using System;
using System.Collections;
using System.Collections.Generic;
using UnityEngine;

namespace HotUpdate.UI
{
    /// <summary>
    /// 竖屏 UI 页面栈：加载 Prefab、打开/关闭、按名查找。
    /// </summary>
    public sealed class UiManager : MonoBehaviour
    {
        public static UiManager Instance { get; private set; }

        readonly Dictionary<string, GameObject> _opened = new Dictionary<string, GameObject>(StringComparer.Ordinal);
        Transform _root;
        UiPrefabLoader _loader;
        readonly HashSet<string> _loading = new HashSet<string>(StringComparer.Ordinal);
        public string Theme { get; private set; } = UiThemeCatalog.Candy;

        public void Init(Transform root, UiPrefabLoader loader, string theme = UiThemeCatalog.Candy)
        {
            Instance = this;
            _root = root;
            _loader = loader ?? new UiPrefabLoader();
            Theme = UiThemeCatalog.Normalize(theme);
        }

        public IEnumerator OpenAsync(string prefabName, Action<GameObject> onOpened, int siblingIndex = -1)
        {
            if (string.IsNullOrEmpty(prefabName)) { onOpened?.Invoke(null); yield break; }
            while (_loading.Contains(prefabName)) yield return null;
            if (_opened.TryGetValue(prefabName, out var existing) && existing != null)
            {
                existing.SetActive(true);
                onOpened?.Invoke(existing);
                yield break;
            }

            _loading.Add(prefabName);
            GameObject prefab = null;
            try
            {
                var assetName = UiThemeCatalog.Resolve(prefabName, Theme);
                yield return _loader.LoadAsync(assetName, loaded => prefab = loaded);
                if (prefab == null && assetName != prefabName)
                {
                    Debug.LogWarning($"[UI] Missing {assetName}; falling back to {prefabName}. Include both themes in the resource package.");
                    yield return _loader.LoadAsync(prefabName, loaded => prefab = loaded);
                }
            }
            finally { _loading.Remove(prefabName); }
            if (prefab == null)
            {
                Debug.LogError($"[UiManager] prefab not found: {prefabName}");
                onOpened?.Invoke(null);
                yield break;
            }

            var go = Instantiate(prefab, _root, false);
            go.name = prefabName;
            if (siblingIndex >= 0)
                go.transform.SetSiblingIndex(siblingIndex);
            _opened[prefabName] = go;
            onOpened?.Invoke(go);
        }

        public void Close(string prefabName, bool destroy = false)
        {
            if (!_opened.TryGetValue(prefabName, out var go) || go == null)
                return;
            if (destroy)
            {
                Destroy(go);
                _opened.Remove(prefabName);
            }
            else go.SetActive(false);
        }

        public GameObject Get(string prefabName)
        {
            _opened.TryGetValue(prefabName, out var go);
            return go;
        }

        void OnDestroy()
        {
            StopAllCoroutines();
            _loader?.Dispose();
            if (Instance == this) Instance = null;
        }
    }
}