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/**
 * @file navigator_rtl.cpp
 * Helper class to access RTL
 * @author Julian Oes <julian@oes.ch>
 * @author Anton Babushkin <anton.babushkin@me.com>
 */

#include <string.h>
#include <stdlib.h>
#include <math.h>
#include <fcntl.h>

#include <mavlink/mavlink_log.h>
#include <systemlib/err.h>

#include <uORB/uORB.h>
#include <uORB/topics/mission.h>
#include <uORB/topics/home_position.h>

#include "navigator.h"
#include "rtl.h"

RTL::RTL(Navigator *navigator, const char *name) :
	NavigatorMode(navigator, name),
	MissionBlock(navigator),
	_rtl_state(RTL_STATE_NONE),
	_param_return_alt(this, "RETURN_ALT"),
	_param_descend_alt(this, "DESCEND_ALT"),
	_param_land_delay(this, "LAND_DELAY"),
	_param_acceptance_radius(this, "ACCEPT_RAD")
{
	/* load initial params */
	updateParams();
	/* initial reset */
	reset();
}

RTL::~RTL()
{
}

void
RTL::reset()
{
	_first_run = true;
	_rtl_state = RTL_STATE_NONE;
}

bool
RTL::update(struct position_setpoint_triplet_s *pos_sp_triplet)
{
	bool updated = false;

	if (_first_run) {
		set_rtl_item(pos_sp_triplet);
		updated = true;
		_first_run = false;
	}

	if ((_rtl_state == RTL_STATE_CLIMB
	     || _rtl_state == RTL_STATE_RETURN)
	    && is_mission_item_reached()) {
		advance_rtl();
		set_rtl_item(pos_sp_triplet);
		updated = true;
	}

	return updated;
}

void
RTL::set_rtl_item(position_setpoint_triplet_s *pos_sp_triplet)
{
	/* make sure we have the latest params */
	updateParams();

	/* decide where to enter the RTL procedure when we switch into it */
	if (_rtl_state == RTL_STATE_NONE) {
		/* for safety reasons don't go into RTL if landed */
		if (_navigator->get_vstatus()->condition_landed) {
			_rtl_state = RTL_STATE_FINISHED;
			mavlink_log_info(_navigator->get_mavlink_fd(), "#audio: no RTL when landed");
		/* if lower than return altitude, climb up first */
		} else if (_navigator->get_global_position()->alt < _navigator->get_home_position()->alt
			   + _param_return_alt.get()) {
			_rtl_state = RTL_STATE_CLIMB;
		/* otherwise go straight to return */
		} else {
			_rtl_state = RTL_STATE_RETURN;
		}
	}

	/* if switching directly to return state, set altitude setpoint to current altitude */
	if (_rtl_state == RTL_STATE_RETURN) {
		_mission_item.altitude_is_relative = false;
		_mission_item.altitude = _navigator->get_global_position()->alt;
	}

	switch (_rtl_state) {
	case RTL_STATE_CLIMB: {

		float climb_alt = _navigator->get_home_position()->alt + _param_return_alt.get();

		_mission_item.lat = _navigator->get_global_position()->lat;
		_mission_item.lon = _navigator->get_global_position()->lon;
		_mission_item.altitude_is_relative = false;
		_mission_item.altitude = climb_alt;
		_mission_item.yaw = NAN;
		_mission_item.loiter_radius = _navigator->get_loiter_radius();
		_mission_item.loiter_direction = 1;
		_mission_item.nav_cmd = NAV_CMD_WAYPOINT;
		_mission_item.acceptance_radius = _param_acceptance_radius.get();
		_mission_item.time_inside = 0.0f;
		_mission_item.pitch_min = 0.0f;
		_mission_item.autocontinue = true;
		_mission_item.origin = ORIGIN_ONBOARD;

		_navigator->set_is_in_loiter(false);

		mavlink_log_info(_navigator->get_mavlink_fd(), "#audio: RTL: climb to %d meters above home",
			(int)(climb_alt - _navigator->get_home_position()->alt));
		break;
	}
	case RTL_STATE_RETURN: {

		_mission_item.lat = _navigator->get_home_position()->lat;
		_mission_item.lon = _navigator->get_home_position()->lon;

		/* TODO: add this again */
		// don't change altitude
		// if (_pos_sp_triplet.previous.valid) {
		// 	/* if previous setpoint is valid then use it to calculate heading to home */
		// 	_mission_item.yaw = get_bearing_to_next_waypoint(_pos_sp_triplet.previous.lat, _pos_sp_triplet.previous.lon, _mission_item.lat, _mission_item.lon);

