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/**
 * @file Subscription.hpp
 *
 */

#pragma once

#include <uORB/uORB.h>
#include <containers/List.hpp>
#include <systemlib/err.h>

namespace uORB
{

/**
 * Base subscription wrapper class, used in list traversal
 * of various subscriptions.
 */
class __EXPORT SubscriptionBase
{
public:
	/**
	 * Constructor
	 *
	 * @param meta The uORB metadata (usually from the ORB_ID()
	 * 	macro) for the topic.
	 * @param interval  The minimum interval in milliseconds
	 * 	between updates
	 * @param instance The instance for multi sub.
	 */
	SubscriptionBase(const struct orb_metadata *meta, unsigned interval = 0, unsigned instance = 0);
	virtual ~SubscriptionBase();

	// no copy, assignment, move, move assignment
	SubscriptionBase(const SubscriptionBase &) = delete;
	SubscriptionBase &operator=(const SubscriptionBase &) = delete;
	SubscriptionBase(SubscriptionBase &&) = delete;
	SubscriptionBase &operator=(SubscriptionBase &&) = delete;

	/**
	 * Check if there is a new update.
	 * */
	bool updated();

	/**
	 * Update the struct
	 * @param data The uORB message struct we are updating.
	 */
	bool update(void *data);

	int getHandle() const { return _handle; }

protected:
	const struct orb_metadata *_meta;
	unsigned _instance;
	int _handle;
};

/**
 * alias class name so it is clear that the base class
 */
typedef SubscriptionBase SubscriptionTiny;

/**
 * The subscription base class as a list node.
 */
class __EXPORT SubscriptionNode : public SubscriptionBase, public ListNode<SubscriptionNode *>
{
public:
	/**
	 * Constructor
	 *
	 * @param meta The uORB metadata (usually from the ORB_ID()
	 * 	macro) for the topic.
	 * @param interval  The minimum interval in milliseconds
	 * 	between updates
	 * @param instance The instance for multi sub.
	 * @param list 	A pointer to a list of subscriptions
	 * 	that this should be appended to.
	 */
	SubscriptionNode(const struct orb_metadata *meta, unsigned interval = 0, unsigned instance = 0,
			 List<SubscriptionNode *> *list = nullptr);

	virtual ~SubscriptionNode() override = default;

	/**
	 * This function is the callback for list traversal
	 * updates, a child class must implement it.
	 */
	virtual bool update() = 0;

};

/**
 * Subscription wrapper class
 */
template<class T>
class __EXPORT Subscription final : public SubscriptionNode
{
public:
	/**
	 * Constructor
	 *
	 * @param meta The uORB metadata (usually from
	 * 	the ORB_ID() macro) for the topic.
	 * @param interval  The minimum interval in milliseconds
	 * 	between updates
	 * @param list A list interface for adding to
	 * 	list during construction
	 */
	Subscription(const struct orb_metadata *meta, unsigned interval = 0, unsigned instance = 0,
		     List<SubscriptionNode *> *list = nullptr):
		SubscriptionNode(meta, interval, instance, list),
		_data() // initialize data structure to zero
	{}

	~Subscription() override final = default;

	// no copy, assignment, move, move assignment
	Subscription(const Subscription &) = delete;
	Subscription &operator=(const Subscription &) = delete;
	Subscription(Subscription &&) = delete;
	Subscription &operator=(Subscription &&) = delete;

	/**
	 * Create an update function that uses the embedded struct.
	 */
	bool update() override final
	{
		return SubscriptionBase::update((void *)(&_data));
	}

	/*
	 * This function gets the T struct data
	 * */
	const T &get() const
	{
		return _data;
	}

private:
	T _data;
};

} // namespace uORB