using System.Collections.Generic;
using UnityEngine;
using UnityEngine.UI;
using BaseGames.Core;
using BaseGames.Core.Events;
using BaseGames.Core.Save;

namespace BaseGames.World.Map
{
    /// <summary>
    /// 角落小地图 HUD（架构 15_MapShopModule §1.6）。
    /// 以玩家当前房间为中心，仅渲染 ±ViewRadiusCells 格范围内的房间。
    /// 玩家跨格进入新房间时（OnRoomChanged 事件）触发增量重建，无需每帧扫描全局。
    /// <para>
    /// 挂载位置：HUD Canvas 下 Minimap 根节点（需配有 RectMask2D 用于裁剪）。
    /// </para>
    /// 依赖 <see cref="IPlayerPositionProvider"/> 和 <see cref="IMapService"/>，
    /// 均通过 <see cref="ServiceLocator"/> 获取，不持有具体类的 SerializeField 引用。
    /// </summary>
    public class MinimapHUD : MonoBehaviour
    {
        [SerializeField] private MapRoomCellUI _cellPrefab;
        [SerializeField] private RectTransform _cellContainer;  // 带 RectMask2D 的容器，内容在此节点内平移
        [SerializeField] private Image         _playerDot;      // 玩家位置圆点（在 _cellContainer 内）

        [Header("显示范围")]
        [SerializeField, Min(1)] private int   _viewRadiusCells = 3;   // 以玩家房间中心为圆心的可视半径（格）
        [SerializeField]          private float _cellPixels      = 16f; // 每格显示像素数

        [Header("颜色（Inspector 覆盖）")]
        [SerializeField] private Color _colorExplored = Color.white;
        [SerializeField] private Color _colorMapped   = new Color(0.45f, 0.45f, 0.45f, 1f);
        [SerializeField] private Color _colorUnknown  = Color.black;

        [Header("Event Channels")]
        // R18-N3 _onMapUpdated 订阅已废弃（对齐 MapPanel R12-N8）：
        // OnExplorationChanged 全量刷新完全覆盖 OnMapUpdated 的单格更新，订阅形成冗余双重刷新。
        // 保留 [HideInInspector, SerializeField] 维持 Prefab 序列化兼容，不再订阅事件。
        [HideInInspector, SerializeField] private StringEventChannelSO _onMapUpdated;

        [Header("地图标记（可选）")]
        [SerializeField] private Image          _pinPrefab;         // 留空则不渲染 Pin
        [SerializeField] private MapPinConfigSO _pinConfig;         // R12-N3 集中 PinType→Sprite 映射

        [Header("房间类型图标（可选，与全屏地图保持视觉一致）")]
        [SerializeField] private Sprite _iconSavePoint;
        [SerializeField] private Sprite _iconBossRoom;
        [SerializeField] private Sprite _iconShop;
        [Tooltip("传送站图标；房间含 TeleportStation 标志时显示。")]
        [SerializeField] private Sprite _iconTeleport;

        [Header("缩放档位（可选）")]
        [SerializeField] private int[] _zoomLevels = { 2, 3, 5 };  // R12-FA 可用视野半径档位（格）
        private int _zoomLevelIndex;

        private IMapService             _mapSvc;
        private IPlayerPositionProvider _playerProvider;
        private IPinService             _pinService;
        private readonly Dictionary<string, MapRoomCellUI> _cells = new();
        private readonly List<Image>    _pinImages = new();
        private readonly Stack<Image>   _pinPool   = new();   // R10-N3 Pin 对象池
        private readonly Stack<MapRoomCellUI> _cellPool = new(); // R11-N5 Cell 对象池
        private int _lastPinVersion = -1;
        private bool _viewDirty;       // R10-N2 关闭期间收到 OnRoomChanged → 下次 OnEnable RefreshView
        private bool _databaseDirty;   // R10-N1 关闭期间收到 OnDatabaseChanged → 下次 OnEnable 完整重建
        private bool _servicesReady;   // R21-N1 三服务全部就绪后置 true，短路 LateUpdate 的每帧 ServiceLocator 查询（对齐 MapPanel）

        // 复用 List 避免 RefreshView 每次分配临时 List（GC 友好）
        private readonly List<string> _toRemove = new List<string>(8);

        // 复用 HashSet 避免 RefreshView 每次分配（GC 友好）
        private readonly HashSet<string> _roomsInViewBuffer = new HashSet<string>(32);
        private readonly HashSet<string> _newlyAddedBuffer  = new HashSet<string>(16);

        private Vector2Int _currentCenter;
        private string  _lastDotRoomId;
        private Vector2 _lastDotNormPos;

