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

public class ScreenCameraRay : MonoBehaviour
{

    // Start is called before the first frame update
    void Start()
    {
        
    }

    /// <summary>
    /// 输入设备上一次检测到的目标物体
    /// </summary>
    protected GameObject target;
    // Update is called once per frame
    void Update()
    {
        if (Input.GetMouseButtonDown(0))
        {
            //Debug.Log("点击屏幕");
            CheckRay(Input.mousePosition, TouchPhase.Began);
        }
        else if(Input.GetMouseButtonUp(0))
        {
            CheckRay(Input.mousePosition, TouchPhase.Ended);
        }
        else if (Input.touchCount == 1)
        {
            if (Input.GetTouch(0).phase == TouchPhase.Began)
            {
                CheckRay(Input.GetTouch(0).position, TouchPhase.Began);
            }
            else if (Input.GetTouch(0).phase == TouchPhase.Ended)
            {
                CheckRay(Input.GetTouch(0).position, TouchPhase.Ended);
            }
        }
        else
        {
            CheckRay(Input.mousePosition, TouchPhase.Canceled);
        }
    }

    private void CheckRay(Vector3 point, TouchPhase mode)
    {
        RaycastHit hit;
        Ray ray = Camera.main.ScreenPointToRay(point);
        if (Physics.Raycast(ray, out hit))
        {
            if(!hit.transform.gameObject.Equals(target))
            {
                ExecuteEvents.Execute<IPointerExitHandler>(target, null, (x, y) => x.OnPointerExit(null));
            }
            target = hit.transform.gameObject;
            //CDebug.Log(hit.transform.name);
            //Debug.Log(hit.transform.tag);
            if(mode == TouchPhase.Began)
            {
                ExecuteEvents.Execute<IPointerDownHandler>(hit.transform.gameObject, null, (x, y) => x.OnPointerDown(null));
                ExecuteEvents.Execute<IPointerClickHandler>(hit.transform.gameObject, null, (x, y) => x.OnPointerClick(null));
            }
            else if (mode == TouchPhase.Ended)
            {
                ExecuteEvents.Execute<IPointerUpHandler>(hit.transform.gameObject, null, (x, y) => x.OnPointerUp(null));
            }
        }
    }
}