/**************************************************************************/
/*  openxr_hand_tracking_extension.h                                      */
/**************************************************************************/
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#ifndef OPENXR_HAND_TRACKING_EXTENSION_H
#define OPENXR_HAND_TRACKING_EXTENSION_H

#include "../util.h"
#include "core/math/quaternion.h"
#include "openxr_extension_wrapper.h"

class OpenXRHandTrackingExtension : public OpenXRExtensionWrapper {
public:
	enum HandTrackedHands {
		OPENXR_TRACKED_LEFT_HAND,
		OPENXR_TRACKED_RIGHT_HAND,
		OPENXR_MAX_TRACKED_HANDS
	};

	struct HandTracker {
		bool is_initialized = false;
		XrHandJointsMotionRangeEXT motion_range = XR_HAND_JOINTS_MOTION_RANGE_UNOBSTRUCTED_EXT;

		XrHandTrackerEXT hand_tracker = XR_NULL_HANDLE;
		XrHandJointLocationEXT joint_locations[XR_HAND_JOINT_COUNT_EXT];
		XrHandJointVelocityEXT joint_velocities[XR_HAND_JOINT_COUNT_EXT];

		XrHandJointVelocitiesEXT velocities;
		XrHandJointLocationsEXT locations;
	};

	static OpenXRHandTrackingExtension *get_singleton();

	OpenXRHandTrackingExtension();
	virtual ~OpenXRHandTrackingExtension() override;

	virtual HashMap<String, bool *> get_requested_extensions() override;

	virtual void on_instance_created(const XrInstance p_instance) override;
	virtual void on_instance_destroyed() override;
	virtual void on_session_destroyed() override;

	virtual void *set_system_properties_and_get_next_pointer(void *p_next_pointer) override;
	virtual void on_state_ready() override;
	virtual void on_process() override;
	virtual void on_state_stopping() override;

	bool get_active();
	const HandTracker *get_hand_tracker(HandTrackedHands p_hand) const;

	XrHandJointsMotionRangeEXT get_motion_range(HandTrackedHands p_hand) const;
	void set_motion_range(HandTrackedHands p_hand, XrHandJointsMotionRangeEXT p_motion_range);

	XrSpaceLocationFlags get_hand_joint_location_flags(HandTrackedHands p_hand, XrHandJointEXT p_joint) const;
	Quaternion get_hand_joint_rotation(HandTrackedHands p_hand, XrHandJointEXT p_joint) const;
	Vector3 get_hand_joint_position(HandTrackedHands p_hand, XrHandJointEXT p_joint) const;
	float get_hand_joint_radius(HandTrackedHands p_hand, XrHandJointEXT p_joint) const;

	XrSpaceVelocityFlags get_hand_joint_velocity_flags(HandTrackedHands p_hand, XrHandJointEXT p_joint) const;
	Vector3 get_hand_joint_linear_velocity(HandTrackedHands p_hand, XrHandJointEXT p_joint) const;
	Vector3 get_hand_joint_angular_velocity(HandTrackedHands p_hand, XrHandJointEXT p_joint) const;

private:
	static OpenXRHandTrackingExtension *singleton;

	// state
	XrSystemHandTrackingPropertiesEXT handTrackingSystemProperties;
	HandTracker hand_trackers[OPENXR_MAX_TRACKED_HANDS]; // Fixed for left and right hand

	// related extensions
	bool hand_tracking_ext = false;
	bool hand_motion_range_ext = false;

	// functions
	void cleanup_hand_tracking();

	// OpenXR API call wrappers
	EXT_PROTO_XRRESULT_FUNC3(xrCreateHandTrackerEXT, (XrSession), p_session, (const XrHandTrackerCreateInfoEXT *), p_createInfo, (XrHandTrackerEXT *), p_handTracker)
	EXT_PROTO_XRRESULT_FUNC1(xrDestroyHandTrackerEXT, (XrHandTrackerEXT), p_handTracker)
	EXT_PROTO_XRRESULT_FUNC3(xrLocateHandJointsEXT, (XrHandTrackerEXT), p_handTracker, (const XrHandJointsLocateInfoEXT *), p_locateInfo, (XrHandJointLocationsEXT *), p_locations)
};

#endif // OPENXR_HAND_TRACKING_EXTENSION_H