using UnityEngine;
using BaseGames.Core;
using BaseGames.Dialogue;
using BaseGames.Player;
using QuestStateEnum = BaseGames.Core.Events.QuestState;
using SL = BaseGames.Core.ServiceLocator;
using L10n = BaseGames.Localization.LocalizationManager;

namespace BaseGames.Quest
{
    /// <summary>
    /// 可发布/完成任务的 NPC（架构 22_QuestChallengeModule §6）。
    /// 继承 InteractableNPC，根据任务状态切换对话版本，在交互时处理任务接收/完成。
    /// </summary>
    public class QuestGiver : InteractableNPC
    {
        [Header("任务")]
        [Tooltip("该 NPC 可提供的所有任务，按优先级从高到低排列。\n" +
                 "交互时从列表头部找到第一个 Available 或 Active 状态的任务作为当前任务；\n" +
                 "若全部已完成，显示最后一个已完成任务的 completedDialogue。")]
        [SerializeField] private QuestSO[] _offeredQuests;

        [Header("对话版本（根据任务状态切换）")]
        [Tooltip("任务尚未接取（QuestState.Available）时播放。通常是 NPC 发布任务、介绍背景的对话。")]
        [SerializeField] private DialogueSequenceSO _availableDialogue;
        [Tooltip("任务已接取、目标尚未全部完成（QuestState.Active）时播放。通常是 NPC 催促或加油打气的对话。")]
        [SerializeField] private DialogueSequenceSO _activeDialogue;
        [Tooltip("全部非可选目标已达成、任务可以交付时播放（IsReadyToComplete = true）。\n" +
                 "通常是 NPC 感谢、确认收取物品的对话，播放后执行 CompleteQuest 逻辑。")]
        [SerializeField] private DialogueSequenceSO _readyDialogue;
        [Tooltip("任务已完成（QuestState.Completed）后再次交互时播放。通常是 NPC 闲聊或后续剧情的对话。")]
        [SerializeField] private DialogueSequenceSO _completedDialogue;

        // ── InteractableNPC 覆盖 ──────────────────────────────────────────────

        // 缓存上次查找结果，避免 InteractPrompt get（每帧调用）重复遍历 _offeredQuests。
        // 当状态可能变更时（OnEnable、Interact_Internal 后）标记为脏。
        private QuestSO          _cachedQuest;
        private QuestStateEnum   _cachedState;
        private bool             _cacheDirty = true;

        // 本地化 Key 常量 — 对应 UI 本地化表中的条目；
        // 如本地化表未配置该 Key，GetPrompt 会降级为内联的中文默认文本。
        private const string K_Accept     = "QUEST_PROMPT_ACCEPT";
        private const string K_Submit     = "QUEST_PROMPT_SUBMIT";
        private const string K_InProgress = "QUEST_PROMPT_IN_PROGRESS";
        private const string K_Paused     = "QUEST_PROMPT_PAUSED";
        private const string K_Talk       = "QUEST_PROMPT_TALK";

        // 缓存 IQuestManager + IQuestEventSource 引用，避免每次访问 InteractPrompt 调用 SL.GetOrDefault
        private IQuestManager   _questManager;
        private IQuestEventSource _questEvents;

        protected override void OnEnable()
        {
            base.OnEnable();
            _cacheDirty = true;
            _questManager = SL.GetOrDefault<IQuestManager>();
            _questEvents  = _questManager as IQuestEventSource;
            if (_questEvents != null)
            {
                _questEvents.OnQuestStateChanged += HandleQuestStateChanged;
                _questEvents.OnAfterSaveLoaded   += HandleAfterSaveLoaded;
            }
        }

        protected override void OnDisable()
        {
            base.OnDisable();
            if (_questEvents != null)
            {
                _questEvents.OnQuestStateChanged -= HandleQuestStateChanged;
                _questEvents.OnAfterSaveLoaded   -= HandleAfterSaveLoaded;
                _questEvents = null;
            }
            _questManager = null;
        }

        // 任务状态变化时自动标记缓存失效（无需再手动设 _cacheDirty）
        private void HandleQuestStateChanged(string questId, QuestStateEnum from, QuestStateEnum to)
        {
            if (_offeredQuests == null) return;
            foreach (var q in _offeredQuests)
                if (q != null && q.questId == questId) { _cacheDirty = true; return; }
        }

