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/**
 * @file mission_feasibility_checker.cpp
 * Provides checks if mission is feasible given the navigation capabilities
 *
 * @author Lorenz Meier <lm@inf.ethz.ch>
 * @author Thomas Gubler <thomasgubler@student.ethz.ch>
 */

#include "mission_feasibility_checker.h"

#include <geo/geo.h>
#include <math.h>
#include <mathlib/mathlib.h>
#include <mavlink/mavlink_log.h>
#include <fw_pos_control_l1/landingslope.h>
#include <systemlib/err.h>
#include <stdio.h>
#include <fcntl.h>
#include <errno.h>
#include <uORB/topics/fence.h>

/* oddly, ERROR is not defined for c++ */
#ifdef ERROR
# undef ERROR
#endif
static const int ERROR = -1;

MissionFeasibilityChecker::MissionFeasibilityChecker() : _mavlink_fd(-1), _capabilities_sub(-1), _initDone(false)
{
	_nav_caps = {0};
}


bool MissionFeasibilityChecker::checkMissionFeasible(bool isRotarywing, dm_item_t dm_current, size_t nMissionItems, Geofence &geofence, float home_alt)
{
	/* Init if not done yet */
	init();

	/* Open mavlink fd */
	if (_mavlink_fd < 0) {
		/* try to open the mavlink log device every once in a while */
		_mavlink_fd = open(MAVLINK_LOG_DEVICE, 0);
	}


	if (isRotarywing)
		return checkMissionFeasibleRotarywing(dm_current, nMissionItems, geofence, home_alt);
	else
		return checkMissionFeasibleFixedwing(dm_current, nMissionItems, geofence, home_alt);
}

bool MissionFeasibilityChecker::checkMissionFeasibleRotarywing(dm_item_t dm_current, size_t nMissionItems, Geofence &geofence, float home_alt)
{

	/* Perform checks and issue feedback to the user for all checks */
	bool resGeofence = checkGeofence(dm_current, nMissionItems, geofence);
	bool resHomeAltitude = checkHomePositionAltitude(dm_current, nMissionItems, home_alt);

	/* Mission is only marked as feasible if all checks return true */
	return (resGeofence && resHomeAltitude);
}

bool MissionFeasibilityChecker::checkMissionFeasibleFixedwing(dm_item_t dm_current, size_t nMissionItems, Geofence &geofence, float home_alt)
{
	/* Update fixed wing navigation capabilites */
	updateNavigationCapabilities();
//	warnx("_nav_caps.landing_slope_angle_rad %.4f, _nav_caps.landing_horizontal_slope_displacement %.4f", _nav_caps.landing_slope_angle_rad, _nav_caps.landing_horizontal_slope_displacement);

	/* Perform checks and issue feedback to the user for all checks */
	bool resLanding = checkFixedWingLanding(dm_current, nMissionItems);
	bool resGeofence = checkGeofence(dm_current, nMissionItems, geofence);
	bool resHomeAltitude = checkHomePositionAltitude(dm_current, nMissionItems, home_alt);

	/* Mission is only marked as feasible if all checks return true */
	return (resLanding && resGeofence && resHomeAltitude);
}

bool MissionFeasibilityChecker::checkGeofence(dm_item_t dm_current, size_t nMissionItems, Geofence &geofence)
{
	/* Check if all mission items are inside the geofence (if we have a valid geofence) */
	if (geofence.valid()) {
		for (size_t i = 0; i < nMissionItems; i++) {
			struct mission_item_s missionitem;
			const ssize_t len = sizeof(missionitem);

			if (dm_read(dm_current, i, &missionitem, len) != len) {
				/* not supposed to happen unless the datamanager can't access the SD card, etc. */
				return false;
			}

			if (!geofence.inside_polygon(missionitem.lat, missionitem.lon, missionitem.altitude)) {
				mavlink_log_info(_mavlink_fd, "#audio: Geofence violation waypoint %d", i);
				return false;
			}
		}
	}

	return true;
}

bool MissionFeasibilityChecker::checkHomePositionAltitude(dm_item_t dm_current, size_t nMissionItems, float home_alt, bool throw_error)
{
	/* Check if all all waypoints are above the home altitude, only return false if bool throw_error = true */
	for (size_t i = 0; i < nMissionItems; i++) {
		static struct mission_item_s missionitem;
		const ssize_t len = sizeof(struct mission_item_s);

		if (dm_read(dm_current, i, &missionitem, len) != len) {
			/* not supposed to happen unless the datamanager can't access the SD card, etc. */
			if (throw_error) {
				return false;
			} else	{
				return true;
			}
		}

