using System.Collections.Generic;
using UnityEngine;
using UnityEngine.AddressableAssets;
using UnityEngine.ResourceManagement.AsyncOperations;
using BaseGames.Core;
using BaseGames.Core.Assets;
using BaseGames.Core.Events;

namespace BaseGames.UI
{
    /// <summary>
    /// 面板 ID 枚举。新增面板时只需在此添加值并在 Inspector 的 _panels 数组中注册，
    /// 无需修改 UIManager 的其他代码，满足开闭原则。
    /// </summary>
    public enum PanelId
    {
        Pause,
        Settings,
        Map,
        Shop,
        CharmPanel,
        SpellSelect,
        Inventory,
    }

    [DefaultExecutionOrder(+50)]
    public class UIManager : MonoBehaviour, IUIManager
    {
        // ── 状态驱动根节点（不进入面板栈，仅根据 GameState 显示/隐藏）─────────
        [Header("状态驱动根节点（非面板栈）")]
        [SerializeField] private GameObject _hudRoot;
        [SerializeField] private GameObject _deathScreenRoot;

        // ── 面板栈注册表 ──────────────────────────────────────────────────────
        [Header("面板栈注册表（Inspector 配置，可运行时扩展）")]
        [Tooltip("将 PanelId 与对应的根 GameObject 绑定。新增面板只需在此添加一行，无需修改 UIManager 代码。")]
        [SerializeField] private PanelRegistration[] _panels;

        [Header("Addressable 面板（按需异步加载，首次打开时实例化）")]
        [Tooltip("配置 PanelId → AssetReferenceGameObject；同 _panels 重复定义时，本表优先生效。" +
                 "未在此处也未在 _panels 中注册的 PanelId 调用 OpenPanel 将记录警告。")]
        [SerializeField] private AddressablePanelRegistration[] _addressablePanels;
        [Tooltip("Addressable 面板实例化后挂载的父节点；为空时挂在 UIManager.transform。")]
        [SerializeField] private Transform _addressablePanelParent;

        [Header("Event Channels")]
        [SerializeField] private GameStateEventChannelSO _onGameStateChanged;
        [SerializeField] private VoidEventChannelSO      _onPauseRequested;
        [SerializeField] private VoidEventChannelSO      _onFastTravelOpen;
        [SerializeField] private StringEventChannelSO    _onShopOpen;
        [SerializeField] private VoidEventChannelSO      _onMapOpen;
        [SerializeField] private VoidEventChannelSO      _onCharmPanelOpen;
        [SerializeField] private VoidEventChannelSO      _onSpellSelectOpen;
        [Tooltip("打开统一背包菜单（InventoryHub）。对应 EVT_InventoryOpen。")]
        [SerializeField] private VoidEventChannelSO      _onInventoryOpen;

        // ── 面板栈：委托给统一的 UINavigator（不再自管栈）─────────────────────
        private IUINavigator _navigator;
        private readonly Dictionary<PanelId, GameObject> _panelRegistry = new();
        private readonly CompositeDisposable             _subs          = new();

        // ── 序列化辅助结构 ────────────────────────────────────────────────────
        [System.Serializable]
        private struct PanelRegistration
        {
            [Tooltip("面板标识符（与代码中的 PanelId 枚举对应）。")]
            public PanelId    id;
            [Tooltip("该面板的根 GameObject（通常是 Canvas 的直接子节点）。")]
            public GameObject root;
        }

        [System.Serializable]
        private struct AddressablePanelRegistration
        {
            [Tooltip("面板标识符。")]
            public PanelId id;
            [Tooltip("Addressable 引用；首次 OpenPanel 时异步加载并实例化。")]
            public AssetReferenceGameObject reference;
            [Tooltip("关闭后保留实例（仅隐藏，不释放）。开启时常驻内存，避免反复加载抖动；适合频繁打开的面板。")]
            public bool keepLoadedAfterClose;
        }

        /// <summary>记录 Addressable 加载状态，避免重复加载与正确释放。</summary>
        private class AddressablePanelHandle
        {
            public AsyncOperationHandle<GameObject> Handle;
            public GameObject Instance;
            public bool       IsLoading;
            public bool       KeepLoaded;
        }
        private readonly Dictionary<PanelId, AddressablePanelHandle>      _addressableHandles = new();
        private readonly Dictionary<PanelId, AssetReferenceGameObject>    _addressableRefs    = new();
        private readonly Dictionary<PanelId, bool>                        _addressableKeep    = new();

