///                MentOS, The Mentoring Operating system project
/// @file queue.h
/// @brief Implementation of queue data structure.
/// @copyright (c) 2019 This file is distributed under the MIT License.
/// See LICENSE.md for details.

#pragma once

#include "stddef.h"
#include "stdbool.h"

/// @brief A node of the queue.
typedef struct queue_node_t {
	/// The wrapped data.
	void *data;
	/// The next node of the queue.
	struct queue_node_t *next;
} queue_node_t;

/// @brief The queue.
typedef struct queue_t {
	/// The front of the queue.
	queue_node_t *front;
	/// The back of the queue.
	queue_node_t *back;
	/// The size of the data contained inside the queue.
	size_t data_size;
} * queue_t;

/// @brief           Creates a queue.
/// @param data_size The size of the stored elements.
/// @return          The created queue.
queue_t queue_create(size_t data_size);

/// @brief       Destroys the queue.
/// @param queue The queue to be destroyed.
/// @return      If the queue is destroyed.
bool_t queue_destroy(queue_t queue);

/// @brief       Returns if the queue is empty.
/// @param queue The queue.
bool_t queue_is_empty(queue_t queue);

/// @brief       Allows to add data to the queue.
/// @param queue The queue.
/// @param data  The data to add.
/// @return      If the data has been pushed inside the queue.
bool_t queue_enqueue(queue_t queue, void *data);

/// @brief       Removes the first element of the queue.
/// @param queue The queue.
/// @return      If the data has been removed.
bool_t queue_dequeue(queue_t queue);

/// @brief          Returns the first element of the queue.
/// @param queue    The queue.
/// @param data     The data.
/// @return         If the data has been correctly retrieved.
bool_t queue_front(queue_t queue, void *data);

/// @brief          Returns the last element of the queue.
/// @param queue    The queue.
/// @param data     The data.
/// @return         If the data has been correctly retrieved.
bool_t queue_back(queue_t queue, void *data);

/// @brief          Returns the first element of the queue and removes it.
/// @param queue    The queue.
/// @param data     The data.
/// @return         If the data has been correctly retrieved.
bool_t queue_front_and_dequeue(queue_t queue, void *data);

/// @brief       Deletes all the elements inside the queue.
/// @param queue The queue.
/// @return      If the queue has been cleared.
bool_t queue_clear(queue_t queue);