/**
 * array-queue.c
 *   An implementation of linear structures using array-based queues.
 */

// +---------+--------------------------------------------------------
// | Headers |
// +---------+

#include "collection.h"
#include <stdlib.h> 	// For malloc
#include <string.h>	// For strdup


// +-----------+------------------------------------------------------
// | Constants |
// +-----------+

#ifndef QUEUE_CAPACITY
#define QUEUE_CAPACITY 100
#endif // QUEUE_CAPACITY


// +-------+----------------------------------------------------------
// | Types |
// +-------+

struct collection {
  char *contents[QUEUE_CAPACITY];
  int size;
  int front;
  int back;
};


// +-----------+------------------------------------------------------
// | Functions |
// +-----------+

struct collection *
new_collection (int recommended_capacity)
{
  struct collection *result;
  result = malloc (sizeof (struct collection));
  if (result == NULL)
    return NULL;
  result->size = 0;
  result->front = 0;
  result->back = 0;
  return result;
} // new_collection

void 
collection_free (struct collection *stuff)
{
  int i;
  for (i = stuff->front; i != stuff->back; i = (i + 1) % QUEUE_CAPACITY)
    {
      free (stuff->contents[i]);
      stuff->contents[i] = NULL;
    }
  free (stuff);
} // collection_free

int
collection_put (struct collection *stuff, char *str)
{
  if (collection_is_full (stuff))
    return 0;
  stuff->contents[stuff->back] = strdup (str);
  stuff->back = (stuff->back + 1) % QUEUE_CAPACITY;
  ++(stuff->size);
  return 1;
} // collection_put

char *
collection_get (struct collection *stuff)
{
  if (collection_is_empty (stuff))
    return NULL;
  char *result = stuff->contents[stuff->front];
  stuff->contents[stuff->front] = NULL; // Don't keep pointers around
  stuff->front = (stuff->front + 1) % QUEUE_CAPACITY;
  --(stuff->size);
  return result;
} // collection_get

char *
collection_peek (struct collection *stuff)
{
  if (collection_is_empty (stuff))
    return NULL;
  return stuff->contents[stuff->front];
} // collection_peek

int
collection_size (struct collection *stuff)
{
  return stuff->size;
} // collection_size

int 
collection_is_empty (struct collection *stuff)
{
  return (stuff->size == 0);
} // collection_is_empty

int 
collection_is_full (struct collection *stuff)
{
  return (stuff->size == QUEUE_CAPACITY);
} // collection_is_full