/******************************************************************************\
* Copyright (C) Leap Motion, Inc. 2011-2014.                                   *
* Leap Motion proprietary. Licensed under Apache 2.0                           *
* Available at http://www.apache.org/licenses/LICENSE-2.0.html                 *
\******************************************************************************/

using UnityEngine;
using System.Collections;
using Leap;

/**
* The base class for all fingers.
* 
* This class serves as the interface between the HandController object,
* the parent Hand object and the concrete finger objects.
*
* Subclasses of FingerModel must implement InitFinger() and UpdateFinger(). The InitHand() function
* is typically called by the parent HandModel InitHand() method; likewise, the UpdateFinger()
* function is typically called by the parent HandModel UpdateHand() function.
*/

public abstract class FingerModel : MonoBehaviour {

  /** The number of bones in a finger. */
  public const int NUM_BONES = 4;

  /** The number of joints in a finger. */
  public const int NUM_JOINTS = 3;

  [HideInInspector]
  public Finger.FingerType fingerType = Finger.FingerType.TYPE_INDEX;

  // Unity references
  /** Bones positioned and rotated by FingerModel. */
  public Transform[] bones = new Transform[NUM_BONES];
  /** Joints positioned and rotated by FingerModel. */
  public Transform[] joints = new Transform[NUM_BONES - 1];
  
  // Leap references
  /** The Leap Hand object. */
  protected Hand hand_;
  /** The Leap Finger object. */
  protected Finger finger_;
  /** An added offset vector. */
  protected Vector3 offset_ = Vector3.zero;
  /** Whether this finger is mirrored. */
  protected bool mirror_z_axis_ = false;

  /** The parent HandController instance. */
  protected HandController controller_;

  /** Assigns the HandController parent for this FingerModel object. */
  public void SetController(HandController controller) {
    controller_ = controller;
  }

  /** The parent HandController instance. */
  public HandController GetController() {
    return controller_;
  }

  /** Sets the Leap Hand and Leap Finger for this finger.
  * Note that Leap Hand and Finger objects are recreated every frame. The
  * parent HandModel object calls this function to set or update the underlying
  * finger. The tracking data in the Leap objects are used to update the FingerModel.
  */ 
  public void SetLeapHand(Hand hand) {
    hand_ = hand;
    if (hand_ != null)
      finger_ = hand.Fingers[(int)fingerType];
  }

  /** Sets an offset vector to displace the finger from its normally calculated
  * position relative to the HandController. Typically, this offset is used to
  * give the virtual hands a larger range of motion then they would have based on their 
  * scaled size in the Unity scene.
  */
  public void SetOffset(Vector3 offset) {
    offset_ = offset;
  }

  /** 
  * Sets the mirror z-axis flag for this Finger Model.
  * Mirroring the z axis reverses the hand so that they face the opposite direction -- as if in a mirror.
  * @param mirror Set true, the default value to mirror; false for normal rendering. 
  */
  public void MirrorZAxis(bool mirror = true) {
    mirror_z_axis_ = mirror;
  }

  /** The Leap Hand object. */
  public Hand GetLeapHand() { return hand_; }
  /** The Leap Finger object. */
  public Finger GetLeapFinger() { return finger_; }

  /** 
  * Implement this function to initialize this finger after it is created.
  * Typically, this function is called by the parent HandModel object.
  */
  public virtual void InitFinger() {
    UpdateFinger();
  }

  /** 
  * Implement this function to update this finger once per game loop.
  * Typically, this function is called by the parent HandModel object's
  * UpdateHand() function, which is called in the Unity Update() phase for
  * graphics hand models and in the FixedUpdate() phase for physics hand
  * models.
  */
  public abstract void UpdateFinger();

  /** Returns any additional movement the finger needs because of non-relative palm movement.*/
  public Vector3 GetOffset() {
    return offset_;
  }

  /** Returns the location of the tip of the finger in relation to the controller.*/
  public Vector3 GetTipPosition() {
    if (controller_ != null && finger_ != null) {
      Vector3 local_tip = finger_.Bone ((Bone.BoneType.TYPE_DISTAL)).NextJoint.ToUnityScaled (mirror_z_axis_);
      return controller_.transform.TransformPoint (local_tip) + offset_;
    }
    if (bones [NUM_BONES - 1] && joints [NUM_JOINTS - 2]) {
      return 2f*bones [NUM_BONES - 1].position - joints [NUM_JOINTS - 2].position;
    }
    return Vector3.zero;
  }

  /** Returns the location of the given joint on the finger in relation to the controller.*/
  public Vector3 GetJointPosition(int joint) {
    if (joint >= NUM_BONES) {
      return GetTipPosition ();
    }
    if (controller_ != null && finger_ != null) {
      Vector3 local_position = finger_.Bone ((Bone.BoneType)(joint)).PrevJoint.ToUnityScaled (mirror_z_axis_);
      return controller_.transform.TransformPoint (local_position) + offset_;
    }
    if (joints [joint]) {
      return joints[joint].position;
    }
    return Vector3.zero;
  }

  /** Returns a ray from the tip of the finger in the direction it is pointing.*/
  public Ray GetRay() {
    Ray ray = new Ray(GetTipPosition(), GetBoneDirection(NUM_BONES - 1));
    return ray;
  }

