/******************************************************************************
 * 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 when specified fingers are pointing in the specified manner.
   * 
   * 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
   * finger 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 FingerDirectionDetector : Detector {
    /**
     * The interval at which to check finger state.
     * @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;  

    /**
     * The finger to compare to the specified direction.
     * @since 4.1.2
     */
    [Tooltip("The finger to observe.")]
    public Finger.FingerType FingerName = Finger.FingerType.TYPE_INDEX;


    /**
     * 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 specified finger 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 = 15f; //degrees

    /**
    * The turn-off angle. The detector deactivates when the specified finger 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 = 25f; //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 = fingerPointingWatcher();
    }

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

    private IEnumerator fingerPointingWatcher() {
      Hand hand;
      Vector3 fingerDirection;
      Vector3 targetDirection;
      int selectedFinger = selectedFingerOrdinal();
      while(true){
        if(HandModel != null && HandModel.IsTracked){
          hand = HandModel.GetLeapHand();
          if(hand != null){
            targetDirection = selectedDirection(hand.Fingers[selectedFinger].TipPosition.ToVector3());
            fingerDirection = hand.Fingers[selectedFinger].Bone(Bone.BoneType.TYPE_DISTAL).Direction.ToVector3();
            float angleTo = Vector3.Angle(fingerDirection, targetDirection);
            if(HandModel.IsTracked && angleTo <= OnAngle){
              Activate();
            } else if (!HandModel.IsTracked || 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:
          return TargetObject.position - tipPosition;
        default:
          return PointingDirection;
      }
    }

    private int selectedFingerOrdinal(){
      switch(FingerName){
        case Finger.FingerType.TYPE_INDEX:
          return 1;
        case Finger.FingerType.TYPE_MIDDLE:
          return 2;
        case Finger.FingerType.TYPE_PINKY:
          return 4;
        case Finger.FingerType.TYPE_RING:
          return 3;
        case Finger.FingerType.TYPE_THUMB:
          return 0;
        default:
          return 1;
      }
    }

  #if UNITY_EDITOR
    private void OnDrawGizmos () {
      if (ShowGizmos && HandModel != null && HandModel.IsTracked) {
        Color innerColor;
        if (IsActive) {
          innerColor = OnColor;
        } else {
          innerColor = OffColor;
        }
        Finger finger = HandModel.GetLeapHand().Fingers[selectedFingerOrdinal()];
        Vector3 fingerDirection = finger.Bone(Bone.BoneType.TYPE_DISTAL).Direction.ToVector3();
        Utils.DrawCone(finger.TipPosition.ToVector3(), fingerDirection, OnAngle, finger.Length, innerColor);
        Utils.DrawCone(finger.TipPosition.ToVector3(), fingerDirection, OffAngle, finger.Length, LimitColor);
        Gizmos.color = DirectionColor;
        Gizmos.DrawRay(finger.TipPosition.ToVector3(), selectedDirection(finger.TipPosition.ToVector3()));
      }
    }
  #endif
  }
}
