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/**
 * @file mavlink_ulog.cpp
 * ULog data streaming via MAVLink
 *
 * @author Beat Küng <beat-kueng@gmx.net>
 */

#include "mavlink_ulog.h"
#include <px4_platform_common/log.h>
#include <errno.h>
#include <mathlib/mathlib.h>

bool MavlinkULog::_init = false;
MavlinkULog *MavlinkULog::_instance = nullptr;
px4_sem_t MavlinkULog::_lock;
const float MavlinkULog::_rate_calculation_delta_t = 0.1f;


MavlinkULog::MavlinkULog(int datarate, float max_rate_factor, uint8_t target_system, uint8_t target_component)
	: _target_system(target_system), _target_component(target_component),
	  _max_rate_factor(max_rate_factor),
	  _max_num_messages(math::max(1, (int)ceilf(_rate_calculation_delta_t *_max_rate_factor * datarate /
				      (MAVLINK_MSG_ID_LOGGING_DATA_LEN + MAVLINK_NUM_NON_PAYLOAD_BYTES)))),
	  _current_rate_factor(max_rate_factor)
{
	// make sure we won't read any old messages
	while (_ulog_stream_sub.update()) {

	}

	_waiting_for_initial_ack = true;
	_last_sent_time = hrt_absolute_time(); //(ab)use this timestamp during initialization
	_next_rate_check = _last_sent_time + _rate_calculation_delta_t * 1.e6f;
}

void MavlinkULog::start_ack_received()
{
	if (_waiting_for_initial_ack) {
		_last_sent_time = 0;
		_waiting_for_initial_ack = false;
		PX4_DEBUG("got logger ack");
	}
}

int MavlinkULog::handle_update(mavlink_channel_t channel)
{
	static_assert(sizeof(ulog_stream_s::data) == MAVLINK_MSG_LOGGING_DATA_FIELD_DATA_LEN,
		      "Invalid uorb ulog_stream.data length");
	static_assert(sizeof(ulog_stream_s::data) == MAVLINK_MSG_LOGGING_DATA_ACKED_FIELD_DATA_LEN,
		      "Invalid uorb ulog_stream.data length");

	if (_waiting_for_initial_ack) {
		if (hrt_elapsed_time(&_last_sent_time) > 3e5) {
			PX4_WARN("no ack from logger (is it running?)");
			return -1;
		}

		return 0;
	}

	// check if we're waiting for an ACK
	if (_last_sent_time) {
		bool check_for_updates = false;

		if (_ack_received) {
			_last_sent_time = 0;
			check_for_updates = true;

		} else {

			if (hrt_elapsed_time(&_last_sent_time) > ulog_stream_ack_s::ACK_TIMEOUT * 1000) {
				if (++_sent_tries > ulog_stream_ack_s::ACK_MAX_TRIES) {
					return -ETIMEDOUT;

				} else {
					PX4_DEBUG("re-sending ulog mavlink message (try=%i)", _sent_tries);
					_last_sent_time = hrt_absolute_time();

					const ulog_stream_s &ulog_data = _ulog_stream_sub.get();

					mavlink_logging_data_acked_t msg;
					msg.sequence = ulog_data.msg_sequence;
					msg.length = ulog_data.length;
					msg.first_message_offset = ulog_data.first_message_offset;
					msg.target_system = _target_system;
					msg.target_component = _target_component;
					memcpy(msg.data, ulog_data.data, sizeof(msg.data));
					mavlink_msg_logging_data_acked_send_struct(channel, &msg);
				}
			}
		}

		if (!check_for_updates) {
			return 0;
		}
	}

	while ((_current_num_msgs < _max_num_messages) && _ulog_stream_sub.update()) {
		const ulog_stream_s &ulog_data = _ulog_stream_sub.get();

		if (ulog_data.timestamp > 0) {
			if (ulog_data.flags & ulog_stream_s::FLAGS_NEED_ACK) {
				_sent_tries = 1;
				_last_sent_time = hrt_absolute_time();
				lock();
				_wait_for_ack_sequence = ulog_data.msg_sequence;
				_ack_received = false;
				unlock();

				mavlink_logging_data_acked_t msg;
				msg.sequence = ulog_data.msg_sequence;
				msg.length = ulog_data.length;
				msg.first_message_offset = ulog_data.first_message_offset;
				msg.target_system = _target_system;
				msg.target_component = _target_component;
				memcpy(msg.data, ulog_data.data, sizeof(msg.data));
				mavlink_msg_logging_data_acked_send_struct(channel, &msg);

			} else {
				mavlink_logging_data_t msg;
				msg.sequence = ulog_data.msg_sequence;
				msg.length = ulog_data.length;
				msg.first_message_offset = ulog_data.first_message_offset;
				msg.target_system = _target_system;
				msg.target_component = _target_component;
				memcpy(msg.data, ulog_data.data, sizeof(msg.data));
				mavlink_msg_logging_data_send_struct(channel, &msg);
			}
		}

		++_current_num_msgs;
	}

	//need to update the rate?
	hrt_abstime t = hrt_absolute_time();

	if (t > _next_rate_check) {
		if (_current_num_msgs < _max_num_messages) {
			_current_rate_factor = _max_rate_factor * (float)_current_num_msgs / _max_num_messages;

		} else {
			_current_rate_factor = _max_rate_factor;
		}

		_current_num_msgs = 0;
		_next_rate_check = t + _rate_calculation_delta_t * 1.e6f;
		PX4_DEBUG("current rate=%.3f (max=%i msgs in %.3fs)", (double)_current_rate_factor, _max_num_messages,
			  (double)_rate_calculation_delta_t);
	}

	return 0;
}

void MavlinkULog::initialize()
{
	if (_init) {
		return;
	}

	px4_sem_init(&_lock, 1, 1);
	_init = true;
}

MavlinkULog *MavlinkULog::try_start(int datarate, float max_rate_factor, uint8_t target_system,
				    uint8_t target_component)
{
	MavlinkULog *ret = nullptr;
	bool failed = false;
	lock();

	if (!_instance) {
		ret = _instance = new MavlinkULog(datarate, max_rate_factor, target_system, target_component);

		if (!_instance) {
			failed = true;
		}
	}

	unlock();

	if (failed) {
		PX4_ERR("alloc failed");
	}

	return ret;
}

void MavlinkULog::stop()
{
	lock();

	if (_instance) {
		delete _instance;
		_instance = nullptr;
	}

	unlock();
}

void MavlinkULog::handle_ack(mavlink_logging_ack_t ack)
{
	lock();

	if (_instance) { // make sure stop() was not called right before
		if (_wait_for_ack_sequence == ack.sequence) {
			_ack_received = true;
			publish_ack(ack.sequence);
		}
	}

	unlock();
}

void MavlinkULog::publish_ack(uint16_t sequence)
{
	ulog_stream_ack_s ack;
	ack.timestamp = hrt_absolute_time();
	ack.msg_sequence = sequence;

	_ulog_stream_ack_pub.publish(ack);
}
