#include <stdio.h>
#include <stdlib.h>
#include <sys/shm.h>
#include <unistd.h>

#define NUM_PROCS 4
#define SHM_SIZE 1024
#define PATHNAME "."
#define PROJ_ID 65

int create_mem_segment(int **shm_array) {
  int shmid;
  key_t key = ftok(PATHNAME, PROJ_ID);

  // Create a new shared segment
  if ((shmid = shmget(key, SHM_SIZE, IPC_CREAT | 0666)) < 0) {
    perror("[!] Shmget failed");
    exit(EXIT_FAILURE);
  }

  // Attach (system chooses a suitable address)
  if ((*shm_array = (int *)shmat(shmid, NULL, 0)) == (int *)-1) {
    perror("[!] Shmat failed");
    exit(EXIT_FAILURE);
  }

  return shmid;
}

int compare(const void *a, const void *b) { return (*(int *)a - *(int *)b); }

int main() {
  int *shm_array;

  int delay = 5;

  // Creation and attaching into a new shared segment
  int shmid = create_mem_segment(&shm_array);
  printf("[SCHEDULER] Shared segment %d created (%p)\n", shmid,
         (void *)shm_array);

  // Wait until init has finished writing into the segment
  printf("[SCHEDULER] Sleeping for %d seconds before reading\n", delay);
  sleep(delay);

  // Copying array to a local variable
  int priorities[NUM_PROCS];

  for (int i = 0; i < NUM_PROCS; i++) {
    priorities[i] = shm_array[i];
  }

  // TODO: "After scheduler prints the data, init should detach from shared
  // memory" -> Some mechanism to indicate when init has detached must be put in
  // place

  // Detaching and deleting the segment
  shmdt(shm_array);
  shmctl(shmid, IPC_RMID, NULL);

  // Sorting and printing the priorities
  qsort(&priorities, NUM_PROCS, sizeof(int), compare);

  printf("[SCHEDULER] Priorities: ");

  for (int i = 0; i < NUM_PROCS; i++) {
    printf("%d ", priorities[i]);
  }

  printf("\n");

  return 0;
}