using UnityEngine;
using System.Collections.Generic;

namespace UnityThreadingUtils
{
    /// <summary>
    /// 用于在子线程中将任务安全地调度到Unity主线程执行的工具类
    /// </summary>
    public class UnityMainThreadDispatcher : MonoBehaviour
    {
        private static UnityMainThreadDispatcher _instance;

        // 用于存储需要在主线程执行的任务队列
        private readonly Queue<System.Action> _actionQueue = new Queue<System.Action>();

        private void Awake()
        {
            if (_instance == null)
            {
                _instance = this;
                // 让这个游戏对象在场景切换时不被销毁，确保持续可用
                DontDestroyOnLoad(gameObject);
            }
            else
            {
                //Destroy(gameObject);
            }
        }

        /// <summary>
        /// 获取单例实例
        /// </summary>
        /// <returns>UnityMainThreadDispatcher单例对象</returns>
        public static UnityMainThreadDispatcher Instance()
        {
            if (_instance == null)
            {
                // 创建一个新的游戏对象来挂载该组件
                GameObject dispatcherGameObject = new GameObject("UnityMainThreadDispatcher");
                _instance = dispatcherGameObject.AddComponent<UnityMainThreadDispatcher>();
                // 让这个游戏对象在场景切换时不被销毁，确保持续可用
                UnityEngine.Object.DontDestroyOnLoad(dispatcherGameObject);
            }

            return _instance;
        }

        /// <summary>
        /// 将一个任务添加到主线程执行的队列中
        /// </summary>
        /// <param name="action">需要在主线程执行的任务（以Action委托表示）</param>
        public void Enqueue(System.Action action)
        {
            lock (_actionQueue)
            {
                _actionQueue.Enqueue(action);
            }
        }

        private void Update()
        {
            // 加锁确保线程安全地处理任务队列
            lock (_actionQueue)
            {
                while (_actionQueue.Count > 0)
                {
                    System.Action action = _actionQueue.Dequeue();
                    try
                    {
                        action.Invoke();
                    }
                    catch (System.Exception ex)
                    {
                        //Debug.LogError($"执行主线程任务时出错: {ex.Message}");
                    }
                }
            }
        }
    }
}