using System.Collections.Generic;
using System.Linq;
using Ichni.Story.UI;
using Sirenix.OdinInspector;
using UniRx;
using UnityEngine;

namespace Ichni.Story
{
    /// <summary>
    /// 故事树控制器。从 <see cref="StoryData"/> 一次性全量构建所有 block 视图与连接线，
    /// 布局由每个 block 的 (gridColumn, gridRow) 静态决定；每个 block 的
    /// <see cref="StoryBlockState"/> 由"已完成集合 + 解锁条件"实时推导。
    /// 存档只保存已完成 block 的 id 集合。
    /// </summary>
    public class StoryTreeController : MonoBehaviour
    {
        [Header("UI References")]
        [Tooltip("blocks 与 connectors 共用的单一容器（即 ScrollRect 的 content，localScale 必须为 1）")]
        public RectTransform content;
        public GameObject textBlockPrefab;
        public GameObject songBlockPrefab;
        public GameObject tutorialBlockPrefab;
        public GameObject connectorPrefab;

        [Header("Layout Settings")]
        [Tooltip("网格单元格尺寸（决定相邻列/行的步距，全局统一）")]
        public Vector2 cellSize = new Vector2(400f, 200f);

        [Tooltip("相邻单元格之间的间隔（水平 x、垂直 y）")]
        public Vector2 cellSpacing = new Vector2(120f, 150f);

        public float marginLeft = 50f;
        public float marginRight = 50f;
        public float marginTop = 50f;
        public float marginBottom = 50f;
        public float minContentWidth = 2560f;
        public float minContentHeight = 1440f;

        [Header("Runtime")]
        public StoryBlockView currentBlock;
        public List<StoryBlockView> blocks = new List<StoryBlockView>();
        public List<BlockConnectorView> connectors = new List<BlockConnectorView>();

        private string _chapterIndex;
        private StoryData _storyData;

        /// <summary>当前已构建章节的 StoryData（供对话控制器切换 YarnProject 等使用）。</summary>
        public StoryData ActiveStoryData => _storyData;

        /// <summary>当前已构建章节的索引。</summary>
        public string ActiveChapterIndex => _chapterIndex;

        // 当前章节已完成的 block id 集合（状态推导的唯一进度来源）
        private readonly HashSet<string> _completed = new HashSet<string>();

        private void Start()
        {
            // 存档系统未就绪时跳过；正式流程由 StoryManager.OpenChapter 在进入剧情页时触发构建。
            if (GameSaveManager.instance == null || GameSaveManager.instance.StorySaveModule == null)
                return;

            if (ChapterSelectionManager.instance != null &&
                ChapterSelectionManager.instance.currentChapter != null)
            {
                BuildChapter(ChapterSelectionManager.instance.currentChapter.chapterIndex);
            }
        }

        // ── Build ─────────────────────────────────────────────────────────────────

        /// <summary>
        /// 构建指定章节的故事树：全量生成所有 block 与连接线，状态由存档中的已完成集合推导。
        /// </summary>
        public void BuildChapter(string chapterIndex)
        {
            _chapterIndex = chapterIndex;
            _storyData = StoryManager.instance != null ? StoryManager.instance.GetStoryData(chapterIndex) : null;

            if (_storyData == null)
            {
                Debug.LogError($"[StoryTreeController] 找不到章节 '{chapterIndex}' 的 StoryData，请在 StoryManager.storyDatas 中登记。");
                return;
            }

            if (GameSaveManager.instance == null || GameSaveManager.instance.StorySaveModule == null)
            {
                Debug.LogWarning("[StoryTreeController] 存档系统尚未就绪（GameSaveManager.StorySaveModule 为空），跳过构建。");
                return;
            }

            ClearTree();

            // 载入已完成集合（新章节为空）
            ChapterStorySave save = GameSaveManager.instance.StorySaveModule.GetChapter(chapterIndex);
            _completed.Clear();
            foreach (string id in save.completedBlockIds)
                _completed.Add(id);

            // 全量生成所有 block（位置按网格换算，状态按已完成集合 + 解锁条件推导）
            foreach (StoryBlockDefinition def in _storyData.blocks)
                GenerateBlock(def);

            // 全量生成所有连接线
            foreach (StoryBlockDefinition def in _storyData.blocks)
                foreach (string nextId in def.nextBlockIds)
                    GenerateConnector(def.blockId, nextId);

            SetUpBackground();

            // 连线在下一帧刷新（见 RefreshConnectors）：等待 Unity 完成 Canvas 布局，
            // 使 block 端口的世界坐标稳定，避免端口坐标尚未生效时塌缩到同一点。
            RefreshConnectors();
        }