        // ── 生命周期 ──────────────────────────────────────────────────────────
        private void Awake()
        {
            if (_panels != null)
                foreach (var p in _panels)
                    if (p.root != null) _panelRegistry[p.id] = p.root;

            if (_addressablePanels != null)
                foreach (var p in _addressablePanels)
                {
                    if (p.reference != null) _addressableRefs[p.id] = p.reference;
                    _addressableKeep[p.id] = p.keepLoadedAfterClose;
                }
        }

        private void OnEnable()
        {
            ServiceLocator.Register<IUIManager>(this);
            _navigator = ServiceLocator.GetOrDefault<IUINavigator>();
            _onGameStateChanged?.Subscribe(HandleGameStateChanged).AddTo(_subs);
            _onPauseRequested?.Subscribe(TogglePause).AddTo(_subs);
            _onFastTravelOpen?.Subscribe(OpenMap).AddTo(_subs);
            _onShopOpen?.Subscribe(OpenShop).AddTo(_subs);
            _onMapOpen?.Subscribe(OpenMap).AddTo(_subs);
            _onCharmPanelOpen?.Subscribe(OpenCharmPanel).AddTo(_subs);
            _onSpellSelectOpen?.Subscribe(OpenSpellSelect).AddTo(_subs);
            _onInventoryOpen?.Subscribe(OpenInventory).AddTo(_subs);
            // 取消键（ESC / 手柄 B）由 UINavigator 统一消费，UIManager 不再订阅。
        }

        private void OnDisable()
        {
            ServiceLocator.Unregister<IUIManager>(this);
            _subs.Clear();
            ReleaseAllAddressablePanels();
        }

        /// <summary>释放所有由 Addressables 加载的面板（防止场景切换泄漏）。</summary>
        private void ReleaseAllAddressablePanels()
        {
            foreach (var kv in _addressableHandles)
            {
                var h = kv.Value;
                if (h == null) continue;
                if (h.Instance != null && _addressableRefs.TryGetValue(kv.Key, out var aref))
                {
                    aref.ReleaseInstance(h.Instance);
                }
                else if (h.Handle.IsValid())
                {
                    AssetLoader.Release(h.Handle);
                }
            }
            _addressableHandles.Clear();
        }

        // ── 面板注册（运行时动态扩展入口）────────────────────────────────────
        /// <summary>运行时注册或覆盖面板绑定（如场景加载后动态添加的面板）。</summary>
        public void RegisterPanel(PanelId id, GameObject root)
        {
            if (root != null) _panelRegistry[id] = root;
        }

        // ── 状态响应 ──────────────────────────────────────────────────────────
        private void HandleGameStateChanged(GameStateId state)
        {
            bool showHud = state == GameStates.Gameplay || state == GameStates.BossFight;
            if (_hudRoot != null) _hudRoot.SetActive(showHud);

            if (state == GameStates.Dead)
            {
                if (_deathScreenRoot != null) _deathScreenRoot.SetActive(true);
            }
            else
            {
                if (_deathScreenRoot != null) _deathScreenRoot.SetActive(false);

                if (state == GameStates.Cutscene)
                    if (_hudRoot != null) _hudRoot.SetActive(false);
            }
        }

        // ── 面板栈 API ────────────────────────────────────────────────────────
        /// <summary>通过 ID 打开面板：优先同步注册表，其次 Addressable 异步加载。</summary>
        public void OpenPanel(PanelId id)
        {
            if (_panelRegistry.TryGetValue(id, out var panel))
            {
                OpenPanel(panel);
                return;
            }
            if (_addressableRefs.ContainsKey(id))
            {
                OpenPanelAsync(id);
                return;
            }
            Debug.LogWarning($"[UIManager] PanelId.{id} 未注册（Inspector 中既无 _panels 也无 _addressablePanels）。", this);
        }

        /// <summary>异步加载并打开 Addressable 面板。首次触发 InstantiateAsync，后续复用。</summary>
        private void OpenPanelAsync(PanelId id)
        {
            if (!_addressableRefs.TryGetValue(id, out var aref) || aref == null)
            {
                Debug.LogWarning($"[UIManager] Addressable 面板 {id} 未配置 AssetReference。", this);
                return;
            }

            if (!_addressableHandles.TryGetValue(id, out var entry))
            {
                _addressableKeep.TryGetValue(id, out var keep);
                entry = new AddressablePanelHandle { IsLoading = true, KeepLoaded = keep };
                _addressableHandles[id] = entry;
            }

            // 已加载完成：直接复用实例。
            if (entry.Instance != null)
            {
                _panelRegistry[id] = entry.Instance;
                OpenPanel(entry.Instance);
                return;
            }

            // 加载中：忽略重复请求。
            if (entry.IsLoading && entry.Handle.IsValid()) return;

            entry.IsLoading = true;
            var parent = _addressablePanelParent != null ? _addressablePanelParent : transform;
            entry.Handle = aref.InstantiateAsync(parent, instantiateInWorldSpace: false);
            entry.Handle.Completed += op =>
            {
                entry.IsLoading = false;
                if (op.Status != AsyncOperationStatus.Succeeded || op.Result == null)
                {
                    Debug.LogError($"[UIManager] Addressable 面板 {id} 加载失败: {op.OperationException}", this);
                    return;
                }
                entry.Instance = op.Result;
                entry.Instance.SetActive(false);            // 与 PanelRegistration 同语义：默认隐藏
                _panelRegistry[id] = entry.Instance;
                OpenPanel(entry.Instance);
            };
        }