        // ── 生命周期 ──────────────────────────────────────────────────────────

        private void Awake()
        {
            // R10-N2/N1 服务订阅在 Awake/OnDestroy 长期持有，OnDisable 不解绑
            // 即便 HUD 隐藏期间发生 OnRoomChanged / OnDatabaseChanged，也能记录 dirty 标志
            SubscribeServices();
        }

        private void OnEnable()
        {
            // 启动顺序兜底
            SubscribeServices();

            // R10-N1/N2 应用关闭期间累积的状态变化
            if (_databaseDirty)
            {
                ClearAllCells();
                ClearPins();
                _lastPinVersion = -1;
                _databaseDirty  = false;
                _viewDirty      = true;  // 重建后需 RefreshView
            }

            if (_viewDirty || _cells.Count == 0)
            {
                _viewDirty = false;
                RefreshView();
            }
        }

        private void OnDisable()
        {
            _lastDotRoomId = null;
            // R10-N2 保留 cells/pins/服务订阅；HUD 频繁开关时避免 GC 抖动
        }

        private void OnDestroy()
        {
            UnsubscribeServices();
            ClearAllCells();
            ClearPins();
            foreach (var img in _pinPool)
                if (img != null) Destroy(img.gameObject);
            _pinPool.Clear();
            foreach (var cell in _cellPool)
                if (cell != null) Destroy(cell.gameObject);
            _cellPool.Clear();
        }

        private void SubscribeServices()
        {
            // 各服务独立守门：任意服务迟到就绪时，后续调用仍能补订阅（R11-N1 修复）
            if (_playerProvider == null)
            {
                _playerProvider = ServiceLocator.GetOrDefault<IPlayerPositionProvider>();
                if (_playerProvider != null)
                    _playerProvider.OnRoomChanged += OnRoomChanged;
            }
            if (_mapSvc == null)
            {
                _mapSvc = ServiceLocator.GetOrDefault<IMapService>();
                if (_mapSvc != null)
                {
                    _mapSvc.OnDatabaseChanged    += OnDatabaseChanged;
                    _mapSvc.OnExplorationChanged += OnExplorationChanged;
                }
            }
            _pinService ??= ServiceLocator.GetOrDefault<IPinService>();

            // R21-N1 三服务全部就绪后置 true，短路 LateUpdate 的每帧查询（对齐 MapPanel._servicesReady）
            if (_playerProvider != null && _mapSvc != null && _pinService != null)
                _servicesReady = true;
        }

        private void UnsubscribeServices()
        {
            _servicesReady = false; // R21-N3 重置，确保重建场景后的实例能重新订阅
            if (_playerProvider != null)
            {
                _playerProvider.OnRoomChanged -= OnRoomChanged;
                _playerProvider = null;
            }
            if (_mapSvc != null)
            {
                _mapSvc.OnDatabaseChanged    -= OnDatabaseChanged;
                _mapSvc.OnExplorationChanged -= OnExplorationChanged;
                _mapSvc = null;
            }
            _pinService = null;
        }

        private void ClearAllCells()
        {
            // R11-N5 禁用入池而非销毁
            foreach (var cell in _cells.Values)
            {
                if (cell == null) continue;
                cell.gameObject.SetActive(false);
                _cellPool.Push(cell);
            }
            _cells.Clear();
        }

        private void ClearPins()
        {
            // R10-N3 禁用入池而非销毁
            foreach (var img in _pinImages)
            {
                if (img == null) continue;
                img.gameObject.SetActive(false);
                _pinPool.Push(img);
            }
            _pinImages.Clear();
        }

        private void LateUpdate()
        {
            // R21-N1 服务懒加载重试：_servicesReady 置 true 后短路，消除每帧 ServiceLocator 查询（对齐 MapPanel）
            if (!_servicesReady)
                SubscribeServices();
            UpdatePlayerDot();
            RenderPinsIfDirty();
        }

        // ── 事件响应 ──────────────────────────────────────────────────────────

        private void OnRoomChanged(string _)
        {
            // R10-N2 禁用时累积 dirty；OnEnable 后再 RefreshView
            if (!isActiveAndEnabled) { _viewDirty = true; return; }
            RefreshView();
        }

