#include <stdio.h>
#include <sys/types.h>
#include "shop.h"

CDATA *data = NULL;
int mutex, customers, barbers;

void cut_hair(pid_t pid)
{
  printf("Barber (%d) cutting %d's hair...\n", getpid(), pid);
  sleep(lrand48() % 10);
}

void inthandler(int sig)
{
  sem_close(mutex);
  sem_close(customers);
  sem_close(barbers);
  shmdt((char*)data);
  exit(0);
}

main( int argc, char *argv[] )
{
  int i, shmid;
  pid_t pid;

  mutex = sem_open(MUTEXKEY);
  customers = sem_open(CUSTOMERSKEY);
  barbers = sem_open(BARBERSKEY);

  shmid = shmget(SHMKEY, sizeof(CDATA), 0);
  if (shmid < 0) {
    fprintf(stderr, "shmget: %s\n", sys_errlist[errno]);
    exit(1);
  }

  data = (CDATA*)shmat(shmid, (char *)0, 0);

  if (data < 0) {
    fprintf(stderr, "shmat: %s\n", sys_errlist[errno]);
    exit(1);
  }

  signal(SIGINT, inthandler);

  while(1) {
    sem_wait(customers);
    sem_wait(mutex);

    pid = data->chairs[0];
    for (i=1; i<NUM_CHAIRS; i++)
      data->chairs[i-1] = data->chairs[i];
    data->waiting--;

    sem_signal(barbers);
    sem_signal(mutex);

    cut_hair(pid);
  }

  sem_close(mutex);
  sem_close(customers);
  sem_close(barbers);
  shmdt((char*)data);
  exit(0);
}