using System.Collections.Generic;
using Cielonos.MainGame.Map;
using SLSUtilities.UI;
using UnityEngine;
using UnityEngine.UI.Extensions;

namespace Cielonos.MainGame.UI
{
    /// <summary>
    /// 地图 UI 页面。根据 RunMapData 动态生成节点和连接线元素。
    /// 监听 RunManager 阶段变化，自动在 MapSelection 阶段打开/刷新，其他阶段关闭。
    /// 节点点击后调用 RunManager.SelectNode 执行传送。
    /// 支持通过 MapPanZoom 组件进行拖拽平移和滚轮缩放。
    /// </summary>
    public class MapUIPage : UIPageBase
    {
        // ================================================================
        // 常量
        // ================================================================

        private const float CONNECTION_LINE_THICKNESS = 3f;
        private static readonly Color CONNECTION_LINE_COLOR = new Color(0.5f, 0.5f, 0.5f, 0.8f);

        // ================================================================
        // 序列化字段
        // ================================================================

        [Header("Containers")]
        public RectTransform mapContainer;
        [SerializeField] private RectTransform nodeContainer;
        [SerializeField] private RectTransform connectionContainer;

        [Header("Prefabs")]
        [SerializeField] private GameObject nodePrefab;

        [Header("Pan & Zoom")]
        [SerializeField] private MapPanZoom panZoom;

        // ================================================================
        // 运行时状态
        // ================================================================

        /// <summary>已生成的节点元素，按网格坐标索引。</summary>
        private readonly Dictionary<Vector2Int, MapNodeElement> _nodeElements =
            new Dictionary<Vector2Int, MapNodeElement>();

        /// <summary>已生成的连接线 GameObject 列表。</summary>
        private readonly List<GameObject> _connectionObjects = new List<GameObject>();

        /// <summary>当前绑定的地图数据。</summary>
        private RunMapData _mapData;

        // ================================================================
        // 生命周期
        // ================================================================

        protected override void Start()
        {
            base.Start();

            // 订阅 RunManager 阶段切换事件，自动控制地图页面的开关
            if (RunManager.Instance != null)
            {
                RunManager.Instance.OnPhaseChanged += OnRunPhaseChanged;
            }
            else
            {
                Debug.LogWarning("[MapUIPage] RunManager.Instance 不存在，无法自动切换地图页面。");
            }
        }

        private void OnDestroy()
        {
            // 取消订阅，防止 RunManager 被先销毁时的空引用
            if (RunManager.Instance != null)
            {
                RunManager.Instance.OnPhaseChanged -= OnRunPhaseChanged;
            }
        }

        // ================================================================
        // 阶段切换响应
        // ================================================================

        /// <summary>
        /// RunManager 阶段切换回调。
        /// 离开 MapSelection 阶段时自动关闭地图；打开由玩家手动操作（地图按钮）。
        /// </summary>
        private void OnRunPhaseChanged(RunPhase phase)
        {
            if (phase != RunPhase.MapSelection && IsOpen)
            {
                Close();
            }
        }

        /// <summary>
        /// 页面打开时自动刷新节点显示状态并居中到当前节点。
        /// </summary>
        protected override void OnPageOpened()
        {
            base.OnPageOpened();

            if (RunManager.Instance != null && RunManager.Instance.currentRun != null)
            {
                RefreshDisplayStates(RunManager.Instance.currentRun);
                CenterOnCurrentNode();
            }
        }

        // ================================================================
        // 公共 API
        // ================================================================

        /// <summary>
        /// 根据 RunMapData 生成所有地图 UI 元素（节点 + 连接线）。
        /// 若之前已生成则先清除。生成完成后自动应用初始显示状态。
        /// </summary>
        /// <param name="mapData">要显示的地图数据。</param>
        public void Populate(RunMapData mapData)
        {
            if (mapData == null)
            {
                Debug.LogWarning("[MapUIPage] 传入的 RunMapData 为 null，无法生成地图。");
                return;
            }

            _mapData = mapData;

            ClearAll();
            CreateNodes(mapData);
            CreateConnections(mapData);

            // 生成完成后立即应用初始显示状态（避免短暂显示原始外观）
            if (RunManager.Instance != null && RunManager.Instance.currentRun != null)
            {
                RefreshDisplayStates(RunManager.Instance.currentRun);
            }
        }

        /// <summary>
        /// 根据 RunState 更新所有节点的显示状态（迷雾、交互、使用状态、边框颜色）。
        /// </summary>
        /// <param name="state">当前 Run 的状态。</param>
        public void RefreshDisplayStates(RunState state)
        {
            Dictionary<Vector2Int, NodeDisplayState> displayStates = MapFogCalculator.Calculate(state);

            foreach (KeyValuePair<Vector2Int, NodeDisplayState> kvp in displayStates)
            {
                if (_nodeElements.TryGetValue(kvp.Key, out MapNodeElement element))
                {
                    element.ApplyDisplayState(kvp.Value);
                }
            }

