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

/// <summary>
/// 朝向提示UI
/// </summary>
public class ArrowTips_EyeMode : MonoBehaviour
{
    private Transform _arrow_Rot;
    public bool _openTips = false;
    public Transform _target;
    public Camera _camera;
    private float targetAngle;
    public float lerpIndex = 0.9f;
    private void Awake()
    {
        Init();
    }

    public void Init()
    {
        _arrow_Rot = this.transform.GetChild(0).Find("Arrow_Eye_Rot");
        if (!_openTips)
        {
            _arrow_Rot.gameObject.SetActive(false);
        }
    }

    // Update is called once per frame
    void Update()
    {
        if (_openTips)
        {
            ArrowController();
        }
    }

    public void ArrowController()
    {
        if (_target == null) return;

        if (!_target.gameObject.activeSelf && _arrow_Rot.gameObject.activeSelf)
        {
            _arrow_Rot.gameObject.SetActive(false);
        }
        else if (_target.gameObject.activeSelf && !_arrow_Rot.gameObject.activeSelf)
        {
            _arrow_Rot.gameObject.SetActive(true);
        }

        if (!_target.gameObject.activeSelf) return;

        //物体转化为摄像机屏幕坐标
        Vector3 screenPointInV3 = _camera.WorldToScreenPoint(_target.position);
        Vector2 screenPoint = new Vector2(screenPointInV3.x, screenPointInV3.y);

        if (screenPointInV3.z <= 0)      //物体在摄像机后方
        {
            Vector3 screenCenterPos = new Vector3(_camera.pixelWidth / 2, _camera.pixelHeight / 2, 0);

            float angle = 90;
            if (Vector3.Cross(Vector3.up, (screenPointInV3 - screenCenterPos)).z < 0)
            {
                angle = -angle;
            }
            targetAngle = -angle;
        }
        else if (!_camera.pixelRect.Contains(screenPoint)) //摄像机正面且不在画面中
        {
            Vector3 screenCenterPos = new Vector3(_camera.pixelWidth / 2, _camera.pixelHeight / 2, 0);
            float angle = Vector3.Angle(Vector3.up, (screenPointInV3 - screenCenterPos));
            if (Vector3.Cross(Vector3.up, (screenPointInV3 - screenCenterPos)).z > 0)
            {
                angle = -angle;
            }
            targetAngle = -angle;

            if (!_arrow_Rot.gameObject.activeSelf)
            {
                _arrow_Rot.gameObject.SetActive(true);
                _arrow_Rot.transform.localRotation = Quaternion.Euler(0, 0, targetAngle);
            }
        }
        else
        {
            _arrow_Rot.gameObject.SetActive(false);
        }

        //_Arrow朝向是反的
        _arrow_Rot.transform.localRotation = Quaternion.Lerp(_arrow_Rot.transform.localRotation, Quaternion.Euler(0, 0, targetAngle), lerpIndex);
    }

    public void OpenEyeTips(Transform t)
    {
        _target = t;
        if (t != null)
        {
            _openTips = true;
        }
    }

    public void CloseEyeTips()
    {
        _target = null;
        _openTips = false;
    }
}