#if UNITY_EDITOR

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

namespace UguiToolkit.Editor
{
    [ExecuteAlways]
    public class UnityMainThreadDispatcher : MonoBehaviour
    {
        private static readonly Queue<Action> _executionQueue = new Queue<Action>();

        private static UnityMainThreadDispatcher _instance = null;

        public static UnityMainThreadDispatcher Instance()
        {
            if (!_instance)
            {
                _instance = FindObjectOfType<UnityMainThreadDispatcher>();
                if (!_instance)
                {
                    var obj = new GameObject("UnityMainThreadDispatcher");
                    _instance = obj.AddComponent<UnityMainThreadDispatcher>();
                }
            }
            return _instance;
        }

        private void Update()
        {
            lock (_executionQueue)
            {
                while (_executionQueue.Count > 0)
                {
                    _executionQueue.Dequeue().Invoke();
                }
            }
        }

        public void Enqueue(IEnumerator action)
        {
            lock (_executionQueue)
            {
                _executionQueue.Enqueue(() => { StartCoroutine(action); });
            }
        }

        public void Enqueue(Action action)
        {
            Enqueue(ActionWrapper(action));
        }

        IEnumerator ActionWrapper(Action a)
        {
            a();
            yield return null;
        }

        public static void EnqueueMainThread(Action action)
        {
            Instance().Enqueue(action);
        }
    }
}

#endif