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/**
 * @file FixedwingLandDetector.cpp
 * Land detection algorithm for fixedwings
 *
 * @author Johan Jansen <jnsn.johan@gmail.com>
 */

#include "FixedwingLandDetector.h"

#include <cmath>
#include <drivers/drv_hrt.h>

FixedwingLandDetector::FixedwingLandDetector() : LandDetector(),
	_paramHandle(),
	_params(),
	_vehicleLocalPositionSub(-1),
	_vehicleLocalPosition({}),
	_airspeedSub(-1),
	_airspeed({}),
	_parameterSub(-1),
	_velocity_xy_filtered(0.0f),
	_velocity_z_filtered(0.0f),
	_airspeed_filtered(0.0f),
	_landDetectTrigger(0)
{
	_paramHandle.maxVelocity = param_find("LNDFW_VEL_XY_MAX");
	_paramHandle.maxClimbRate = param_find("LNDFW_VEL_Z_MAX");
	_paramHandle.maxAirSpeed = param_find("LNDFW_AIRSPD_MAX");
}

void FixedwingLandDetector::initialize()
{
	// Subscribe to local position and airspeed data
	_vehicleLocalPositionSub = orb_subscribe(ORB_ID(vehicle_local_position));
	_airspeedSub = orb_subscribe(ORB_ID(airspeed));

	updateParameterCache(true);
}

void FixedwingLandDetector::updateSubscriptions()
{
	orb_update(ORB_ID(vehicle_local_position), _vehicleLocalPositionSub, &_vehicleLocalPosition);
	orb_update(ORB_ID(airspeed), _airspeedSub, &_airspeed);
}

bool FixedwingLandDetector::update()
{
	// First poll for new data from our subscriptions
	updateSubscriptions();

	const uint64_t now = hrt_absolute_time();
	bool landDetected = false;

	// TODO: reset filtered values on arming?
	_velocity_xy_filtered = 0.95f * _velocity_xy_filtered + 0.05f * sqrtf(_vehicleLocalPosition.vx *
				_vehicleLocalPosition.vx + _vehicleLocalPosition.vy * _vehicleLocalPosition.vy);
	_velocity_z_filtered = 0.95f * _velocity_z_filtered + 0.05f * fabsf(_vehicleLocalPosition.vz);
	_airspeed_filtered = 0.95f * _airspeed_filtered + 0.05f * _airspeed.true_airspeed_m_s;

	// crude land detector for fixedwing
	if (_velocity_xy_filtered < _params.maxVelocity
	    && _velocity_z_filtered < _params.maxClimbRate
	    && _airspeed_filtered < _params.maxAirSpeed) {

		// these conditions need to be stable for a period of time before we trust them
		if (now > _landDetectTrigger) {
			landDetected = true;
		}

	} else {
		// reset land detect trigger
		_landDetectTrigger = now + LAND_DETECTOR_TRIGGER_TIME;
	}

	return landDetected;
}

void FixedwingLandDetector::updateParameterCache(const bool force)
{
	bool updated;
	parameter_update_s paramUpdate;

	orb_check(_parameterSub, &updated);

	if (updated) {
		orb_copy(ORB_ID(parameter_update), _parameterSub, &paramUpdate);
	}

	if (updated || force) {
		param_get(_paramHandle.maxVelocity, &_params.maxVelocity);
		param_get(_paramHandle.maxClimbRate, &_params.maxClimbRate);
		param_get(_paramHandle.maxAirSpeed, &_params.maxAirSpeed);
	}
}