using UnityEngine;
using System.Collections;
using UnityEngine.UI;
using DG.Tweening;
public class CardMove : MonoBehaviour {
 GameObject[] sprites;
 int halfSize;
 Vector2 screenCenterPos;
 public float startAngle;//中間卡牌的角度
 public float deltaAngle;//相鄰卡牌的角度差值
 public float moveSpeed;//移動動畫的速度

 public Vector3 center;//橢圓中心點
 public float A = 1;//long axis
 public float B = 1;//short axis
 int cardcount;
 // Use this for initialization
 void Start () {
  init ();
 }

 // Update is called once per frame
 void Update () {

 }
 /// <summary>
 /// 初始化卡牌顯示位置
 /// </summary>
 void init(){
  screenCenterPos = new Vector2 (Screen.width*0.5f,Screen.height*0.5f);
  cardcount = transform.childCount;
   halfSize = (cardcount - 1) / 2;
  sprites=new GameObject[cardcount];
  for (int i = 0; i < cardcount; i++) {
   sprites [i] = transform.GetChild (i).gameObject;
   setPosition (i,false);
   setDeeps (i);

  }

 }
 /// <summary>
 /// 橢圓的半長軸為A，半短軸為B，計算橢圓上一點的位置
 /// x=A*cos(angle),y=B*sin(angle)
 /// </summary>
 /// <param name="index">Index.</param>
 /// <param name="userTweener">是否使用tween動畫.</param>
 void setPosition(int index,bool userTweener=true){
  //計算每一張卡片在橢圓上相對中間卡牌的角度
  float angle = 0;
  if(index<halfSize){//left
   angle=startAngle-(halfSize-index)*deltaAngle;

  }else if(index>halfSize){//right

   angle = startAngle + (index - halfSize) * deltaAngle;
  }else{//medim
   angle=startAngle;
  }


  //通過卡牌的角度，計算對應的位置
  float xpos = A*Mathf.Cos((angle/180)*Mathf.PI);//+center.x;
  float ypos = B*Mathf.Sin((angle/180)*Mathf.PI);//+center.y;
  Debug.Log ("index="+index+",xpos="+xpos+",ypos="+ypos);

  Vector2 pos = new Vector2 (xpos,ypos);
//  Debug.Log ("screenPos="+screenPos+",wordPos="+wordPos);

//通過doTween控制卡片移動動畫
  if(!userTweener){
   sprites [index].GetComponent<Image> ().rectTransform.DOMove(new Vector2(screenCenterPos.x+pos.x,screenCenterPos.y+pos.y),0f);
  }else
   sprites [index].GetComponent<Image> ().rectTransform.DOMove(new Vector2(screenCenterPos.x+pos.x,screenCenterPos.y+pos.y),1f);

 }
 /// <summary>
 /// 計算每一張卡片的層級
 /// </summary>
 /// <param name="index">Index.</param>
 void setDeeps(int index){
  int deep = 0;
  if (index < halfSize) {//左側卡牌層級，從左側到中間，層級依此遞增
   deep=index;
  } else if (deep > halfSize) {//右側卡牌層級，從中間到右側，層級依此遞減
   deep=sprites.Length-(index+1);
  } else {
   deep = halfSize;
  }

  sprites [index].GetComponent<RectTransform> ().SetSiblingIndex (deep);
 }
 /// <summary>
 /// 左側按鈕點擊，向左移動
 /// </summary>
 public void OnLeftBtnClick(){
  int length = sprites.Length;

  GameObject temp=sprites[0];
  for (int i = 0; i < length; i++) {//移動卡片在數組中的位置，依此向前移動一位
   if (i == length - 1)
    sprites [i] = temp;
   else
    sprites [i] = sprites [i + 1];
  }

  for (int i = 0; i < length; i++) {//跟新數組卡片需要顯示的位置和層級
   setPosition (i);
   setDeeps (i);
  }
 }

 /// <summary>
 /// 右側按鈕點擊，向右移動
 /// </summary>
 public void RightBtnClick(){
  int length = sprites.Length;

  GameObject temp=sprites[length-1];
  for (int i = length-1; i >=0; i--) {
   if (i == 0)
    sprites [i] = temp;
   else
    sprites [i] = sprites [i - 1];
  }
  for (int i = 0; i < length; i++) {
   setPosition (i);
   setDeeps (i);
  }
 }
}