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

typedef struct _Queue {
	void** elems;
	int size;
	QueueFreeFunc free;
} Queue;

static void free_elem(Queue* queue) {
	if (queue->free) {
		for (int i = 0; i < queue->size; i++)
			queue->free(queue->elems[i]);
	}
	free(queue->elems);
}

Queue* queue_new() {
	Queue* q = malloc(sizeof(Queue));
	q->size = 0;
	q->elems = NULL;
	q->free = NULL;
	return q;
}

Queue* queue_new_full(QueueFreeFunc free){
	Queue* q = malloc(sizeof(Queue));
	q->size = 0;
	q->elems = NULL;
	q->free = free;
	return q;
}

void queue_destroy(Queue* queue) {
	free_elem(queue);
	free(queue);
}

/*
static void extend(Queue* queue, void* elem) {
	while (int i = queue->size - 1; i > 0; i--) {
		queue->elems[i] = queue->elems[i - 1]
	}
	queue->elems[0] elem;
}
*/
void* queue_dequeue(Queue* queue) {
	if (queue_empty(queue))
		return NULL;
	queue->size -= 1;
	void* elem = queue->elems[queue->size];
	queue->elems[queue->size] = NULL;
	queue->elems = realloc(queue->elems, queue->size * sizeof(void*));

	return elem;
}

void queue_enqueue(Queue* queue, void* elem) {
	if (queue == NULL)
		return;

	queue->size += 1;
	queue->elems = realloc(queue->elems, queue->size * sizeof(void*));
	for (int i = queue->size - 1; i > 0; i--) {
		queue->elems[i] = queue->elems[i - 1];
	}
	queue->elems[0] = elem;
}

void* queue_front(Queue* queue) {
	if (queue_empty(queue))
		return NULL;
	return queue->elems[0];
}

void* queue_back(Queue* queue) {
	if (queue_empty(queue))
		return NULL;
	return queue->elems[queue->size - 1];
}

bool queue_empty(Queue* queue) {
	return (queue == NULL || queue->size == 0);
}

void queue_clear(Queue* queue) {
	if (queue == NULL)
		return;

	free_elem(queue);
	queue->size = 0;
	queue->elems = NULL;
}

int queue_size(Queue* queue) {
	if (queue_empty(queue))
		return 0;
	return queue->size;
}