using System.Collections.Generic;
using UnityEngine;
using BaseGames.Core.Events;
using BaseGames.Core.Save;
using QuestStateEnum = BaseGames.Core.Events.QuestState;

namespace BaseGames.Quest
{
    /// <summary>
    /// 运行时任务管理器（架构 22_QuestChallengeModule §5）。
    /// 挂在 Persistent 场景 [GameManagers] 下。
    /// 事件驱动追踪目标进度，不主动轮询。
    /// 实现 ISaveable，通过 SaveManager 持久化任务状态。
    /// </summary>
    public class QuestManager : MonoBehaviour, ISaveable, IQuestManager
    {
        // ── Inspector ────────────────────────────────────────────────────────
        [SerializeField] private QuestSO[]                        _allQuests;

        [Header("Event Channels（监听）")]
        [SerializeField] private StringEventChannelSO          _onEnemyDied;            // EVT_EnemyDied（enemyId）
        [SerializeField] private StringEventChannelSO             _onCollectiblePickup;    // EVT_CollectiblePickup（itemId）
        [SerializeField] private StringEventChannelSO             _onSceneLoaded;          // EVT_SceneLoaded（sceneName）
        [SerializeField] private StringEventChannelSO             _onNpcDialogueCompleted; // EVT_NpcDialogueCompleted（npcId）

        [Header("Event Channels（广播）")]
        [SerializeField] private StringEventChannelSO             _onQuestStarted;         // questId
        [SerializeField] private StringEventChannelSO             _onQuestCompleted;       // questId
        [SerializeField] private StringEventChannelSO             _onQuestFailed;          // questId
        [SerializeField] private QuestObjectiveEventChannelSO     _onObjectiveUpdated;

        // ── Runtime State ────────────────────────────────────────────────────
        private readonly Dictionary<string, QuestStateEnum>       _questStates      = new();
        private readonly Dictionary<string, QuestObjectiveState>  _objectiveStates  = new();
        /// <summary>questId → QuestSO 快速查找表（由 Awake 构建，将 GetQuestSO O(n) 降为 O(1)）。</summary>
        private Dictionary<string, QuestSO>                        _questIndex;
        private readonly CompositeDisposable                       _subs             = new();
        public StringEventChannelSO OnQuestStarted   => _onQuestStarted;
        public StringEventChannelSO OnQuestCompleted => _onQuestCompleted;

        /// <summary>供 SaveManager 迭代的任务状态字典（只读视图）。</summary>
        public IReadOnlyDictionary<string, QuestStateEnum> QuestStates => _questStates;

        private void Awake()
        {
            if (BaseGames.Core.ServiceLocator.GetOrDefault<IQuestManager>() != null) { Destroy(gameObject); return; }
            BaseGames.Core.ServiceLocator.Register<IQuestManager>(this);

            // 构建任务字典索引，将 GetQuestSO 变为 O(1)
            _questIndex = new Dictionary<string, QuestSO>(_allQuests?.Length ?? 0);
            if (_allQuests != null)
                foreach (var q in _allQuests)
                    if (q != null && !string.IsNullOrEmpty(q.questId))
                        _questIndex[q.questId] = q;
        }

        private void OnEnable()
        {
            _onEnemyDied?.Subscribe(HandleEnemyDefeated).AddTo(_subs);
            _onCollectiblePickup?.Subscribe(HandleItemCollected).AddTo(_subs);
            _onSceneLoaded?.Subscribe(HandleSceneLoaded).AddTo(_subs);
            _onNpcDialogueCompleted?.Subscribe(HandleNpcDialogue).AddTo(_subs);
            BaseGames.Core.ServiceLocator.GetOrDefault<BaseGames.Core.Save.ISaveableRegistry>()?.Register(this);
        }

        private void OnDisable()
        {
            _subs.Clear();
            BaseGames.Core.ServiceLocator.GetOrDefault<BaseGames.Core.Save.ISaveableRegistry>()?.Unregister(this);
        }

        private void OnDestroy()
        {
            BaseGames.Core.ServiceLocator.Unregister<IQuestManager>(this);
        }

        // ── 公共 API ──────────────────────────────────────────────────────────

        /// <summary>NPC 接受任务时调用。</summary>
        public void AcceptQuest(string questId)
        {
            if (!CanAccept(questId)) return;
            _questStates[questId] = QuestStateEnum.Active;
            _onQuestStarted?.Raise(questId);
        }

        /// <summary>NPC 完成任务时调用。</summary>
        public void CompleteQuest(string questId, IRewardTarget rewardTarget)
        {
            if (!IsReadyToComplete(questId)) return;
            var quest = GetQuestSO(questId);
            quest.reward?.Apply(rewardTarget);
            _questStates[questId] = QuestStateEnum.Completed;
            _onQuestCompleted?.Raise(questId);

