#include <stdio.h>
#include <errno.h>
#include <string.h>
#include <unistd.h>
#include <stdlib.h>
#include <signal.h>
#include <sys/wait.h>
#include <arpa/inet.h>
#include <sys/types.h>
#include <netinet/in.h>
#include <netinet/ip.h>
#include <sys/socket.h>


#define MESSAGE_LENGHT 64
#define USER_LENGHT 16

//client side

int cfd;
int masterpid;

static void signal_close_handler(int);

int main(int argc, char* argv[]) {

 //INIT PHASE
 int sockfd,res,PORT;
 char buffer[MESSAGE_LENGHT];
 char myuser[USER_LENGHT];
 char otheruser[USER_LENGHT];
 pid_t fpid, childpid = 0, sread = 0, swrite = 0;
 socklen_t clen;
 sigset_t set;
 struct sockaddr_in CLIENT_ADDRESS;
 struct sigaction act;

 //defining the port
 PORT = atoi(argv[1]);

 //defining the master pid
 masterpid = fpid = getpid();

 //handling
 sigfillset(&set);
 act.sa_handler = &signal_close_handler;
 act.sa_mask = set;
 act.sa_flags = SA_RESTART;
 sigaction(SIGINT, &act, 0);


 //creating a new socket using NETINET TCP/IP protocol
 if((sockfd = socket(AF_INET, SOCK_STREAM, 0)) == -1) {
    perror("ops");
    exit(EXIT_FAILURE);
 }

 //now defining the socket address name
 CLIENT_ADDRESS.sin_family = AF_INET;
 CLIENT_ADDRESS.sin_port = htons(PORT);
 CLIENT_ADDRESS.sin_addr.s_addr = inet_addr("192.168.1.68");

 //defining the username
 printf("Welcome to the chatting system.\n");
 printf("Choose a username: ");
 scanf("%s", myuser);
 myuser[strlen(myuser)] = '\0';
 printf("Hello, %s!\n",myuser);

 //trying to connect
 printf("Waiting for the server response..\n");

 clen = sizeof(CLIENT_ADDRESS);
 if((res = connect(sockfd, (struct sockaddr*)&CLIENT_ADDRESS, clen)) == -1) {
    perror("ops");
    exit(EXIT_FAILURE);
 } else {
    printf("Welcome to the server, %s!\n",myuser);
    recv(sockfd, &otheruser, USER_LENGHT, 0);
    send(sockfd, &myuser, strlen(myuser)+1, 0);
    printf("chatting with: %s\n",otheruser);
   }

 //chat phase
 while(1) {
    //creating two process that will manage read and write respectively
    if((childpid = fork()) == 0) {
        sread=getpid();
    } else if (childpid > 0) {
        childpid = 0;
        if((childpid = fork()) == 0) {
            swrite = getpid();
        } else if (childpid < 0) {
            perror("fork");
            exit(EXIT_FAILURE);
         }
      } else {
        perror("fork");
        exit(EXIT_FAILURE);
       }

    //until the user press CTRL+C
    while(1) {
        if(sread) {
            recv(sockfd, &buffer, MESSAGE_LENGHT, MSG_WAITALL);
            printf("%s: %s\n",otheruser, buffer);
            fflush(stdin);
        }

        if(swrite) {
            scanf("%s",buffer);
            send(sockfd, &buffer, MESSAGE_LENGHT, 0);
            fflush(stdin);
        }
    }
 }

}


static void signal_close_handler(int signo) {

 if(getpid() == masterpid) {
    printf("\nClosing CLIENT..\n");
    close(cfd);
    while(wait(NULL) != -1);
    exit(EXIT_SUCCESS);
 } else exit(EXIT_SUCCESS);
}