printf("client %i read error n",1);
    //}
    //else
        //printf("client %i receive %s n",1,clientbuffer);
    //close(clients[0].fd[0]);
    while(1){
    write(clients[0].fd[1], message, (strlen(message)+1));
    printf("client %i send: %s n", 0, message);
    sleep(3);
    }
    exit(0);
}
return 0;

}