            // 更新连接线的可见性（所有连接线始终可见，因为所有节点至少显示为 Silhouette）
            RefreshConnectionVisibility(displayStates);
        }

        // ================================================================
        // 节点点击处理
        // ================================================================

        /// <summary>
        /// 节点被玩家点击后的回调。调用 RunManager.SelectNode 执行传送逻辑。
        /// RunManager 内部会验证可达性并处理阶段切换和场景加载。
        /// </summary>
        /// <param name="gridPosition">被点击节点的网格坐标。</param>
        private void OnNodeClicked(Vector2Int gridPosition)
        {
            if (RunManager.Instance == null)
            {
                Debug.LogWarning("[MapUIPage] RunManager 不存在，无法处理节点点击。");
                return;
            }

            //Debug.Log($"[MapUIPage] 玩家点击节点 {gridPosition}，请求传送。");
            RunManager.Instance.SelectNode(gridPosition);
        }

        // ================================================================
        // 视角控制
        // ================================================================

        /// <summary>
        /// 将地图视角居中到玩家当前所在节点的 UI 位置。
        /// </summary>
        private void CenterOnCurrentNode()
        {
            if (panZoom == null || _mapData == null) return;
            if (RunManager.Instance == null || RunManager.Instance.currentRun == null) return;

            Vector2Int currentPos = RunManager.Instance.currentRun.currentPosition;
            if (_mapData.nodes.TryGetValue(currentPos, out RunMapNode node))
            {
                panZoom.CenterOn(node.position);
            }
        }

        // ================================================================
        // 节点生成
        // ================================================================

        /// <summary>
        /// 为每个 RunMapNode 实例化一个节点 UI 元素，并绑定点击事件。
        /// </summary>
        private void CreateNodes(RunMapData mapData)
        {
            if (nodePrefab == null)
            {
                Debug.LogError("[MapUIPage] nodePrefab 未赋值，无法生成节点。");
                return;
            }

            Transform parent = nodeContainer != null ? nodeContainer : mapContainer;

            foreach (KeyValuePair<Vector2Int, RunMapNode> kvp in mapData.nodes)
            {
                RunMapNode node = kvp.Value;
                GameObject nodeGo = Instantiate(nodePrefab, parent);
                nodeGo.name = $"Node_{node.gridPosition.x}_{node.gridPosition.y}";

                MapNodeElement element = nodeGo.GetComponent<MapNodeElement>();
                if (element == null)
                {
                    Debug.LogWarning($"[MapUIPage] nodePrefab 缺少 MapNodeElement 组件，跳过节点 {node.gridPosition}。");
                    Destroy(nodeGo);
                    continue;
                }

                element.Setup(node);

                // 绑定点击事件 → OnNodeClicked → RunManager.SelectNode
                element.OnClicked += OnNodeClicked;

                _nodeElements[kvp.Key] = element;
            }
        }

        // ================================================================
        // 连接线生成
        // ================================================================

        /// <summary>
        /// 为所有节点之间的连接创建 UILineRenderer。
        /// 使用 HashSet 去重，确保双向连接只生成一条线。
        /// </summary>
        private void CreateConnections(RunMapData mapData)
        {
            Transform parent = connectionContainer != null ? connectionContainer : mapContainer;
            HashSet<long> processedEdges = new HashSet<long>();

            foreach (KeyValuePair<Vector2Int, RunMapNode> kvp in mapData.nodes)
            {
                Vector2Int fromPos = kvp.Key;
                RunMapNode fromNode = kvp.Value;

                foreach (Vector2Int toPos in fromNode.connectedPositions)
                {
                    // 使用排序后的 hash 去重双向边
                    long edgeKey = GetEdgeKey(fromPos, toPos);
                    if (!processedEdges.Add(edgeKey)) continue;

                    // 确保目标节点存在
                    if (!mapData.nodes.TryGetValue(toPos, out RunMapNode toNode)) continue;

                    CreateConnectionLine(parent, fromNode.position, toNode.position, fromPos, toPos);
                }
            }
        }

        /// <summary>
        /// 创建一条从 startPos 到 endPos 的 UILineRenderer 连接线。
        /// </summary>
        private void CreateConnectionLine(Transform parent, Vector2 startUIPos, Vector2 endUIPos,
            Vector2Int fromGrid, Vector2Int toGrid)
        {
            GameObject lineGo = new GameObject($"Connection_{fromGrid.x},{fromGrid.y}_to_{toGrid.x},{toGrid.y}");
            lineGo.transform.SetParent(parent, false);

