#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <sys/sem.h>
#include <sys/shm.h>
#include "semafori.h"

#define SHM_KEY (key_t)1234
#define SEM_KEY1 (key_t)5678
#define SEM_KEY2 (key_t)9012

#define TEXT_SIZE 2048
char text[TEXT_SIZE];

int main(int argc, char* argv[]){
    int continua=1;
    int ShmID;
    int SEM_USER_1, SEM_USER_2;
    void *ShmP=(void*)0;
    char   *buf;
    int mySem;
    int yourSem;
    printf("Benvenuti nella chat, scrivi fine per terminare.\n");

    if (argc<2){
        ShmID = shmget(SHM_KEY, TEXT_SIZE, 0666 | IPC_CREAT);
        if(ShmID==-1){
            perror("errore di shmget");
            exit(EXIT_FAILURE);
        }
        ShmP= shmat(ShmID, (void *)0, 0);
        if(ShmP==(void *)-1){
            perror("errore shmat");
            exit(EXIT_FAILURE);
        }

        buf =(char *)ShmP;
        printf(buf, " ");

        SEM_USER_1=semget(SEM_KEY1, 1, 0666 | IPC_CREAT);
        if(SEM_USER_1==-1){
            perror("Errore semget 1");
            exit(EXIT_FAILURE);
        }
        SEM_USER_2=semget(SEM_KEY1, 1, 0666 | IPC_CREAT);
        if(SEM_USER_2==-1){
            perror("Errore semget 1");
            exit(EXIT_FAILURE);
        }

        if(SEM_SET(SEM_USER_2, 0)==-1) exit(EXIT_FAILURE);
        if(SEM_SET(SEM_USER_1, 1)==-1) exit(EXIT_FAILURE);

        mySem=SEM_USER_2;
        yourSem=SEM_USER_1;
        printf("Tu sei l'utente 2\n");
    } else
        {
        ShmID = shmget(SHM_KEY, TEXT_SIZE, 0666 | IPC_CREAT);
        if(ShmID==-1){
            perror("errore di shmget");
            exit(EXIT_FAILURE);
        }
        ShmP= shmat(ShmID, (void *)0, 0);
        if(ShmP==(void *)-1){
            perror("errore shmat");
            exit(EXIT_FAILURE);
        }

        buf=(char *) ShmP;

        SEM_USER_1=semget(SEM_KEY1, 1, 0666 | IPC_CREAT);
        if(SEM_USER_1==-1){
            perror("Errore semget 1");
            exit(EXIT_FAILURE);
        }
        SEM_USER_2=semget(SEM_KEY1, 1, 0666 | IPC_CREAT);
        if(SEM_USER_2==-1){
            perror("Errore semget 1");
            exit(EXIT_FAILURE);
        }

        mySem=SEM_USER_1;
        yourSem=SEM_USER_2;
        printf("Tu sei l'utente 1\n");
    }

    while (continua){
        SEM_P(mySem);
        if(strncmp(buf, "fine", 4)==0) continua=0;
        else{
            if(strlen(buf)>0)
                printf("Risposta: %s\n", buf);
            printf("> ");
            fgets(buf, TEXT_SIZE, stdin);
            if(strncmp(buf, "fine", 4)==0) continua=0;
        }
        SEM_V(yourSem);
    }

    if(mySem==SEM_USER_2){
        if(shmdt(ShmP)==-1){
            perror("Shmdt fallita\n");
            exit(EXIT_FAILURE);
        }
        if(shmctl(ShmID,     IPC_RMID, 0) ==-1){
            perror("Shmctl errore");
            exit(EXIT_FAILURE);
        }
        SEM_DEL(SEM_USER_1);
        SEM_DEL(SEM_USER_2);
    }
    if(mySem==SEM_USER_1){
        if(shmdt(ShmP)==-1){
            perror("Shmdt fallita \n");
            exit(EXIT_FAILURE);
        }
    }
    exit(EXIT_SUCCESS);
}