        // ── Generation ──────────────────────────────────────────────────────────

        /// <summary>
        /// 按定义生成一个 block 视图：位置由网格换算，状态由推导得出。
        /// </summary>
        public StoryBlockView GenerateBlock(StoryBlockDefinition def)
        {
            GameObject prefab = def.blockType switch
            {
                StoryBlockType.Text => textBlockPrefab,
                StoryBlockType.Song => songBlockPrefab,
                StoryBlockType.Tutorial => tutorialBlockPrefab,
                _ => null
            };

            if (prefab == null)
            {
                Debug.LogError($"[StoryTreeController] block 类型 {def.blockType} 未配置预制体。");
                return null;
            }

            StoryBlockView view = Instantiate(prefab, content).GetComponent<StoryBlockView>();
            if (view == null)
            {
                Debug.LogError($"[StoryTreeController] 预制体 '{prefab.name}' 缺少 StoryBlockView 组件。");
                return null;
            }

            view.Initialize(def, GetGridPosition(def), DeriveState(def));
            blocks.Add(view);
            return view;
        }

        /// <summary>
        /// 在两个已存在的 block 之间生成连接线。
        /// </summary>
        public void GenerateConnector(string fromBlockId, string toBlockId)
        {
            StoryBlockView from = GetBlockView(fromBlockId);
            StoryBlockView to = GetBlockView(toBlockId);

            if (from == null || to == null)
            {
                Debug.LogWarning($"[StoryTreeController] 无法连线：'{fromBlockId}' -> '{toBlockId}'（block 不存在）。");
                return;
            }

            // 连接线与 block 同处一个容器（content）；置为第一个子物体，渲染在所有 block 之后方。
            GameObject connectorObject = Instantiate(connectorPrefab, content);
            connectorObject.transform.SetAsFirstSibling();

            BlockConnectorView connector = connectorObject.GetComponent<BlockConnectorView>();
            if (connector == null)
            {
                Debug.LogError($"[StoryTreeController] 连接线预制体 '{connectorPrefab.name}' 缺少 BlockConnectorView 组件。");
                Destroy(connectorObject);
                return;
            }

            // 仅记录起止 block 引用；曲线在布局刷新后由 RefreshConnectors 统一计算。
            connector.startBlock = from;
            connector.endBlock = to;
            connectors.Add(connector);
        }

        // ── State / Unlocking ─────────────────────────────────────────────────────

        /// <summary>
        /// 依据"已完成集合 + 解锁条件"推导单个 block 的状态。
        /// 已完成 → Completed；否则满足解锁条件 → Current；否则 → Locked。
        /// 解锁条件为空视为无条件满足（章节起始即为 Current）。
        /// </summary>
        private StoryBlockState DeriveState(StoryBlockDefinition def)
        {
            if (_completed.Contains(def.blockId))
                return StoryBlockState.Completed;

            if (def.unlockCondition.IsSatisfied(GetVariable, IsBlockCompleted))
                return StoryBlockState.Current;

            return StoryBlockState.Locked;
        }

        /// <summary>
        /// 重新推导并应用所有 block 的状态（在完成某 block 或变量变化后调用）。
        /// </summary>
        public void RefreshAllStates()
        {
            foreach (StoryBlockView view in blocks)
            {
                StoryBlockDefinition def = _storyData.GetBlock(view.blockId);
                if (def == null) continue;

                view.ApplyState(DeriveState(def));
            }
        }

        /// <summary>
        /// 标记某 block 完成，推导重算并保存。对话系统（阶段 2）在对话结束时调用。
        /// </summary>
        public void OnBlockCompleted(string blockId)
        {
            if (!_completed.Add(blockId))
                return; // 已完成，无需处理

            RefreshAllStates();
            SaveChapter();
        }

        private bool IsBlockCompleted(string blockId) => _completed.Contains(blockId);

        // 阶段 2 将改由 StoryVariableStorage 提供；此处从全局变量存档读取作占位
        private int GetVariable(string variableName)
        {
            StoryVariablesSave vars = GameSaveManager.instance.StorySaveModule.variables;

            if (vars.floatVariables.TryGetValue(variableName, out float f))
                return Mathf.RoundToInt(f);

            if (vars.boolVariables.TryGetValue(variableName, out bool b))
                return b ? 1 : 0;

            return 0;
        }

        // ── Persistence ─────────────────────────────────────────────────────────

        /// <summary>
        /// 保存当前章节进度（已完成 block 集合）。选项由对话系统维护、不在此覆盖。
        /// </summary>
        [Button]
        public void SaveChapter()
        {
            if (string.IsNullOrEmpty(_chapterIndex)) return;