            RectTransform rt = lineGo.AddComponent<RectTransform>();
            // 锚定到容器中心，不拉伸
            rt.anchorMin = new Vector2(0.5f, 0.5f);
            rt.anchorMax = new Vector2(0.5f, 0.5f);
            rt.pivot = new Vector2(0.5f, 0.5f);
            rt.anchoredPosition = Vector2.zero;
            rt.sizeDelta = mapContainer != null ? mapContainer.sizeDelta : new Vector2(1200f, 675f);

            UILineRenderer lineRenderer = lineGo.AddComponent<UILineRenderer>();
            lineRenderer.LineThickness = CONNECTION_LINE_THICKNESS;
            lineRenderer.color = CONNECTION_LINE_COLOR;
            lineRenderer.raycastTarget = false;

            // UILineRenderer 使用相对于自身 RectTransform 的坐标
            // 由于 RectTransform 的 pivot 在 (0.5, 0.5)，节点的 position 是相对于 mapContainer 中心的坐标
            lineRenderer.Points = new Vector2[] { startUIPos, endUIPos };

            _connectionObjects.Add(lineGo);
        }

        /// <summary>
        /// 生成一条边的唯一标识 key（与方向无关）。
        /// </summary>
        private static long GetEdgeKey(Vector2Int a, Vector2Int b)
        {
            // 确保小的坐标在前，保证 (a→b) 和 (b→a) 生成相同的 key
            Vector2Int min, max;
            if (a.x < b.x || (a.x == b.x && a.y < b.y))
            {
                min = a;
                max = b;
            }
            else
            {
                min = b;
                max = a;
            }

            // 将两个 Vector2Int 打包为 long
            // 每个坐标分量占 16 位，总共 64 位
            return ((long)(min.x + 32768) << 48)
                 | ((long)(min.y + 32768) << 32)
                 | ((long)(max.x + 32768) << 16)
                 | (long)(max.y + 32768);
        }

        // ================================================================
        // 连接线可见性
        // ================================================================

        /// <summary>
        /// 根据节点的显示状态更新连接线的可见性。
        /// 两端节点都隐藏时，连接线也隐藏。
        /// </summary>
        private void RefreshConnectionVisibility(Dictionary<Vector2Int, NodeDisplayState> displayStates)
        {
            foreach (GameObject connectionGo in _connectionObjects)
            {
                if (connectionGo == null) continue;

                // 从命名中解析连接的两个节点坐标
                if (!TryParseConnectionName(connectionGo.name, out Vector2Int fromPos, out Vector2Int toPos))
                    continue;

                bool fromVisible = displayStates.TryGetValue(fromPos, out NodeDisplayState fromState)
                                   && fromState.visibility != MapNodeVisibility.Hidden;
                bool toVisible = displayStates.TryGetValue(toPos, out NodeDisplayState toState)
                                 && toState.visibility != MapNodeVisibility.Hidden;

                connectionGo.SetActive(fromVisible || toVisible);
            }
        }

        /// <summary>
        /// 从连接线 GameObject 名称中解析两端节点坐标。
        /// 命名格式：Connection_{x1},{y1}_to_{x2},{y2}
        /// </summary>
        private static bool TryParseConnectionName(string name, out Vector2Int from, out Vector2Int to)
        {
            from = Vector2Int.zero;
            to = Vector2Int.zero;

            // Connection_{x1},{y1}_to_{x2},{y2}
            if (!name.StartsWith("Connection_")) return false;

            string body = name.Substring("Connection_".Length);
            string[] parts = body.Split(new[] { "_to_" }, System.StringSplitOptions.None);
            if (parts.Length != 2) return false;

            return TryParseCoord(parts[0], out from) && TryParseCoord(parts[1], out to);
        }

        private static bool TryParseCoord(string s, out Vector2Int result)
        {
            result = Vector2Int.zero;
            string[] components = s.Split(',');
            if (components.Length != 2) return false;
            if (!int.TryParse(components[0], out int x)) return false;
            if (!int.TryParse(components[1], out int y)) return false;
            result = new Vector2Int(x, y);
            return true;
        }

        // ================================================================
        // 清理
        // ================================================================

        /// <summary>
        /// 清除所有已生成的节点和连接线。
        /// </summary>
        private void ClearAll()
        {
            ClearNodes();
            ClearConnections();
        }

        private void ClearNodes()
        {
            foreach (KeyValuePair<Vector2Int, MapNodeElement> kvp in _nodeElements)
            {
                if (kvp.Value != null)
                {
                    // 取消订阅点击事件，防止内存泄漏
                    kvp.Value.OnClicked -= OnNodeClicked;
                    Destroy(kvp.Value.gameObject);
                }
            }

            _nodeElements.Clear();
        }

        private void ClearConnections()
        {
            foreach (GameObject go in _connectionObjects)
            {
                if (go != null) Destroy(go);
            }

            _connectionObjects.Clear();
        }
    }
}