// MainThreadDispatcher.cs
// 非常轻量的主线程派发器（单例 MonoBehaviour）
// CMDManager 会自动 EnsureCreated()

using System;
using System.Collections.Concurrent;
using UnityEngine;

public class MainThreadDispatcher : MonoBehaviour
{
    private static MainThreadDispatcher _instance;
    private static readonly ConcurrentQueue<Action> queue = new ConcurrentQueue<Action>();

    [RuntimeInitializeOnLoadMethod(RuntimeInitializeLoadType.SubsystemRegistration)]
    private static void InitOnLoad()
    {
        // 清理旧实例引用（域重载时）
        _instance = null;
    }

    public static void EnsureCreated()
    {
        if (_instance != null) return;
        var go = new GameObject("MainThreadDispatcher");
        DontDestroyOnLoad(go);
        _instance = go.AddComponent<MainThreadDispatcher>();
    }

    public static void Enqueue(Action action)
    {
        if (action == null) return;
        queue.Enqueue(action);
    }

    private void Update()
    {
        while (queue.TryDequeue(out var action))
        {
            try
            {
                action();
            }
            catch (Exception e)
            {
                Debug.LogError("[MainThreadDispatcher] action error: " + e);
            }
        }
    }
}