#include <stdlib.h>
#include "cqueue.h"

typedef struct {
  void **data;
  int capacity;
  int front;
  int size;
} Queue;

void *new_queue(int capacity) {
  Queue *new_q = (Queue *)malloc(sizeof(Queue));
  new_q->data = (void **)malloc(sizeof(void *) * capacity);
  new_q->capacity = capacity;
  new_q->front = 0;
  new_q->size = 0;
}

void free_queue(void *queue) {
  Queue *q = (Queue *)queue;
  free(q->data);
  free(q);
}

void queue_enqueue(void *queue, void *value) {
  Queue *q = (Queue *)queue;
  int back;
  if (!queue_full(queue)) {
    back = (q->front + q->size) % q->capacity;
    q->data[back] = value;
    q->size++;
  }
}

void *queue_dequeue(void *queue) {
  Queue *q = (Queue *)queue;
  int old_front = q->front;
  if (queue_empty(queue))
    return NULL;
  q->size--;
  q->front = (q->front + 1) % q->capacity;
  return q->data[old_front];
}

void *queue_peek(void *queue) {
  Queue *q = (Queue *)queue;
  if (queue_empty(queue))
    return NULL;
  return q->data[q->front];
}

int queue_empty(void *queue) {
  Queue *q = (Queue *)queue;
  return (q->size == 0);
}

int queue_full(void *queue) {
  Queue *q = (Queue *)queue;
  return (q->size == q->capacity);
}

int queue_size(void *queue) {
  Queue *q = (Queue *)queue;
  return q->size;
}