            // 解锁后续任务（分支）
            if (quest.branches != null)
            {
                foreach (var branch in quest.branches)
                {
                    if (string.IsNullOrEmpty(branch.conditionQuestId) ||
                        GetState(branch.conditionQuestId) == QuestStateEnum.Completed)
                    {
                        if (branch.nextQuest != null)
                            _questStates[branch.nextQuest.questId] = QuestStateEnum.Available;
                        break;
                    }
                }
            }
        }

        public QuestStateEnum GetState(string questId)
            => _questStates.TryGetValue(questId, out var s) ? s : QuestStateEnum.Unavailable;

        public bool IsReadyToComplete(string questId)
        {
            var quest = GetQuestSO(questId);
            if (quest == null || GetState(questId) != QuestStateEnum.Active) return false;
            if (quest.objectives == null) return true;
            foreach (var obj in quest.objectives)
            {
                if (!obj.IsOptional && !IsObjectiveComplete(obj)) return false;
            }
            return true;
        }

        // ── ISaveable ─────────────────────────────────────────────────────────

        public void OnSave(SaveData data)
        {
            data.Quests.QuestStates.Clear();
            data.Quests.AvailableQuestIds.Clear();
            foreach (var (id, state) in _questStates)
            {
                data.Quests.QuestStates[id] = new BaseGames.Core.Save.QuestState
                {
                    Status          = state.ToString(),
                    ObjectiveIndex  = 0,
                    ProgressCounts  = BuildProgressList(id),
                };
                if (state == QuestStateEnum.Available) data.Quests.AvailableQuestIds.Add(id);
            }
        }

        public void OnLoad(SaveData data)
        {
            _questStates.Clear();
            _objectiveStates.Clear();
            foreach (var (id, saved) in data.Quests.QuestStates)
            {
                if (System.Enum.TryParse<QuestStateEnum>(saved.Status, out var parsedState))
                    _questStates[id] = parsedState;

                // 恢复各目标进度
                var quest = GetQuestSO(id);
                if (quest?.objectives != null && saved.ProgressCounts != null)
                {
                    for (int i = 0; i < quest.objectives.Length && i < saved.ProgressCounts.Count; i++)
                    {
                        var obj = quest.objectives[i];
                        if (obj == null) continue;
                        if (!_objectiveStates.TryGetValue(obj.objectiveId, out var os))
                            os = _objectiveStates[obj.objectiveId] = new QuestObjectiveState();
                        os.progressCount = saved.ProgressCounts[i];
                    }
                }
            }
        }

        // ── 私有辅助 ─────────────────────────────────────────────────────────

        private bool CanAccept(string questId)
        {
            if (GetState(questId) != QuestStateEnum.Available) return false;
            var quest = GetQuestSO(questId);
            if (quest?.prerequisiteQuestIds == null) return true;
            foreach (var pre in quest.prerequisiteQuestIds)
                if (GetState(pre) != QuestStateEnum.Completed) return false;
            return true;
        }

        private bool IsObjectiveComplete(QuestObjectiveSO obj)
        {
            _objectiveStates.TryGetValue(obj.objectiveId, out var s);
            s ??= new QuestObjectiveState();
            return obj.EvaluateCompletion(s);
        }

        private List<int> BuildProgressList(string questId)
        {
            var list  = new List<int>();
            var quest = GetQuestSO(questId);
            if (quest?.objectives == null) return list;
            foreach (var obj in quest.objectives)
            {
                _objectiveStates.TryGetValue(obj?.objectiveId ?? string.Empty, out var os);
                list.Add(os?.progressCount ?? 0);
            }
            return list;
        }

        // ── 事件处理 ─────────────────────────────────────────────────────────

        private void HandleEnemyDefeated(string enemyId)
        {
            ForEachActiveObjective<DefeatEnemyObjective>(obj =>
            {
                if (obj.targetEnemyId == enemyId)
                    IncrementProgress(obj.objectiveId);
            });
        }

        private void HandleItemCollected(string itemId)
        {
            ForEachActiveObjective<CollectItemObjective>(obj =>
            {
                if (obj.itemId == itemId)
                    IncrementProgress(obj.objectiveId);
            });
        }

        private void HandleNpcDialogue(string npcId)
        {
            ForEachActiveObjective<TalkToNPCObjective>(obj =>
            {
                if (obj.targetNpcId == npcId)
                    IncrementProgress(obj.objectiveId);
            });
        }

        private void HandleSceneLoaded(string sceneName)
        {
            ForEachActiveObjective<ReachAreaObjective>(obj =>
            {
                if (obj.sceneName == sceneName)
                    IncrementProgress(obj.objectiveId);
            });
        }

        private void ForEachActiveObjective<T>(System.Action<T> action) where T : QuestObjectiveSO
        {
            foreach (var (qid, state) in _questStates)
            {
                if (state != QuestStateEnum.Active) continue;
                var quest = GetQuestSO(qid);
                if (quest?.objectives == null) continue;
                foreach (var obj in quest.objectives)
                {
                    if (obj is T typed) action(typed);
                }
            }
        }

        private void IncrementProgress(string objectiveId)
        {
            if (!_objectiveStates.TryGetValue(objectiveId, out var s))
                s = _objectiveStates[objectiveId] = new QuestObjectiveState();
            s.progressCount++;
            _onObjectiveUpdated?.Raise(new QuestObjectiveEvent
            {
                ObjectiveId = objectiveId,
                Progress    = s.progressCount,
            });
        }

        private QuestSO GetQuestSO(string id)
            => _questIndex != null && _questIndex.TryGetValue(id, out var q) ? q : null;
    }
}