        // 存档加载完成后统一刷新缓存，确保 NPC 交互提示反映最新任务状态
        private void HandleAfterSaveLoaded() => _cacheDirty = true;

        // 本地化提示词辅助：如 Key 在表中找不到（返回值等于 Key 自身），回退到内联默认文本
        private static string GetPrompt(string key, string fallback)
        {
            var v = L10n.Get(key, "UI");
            return v != key ? v : fallback;
        }

        public override string InteractPrompt
        {
            get
            {
                var quest = GetCachedQuest();
                if (quest == null || _questManager == null) return base.InteractPrompt;
                return _cachedState switch
                {
                    QuestStateEnum.Available => GetPrompt(K_Accept,     "接受任务"),
                    QuestStateEnum.Active    => _questManager.IsReadyToComplete(quest.questId)
                                                   ? GetPrompt(K_Submit, "提交任务")
                                                   : GetPrompt(K_InProgress, "进行中…"),
                    QuestStateEnum.Paused    => GetPrompt(K_Paused, "暂停中…"),
                    QuestStateEnum.Completed => GetPrompt(K_Talk,   "对话"),
                    _                        => base.InteractPrompt,
                };
            }
        }

        protected override void Interact_Internal(Transform player)
        {
            var quest = GetCachedQuest();
            if (quest == null || _questManager == null) return;

            if (_cachedState == QuestStateEnum.Available)
            {
                _questManager.AcceptQuest(quest.questId);
                // OnQuestStateChanged 事件会自动触发 HandleQuestStateChanged → _cacheDirty = true
            }
            else if (_cachedState == QuestStateEnum.Active && _questManager.IsReadyToComplete(quest.questId))
            {
                // 直接从 player 获取 PlayerStats，避免对 PlayerController 的程序集依赖
                var stats = player.GetComponentInParent<PlayerStats>();
                _questManager.CompleteQuest(quest.questId, stats);
                // OnQuestStateChanged 事件会自动触发 HandleQuestStateChanged → _cacheDirty = true
            }
        }

        protected override DialogueSequenceSO GetCurrentDialogue()
        {
            var quest = GetCachedQuest();
            if (quest == null || _questManager == null) return base.GetCurrentDialogue();

            return _cachedState switch
            {
                QuestStateEnum.Available => _availableDialogue,
                QuestStateEnum.Active    => _questManager.IsReadyToComplete(quest.questId)
                                               ? _readyDialogue : _activeDialogue,
                QuestStateEnum.Paused    => _activeDialogue,   // 暂停中显示"催促"对话，不触发任何状态推进
                QuestStateEnum.Completed => _completedDialogue,
                _                        => base.GetCurrentDialogue(),
            };
        }

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

        /// <summary>
        /// 返回缓存的当前任务（处于 Available/Active/Paused 的第一个，或最后一个已完成任务）。
        /// 若缓存不脏，直接返回上次结果，避免每帧遍历 _offeredQuests。
        /// 任务状态事件（HandleQuestStateChanged）或 OnEnable 会自动将 _cacheDirty 置 true，
        /// 确保下次访问状态是最新的。
        /// </summary>
        private QuestSO GetCachedQuest()
        {
            if (!_cacheDirty && _cachedQuest != null) return _cachedQuest;

            var qm = _questManager;
            if (_offeredQuests == null || qm == null) { _cacheDirty = false; return null; }

            QuestSO lastCompleted = null;
            foreach (var q in _offeredQuests)
            {
                if (q == null) continue;
                var s = qm.GetState(q.questId);
                if (s == QuestStateEnum.Available || s == QuestStateEnum.Active || s == QuestStateEnum.Paused)
                {
                    _cachedQuest  = q;
                    _cachedState  = s;
                    _cacheDirty   = false;
                    return _cachedQuest;
                }
                if (s == QuestStateEnum.Completed) lastCompleted = q;
            }

            _cachedQuest  = lastCompleted;
            _cachedState  = lastCompleted != null ? QuestStateEnum.Completed : QuestStateEnum.Unavailable;
            _cacheDirty   = false;
            return _cachedQuest;
        }
    }
}