		/* calculate the global waypoint altitude */
		float wp_alt = (missionitem.altitude_is_relative) ? missionitem.altitude + home_alt : missionitem.altitude;

		if (home_alt > wp_alt) {
			if (throw_error) {
				mavlink_log_critical(_mavlink_fd, "Rejecting Mission: Waypoint %d below home", i);
				return false;
			} else	{
				mavlink_log_critical(_mavlink_fd, "Warning: Waypoint %d below home", i);
				return true;
			}
		}
	}

	return true;
}

bool MissionFeasibilityChecker::checkFixedWingLanding(dm_item_t dm_current, size_t nMissionItems)
{
	/* Go through all mission items and search for a landing waypoint
	 * if landing waypoint is found: the previous waypoint is checked to be at a feasible distance and altitude given the landing slope */


	for (size_t i = 0; i < nMissionItems; i++) {
		struct mission_item_s missionitem;
		const ssize_t len = sizeof(missionitem);
		if (dm_read(dm_current, i, &missionitem, len) != len) {
			/* not supposed to happen unless the datamanager can't access the SD card, etc. */
			return false;
		}

		if (missionitem.nav_cmd == NAV_CMD_LAND) {
			struct mission_item_s missionitem_previous;
			if (i != 0) {
				if (dm_read(dm_current, i-1, &missionitem_previous, len) != len) {
					/* not supposed to happen unless the datamanager can't access the SD card, etc. */
					return false;
				}

				float wp_distance = get_distance_to_next_waypoint(missionitem_previous.lat , missionitem_previous.lon, missionitem.lat, missionitem.lon);
				float slope_alt_req = Landingslope::getLandingSlopeAbsoluteAltitude(wp_distance, missionitem.altitude, _nav_caps.landing_horizontal_slope_displacement, _nav_caps.landing_slope_angle_rad);
				float wp_distance_req = Landingslope::getLandingSlopeWPDistance(missionitem_previous.altitude, missionitem.altitude, _nav_caps.landing_horizontal_slope_displacement, _nav_caps.landing_slope_angle_rad);
				float delta_altitude = missionitem.altitude - missionitem_previous.altitude;
//				warnx("wp_distance %.2f, delta_altitude %.2f, missionitem_previous.altitude %.2f, missionitem.altitude %.2f, slope_alt_req %.2f, wp_distance_req %.2f",
//						wp_distance, delta_altitude, missionitem_previous.altitude, missionitem.altitude, slope_alt_req, wp_distance_req);
//				warnx("_nav_caps.landing_horizontal_slope_displacement %.4f, _nav_caps.landing_slope_angle_rad %.4f, _nav_caps.landing_flare_length %.4f",
//						_nav_caps.landing_horizontal_slope_displacement, _nav_caps.landing_slope_angle_rad, _nav_caps.landing_flare_length);

				if (wp_distance > _nav_caps.landing_flare_length) {
					/* Last wp is before flare region */

					if (delta_altitude < 0) {
						if (missionitem_previous.altitude <= slope_alt_req) {
							/* Landing waypoint is at or below altitude of slope at the given waypoint distance: this is ok, aircraft will intersect the slope */
							return true;
						} else {
							/* Landing waypoint is above altitude of slope at the given waypoint distance */
							mavlink_log_info(_mavlink_fd, "#audio: Landing: last waypoint too high/too close");
							mavlink_log_info(_mavlink_fd, "Move down to %.1fm or move further away by %.1fm",
									(double)(slope_alt_req),
									(double)(wp_distance_req - wp_distance));
							return false;
						}
					} else {
						/* Landing waypoint is above last waypoint */
						mavlink_log_info(_mavlink_fd, "#audio: Landing waypoint above last nav waypoint");
						return false;
					}
				} else {
					/* Last wp is in flare region */
					//xxx give recommendations
					mavlink_log_info(_mavlink_fd, "#audio: Warning: Landing: last waypoint in flare region");
					return false;
				}
			} else {
				mavlink_log_info(_mavlink_fd, "#audio: Warning: starting with land waypoint");
				return false;
			}
		}
	}

	/* No landing waypoints or no waypoints */
	return true;
}

void MissionFeasibilityChecker::updateNavigationCapabilities()
{
	(void)orb_copy(ORB_ID(navigation_capabilities), _capabilities_sub, &_nav_caps);
}

void MissionFeasibilityChecker::init()
{
	if (!_initDone) {

		_capabilities_sub = orb_subscribe(ORB_ID(navigation_capabilities));

		_initDone = true;
	}
}