#nullable enable
using Cysharp.Threading.Tasks;
using ShrinkApp;
using UnityEngine;

namespace ShrinkContext.AppAdapter
{
    /// <summary>
    /// ShrinkApp 加载器宿主的自动引导：
    /// hostingMode == ContextLoader 时在 BeforeSceneLoad 创建常驻 GameObject 并启动 ShrinkAppLoaderHost，
    /// 同时把服务容器接回 ShrinkApp 静态入口（InitializeForExternalHost），保证场景脚本照常访问 ShrinkApp.Services。
    /// ClassicHost 模式下完全不动——经典路径零行为变化。
    /// </summary>
    public sealed class ShrinkAppLoaderBootstrapper : MonoBehaviour
    {
        private static ShrinkAppLoaderBootstrapper? _instance;

        /// <summary>
        /// Starter/组合包在 SubsystemRegistration 阶段设置的默认装配表。
        /// AppAdapter 保持不依赖具体业务模块，组合根负责把原生组件挂到已发现的模块 id。
        /// </summary>
        public static System.Action<ShrinkAppLoaderHost>? DefaultComposition { get; set; }

        public static ShrinkAppLoaderBootstrapper? Instance => _instance;

        public ShrinkAppLoaderHost Host { get; private set; } = null!;

        [RuntimeInitializeOnLoadMethod(RuntimeInitializeLoadType.BeforeSceneLoad)]
        private static void AutoBootstrap()
        {
            if (ShrinkAppSettings.Instance.hostingMode != ShrinkAppHostingMode.ContextLoader)
                return;

            var gameObject = new GameObject("ShrinkAppLoaderHost");
            DontDestroyOnLoad(gameObject);
            gameObject.AddComponent<ShrinkAppLoaderBootstrapper>();
        }

        private void Awake()
        {
            if (_instance != null && _instance != this)
            {
                Destroy(gameObject);
                return;
            }

            _instance = this;
            Host = new ShrinkAppLoaderHost();
            DefaultComposition?.Invoke(Host);
            var profile = ShrinkAppCompositionProfile.LoadDefault();
            if (profile != null)
                Host.ApplyComposition(profile.ResolveDocument());
            global::ShrinkApp.ShrinkApp.InitializeForExternalHost(Host.Services);
            Host.StartAsync().Forget(ex =>
            {
                Debug.LogException(ex);
                Debug.LogError("[ShrinkApp.LoaderHost] 启动失败: " + ex.Message);
            });
        }

        private void OnDestroy()
        {
            if (_instance == this)
                _instance = null;
        }
    }
}