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

public class MonoSingleton<T> : MonoBehaviour where T : MonoSingleton<T>
{
    private static T instance;
    private static object locker = new object();

    // public static T Instance
    // {
    //     get
    //     {
    //         return instance;
    //     }
    // }

    public static T Instance
    {
        get
        {
            if (instance == null)
            {
                lock (locker)
                {
                    instance = FindObjectOfType<T>();
                    if (FindObjectsOfType<T>().Length > 1)
                    {
                        #if UNITY_EDITOR
                        Debug.LogError($"{typeof(T)} 不应该存在多个单例！");
                        #endif
                        return instance;
                    }

                    if (instance == null && Application.isPlaying)
                    {
                        var singleton = new GameObject();
                        instance = singleton.AddComponent<T>();
                        singleton.name = "(singleton)_" + typeof(T);
                        // singleton.hideFlags = HideFlags.None;
                        // DontDestroyOnLoad(singleton);
                    }
                    else
                    {
                        // DontDestroyOnLoad(instance.gameObject);
                    }
                }
                // instance.hideFlags = HideFlags.None;
            }

            return instance;
        }
    }

    // public static bool IsInitialized
    // {
    //     get
    //     {
    //         return instance != null;
    //     }
    // }

    // public virtual void Awake()
    // {
    //     if (instance != null)
    //     {
    //         Debug.LogErrorFormat("Trying to instantiate a second instance of singleton class {0}", GetType().Name);
    //     }
    //     else
    //     {
    //         instance = (T)this;
    //     }
    // }

    // public virtual void OnDestroy()
    // {
    //     if (instance == this)
    //     {
    //         instance = null;
    //     }
    // }
}