using System.Collections;
using System.Collections.Generic;
using UnityEngine;

public class SwayBone : MonoBehaviour
{
    [Range(0.0f,1.0f)]
	[Tooltip("How much inertia each bone has - makes it more bouncy")]
	public float inertia = 0.75f;  // how much the force slows each second.

	[Range(1.0f,2.0f)]
	[Tooltip("How far something can stretch - 1.0 = no stretch")]
	public float limit = 2.0f;

	[Range(1.0f, 4.0f)]
	[Tooltip("How much it can pull away during movement")]
	public float elasticity = 2.0f;
	[Tooltip("Only rotate. Not supported in v1")]
	public bool OrientOnly;
	[Tooltip("Also reorient bones")]
	public bool Reorient;

	protected Vector3 LastWorldPos;     // Where this was last in the world. Used for detecting world movement.
	protected Vector3 localRestingPos;  // Where this is at rest.
	protected Vector3 currentForce;
	protected Vector3 localTarget;
	Vector3 targetvector;
	protected Quaternion localOrientation; // current angles
	protected float MaxDistance;
	public float frameInertia;
	public bool isTopLevel;

	public Vector3 ViewLocalOrientation;
	public Vector3 ViewInverseLocalOrientation;
	public Vector3 ViewLocalRotation;
	public Vector3 ViewInverseLocalRotation;
	public Vector3 ViewRotation;
	public Vector3 ViewInverseRotation;

	public void Initialize()
	{
		currentForce = Vector3.zero;
		localRestingPos = transform.localPosition;
		localOrientation = transform.localRotation;
		localTarget = localRestingPos * -1;
		LastWorldPos = transform.position;
		MaxDistance = limit * localRestingPos.magnitude;
	}

	public void DoUpdate(float step)
	{
		// Get the new position.
		Vector3 worldRestingPosition = transform.parent.TransformPoint(localRestingPos);
		Vector3 worldLookAtPosition = transform.parent.position;

		Vector3 GlobalForce = (worldRestingPosition - LastWorldPos) * step * elasticity;
		if (!OrientOnly)
		{
			transform.position = LastWorldPos + GlobalForce + currentForce;
		}

		// Clamp the position at the limit.
		if ((transform.position - worldRestingPosition).magnitude > MaxDistance) 
		{
		    targetvector = worldRestingPosition - transform.position;
			if (!OrientOnly)
			{
				transform.position = worldRestingPosition - (targetvector.normalized * MaxDistance);
			}
		}
		
#if false
		// orient toward the parent. 
		if (Reorient)
		{
			//float BoneLength = Vector3.Distance(child.position, child.parent.position);
			//Scale.Set(BoneLength / 10.0f, BoneLength / 10.0f, BoneLength);
			Vector3 relativePos = transform.position - transform.parent.transform.position;
			Quaternion rotation = (relativePos == Vector3.zero) ? Quaternion.identity : Quaternion.LookRotation(relativePos);
			Quaternion LocalRotation = Quaternion.Inverse(transform.rotation) * rotation;

			ViewLocalOrientation = localOrientation.eulerAngles; // orientation without pointing.
			ViewRotation = rotation.eulerAngles;                 // orientation to point to 
			ViewLocalRotation = LocalRotation.eulerAngles;       // End orientation in local space. 

			ViewInverseLocalOrientation = Quaternion.Inverse(localOrientation).eulerAngles;
			ViewInverseRotation = Quaternion.Inverse(rotation).eulerAngles;
			ViewInverseLocalRotation = Quaternion.Inverse(LocalRotation).eulerAngles;

			transform.localRotation = LocalRotation; // rotation * localOrientation;// Quaternion.Inverse(this.localOrientation); // LocalRotation;
		}
#endif
		currentForce += GlobalForce;
		currentForce *= inertia;
		LastWorldPos = transform.position;

		targetvector = worldRestingPosition;
	}
}