        /// <summary>R10-N12 探索进度变化：仅刷新已实例化的格子可见性。</summary>
        private void OnExplorationChanged()
        {
            if (!isActiveAndEnabled) { _viewDirty = true; return; }
            if (_mapSvc == null) return;
            foreach (var (id, cell) in _cells)
                if (cell != null) cell.SetVisibility(_mapSvc.GetVisibility(id));
        }

        /// <summary>数据库结构变更时完整重建：清空所有格子，下次 RefreshView 重新实例化。</summary>
        private void OnDatabaseChanged()
        {
            if (!isActiveAndEnabled) { _databaseDirty = true; return; }
            ClearAllCells();
            ClearPins();
            _lastPinVersion = -1;
            RefreshView();
        }

        // ── Pin 渲染（可视范围内）─────────────────────────────────────────────

        /// <summary>
        /// 仅渲染当前小地图视野内（已实例化格子的房间）的 Pin。
        /// 基于 PinsVersion + RefreshView 时机做脏检查：版本未变化且格子未变化时跳过。
        /// 单地图 N（视野）级别开销，远小于 MapPanel 的全图 Pin 渲染。
        /// </summary>
        private void RenderPinsIfDirty()
        {
            if (_pinService == null || _pinPrefab == null) return;
            if (_pinService.PinsVersion == _lastPinVersion) return;
            _lastPinVersion = _pinService.PinsVersion;
            RebuildPins();
        }

        private void RebuildPins()
        {
            ClearPins();
            foreach (var pin in _pinService.Pins)
            {
                if (!_cells.TryGetValue(pin.RoomId, out var cell)) continue;
                // R10-N3 优先从对象池取
                Image img;
                if (_pinPool.Count > 0)
                {
                    img = _pinPool.Pop();
                    img.gameObject.SetActive(true);
                }
                else
                {
                    img = Instantiate(_pinPrefab, _cellContainer);
                }
                img.sprite = _pinConfig != null ? _pinConfig.GetSprite((PinType)pin.PinTypeInt) : null;
                img.rectTransform.anchoredPosition = cell.RT.anchoredPosition
                    + new Vector2(pin.NormalizedPosX * cell.RT.sizeDelta.x,
                                  pin.NormalizedPosY * cell.RT.sizeDelta.y);
                _pinImages.Add(img);
            }
        }

        // ── 视图重建 ──────────────────────────────────────────────────────────

        /// <summary>
        /// 以玩家当前房间中心为基准，增量更新可视格内的格子：
        /// 回收超出范围的旧格子，实例化刚进入范围的新格子，重定位全部格子到新中心。
        /// </summary>
        private void RefreshView()
        {
            var db = _mapSvc?.Database;
            if (db?.AllRooms == null) return;

            var currentRoomId = _playerProvider?.CurrentRoomId;
            if (string.IsNullOrEmpty(currentRoomId)) return;

            var currentRoom = db.GetRoom(currentRoomId);
            if (currentRoom == null) return;

            _currentCenter = currentRoom.GridPosition + currentRoom.GridSize / 2;

            int minX = _currentCenter.x - _viewRadiusCells;
            int maxX = _currentCenter.x + _viewRadiusCells;
            int minY = _currentCenter.y - _viewRadiusCells;
            int maxY = _currentCenter.y + _viewRadiusCells;

            // ① 回收不在可视范围内的格子（复用 _toRemove 避免每帧 new）
            _toRemove.Clear();
            foreach (var (id, cell) in _cells)
            {
                var r = db.GetRoom(id);
                if (r == null || !RoomInView(r, minX, maxX, minY, maxY))
                {
                    // R11-N5 禁用入池而非 Destroy，下次复用避免 GC 抖动
                    if (cell != null)
                    {
                        cell.gameObject.SetActive(false);
                        _cellPool.Push(cell);
                    }
                    _toRemove.Add(id);
                }
            }
            foreach (var id in _toRemove) _cells.Remove(id);

            // ② 通过 MapDatabaseSO 共享空间索引，在可视范围格点上查询所属房间
            // 复杂度：O(viewRadius²) 替代 O(allRooms)，大地图下效果显著
            _roomsInViewBuffer.Clear();
            for (int x = minX; x <= maxX; x++)
            for (int y = minY; y <= maxY; y++)
            {
                var rId = db.GetRoomIdAtCell(new Vector2Int(x, y));
                if (!string.IsNullOrEmpty(rId)) _roomsInViewBuffer.Add(rId);
            }

