#include <stdlib.h>
#include <stdbool.h>
#include <string.h>

#include "request_queue.h"

struct _rqueue
{
  int size;
  int max;
  request *items;
};

rqueue *rqueue_create(int max)
{
  rqueue *q = malloc(sizeof(rqueue));
  if (q != NULL)
    {
      // initialize size and max
      q->size = 0;
      q->max = max;

      // create an array big enough for max-sized queue
      q->items = malloc(sizeof(request) * max);
      if (q->items == NULL)
	{
	  free(q);
	  return NULL;
	}
    }
  return q;
}

void rqueue_destroy(rqueue *q)
{
  if (q != NULL)
    {
      // free the array and all the copies of the data it has
      // pointers to
      for (int i = 0; i < q->size; i++)
	{
	  free(q->items[i].user);
	  free(q->items[i].position);
	}
      free(q->items);

      // zero out the queue to make it more obviously incorrect if
      // someone tries to use a destroyed queue
      q->items = NULL;
      q->size = 0;

      // free the queue
      free(q);
    }
}

int rqueue_size(const rqueue *q)
{
  if (q != NULL)
    {
      return q->size;
    }
  else
    {
      return 0;
    }
}

bool rqueue_add(rqueue *q, const request *r)
{
  if (q == NULL || q->size == q->max || r == NULL || r->user == NULL || r->position == NULL)
    {
      return false;
    }
  else
    {
      // copy the data
      q->items[q->size].user = malloc(sizeof(char) * (strlen(r->user) + 1));
      q->items[q->size].position = malloc(sizeof(char) * (strlen(r->position) + 1));
      if (q->items[q->size].user == NULL || q->items[q->size].position == NULL)
	{
	  free(q->items[q->size].user);
	  free(q->items[q->size].position);
	  return false;
	}
      strcpy(q->items[q->size].user, r->user);
      strcpy(q->items[q->size].position, r->position);

      // update size
      q->size++;
      
      return true;
    }
}

void rqueue_remove(rqueue *q, request *r)
{
  if (q != NULL && q->size > 0)
    {
      // save the data in the reference parameter
      if (r != NULL)
	{
	  *r = q->items[0];
	}

      // update size
      q->size--;

      // move everything back one space so next to remove is
      // always at index 0
      for (int i = 0; i < q->size; i++)
	{
	  q->items[i] = q->items[i + 1];
	}
    }
}