using System.Collections;
using System.Collections.Generic;
using UnityEngine;
using UnityEngine.EventSystems;
using DevelopEngine;
using UnityEngine.UI;
using UnityEngine.Events;
using System.Threading.Tasks;

//必须保证Map大于Mask
public class MyDragMap :MonoBehaviour,IPointerDownHandler,IDragHandler,IPointerUpHandler,IScrollHandler
{
    private Vector2 offsetPos;  //临时记录点击点与UI的相对位置
    private RectTransform rectTransform;
    private Vector2 parentSize;
    private Vector2 thisSize=  new Vector2(8192,8192);
    [SerializeField]
     float maxScale = 3;
    [SerializeField]
    float minScale = 1;
    RawImage thisImage;
    bool canDrag;
    float terrainSize = 10000f;//地形横边长 单位M
    float mapScale=10000f/8000f;//地图和地形之间的比例尺  



    public Texture Texture
    {
        get
        {
            return thisImage.texture;
        }
    }
    // Start is called before the first frame update
    void Awake()
    {
        thisImage = this.GetComponent<RawImage>();
    }

    /// <summary>
    /// 设置需要异步加载图片的完整路径
    /// </summary>
    public async Task<bool> SetTextureAsyncPath(string path)
    {
        Texture2D texture = await OutSpriteLoader.LoadTexture(path);
        if (texture != null)
        {
            SetTexture(texture);
            return true;
        }
        else
        {
            return false;
        }
     
    }

    /// <summary>
    /// 设置地图当前图片
    /// </summary>
    /// <param name="texture"></param>
    public void SetTexture(Texture2D texture)
    {
        thisImage.texture = texture;
        thisImage.SetNativeSize();
        InitSize();
    }

    //图片加载完成后 或图片尺寸发生变化时需调用  否则可能导致地图拖拽功能异常 
    public void InitSize()
    {
        parentSize = this.transform.parent.GetComponent<RectTransform>().rect.size;
        rectTransform = this.GetComponent<RectTransform>();
        thisSize = rectTransform.sizeDelta;
        minScale = parentSize.x/ thisSize.x;
        maxScale = thisSize.x / 3300;
        //if (thisSize.x > 5000)
        //    maxScale = thisSize.x / 5000;
        //else
        //    maxScale = 5000 / thisSize.x;
        mapScale = terrainSize / thisSize.x;
        rectTransform.localScale = new Vector3(minScale, minScale, 1);
        rectTransform.anchoredPosition = new Vector2(0,0);
        MapHelper.InitHelper(new Vector2(terrainSize, terrainSize), thisSize);//初始化地图转换信息
    }

    //需保持子物体大于父物体
    public void OnDrag(PointerEventData eventData)
    {
        if (!canDrag) return;
        transform.position = eventData.position - offsetPos;
        ClampPostion();
    }

    private void ClampPostion()
    {
        Vector2 anchoredPosition = rectTransform.anchoredPosition;
        float xClamp = (thisSize.x * rectTransform.localScale.x - parentSize.x) / 2;
        float yClamp = (thisSize.y * rectTransform.localScale.y - parentSize.y) / 2;
        if (anchoredPosition.x > xClamp)
            anchoredPosition.x = xClamp;
        if (anchoredPosition.x < -xClamp)
            anchoredPosition.x = -xClamp;
        if (anchoredPosition.y > yClamp)
            anchoredPosition.y = yClamp;
        if (anchoredPosition.y < -yClamp)
            anchoredPosition.y = -yClamp;
        rectTransform.anchoredPosition = anchoredPosition;
    }

    public void OnPointerDown(PointerEventData eventData)
    {
        canDrag = true;
        offsetPos = eventData.position - (Vector2)transform.position;
    }

    public void OnPointerUp(PointerEventData eventData)
    {
        canDrag = false;
    }

    public void OnScroll(PointerEventData eventData)
    {
        float delX = Input.mousePosition.x - transform.position.x;
        float delY = Input.mousePosition.y - transform.position.y;

        float scaleX = delX / rectTransform.rect.width / transform.localScale.x;
        float scaleY = delY / rectTransform.rect.height / transform.localScale.y;

        float scroell = Input.GetAxis("Mouse ScrollWheel");
        if (Mathf.Abs(scroell) > 0.05f )
        {
            float scale = rectTransform.localScale.x;
            float newScale = scale+ scroell;
            newScale = Mathf.Clamp(newScale, minScale, maxScale);
            if (scale == newScale)//未发生缩放时不调整位置  避免出现滚轮导致位置移动
                return;
            Vector2 mouseAnchoredPostion = Vector2.zero;
            RectTransformUtility.ScreenPointToLocalPointInRectangle(rectTransform, eventData.position, null, out mouseAnchoredPostion);
           // Debug.Log(mouseAnchoredPostion);
            rectTransform.anchoredPosition -= mouseAnchoredPostion * (newScale-scale);//触发clamp时未完全按照scroll发生变化  因此需计算实际变量
            rectTransform.localScale = new Vector3(newScale, newScale, 1);
            ClampPostion();
        }
    }


}