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/**
 * @file fw_wheel_controller.cpp
 * Implementation of a simple PID wheel controller for heading tracking.
 */

#include "fw_wheel_controller.h"
#include <float.h>
#include <lib/geo/geo.h>
#include <mathlib/mathlib.h>
#include <matrix/math.hpp>

using matrix::wrap_pi;

float WheelController::control_bodyrate(float dt, float body_z_rate, float groundspeed, float groundspeed_scaler)
{
	/* Do not calculate control signal with bad inputs */
	if (!(PX4_ISFINITE(body_z_rate) &&
	      PX4_ISFINITE(groundspeed) &&
	      PX4_ISFINITE(groundspeed_scaler))) {

		return math::constrain(_last_output, -1.f, 1.f);
	}

	const float rate_error = _body_rate_setpoint - body_z_rate;

	if (_k_i > 0.f && groundspeed > 1.f) { // only start integrating when above 1m/s

		float id = rate_error * dt * groundspeed_scaler * groundspeed_scaler;

		if (_last_output < -1.f) {
			/* only allow motion to center: increase value */
			id = math::max(id, 0.f);

		} else if (_last_output > 1.f) {
			/* only allow motion to center: decrease value */
			id = math::min(id, 0.f);
		}

		_integrator = math::constrain(_integrator + id * _k_i, -_integrator_max, _integrator_max);
	}

	/* Apply PI rate controller and store non-limited output */
	_last_output = _body_rate_setpoint * _k_ff * groundspeed_scaler +
		       groundspeed_scaler * groundspeed_scaler * (rate_error * _k_p) + _integrator;

	return math::constrain(_last_output, -1.f, 1.f);
}

float WheelController::control_attitude(float yaw_setpoint, float yaw)
{
	/* Do not calculate control signal with bad inputs */
	if (!(PX4_ISFINITE(yaw_setpoint) &&
	      PX4_ISFINITE(yaw))) {

		return _body_rate_setpoint;
	}

	const float yaw_error = wrap_pi(yaw_setpoint - yaw);

	_body_rate_setpoint = yaw_error / _tc; // assume 0 pitch and roll angle, thus jacobian is simply identity matrix

	if (_max_rate > 0.01f) {
		if (_body_rate_setpoint > 0.f) {
			_body_rate_setpoint = (_body_rate_setpoint > _max_rate) ? _max_rate : _body_rate_setpoint;

		} else {
			_body_rate_setpoint = (_body_rate_setpoint < -_max_rate) ? -_max_rate : _body_rate_setpoint;
		}

	}

	return _body_rate_setpoint;
}