        /// <summary>打开指定 GameObject 面板：经统一 <see cref="IUINavigator"/> 压栈。</summary>
        public void OpenPanel(GameObject panel)
        {
            if (panel == null) return;
            var uiPanel = EnsurePanel(panel);
            if (uiPanel != null) Navigator?.Push(uiPanel);
        }

        /// <summary>关闭栈顶面板并恢复上一层（委托给导航器）。</summary>
        public void CloseTopPanel() => Navigator?.Pop();

        /// <summary>
        /// 适配器：保证面板根挂有 <see cref="UIPanelBase"/>（导航器压栈对象）。
        /// 既有面板若未挂则运行时补 <see cref="UISimplePanel"/> + CanvasGroup，
        /// 使所有游戏内面板无需逐个改脚手架即可纳入统一导航栈。
        /// </summary>
        private static UIPanelBase EnsurePanel(GameObject go)
        {
            var p = go.GetComponent<UIPanelBase>();
            if (p == null)
            {
                if (go.GetComponent<CanvasGroup>() == null) go.AddComponent<CanvasGroup>();
                p = go.AddComponent<UISimplePanel>();
            }
            return p;
        }

        // ── 快捷事件回调 ──────────────────────────────────────────────────────
        private void TogglePause()
        {
            if (_panelRegistry.TryGetValue(PanelId.Pause, out var pausePanel)
                && Navigator?.Top != null && Navigator.Top.gameObject == pausePanel)
                Navigator.Pop();
            else
                OpenPanel(PanelId.Pause);
        }

        private IUINavigator Navigator => _navigator ??= ServiceLocator.GetOrDefault<IUINavigator>();
        private void OpenShop(string _)    => OpenPanel(PanelId.Shop);
        private void OpenMap()             => OpenPanel(PanelId.Map);
        private void OpenCharmPanel()      => OpenPanel(PanelId.CharmPanel);
        private void OpenSpellSelect()     => OpenPanel(PanelId.SpellSelect);
        private void OpenInventory()       => OpenPanel(PanelId.Inventory);

        // ── 编辑器工具 ────────────────────────────────────────────────────────
        [ContextMenu("验证面板注册表")]
        private void EditorValidateRegistry()
        {
            if ((_panels == null || _panels.Length == 0) && (_addressablePanels == null || _addressablePanels.Length == 0))
            {
                Debug.LogWarning("[UIManager] 面板注册表为空！", this);
                return;
            }

            var seen = new HashSet<PanelId>();
            bool ok  = true;
            if (_panels != null)
            {
                foreach (var p in _panels)
                {
                    if (p.root == null)
                    {
                        Debug.LogWarning($"[UIManager] PanelId.{p.id} 的 GameObject 引用为 null！", this);
                        ok = false;
                    }
                    if (!seen.Add(p.id))
                    {
                        Debug.LogError($"[UIManager] PanelId.{p.id} 在 _panels 中重复！", this);
                        ok = false;
                    }
                }
            }
            if (_addressablePanels != null)
            {
                var seenAddr = new HashSet<PanelId>();
                foreach (var p in _addressablePanels)
                {
                    if (p.reference == null)
                    {
                        Debug.LogWarning($"[UIManager] Addressable PanelId.{p.id} 的 reference 为 null！", this);
                        ok = false;
                    }
                    if (!seenAddr.Add(p.id))
                    {
                        Debug.LogError($"[UIManager] PanelId.{p.id} 在 _addressablePanels 中重复！", this);
                        ok = false;
                    }
                }
            }
            if (ok)
                Debug.Log($"[UIManager] 验证通过 ✔  同步 {_panels?.Length ?? 0} 个 / Addressable {_addressablePanels?.Length ?? 0} 个。", this);
        }

#if UNITY_EDITOR
        /// <summary>仅供 UIManagerEditor 实时可视化栈顶面板（栈本体已迁移至 UINavigator）。</summary>
        public GameObject[] EditorGetPanelSnapshot()
            => Navigator?.Top != null ? new[] { Navigator.Top.gameObject } : System.Array.Empty<GameObject>();
#endif

        [ContextMenu("测试：打开 Pause 面板")]
        private void EditorOpenPause() => OpenPanel(PanelId.Pause);

        [ContextMenu("测试：打开 Map 面板")]
        private void EditorOpenMap()   => OpenPanel(PanelId.Map);

        [ContextMenu("测试：打开 Shop 面板")]
        private void EditorOpenShop()  => OpenPanel(PanelId.Shop);

        [ContextMenu("测试：关闭栈顶面板")]
        private void EditorCloseTop()  => CloseTopPanel();
    }
}