            _newlyAddedBuffer.Clear();
            foreach (var roomId in _roomsInViewBuffer)
            {
                if (_cells.ContainsKey(roomId)) continue;
                var room = db.GetRoom(roomId);
                if (room == null) continue;

                // R11-N5 优先从对象池取，避免高频 Instantiate
                MapRoomCellUI cell;
                if (_cellPool.Count > 0)
                {
                    cell = _cellPool.Pop();
                    cell.gameObject.SetActive(true);
                }
                else
                {
                    cell = Instantiate(_cellPrefab, _cellContainer);
                }
                cell.Setup(room, _mapSvc.GetVisibility(room.RoomId), ChooseIcon(room));
                cell.SetColors(_colorExplored, _colorMapped, _colorUnknown);
                PlaceCell(cell, room);  // 立即设置正确的中心相对坐标
                _cells[roomId] = cell;
                _newlyAddedBuffer.Add(roomId);
            }

            // ③ 重定位存量格子（新增格子在 step② 已 PlaceCell，跳过避免重复写入）
            foreach (var (id, cell) in _cells)
            {
                if (cell == null || _newlyAddedBuffer.Contains(id)) continue;
                var r = db.GetRoom(id);
                if (r != null) PlaceCell(cell, r);
            }

            UpdatePlayerDot();
        }

        // ── 格子位置 ──────────────────────────────────────────────────────────

        private void PlaceCell(MapRoomCellUI cell, MapRoomDataSO room)
        {
            cell.RT.sizeDelta = new Vector2(room.GridSize.x * _cellPixels, room.GridSize.y * _cellPixels);
            cell.RT.anchoredPosition = new Vector2(
                (room.GridPosition.x - _currentCenter.x) * _cellPixels,
                (room.GridPosition.y - _currentCenter.y) * _cellPixels);
        }

        /// <summary>
        /// R20-N2 委托到 MapRoomDataSO.ChooseDisplayIcon，消除与 MapPanel 的重复实现。
        /// 优先级：MapIconOverride > SavePoint > BossRoom > Shop > TeleportStation。
        /// </summary>
        private Sprite ChooseIcon(MapRoomDataSO room)
            => room.ChooseDisplayIcon(_iconSavePoint, _iconBossRoom, _iconShop, _iconTeleport);

        private static bool RoomInView(MapRoomDataSO room, int minX, int maxX, int minY, int maxY)
            => room.GridPosition.x + room.GridSize.x > minX &&
               room.GridPosition.x < maxX &&
               room.GridPosition.y + room.GridSize.y > minY &&
               room.GridPosition.y < maxY;

        // ── 玩家圆点 ──────────────────────────────────────────────────────────

        private void UpdatePlayerDot()
        {
            if (_playerDot == null || _playerProvider == null) return;

            var roomId  = _playerProvider.CurrentRoomId;
            var normPos = _playerProvider.NormalizedPositionInRoom;

            // Dirty check: 避免房间和位置均未变化时写 RectTransform
            if (roomId == _lastDotRoomId && normPos == _lastDotNormPos) return;
            _lastDotRoomId  = roomId;
            _lastDotNormPos = normPos;

            if (string.IsNullOrEmpty(roomId) || !_cells.TryGetValue(roomId, out var cell))
            {
                _playerDot.enabled = false;
                return;
            }

            _playerDot.enabled = true;
            _playerDot.rectTransform.anchoredPosition =
                cell.RT.anchoredPosition
                + Vector2.Scale(normPos, cell.RT.sizeDelta);
        }

        // ── 缩放档位切换 ─────────────────────────────────────────────────────

        /// <summary>
        /// R12-FA 循环切换视野半径档位（可绑定到按键/按钮）。
        /// 档位在 Inspector 中通过 _zoomLevels 数组配置（默认：2/3/5 格）。
        /// 安全检查：数组为空时不切换，避免除零或越界。
        /// </summary>
        public void CycleZoom()
        {
            if (_zoomLevels == null || _zoomLevels.Length == 0) return;
            _zoomLevelIndex  = (_zoomLevelIndex + 1) % _zoomLevels.Length;
            _viewRadiusCells = _zoomLevels[_zoomLevelIndex];
            if (isActiveAndEnabled)
            {
                // R29-N1 先清除标志再刷新，防止 HUD 关闭后重新打开触发冗余 RefreshView
                _viewDirty = false;
                RefreshView();
            }
            else
            {
                _viewDirty = true;
            }
        }
    }
}