using System.Collections.Concurrent;
using UnityEngine;

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

    public static MainThreadDispatcher Instance
    {
        get
        {
            if (_instance == null)
            {
                // Check if an instance already exists in the scene
                _instance = FindObjectOfType<MainThreadDispatcher>();
                
                if (_instance == null)
                {
                    // Create new GameObject if none exists
                    var dispatcherObject = new GameObject("MainThreadDispatcher");
                    _instance = dispatcherObject.AddComponent<MainThreadDispatcher>();
                    DontDestroyOnLoad(dispatcherObject);
                }
            }
            return _instance;
        }
    }

    // Add action to the queue
    public void Enqueue(System.Action action)
    {
        if (action == null)
        {
            Debug.LogWarning("Trying to enqueue a null action");
            return;
        }
        
        _executionQueue.Enqueue(action);
    }

    // Update is called once per frame
    void Update()
    {
        // Execute all actions in the queue
        while (_executionQueue.TryDequeue(out var action))
        {
            try
            {
                action.Invoke();
            }
            catch (System.Exception e)
            {
                Debug.LogError($"Exception in dispatched action: {e}");
            }
        }
    }

    // Cleanup when destroyed
    void OnDestroy()
    {
        if (_instance == this)
        {
            _instance = null;
        }
    }
}