using UnityEngine;
using System.Collections;

public abstract class Singleton<T> where T : new()
{
	private static T _instance;
	static object _lock = new object();
	public static T Instance
	{
		get
		{
			if (_instance == null)
			{
				lock (_lock)
				{
					if (_instance == null)
						_instance = new T();
				}
			}
			return _instance;
		}
	}
}


/// <summary>
/// Be aware this will not prevent a non singleton constructor5.
///   such as `T myT = new T();`
/// To prevent that, add `protected T () {}` to your singleton class.
/// </summary>
public class UnitySingleton<T> : MonoBehaviour where T : MonoBehaviour
{
	private static T _instance;
	private static object _lock = new object ();

	public static T Instance {       
		get {         
			lock (_lock) {
				if (applicationIsQuitting) {
					return null;
				}

				if (_instance == null) {
					_instance = (T)FindObjectOfType (typeof(T));
					if (_instance == null) {
						string goName = typeof(T).ToString ();

						GameObject go = GameObject.Find (goName);
						if (go == null) {
							go = new GameObject ();
							_instance = go.AddComponent<T> ();
							go.name = "(singleton) " + typeof(T).ToString ();
							//go.hideFlags = HideFlags.HideAndDontSave;
							DontDestroyOnLoad (go);
						}
					} else {

					}
				}
				return _instance;
			}
		}
	}

	private static bool applicationIsQuitting = false;

	// private static bool ClearMode = false;

	public static void DestorySingleton ()
	{
		lock (_lock) {
			applicationIsQuitting = true;

			if (_instance != null) {
				// ClearMode = true;
				GameObject.Destroy (_instance.gameObject);
				_instance = null;
			}
		}
	}

	// public void OnDestroy() {
	// 	//Debug.LogError ("unitySingle OnDestroy");

	// 	lock (_lock) {
	// 		applicationIsQuitting = true;

	// 		if (_instance != null) {
	// 			GameObject.Destroy (_instance.gameObject);
	// 			_instance = null;
	// 		}
	// 	}
	// }
}

public class UnitySingletonLoadDestory<T> : MonoBehaviour where T : MonoBehaviour
{
	private static T _instance;
	private static object _lock = new object ();

	public static T Instance {       
		get {         
			if (applicationIsQuitting) {
				return null;
			}

			lock (_lock) {
				if (_instance == null) {
					_instance = (T)FindObjectOfType (typeof(T));
					if (_instance == null) {
						string goName = typeof(T).ToString ();

						GameObject go = GameObject.Find (goName);
						if (go == null) {
							go = new GameObject ();
							_instance = go.AddComponent<T> ();
							go.name = "(singleton) " + typeof(T).ToString ();
							//go.hideFlags = HideFlags.HideAndDontSave;
							go.hideFlags = HideFlags.DontSave;
						}
					} else {

					}
				}
				return _instance;
			}
		}
	}

	private static bool applicationIsQuitting = false;

	public static void DestorySingleton ()
	{

		lock (_lock) {
			applicationIsQuitting = true;

			if (_instance != null) {
				GameObject.Destroy (_instance.gameObject);
				_instance = null;
			}
		}
	}

	public void OnDestroy()
	{
		lock (_lock) {
			applicationIsQuitting = true;

			if (_instance != null) {
				GameObject.Destroy (_instance.gameObject);
				_instance = null;
			}
		}
	}
}