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/**
 * @file FixedwingLandDetector.cpp
 *
 * @author Johan Jansen <jnsn.johan@gmail.com>
 * @author Lorenz Meier <lorenz@px4.io>
 * @author Julian Oes <julian@oes.ch>
 */

#include <matrix/math.hpp>

#include "FixedwingLandDetector.h"

namespace land_detector
{

FixedwingLandDetector::FixedwingLandDetector()
{
	// Use Trigger time when transitioning from in-air (false) to landed (true) / ground contact (true).
	_landed_hysteresis.set_hysteresis_time_from(false, LANDED_TRIGGER_TIME_US);
	_landed_hysteresis.set_hysteresis_time_from(true, FLYING_TRIGGER_TIME_US);
}

void FixedwingLandDetector::_update_topics()
{
	_airspeed_sub.update(&_airspeed);
	_vehicle_acceleration_sub.update(&_vehicle_acceleration);
	_vehicle_local_position_sub.update(&_vehicle_local_position);
}

void FixedwingLandDetector::_update_params()
{
	parameter_update_s param_update;

	if (_param_update_sub.update(&param_update)) {
		_update_params();
	}
}

float FixedwingLandDetector::_get_max_altitude()
{
	// TODO
	// This means no altitude limit as the limit
	// is always current position plus 10000 meters
	return roundf(-_vehicle_local_position.z + 10000);
}

bool FixedwingLandDetector::_get_landed_state()
{
	// only trigger flight conditions if we are armed
	if (!_actuator_armed.armed) {
		return true;
	}

	bool landDetected = false;

	if (hrt_elapsed_time(&_vehicle_local_position.timestamp) < 500_ms) {

		// Horizontal velocity complimentary filter.
		float val = 0.97f * _velocity_xy_filtered + 0.03f * sqrtf(_vehicle_local_position.vx * _vehicle_local_position.vx +
				_vehicle_local_position.vy * _vehicle_local_position.vy);

		if (PX4_ISFINITE(val)) {
			_velocity_xy_filtered = val;
		}

		// Vertical velocity complimentary filter.
		val = 0.99f * _velocity_z_filtered + 0.01f * fabsf(_vehicle_local_position.vz);

		if (PX4_ISFINITE(val)) {
			_velocity_z_filtered = val;
		}

		_airspeed_filtered = 0.95f * _airspeed_filtered + 0.05f * _airspeed.true_airspeed_m_s;

		// A leaking lowpass prevents biases from building up, but
		// gives a mostly correct response for short impulses.
		const matrix::Vector3f accel{_vehicle_acceleration.xyz};
		const float acc_hor = sqrtf(accel(0) * accel(0) + accel(1) * accel(1));

		_xy_accel_filtered = _xy_accel_filtered * 0.8f + acc_hor * 0.18f;

		// crude land detector for fixedwing
		landDetected = _xy_accel_filtered       < _param_lndfw_xyaccel_max.get()
			       && _airspeed_filtered    < _param_lndfw_airspd.get()
			       && _velocity_xy_filtered < _param_lndfw_vel_xy_max.get()
			       && _velocity_z_filtered  < _param_lndfw_vel_z_max.get();

	} else {
		// Control state topic has timed out and we need to assume we're landed.
		landDetected = true;
	}

	return landDetected;
}

} // namespace land_detector