/******************************************************************************
 * Copyright (C) Leap Motion, Inc. 2011-2017.                                 *
 * Leap Motion proprietary and  confidential.                                 *
 *                                                                            *
 * Use subject to the terms of the Leap Motion SDK Agreement available at     *
 * https://developer.leapmotion.com/sdk_agreement, or another agreement       *
 * between Leap Motion and you, your company or other organization.           *
 ******************************************************************************/

using UnityEngine;
using System.Collections;
using Leap.Unity.Attributes;

namespace Leap.Unity {

  /**
  * Detects whether the palm of the hand is pointing toward the specified direction.
  * The detector activates when the palm direction is within OnAngle degrees of the
  * desired direction and deactivates when it becomes more than OffAngle degrees.
  *
  * Directions can be specified relative to the global frame of reference, relative to 
  * the camera frame of reference, or using a combination of the two -- relative to the 
  * camera direction in the x-z plane, but not changing relative to the horizon.
  * 
  * You can alternatively specify a target game object.
  * 
  * If added to a IHandModel instance or one of its children, this detector checks the
  * palm direction at the interval specified by the Period variable. You can also specify
  * which hand model to observe explicitly by setting handModel in the Unity editor or 
  * in code.
  * 
  * @since 4.1.2
  */
  public class PalmDirectionDetector : Detector {
    /**
     * The interval at which to check palm direction.
     * @since 4.1.2
     */
    [Units("seconds")]
    [Tooltip("The interval in seconds at which to check this detector's conditions.")]
    [MinValue(0)]
    public float Period = .1f; //seconds
    /**
     * The IHandModel instance to observe. 
     * Set automatically if not explicitly set in the editor.
     * @since 4.1.2
     */
    [Tooltip("The hand model to watch. Set automatically if detector is on a hand.")]
    public IHandModel HandModel = null;

    /**
     * Specifies how to interprete the direction specified by PointingDirection.
     * 
     * - RelativeToCamera -- the target direction is defined relative to the camera's forward vector, i.e. (0, 0, 1) is the cmaera's 
     *                       local forward direction.
     * - RelativeToHorizon -- the target direction is defined relative to the camera's forward vector, 
     *                        except that it does not change with pitch.
     * - RelativeToWorld -- the target direction is defined as a global direction that does not change with camera movement. For example,
     *                      (0, 1, 0) is always world up, no matter which way the camera is pointing.
     * - AtTarget -- a target object is used as the pointing direction (The specified PointingDirection is ignored).
     * 
     * In VR scenes, RelativeToHorizon with a direction of (0, 0, 1) for camera forward and RelativeToWorld with a direction
     * of (0, 1, 0) for absolute up, are often the most useful settings.
     * @since 4.1.2
     */
    [Header("Direction Settings")]
    [Tooltip("How to treat the target direction.")]
    public PointingType PointingType = PointingType.RelativeToHorizon;

    /**
    * The target direction as interpreted by the PointingType setting.
    * Ignored when Pointingtype is "AtTarget."
    * @since 4.1.2
    */
    [Tooltip("The target direction.")]
    [DisableIf("PointingType", isEqualTo: PointingType.AtTarget)]
    public Vector3 PointingDirection = Vector3.forward;

    /**
     * The object to point at when the PointingType is "AtTarget." Ignored otherwise.
     */
    [Tooltip("A target object(optional). Use PointingType.AtTarget")]
    [DisableIf("PointingType", isNotEqualTo: PointingType.AtTarget)]
    public Transform TargetObject = null;

    /**
     * The turn-on angle. The detector activates when the palm points within this
     * many degrees of the target direction.
     * @since 4.1.2
     */
    [Tooltip("The angle in degrees from the target direction at which to turn on.")]
    [Range(0, 180)]
    public float OnAngle = 45; // degrees

    /**
    * The turn-off angle. The detector deactivates when the palm points more than this
    * many degrees away from the target direction. The off angle must be larger than the on angle.
    * @since 4.1.2
    */
    [Tooltip("The angle in degrees from the target direction at which to turn off.")]
    [Range(0, 180)]
    public float OffAngle = 65; //degrees

    /** Whether to draw the detector's Gizmos for debugging. (Not every detector provides gizmos.)
     * @since 4.1.2 
     */
    [Header("")]
    [Tooltip("Draw this detector's Gizmos, if any. (Gizmos must be on in Unity edtor, too.)")]
    public bool ShowGizmos = true;

    private IEnumerator watcherCoroutine;

    private void OnValidate(){
      if( OffAngle < OnAngle){
        OffAngle = OnAngle;
      }
    }

    private void Awake () {
      watcherCoroutine = palmWatcher();
    }

    private void OnEnable () {
      StartCoroutine(watcherCoroutine);
    }

    private void OnDisable () {
      StopCoroutine(watcherCoroutine);
      Deactivate();
    }

    private IEnumerator palmWatcher() {
      Hand hand;
      Vector3 normal;
      while(true){
        if(HandModel != null){
          hand = HandModel.GetLeapHand();
          if(hand != null){
            normal = hand.PalmNormal.ToVector3();
            float angleTo = Vector3.Angle(normal, selectedDirection(hand.PalmPosition.ToVector3()));
            if(angleTo <= OnAngle){
              Activate();
            } else if(angleTo > OffAngle) {
              Deactivate();
            }
          }
        }
        yield return new WaitForSeconds(Period);
      }
    }

    private Vector3 selectedDirection (Vector3 tipPosition) {
      switch (PointingType) {
        case PointingType.RelativeToHorizon:
          Quaternion cameraRot = Camera.main.transform.rotation;
          float cameraYaw = cameraRot.eulerAngles.y;
          Quaternion rotator = Quaternion.AngleAxis(cameraYaw, Vector3.up);
          return rotator * PointingDirection;
        case PointingType.RelativeToCamera:
          return Camera.main.transform.TransformDirection(PointingDirection);
        case PointingType.RelativeToWorld:
          return PointingDirection;
        case PointingType.AtTarget:
          if (TargetObject != null)
            return TargetObject.position - tipPosition;
          else return Vector3.zero;
        default:
          return PointingDirection;
      }
    }

    #if UNITY_EDITOR
    private void OnDrawGizmos(){
      if(ShowGizmos && HandModel != null && HandModel.IsTracked){
        Color centerColor;
        if (IsActive) {
          centerColor = OnColor;
        } else {
          centerColor = OffColor;
        }
        Hand hand = HandModel.GetLeapHand();
        Utils.DrawCone(hand.PalmPosition.ToVector3(), hand.PalmNormal.ToVector3(), OnAngle, hand.PalmWidth, centerColor, 8);
        Utils.DrawCone(hand.PalmPosition.ToVector3(), hand.PalmNormal.ToVector3(), OffAngle, hand.PalmWidth, LimitColor, 8);
        Gizmos.color = DirectionColor;
        Gizmos.DrawRay(hand.PalmPosition.ToVector3(), selectedDirection(hand.PalmPosition.ToVector3()));
      }
    }
    #endif
  }

  /** 
  * Settings for handling pointing conditions
  * - RelativeToCamera -- the target direction is defined relative to the camera's forward vector.
  * - RelativeToHorizon -- the target direction is defined relative to the camera's forward vector, 
  *                        except that it does not change with pitch.
  * - RelativeToWorld -- the target direction is defined as a global direction that does not change with camera movement.
  * - AtTarget -- a target object is used to determine the pointing direction.
  * 
  * @since 4.1.2
  */
  public enum PointingType { RelativeToCamera, RelativeToHorizon, RelativeToWorld, AtTarget }
}
