using UnityEngine;

namespace Roy
{

    public class SingletonMonoBehaviour<T> : MonoBehaviour where T : MonoBehaviour
    {
        private static T _instance;

        public static T Instance
        {
            get
            {
                if (_instance == null)
                {
                    // 尝试找到已存在的实例
                    _instance = FindObjectOfType<T>();

                    // 如果没有找到，则创建一个新的实例
                    if (_instance == null)
                    {
                        GameObject singletonObject = new GameObject(typeof(T).Name);
                        _instance = singletonObject.AddComponent<T>();
                        DontDestroyOnLoad(singletonObject); // 不在场景切换时销毁
                    }
                }

                return _instance;
            }
        }

        // 确保在场景中只存在一个实例
        protected virtual void Awake()
        {
            if (_instance == null)
            {
                _instance = this as T;
            }
            else if (_instance != this)
            {
                Debug.LogWarning($"An instance of {typeof(T)} already exists! Destroying this instance.");
                Destroy(gameObject); // 如果有其他实例，销毁当前对象
            }
        }

        protected virtual void OnDestroy()
        {
            if (_instance == this)
            {
                _instance = null; // 清除引用
            }
        }
    }

}