		// } else {
		// 	/* else use current position */
		// 	_mission_item.yaw = get_bearing_to_next_waypoint(_global_pos.lat, _global_pos.lon, _mission_item.lat, _mission_item.lon);
		// }
		_mission_item.loiter_radius = _navigator->get_loiter_radius();
		_mission_item.loiter_direction = 1;
		_mission_item.nav_cmd = NAV_CMD_WAYPOINT;
		_mission_item.acceptance_radius = _param_acceptance_radius.get();
		_mission_item.time_inside = 0.0f;
		_mission_item.pitch_min = 0.0f;
		_mission_item.autocontinue = true;
		_mission_item.origin = ORIGIN_ONBOARD;

		_navigator->set_is_in_loiter(false);

		mavlink_log_info(_navigator->get_mavlink_fd(), "#audio: RTL: return at %d meters above home",
			(int)(_mission_item.altitude - _navigator->get_home_position()->alt));
		break;
	}
	case RTL_STATE_DESCEND: {

		_mission_item.lat = _navigator->get_home_position()->lat;
		_mission_item.lon = _navigator->get_home_position()->lon;
		_mission_item.altitude_is_relative = false;
		_mission_item.altitude = _navigator->get_home_position()->alt + _param_descend_alt.get();
		_mission_item.yaw = NAN;
		_mission_item.loiter_radius = _navigator->get_loiter_radius();
		_mission_item.loiter_direction = 1;
		_mission_item.nav_cmd = NAV_CMD_LOITER_TIME_LIMIT;
		_mission_item.acceptance_radius = _param_acceptance_radius.get();
		_mission_item.time_inside = _param_land_delay.get() < 0.0f ? 0.0f : _param_land_delay.get();
		_mission_item.pitch_min = 0.0f;
		_mission_item.autocontinue = _param_land_delay.get() > -0.001f;
		_mission_item.origin = ORIGIN_ONBOARD;

		_navigator->set_is_in_loiter(true);

		mavlink_log_info(_navigator->get_mavlink_fd(), "#audio: RTL: descend to %d meters above home",
			(int)(_mission_item.altitude - _navigator->get_home_position()->alt));
		break;
	}

	case RTL_STATE_LAND: {

		_mission_item.lat = _navigator->get_home_position()->lat;
		_mission_item.lon = _navigator->get_home_position()->lon;
		_mission_item.altitude_is_relative = false;
		_mission_item.altitude = _navigator->get_home_position()->alt;
		_mission_item.yaw = NAN;
		_mission_item.loiter_radius = _navigator->get_loiter_radius();
		_mission_item.loiter_direction = 1;
		_mission_item.nav_cmd = NAV_CMD_LAND;
		_mission_item.acceptance_radius = _param_acceptance_radius.get();
		_mission_item.time_inside = 0.0f;
		_mission_item.pitch_min = 0.0f;
		_mission_item.autocontinue = true;
		_mission_item.origin = ORIGIN_ONBOARD;

		_navigator->set_is_in_loiter(false);

		mavlink_log_info(_navigator->get_mavlink_fd(), "#audio: RTL: land at home");
		break;
	}

	case RTL_STATE_FINISHED: {
		/* nothing to do, report fail */
	}

	default:
		break;
	}

	if (_rtl_state == RTL_STATE_FINISHED) {
		pos_sp_triplet->current.valid = false;
		pos_sp_triplet->next.valid = false;
	} else {
		/* if not finished, convert mission item to current position setpoint and make it valid */
		mission_item_to_position_setpoint(&_mission_item, &pos_sp_triplet->current);
		reset_mission_item_reached();
		pos_sp_triplet->current.valid = true;
		pos_sp_triplet->next.valid = false;
	}
}

void
RTL::advance_rtl()
{
	switch (_rtl_state) {
	case RTL_STATE_CLIMB:
		_rtl_state = RTL_STATE_RETURN;
		break;

	case RTL_STATE_RETURN:
		_rtl_state = RTL_STATE_DESCEND;
		break;

	case RTL_STATE_DESCEND:
		/* only go to land if autoland is enabled */
		if (_param_land_delay.get() < 0) {
			_rtl_state = RTL_STATE_FINISHED;
		} else {
			_rtl_state = RTL_STATE_LAND;
		}
		break;

	case RTL_STATE_LAND:
		_rtl_state = RTL_STATE_FINISHED;
		break;

	case RTL_STATE_FINISHED:
		break;

	default:
		break;
	}
}