/******************************************************************************
 * Copyright (C) Ultraleap, Inc. 2011-2021.                                   *
 *                                                                            *
 * Use subject to the terms of the Apache License 2.0 available at            *
 * http://www.apache.org/licenses/LICENSE-2.0, or another agreement           *
 * between Ultraleap and you, your company or other organization.             *
 ******************************************************************************/

using UnityEngine;

namespace Leap.Unity
{

    public class AppGlobals<T> : MonoBehaviour where T : AppGlobals<T>
    {

        protected void Awake()
        {
            if (s_instance != null)
            {
                Debug.LogWarning("Multiple instances of " + typeof(T) + " detected. " +
                  "AppGlobals are supposed to be singletons; the instance that awakens the " +
                  "latest will be the ultimate receiver of static instance calls.");
            }
            s_instance = this as T;
        }

        private static T s_instance = null;
        public static T instance
        {
            get
            {
                if (s_instance == null)
                {
                    s_instance = FindObjectOfType<T>();
                }
                if (s_instance == null)
                {
                    Debug.LogError("No " + typeof(T) + " instance found. App " +
                      "instances are loaded lazily from the Scene hierarchy when first " +
                      "requested; did you forget to add a " + typeof(T) + " to " +
                      "the scene?");
                }
                return s_instance;
            }
        }

    }

}