using System.Collections;
using UnityEngine;

namespace ProjectM.Client
{
    /// <summary>
    /// Persistent (<c>DontDestroyOnLoad</c>) MonoBehaviour that hosts the world-lifecycle coroutines for
    /// <see cref="WorldLauncher"/>. World create/dispose + scene loads must run at a FRAME BOUNDARY (never
    /// inside an ECS system update — that crashes), and must survive the MainMenu&lt;-&gt;Game scene swap, so a
    /// single long-lived runner owns them. Created lazily on first use.
    /// </summary>
    public class SessionRunner : MonoBehaviour
    {
        static SessionRunner _instance;

        static SessionRunner Instance
        {
            get
            {
                if (_instance == null)
                {
                    var go = new GameObject("~SessionRunner");
                    DontDestroyOnLoad(go);
                    _instance = go.AddComponent<SessionRunner>();
                }
                return _instance;
            }
        }

        public static void Run(IEnumerator routine) => Instance.StartCoroutine(routine);
    }
}