#include <stdio.h>
#include <sys/mman.h>
#include <sys/types.h>
#include <unistd.h>
#include <fcntl.h>
#include <sys/stat.h>
#include <stdlib.h>
#include <signal.h>
#include <semaphore.h>
#include <string.h>
#include <stdbool.h>

#define SHM_PATH "/shmue"
#define PERMISSION (0600)

#define SEM_SERVER "/semserver"
#define SEM_CLIENT "/semclient"
#define CLIENT_CONT "/client_cont"

#define LINE_SIZE (100)

sem_t *server_sem;
sem_t *client_cont_sem;
sem_t *client_sem;

int shmfd = -1;

typedef struct{

    int account_nr;
    int response;

    int log_in;
}SHM_msg;

SHM_msg *shared_message;

void setupSharedMemory(void);
void bail_out(int exit_code, char *error_msg);
void free_resources(void);
void check_login(void);
void printSHM(void);
void createSemaphores(void);
void signal_handler(int signum);

int main(int argc, char *argv[])
{
    if(atexit(free_resources) != 0)
    {
        fprintf(stderr,"error at atexit.\n");
    }

    signal(SIGINT,signal_handler);

    createSemaphores();
    setupSharedMemory();

    while(1)
    {
        check_login();
    }

    return 1;
}

void signal_handler(int signum)
{
    free_resources();
    exit(signum);
}

void createSemaphores() {

    client_sem = sem_open(SEM_CLIENT,O_CREAT, PERMISSION,1);
    server_sem = sem_open(SEM_SERVER,O_CREAT, PERMISSION,0);
    client_cont_sem = sem_open(CLIENT_CONT,O_CREAT, PERMISSION,0);

    if(client_sem == SEM_FAILED || server_sem == SEM_FAILED || client_cont_sem == SEM_FAILED) {
        printf("jdsds");
    }

}

/*

void createSemaphores()
{
    client_sem = sem_open(SEM_CLIENT, O_CREAT, PERMISSION,1);
    server_sem = sem_open(SEM_SERVER, O_CREAT, PERMISSION,0);
    client_cont_sem = sem_open(CLIENT_CONT, O_CREAT, PERMISSION,0);

    if(client_sem == SEM_FAILED || server_sem == SEM_FAILED || client_cont_sem == SEM_FAILED)
    {
        bail_out(EXIT_FAILURE, "error at creating semaphores");
    }
}
*/

void check_login(void)
{


    if(shared_message->log_in == 1)
    {
        sem_wait(server_sem);

        printf("%d logged in!\n",shared_message->account_nr);
        printSHM();

        shared_message->response = 1;
        shared_message->log_in = -1;

        sleep(3);

        sem_post(client_cont_sem);
    }


}

void setupSharedMemory()
{
    shmfd = shm_open(SHM_PATH, O_CREAT | O_RDWR, PERMISSION);

    if(shmfd == -1)
    {
        bail_out(EXIT_FAILURE,"could not create shm obj");
    }

    if(ftruncate(shmfd, sizeof(SHM_msg)) == -1)
    {
        bail_out(EXIT_FAILURE,"could not truncate memory");
    }

    shared_message = mmap(NULL, sizeof(SHM_msg), PROT_READ | PROT_WRITE, MAP_SHARED,shmfd,0);

    if(shared_message == MAP_FAILED)
    {
        bail_out(EXIT_FAILURE,"could not map memory");
    }

    shared_message->account_nr = -1;
    shared_message->response = -1;
    shared_message->log_in = -1;

}

void bail_out(int exit_code, char *error_msg)
{
    fprintf(stderr,"Error in program:  %s\n", error_msg);

    free_resources();

    exit(exit_code);
}

void free_resources()
{

    printf("Free Resources\n");
    if(shmfd != -1)
    {
        if(close(shmfd) == -1)
        {
            fprintf(stderr,"could not close shm");
        }

        if(shm_unlink(SHM_PATH) == -1)
        {
            fprintf(stderr,"could not unlink shm");
        }

        if(munmap(shared_message,sizeof(SHM_msg)) == -1)
        {
            fprintf(stderr,"could not unmap shm");
        }


        printf("Resources freed.\n");
    }

    if(sem_close(client_sem) == -1)
    {
        fprintf(stderr,"could not close client_sem\n");
    }
    if(sem_unlink(SEM_CLIENT) == -1)
    {
        fprintf(stderr,"could not unlink SEM_CLIENT\n");
    }



    if(sem_close(server_sem) == -1)
    {
        fprintf(stderr,"could not close client_sem\n");
    }
    if(sem_unlink(SEM_SERVER) == -1)
    {
        fprintf(stderr,"could not unlink SEM_CLIENT\n");
    }



    if(sem_close(client_cont_sem) == -1)
    {
        fprintf(stderr,"could not close client_sem\n");
    }
    if(sem_unlink(CLIENT_CONT) == -1)
    {
        fprintf(stderr,"could not unlink SEM_CLIENT\n");
    }
}

void printSHM()
{
    printf("Account nr: %d\n",shared_message->account_nr);
    printf("Response: %d\n",shared_message->response);
    printf("Login: %d\n",shared_message->log_in);
}