using UnityEngine;
using System.Collections;
using System;
namespace BookCurlPro
{
    public class Tween : MonoBehaviour
    {

        Vector3 from, to;
        float duration;
        Action<Vector3> update;
        Action finish;
        float elapsedtime = 0;
        bool working = false;
        public static Vector3 ValueTo(GameObject obj,
            Vector3 from, Vector3 to, float duration,
            Action<Vector3> update = null, Action finish = null)
        {
            Tween tween = obj.GetComponent<Tween>();
            if (!tween)
                tween = obj.AddComponent<Tween>();
            tween.elapsedtime = 0;
            tween.working = true;
            tween.enabled = true;
            tween.from = from;
            tween.to = to;
            tween.duration = duration;
            tween.update = update;
            tween.finish = finish;
            return Vector3.zero;
        }
        static Vector3 QuadOut(Vector3 start, Vector3 end, float duration, float elapsedTime)
        {
            if (elapsedTime >= duration)
                return end;
            else
            {
                return (elapsedTime / duration) * (elapsedTime / duration - 2) * -(end - start) + start;
            }
        }

        // Update is called once per frame
        void Update()
        {
            if (working)
            {
                elapsedtime += Time.deltaTime;
                Vector3 value = QuadOut(from, to, duration, elapsedtime);
                if (update != null) update(value);
                if (elapsedtime >= duration)
                {
                    working = false;
                    this.enabled = false;
                    if (finish != null)
                    {
                        finish();
                    }
                }
            }
        }
    }
}