            ChapterStorySave save = GameSaveManager.instance.StorySaveModule.GetChapter(_chapterIndex);
            save.chapterIndex = _chapterIndex;
            save.completedBlockIds = _completed.ToList();

            GameSaveManager.instance.StorySaveModule.SaveChapter(save);
        }

        // ── Layout ────────────────────────────────────────────────────────────────

        /// <summary>
        /// 将 block 的网格坐标 (gridColumn, gridRow) 换算为 BlockContainer 中的 anchoredPosition。
        /// 约定左侧中线为原点：列向右为正，行向下为正、向上为负（anchoredPosition.y 取负）。
        /// gridColumn / gridRow 支持负数与小数，可用于微调 block 位置。
        /// </summary>
        private Vector2 GetGridPosition(StoryBlockDefinition def)
        {
            float x = marginLeft + def.gridColumn * (cellSize.x + cellSpacing.x);
            float y = -def.gridRow * (cellSize.y + cellSpacing.y);
            return new Vector2(x, y);
        }

        /// <summary>
        /// 根据 block 分布计算并设置 content(BlockContainer) 尺寸。
        /// block 采用左中 pivot：anchoredPosition.x 为左边缘，y 相对垂直中线（上正下负）。
        /// </summary>
        public void SetUpBackground()
        {
            if (blocks.Count == 0)
            {
                content.sizeDelta = new Vector2(minContentWidth, minContentHeight);
                return;
            }

            float maxRight = 0f;
            float maxVertical = 0f; // 距垂直中线的最大延伸（上下取较大者，用于对称扩展 content 高度）

            foreach (StoryBlockView block in blocks)
            {
                RectTransform rect = block.blockRect;
                Vector2 pos = rect.anchoredPosition;
                Vector2 size = rect.sizeDelta;

                float rightEdge = pos.x + size.x;
                float topExtent = pos.y + size.y * 0.5f;
                float bottomExtent = -(pos.y - size.y * 0.5f);

                if (rightEdge > maxRight) maxRight = rightEdge;
                if (topExtent > maxVertical) maxVertical = topExtent;
                if (bottomExtent > maxVertical) maxVertical = bottomExtent;
            }

            float width = Mathf.Max(maxRight + marginRight, minContentWidth);
            float height = Mathf.Max(maxVertical * 2f + marginTop + marginBottom, minContentHeight);

            content.sizeDelta = new Vector2(width, height);
        }

        /// <summary>
        /// 重算所有连接线曲线（在 block 位置确定后调用）。
        /// </summary>
        public void RefreshConnectors()
        {
            Observable.NextFrame().Subscribe(_ =>
            {
                foreach (BlockConnectorView connector in connectors)
                {
                    connector.SetCurve();
                }
            }).AddTo(this);
        }

        // ── Helpers / Debug ─────────────────────────────────────────────────────

        public StoryBlockView GetBlockView(string blockId) =>
            blocks.FirstOrDefault(b => b.blockId == blockId);

        private void ClearTree()
        {
            foreach (StoryBlockView block in blocks)
                if (block != null) Destroy(block.gameObject);
            blocks.Clear();

            foreach (BlockConnectorView connector in connectors)
                if (connector != null) Destroy(connector.gameObject);
            connectors.Clear();

            if (content != null)
                content.sizeDelta = Vector2.zero;
        }

        /// <summary>
        /// 编辑器测试用：以当前章节重新构建故事树。
        /// </summary>
        [Button]
        public void DebugBuildCurrentChapter()
        {
            if (ChapterSelectionManager.instance != null &&
                ChapterSelectionManager.instance.currentChapter != null)
            {
                BuildChapter(ChapterSelectionManager.instance.currentChapter.chapterIndex);
            }
            else
            {
                Debug.LogWarning("[StoryTreeController] 当前没有选中的章节。");
            }
        }

        /// <summary>
        /// 编辑器测试用：模拟完成当前选中的 block（验证解锁重算与存档），阶段 2 前用于替代对话。
        /// </summary>
        [Button]
        public void DebugCompleteCurrentBlock()
        {
            if (currentBlock == null)
            {
                Debug.LogWarning("[StoryTreeController] currentBlock 为空，请先点击一个 block。");
                return;
            }

            OnBlockCompleted(currentBlock.blockId);
        }

        /// <summary>
        /// 编辑器测试用：清空当前章节进度并重建（全部回到未完成的初始推导状态）。
        /// </summary>
        [Button]
        public void DebugResetChapterProgress()
        {
            if (string.IsNullOrEmpty(_chapterIndex))
            {
                Debug.LogWarning("[StoryTreeController] 尚未构建任何章节。");
                return;
            }

            _completed.Clear();
            SaveChapter();
            BuildChapter(_chapterIndex);
        }
    }
}