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/**
 * @file LandDetector.h
 * Land detector interface for multicopter, fixedwing and VTOL implementations.
 *
 * @author Johan Jansen <jnsn.johan@gmail.com>
 * @author Julian Oes <julian@oes.ch>
 * @author Lorenz Meier <lorenz@px4.io>
 */

#pragma once

#include <float.h>
#include <math.h>

#include <lib/hysteresis/hysteresis.h>
#include <lib/perf/perf_counter.h>
#include <px4_platform_common/defines.h>
#include <px4_platform_common/module.h>
#include <px4_platform_common/module.h>
#include <px4_platform_common/module_params.h>
#include <px4_platform_common/module_params.h>
#include <px4_platform_common/px4_config.h>
#include <px4_platform_common/px4_work_queue/ScheduledWorkItem.hpp>
#include <uORB/Publication.hpp>
#include <uORB/Subscription.hpp>
#include <uORB/SubscriptionCallback.hpp>
#include <uORB/topics/actuator_armed.h>
#include <uORB/topics/parameter_update.h>
#include <uORB/topics/vehicle_acceleration.h>
#include <uORB/topics/vehicle_land_detected.h>
#include <uORB/topics/vehicle_local_position.h>
#include <uORB/topics/vehicle_status.h>

using namespace time_literals;

namespace land_detector
{

class LandDetector : public ModuleBase<LandDetector>, ModuleParams, px4::ScheduledWorkItem
{
public:
	LandDetector();
	virtual ~LandDetector();

	/** @see ModuleBase */
	static int custom_command(int argc, char *argv[])
	{
		return print_usage("unknown command");
	}

	/** @see ModuleBase */
	static int print_usage(const char *reason = nullptr);

	/** @see ModuleBase::print_status() */
	int print_status() override;

	/**
	 * Get the work queue going.
	 */
	void start();

	static int task_spawn(int argc, char *argv[]);

protected:

	/**
	 * Updates parameters.
	 */
	virtual void _update_params() {};

	/**
	 * Updates subscribed uORB topics.
	 */
	virtual void _update_topics() {};

	/**
	 * @return true if UAV is in a landed state.
	 */
	virtual bool _get_landed_state() = 0;

	/**
	 * @return true if UAV is in almost landed state
	 */
	virtual bool _get_maybe_landed_state() { return false; }

	/**
	 * @return true if UAV is touching ground but not landed
	 */
	virtual bool _get_ground_contact_state() { return false; }

	/**
	 * @return true if UAV is in free-fall state.
	 */
	virtual bool _get_freefall_state() { return false; }

	/**
	 *  @return maximum altitude that can be reached
	 */
	virtual float _get_max_altitude() { return INFINITY; }

	/**
	 *  @return true if vehicle could be in ground effect (close to ground)
	 */
	virtual bool _get_ground_effect_state() { return false; }

	virtual bool _get_in_descend() { return false; }
	virtual bool _get_has_low_throttle() { return false; }
	virtual bool _get_horizontal_movement() { return false; }
	virtual bool _get_vertical_movement() { return false; }
	virtual bool _get_close_to_ground_or_skipped_check() {  return false; }
	virtual void _set_hysteresis_factor(const int factor) = 0;

	systemlib::Hysteresis _freefall_hysteresis{false};
	systemlib::Hysteresis _landed_hysteresis{true};
	systemlib::Hysteresis _maybe_landed_hysteresis{true};
	systemlib::Hysteresis _ground_contact_hysteresis{true};
	systemlib::Hysteresis _ground_effect_hysteresis{false};

	vehicle_local_position_s _vehicle_local_position{};
	vehicle_status_s         _vehicle_status{};

	matrix::Vector3f _acceleration{};

	bool _armed{false};
	bool _previous_armed_state{false};	///< stores the previous actuator_armed.armed state
	bool _dist_bottom_is_observable{false};

private:
	void Run() override;

	vehicle_land_detected_s _land_detected = {
		.timestamp = 0,
		.alt_max = -1.0f,
		.freefall = false,
		.ground_contact = true,
		.maybe_landed = true,
		.landed = true,
	};

	hrt_abstime _takeoff_time{0};
	hrt_abstime _total_flight_time{0};	///< total vehicle flight time in microseconds

	perf_counter_t _cycle_perf{perf_alloc(PC_ELAPSED, MODULE_NAME": cycle")};

	uORB::Publication<vehicle_land_detected_s> _vehicle_land_detected_pub{ORB_ID(vehicle_land_detected)};

	uORB::SubscriptionInterval _parameter_update_sub{ORB_ID(parameter_update), 1_s};

	uORB::Subscription _actuator_armed_sub{ORB_ID(actuator_armed)};
	uORB::Subscription _vehicle_acceleration_sub{ORB_ID(vehicle_acceleration)};
	uORB::Subscription _vehicle_status_sub{ORB_ID(vehicle_status)};

	uORB::SubscriptionCallbackWorkItem _vehicle_local_position_sub{this, ORB_ID(vehicle_local_position)};

	DEFINE_PARAMETERS_CUSTOM_PARENT(
		ModuleParams,
		(ParamInt<px4::params::LND_FLIGHT_T_HI>) _param_total_flight_time_high,
		(ParamInt<px4::params::LND_FLIGHT_T_LO>) _param_total_flight_time_low
	);
};

} // namespace land_detector