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/*!
 * @file microRTPS_timesync.h
 * @brief Adds time sync for the microRTPS bridge
 * @author Nuno Marques <nuno.marques@dronesolutions.io>
 * @author Julian Kent <julian@auterion.com>
 */

#pragma once

#include <atomic>
#include <functional>
#include <thread>

#include "Timesync_Publisher.h"
#include "Timesync_Subscriber.h"

static constexpr double ALPHA_INITIAL = 0.05;
static constexpr double ALPHA_FINAL = 0.003;
static constexpr double BETA_INTIIAL = 0.05;
static constexpr double BETA_FINAL = 0.003;
static constexpr int WINDOW_SIZE = 500;
static constexpr int64_t UNKNOWN = 0;
static constexpr int64_t TRIGGER_RESET_THRESHOLD_NS = 100ll * 1000ll * 1000ll;
static constexpr int REQUEST_RESET_COUNTER_THRESHOLD = 5;

class TimeSync {
public:
	TimeSync();
	virtual ~TimeSync();

	void start(const Timesync_Publisher* pub);
	void reset();
	void stop();

	void setNewOffsetCB(std::function<void(int64_t)> callback);

	/**
	 * Returns clock monotonic time in nanoseconds
	 */
	inline int64_t getSystemMonoNanos() {
		timespec t;
		clock_gettime(CLOCK_MONOTONIC_RAW, &t);
		return (int64_t)t.tv_sec * 1000000000ll + t.tv_nsec;
	}

	/**
	 * Returns system realtime in seconds
	 */
	inline uint64_t getSystemTime() {
		timespec t;
		clock_gettime(CLOCK_REALTIME, &t);
		return (uint64_t)t.tv_sec + t.tv_nsec;
	}

	bool addMeasurement(int64_t local_t1_ns, int64_t remote_t2_ns, int64_t local_t3_ns);

	void processTimesyncMsg(const px4_msgs::msg::Timesync* msg);

	px4_msgs::msg::Timesync newTimesyncMsg();

	inline void applyOffset(uint64_t &timestamp) { timestamp += _offset_ns.load(); }

private:
	std::atomic<int64_t> _offset_ns;
	int64_t _skew_ns_per_sync;
	int64_t _num_samples;

	int32_t _request_reset_counter;
	uint8_t _last_msg_seq;

	Timesync_Publisher _Timesync_pub;
	Timesync_Subscriber _Timesync_sub;

	std::unique_ptr<std::thread> _send_timesync_thread;
	std::atomic<bool> _request_stop{false};

	std::function<void(int64_t)> _notifyNewOffset;
};