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

/// <summary>
/// 在多 SceneView 窗口下安全地添加/移除临时回调。
/// 原理：Templist 存放需在下一帧执行的回调，OnSceneGUI 将会把 Templist 转移到 list 来执行。
/// </summary>
public class UXCustomSceneView
{
    static private List<Action<SceneView>> list = new List<Action<SceneView>>();
    static private List<Action<SceneView>> Templist = new List<Action<SceneView>>();

    [InitializeOnLoadMethod]
    static void Init()
    {
        list.Clear();
        Templist.Clear();
        SceneView.duringSceneGui -= OnSceneGUI;
        SceneView.duringSceneGui += OnSceneGUI;
    }

    static public void AddDelegate(Action<SceneView> method)
    {
        if (method == null) return;
        // 去重
        if (!Templist.Contains(method))
            Templist.Add(method);
    }

    static public void RemoveDelegate(Action<SceneView> method)
    {
        if (method == null) return;
        var idx = Templist.FindIndex(i => i == method);
        if (idx >= 0) Templist.RemoveAt(idx);
    }

    static public void OnSceneGUI(SceneView sceneView)
    {
        // 执行上一帧注册的 list
        foreach (Action<SceneView> method in list)
        {
            try
            {
                method.Invoke(sceneView);
            }
            catch (Exception e)
            {
                Debug.LogException(e);
            }
        }

        list.Clear();

        // 将 Templist 拷贝到 list，并在下一帧执行，这样可以避免在枚举时修改集合的问题
        foreach (Action<SceneView> method in Templist)
        {
            if (!list.Contains(method))
                list.Add(method);
        }
    }

    static public void ClearDelegate()
    {
        Templist.Clear();
    }
}