/******************************************************************************
 * Copyright (C) Ultraleap, Inc. 2011-2021.                                   *
 *                                                                            *
 * Use subject to the terms of the Apache License 2.0 available at            *
 * http://www.apache.org/licenses/LICENSE-2.0, or another agreement           *
 * between Ultraleap and you, your company or other organization.             *
 ******************************************************************************/

using Leap.Unity.Query;
using UnityEngine;
using UnityEngine.Events;

namespace Leap.Unity.Interaction.Examples
{

    /// <summary>
    /// This simple example script disables the InteractionHand script and has event
    /// outputs to drive hiding Leap hand renderers when it detects that an
    /// InteractionXRController is tracked and moving (e.g. it has been picked up).
    /// 
    /// It also does some basic checks with hand distance so that you can see your hands
    /// when you put the controller down and you hide the hands when they're obviously
    /// holding the controller (e.g. tracked as very close to the controller).
    /// </summary>
    public class HideInteractionHandWhenControllerMoving : MonoBehaviour
    {

        public InteractionXRController intCtrl;
        public InteractionHand intHand;

        public UnityEvent OnInteractionHandEnabled;
        public UnityEvent OnInteractionHandDisabled;

        private float _handSeparationDistance = 0.23f;
        private float _handHoldingDistance = 0.18f;

        private void Reset()
        {
            if (intCtrl == null)
            {
                intCtrl = GetComponent<InteractionXRController>();
            }
            if (intCtrl != null && intHand == null && this.transform.parent != null)
            {
                intHand = this.transform.parent.GetChildren().Query()
                  .Select(t => t.GetComponent<InteractionHand>())
                  .Where(h => h != null)
                  .FirstOrDefault(h => h.isLeft == intCtrl.isLeft);
            }
        }

        private void Update()
        {
            if (intCtrl != null && intCtrl.isActiveAndEnabled && intHand != null)
            {
                var shouldIntHandBeEnabled = !intCtrl.isBeingMoved;

                if (intCtrl.isTracked)
                {
                    var handPos = intHand.position;
                    var ctrlPos = intCtrl.position;
                    var handControllerDistanceSqr = (handPos - ctrlPos).sqrMagnitude;

                    // Also allow the hand to be active if it's far enough away from the controller.
                    if (handControllerDistanceSqr > _handSeparationDistance * _handSeparationDistance)
                    {
                        shouldIntHandBeEnabled = true;
                    }

                    // Prevent the hand from being active if it's very close to the controller.
                    if (handControllerDistanceSqr < _handHoldingDistance * _handHoldingDistance)
                    {
                        shouldIntHandBeEnabled = false;
                    }
                }

                if (shouldIntHandBeEnabled && !intHand.enabled)
                {
                    intHand.enabled = true;

                    OnInteractionHandEnabled.Invoke();
                }

                if (!shouldIntHandBeEnabled && intHand.enabled)
                {
                    intHand.enabled = false;

                    OnInteractionHandDisabled.Invoke();
                }
            }
        }

    }

}