  /** Returns the center of the given bone on the finger in relation to the controller.*/
  public Vector3 GetBoneCenter(int bone_type) {
    if (controller_ != null && finger_ != null) {
      Bone bone = finger_.Bone ((Bone.BoneType)(bone_type));
      return controller_.transform.TransformPoint (bone.Center.ToUnityScaled (mirror_z_axis_)) + offset_;
    }
    if (bones [bone_type]) {
      return bones[bone_type].position;
    }
    return Vector3.zero;
  }

  /** Returns the direction the given bone is facing on the finger in relation to the controller.*/
  public Vector3 GetBoneDirection(int bone_type) {
    if (controller_ != null && finger_ != null) {
      Vector3 direction = GetJointPosition (bone_type + 1) - GetJointPosition (bone_type);
      return direction.normalized;
    }
    if (bones[bone_type]) {
      return bones[bone_type].forward;
    }
    return Vector3.forward;
  }

  /** Returns the rotation quaternion of the given bone in relation to the controller.*/
  public Quaternion GetBoneRotation(int bone_type) {
    if (controller_ != null && finger_ != null) {
      Quaternion local_rotation = finger_.Bone ((Bone.BoneType)(bone_type)).Basis.Rotation (mirror_z_axis_);
      return controller_.transform.rotation * local_rotation;
    }
    if (bones[bone_type]) {
      return bones[bone_type].rotation;
    }
    return Quaternion.identity;
  }
  
  /** Returns the length of the finger bone.*/
  public float GetBoneLength(int bone_type) {
    return finger_.Bone ((Bone.BoneType)(bone_type)).Length * UnityVectorExtension.INPUT_SCALE;
  }
  
  /** Returns the width of the finger bone.*/
  public float GetBoneWidth(int bone_type) {
    return finger_.Bone((Bone.BoneType)(bone_type)).Width * UnityVectorExtension.INPUT_SCALE;
  }
  
  /**
   * Returns Mecanim stretch angle in the range (-180, +180]
   * NOTE: Positive stretch opens the hand.
   * For the thumb this moves it away from the palm.
   */
  public float GetFingerJointStretchMecanim(int joint_type) {
    // The successive actions of local rotations on a vector yield the global rotation,
    // so the inverse of the parent rotation appears on the left.
    Quaternion jointRotation = Quaternion.identity;
    if (finger_ != null) {
      jointRotation = Quaternion.Inverse (finger_.Bone ((Bone.BoneType)(joint_type)).Basis.Rotation (mirror_z_axis_)) 
        * finger_.Bone ((Bone.BoneType)(joint_type + 1)).Basis.Rotation (mirror_z_axis_);
    } else if (bones [joint_type] && bones [joint_type + 1]) {
      jointRotation = Quaternion.Inverse (GetBoneRotation (joint_type)) * GetBoneRotation (joint_type + 1);
    }
    // Stretch is a rotation around the X axis of the base bone
    // Positive stretch opens joints
    float stretchAngle = -jointRotation.eulerAngles.x;
    if (stretchAngle <= -180f) {
      stretchAngle += 360f;
    }
    // NOTE: eulerAngles range is [0, 360) so stretchAngle > +180f will not occur.
    return stretchAngle;
  }

  /**
   * Returns Mecanim spread angle, which only applies to joint_type = 0
   * NOTE: Positive spread is towards thumb for index and middle,
   * but is in the opposite direction for the ring and pinky.
   * For the thumb negative spread rotates the thumb in to the palm.
   * */
  public float GetFingerJointSpreadMecanim() {
    // The successive actions of local rotations on a vector yield the global rotation,
    // so the inverse of the parent rotation appears on the left.
    Quaternion jointRotation = Quaternion.identity;
    if (finger_ != null) {
      jointRotation = Quaternion.Inverse (finger_.Bone ((Bone.BoneType)(0)).Basis.Rotation (mirror_z_axis_)) 
        * finger_.Bone ((Bone.BoneType)(1)).Basis.Rotation (mirror_z_axis_);
    } else if (bones [0] && bones [1]) {
      jointRotation = Quaternion.Inverse (GetBoneRotation (0)) * GetBoneRotation (1);
    }
    // Spread is a rotation around the Y axis of the base bone when joint_type = 0
    float spreadAngle = 0f;
    Finger.FingerType fType = fingerType;
    if (finger_ != null) { 
      fingerType = finger_.Type;
    }

    if (fType == Finger.FingerType.TYPE_INDEX ||
      fType == Finger.FingerType.TYPE_MIDDLE) {
      spreadAngle = jointRotation.eulerAngles.y;
      if (spreadAngle > 180f) {
        spreadAngle -= 360f;
      }
      // NOTE: eulerAngles range is [0, 360) so spreadAngle <= -180f will not occur.
    }
    if (fType == Finger.FingerType.TYPE_THUMB ||
      fType == Finger.FingerType.TYPE_RING ||
      fType == Finger.FingerType.TYPE_PINKY) {
      spreadAngle = -jointRotation.eulerAngles.y;
      if (spreadAngle <= -180f) {
        spreadAngle += 360f;
      }
      // NOTE: eulerAngles range is [0, 360) so spreadAngle > +180f will not occur.
    }
    return spreadAngle;
  }
}