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

public class BoneController : MonoBehaviour
{
	public BoneController additive_parent;
	public float additive_rate;
	public CCDIKSolver ik_solver;
	public BoneController[] ik_solver_targets;

	public bool add_local;
	public bool add_move;
	public bool add_rotate;

	/// <summary>
	/// 簡略化トランスフォーム
	/// </summary>
	[System.Serializable]
	public class LiteTransform {
		public Vector3 position;	// 位置
		public Quaternion rotation;	// 回転
		
		public LiteTransform(Vector3 p, Quaternion r) {position = p; rotation = r;}
	}
	private LiteTransform prev_global_;
	private LiteTransform prev_local_;

	/// <summary>
	/// 初回更新前処理
	/// </summary>
	void Start()
	{
		if (null != ik_solver) {
			ik_solver = transform.GetComponent<CCDIKSolver>();
			if (0 == ik_solver_targets.Length) {
				ik_solver_targets = Enumerable.Repeat(ik_solver.target, 1)
												.Concat(ik_solver.chains)
												.Select(x=>x.GetComponent<BoneController>())
												.ToArray();
			}
		}
		UpdatePrevTransform();
	}

	/// <summary>
	/// ボーン変形
	/// </summary>
	public void Process()
	{
		if (null != additive_parent) {
			//付与親有りなら
			LiteTransform additive_parent_transform = additive_parent.GetDeltaTransform(add_local);
			if (add_move) {
				//付与移動有りなら
				transform.localPosition += additive_parent_transform.position * additive_rate;
			}
			if (add_rotate) {
				//付与回転有りなら
				Quaternion delta_rotate_rate;
				if (0.0f <= additive_rate) {
					//正回転
					delta_rotate_rate = Quaternion.Slerp(Quaternion.identity, additive_parent_transform.rotation, additive_rate);
				}
				else
				{
					//逆回転
					Quaternion additive_parent_delta_rotate_reverse = Quaternion.Inverse(additive_parent_transform.rotation);
					delta_rotate_rate = Quaternion.Slerp(Quaternion.identity, additive_parent_delta_rotate_reverse, -additive_rate);
				}
				transform.localRotation *= delta_rotate_rate;
			}
		}
	}

	/// <summary>
	/// 差分トランスフォーム取得
	/// </summary>
	/// <returns>差分トランスフォーム</returns>
	/// <param name='is_add_local'>ローカル付与か(true:ローカル付与, false:通常付与)</param>
	public LiteTransform GetDeltaTransform(bool is_add_local) {
		LiteTransform result;
		if (is_add_local) {
			//ローカル付与(親も含めた変形量算出)
			result = new LiteTransform(transform.position - prev_global_.position
									, Quaternion.Inverse(prev_global_.rotation) * transform.rotation
									);
		} else {
			//通常付与(このボーン単体での変形量算出)
			result = new LiteTransform(transform.localPosition - prev_local_.position
									, Quaternion.Inverse(prev_local_.rotation) * transform.localRotation
									);
		}
		return result;
	}
	
	/// <summary>
	/// 差分基点トランスフォーム更新
	/// </summary>
	public void UpdatePrevTransform() {
		prev_global_ = new LiteTransform(transform.position, transform.rotation);
		prev_local_ = new LiteTransform(transform.localPosition, transform.localRotation);
	}
}