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/**
 * @file fake_pos_control.cpp
 * Control functions for ekf fake position fusion
 */

#include "ekf.h"

void Ekf::controlFakePosFusion()
{
	// If we aren't doing any aiding, fake position measurements at the last known position to constrain drift
	// During intial tilt aligment, fake position is used to perform a "quasi-stationary" leveling of the EKF
	const bool fake_pos_data_ready = isTimedOut(_time_last_fake_pos_fuse, (uint64_t)2e5); // Fuse fake position at a limited rate

	if (fake_pos_data_ready) {
		const bool continuing_conditions_passing = !isHorizontalAidingActive();
		const bool starting_conditions_passing = continuing_conditions_passing;

		if (_using_synthetic_position) {
			if (continuing_conditions_passing) {
				fuseFakePosition();

				const bool is_fusion_failing = isTimedOut(_time_last_fake_pos_fuse, (uint64_t)4e5);

				if (is_fusion_failing) {
					resetFakePosFusion();
				}

			} else {
				stopFakePosFusion();
			}

		} else {
			if (starting_conditions_passing) {
				startFakePosFusion();

				if (_control_status.flags.tilt_align) {
					// The fake position fusion is not started for initial alignement
					_warning_events.flags.stopping_navigation = true;
					ECL_WARN("stopping navigation");
				}
			}
		}
	}
}

void Ekf::startFakePosFusion()
{
	if (!_using_synthetic_position) {
		_using_synthetic_position = true;
		_fuse_hpos_as_odom = false; // TODO: needed?
		resetFakePosFusion();
	}
}

void Ekf::resetFakePosFusion()
{
	_last_known_posNE = _state.pos.xy();
	resetHorizontalPosition();
	resetVelocity();
	_time_last_fake_pos_fuse = _time_last_imu;
}

void Ekf::stopFakePosFusion()
{
	_using_synthetic_position = false;
}

void Ekf::fuseFakePosition()
{
	Vector3f fake_pos_obs_var;

	if (_control_status.flags.in_air && _control_status.flags.tilt_align) {
		fake_pos_obs_var(0) = fake_pos_obs_var(1) = sq(fmaxf(_params.pos_noaid_noise, _params.gps_pos_noise));

	} else if (!_control_status.flags.in_air && _control_status.flags.vehicle_at_rest) {
		// Accelerate tilt fine alignment by fusing more
		// aggressively when the vehicle is at rest
		fake_pos_obs_var(0) = fake_pos_obs_var(1) = sq(0.01f);

	} else {
		fake_pos_obs_var(0) = fake_pos_obs_var(1) = sq(0.5f);
	}

	_gps_pos_innov.xy() = Vector2f(_state.pos) - _last_known_posNE;

	const float fake_pos_innov_gate = 3.f;

	if (fuseHorizontalPosition(_gps_pos_innov, fake_pos_innov_gate, fake_pos_obs_var,
	                           _gps_pos_innov_var, _gps_pos_test_ratio, true)) {
		_time_last_fake_pos_fuse = _time_last_imu;
	}
}