using System.Collections;
using UnityEngine;
using UnityEngine.AddressableAssets;
using UnityEngine.ResourceManagement.AsyncOperations;
using UnityEngine.ResourceManagement.ResourceProviders;
using UnityEngine.SceneManagement;
using BaseGames.Core.Events;

namespace BaseGames.Core
{
    /// <summary>
    /// Addressables 场景加载器（Phase 0 骨架）。
    /// 监听 EVT_SceneLoadRequest，Additive 加载指定场景，完成后发布 EVT_SceneLoaded。
    /// Phase 1 完整实现由 SceneService 包装调用。
    /// </summary>
    [DefaultExecutionOrder(-950)]
    public class SceneLoader : MonoBehaviour
    {
        [Header("Event Channels - Listen")]
        [SerializeField] private SceneLoadRequestEventChannelSO _onSceneLoadRequest;

        [Header("Event Channels - Raise")]
        [SerializeField] private StringEventChannelSO _onSceneLoaded;

        private string _currentRoomScene;
        private AsyncOperationHandle<SceneInstance> _currentHandle;

        private void OnEnable()
        {
            if (_onSceneLoadRequest != null)
                _onSceneLoadRequest.OnEventRaised += HandleRequest;
        }

        private void OnDisable()
        {
            if (_onSceneLoadRequest != null)
                _onSceneLoadRequest.OnEventRaised -= HandleRequest;
        }

        private void HandleRequest(SceneLoadRequest request)
            => StartCoroutine(LoadSceneCoroutine(request));

        private IEnumerator LoadSceneCoroutine(SceneLoadRequest request)
        {
            // 卸载旧场景
            if (!string.IsNullOrEmpty(_currentRoomScene) && _currentHandle.IsValid())
            {
                var unloadOp = Addressables.UnloadSceneAsync(_currentHandle);
                yield return unloadOp;
            }

            // 加载新场景（Additive）
            var loadOp = Addressables.LoadSceneAsync(request.SceneName, LoadSceneMode.Additive);
            yield return loadOp;

            if (loadOp.Status == AsyncOperationStatus.Succeeded)
            {
                _currentHandle    = loadOp;
                _currentRoomScene = request.SceneName;
                _onSceneLoaded?.Raise(request.SceneName);
            }
            else
            {
                Debug.LogError($"[SceneLoader] 加载场景失败：{request.SceneName}");
            }
        }

        /// <summary>手动卸载当前房间场景（供 SceneService 调用）。</summary>
        public IEnumerator UnloadCurrentCoroutine()
        {
            if (!_currentHandle.IsValid()) yield break;
            var unloadOp = Addressables.UnloadSceneAsync(_currentHandle);
            yield return unloadOp;
            _currentRoomScene = null;
        }
    }
}