using System.Collections;
using System.Collections.Generic;
using BaseGames.Core;
using BaseGames.Core.Events;
using BaseGames.Input;
using BaseGames.World;
using UnityEngine;

namespace BaseGames.Dialogue
{
    /// <summary>
    /// 对话管理器（架构 14_NarrativeModule §4）。
    /// 驱动 DialogueUI 打字机效果；管理 Action Map 切换；向 QuestManager 广播对话完成事件。
    /// 在 Awake 中注册到 ServiceLocator。
    /// </summary>
    public class DialogueManager : MonoBehaviour, IDialogueService
    {
        [SerializeField] private DialogueUI          _dialogueBox;
        [SerializeField] private InputReaderSO       _inputReader;
        [SerializeField] private WorldStateRegistry  _worldState;

        [Header("事件频道")]
        [SerializeField] private VoidEventChannelSO   _onDialogueStarted;
        [SerializeField] private VoidEventChannelSO   _onDialogueEnded;
        [SerializeField] private StringEventChannelSO _onNpcDialogueCompleted;  // → EVT_NpcDialogueCompleted (npcId)
        [SerializeField] private VoidEventChannelSO   _onLineStarted;           // 每行开始打字时广播
        [SerializeField] private VoidEventChannelSO   _onLineEnded;             // 每行玩家确认后广播

        private bool _skipRequested;

        // ── 复用 Yield 指令，避免协程每行 new WaitUntil 闭包 ───────────────
        private sealed class WaitTypingOrSkip : CustomYieldInstruction
        {
            private readonly DialogueManager _m;
            public WaitTypingOrSkip(DialogueManager m) => _m = m;
            public override bool keepWaiting => _m._dialogueBox.IsTyping && !_m._skipRequested;
        }
        private sealed class WaitSkip : CustomYieldInstruction
        {
            private readonly DialogueManager _m;
            public WaitSkip(DialogueManager m) => _m = m;
            public override bool keepWaiting => !_m._skipRequested;
        }

        private WaitTypingOrSkip _waitTypingOrSkip;
        private WaitSkip         _waitSkip;

        /// <summary>
        /// 当 IsDialogueActive 时排队等待的对话请求。
        /// 支持脚本触发的连续对话序列（如剧情链、事件链触发的对话），
        /// 但容量上限为 8，避免因误触导致无限排队。
        /// </summary>
        private readonly Queue<(DialogueSequenceSO seq, string npcId)> _pending = new();
        private const int PendingCapacity = 8;

        /// <summary>当前是否有对话正在播放。</summary>
        public bool IsDialogueActive { get; private set; }

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

        private void Awake()
        {
            if (ServiceLocator.GetOrDefault<IDialogueService>() != null) { Destroy(gameObject); return; }
            ServiceLocator.Register<IDialogueService>(this);
            _waitTypingOrSkip = new WaitTypingOrSkip(this);
            _waitSkip         = new WaitSkip(this);
        }

        private void OnDestroy()
        {
            ServiceLocator.Unregister<IDialogueService>(this);
        }

        private void OnEnable()
        {
            if (_inputReader != null) _inputReader.SubmitEvent += OnSubmit;
        }

        private void OnDisable()
        {
            if (_inputReader != null) _inputReader.SubmitEvent -= OnSubmit;
            _pending.Clear();

            // 若对话协程在组件禁用或场景切换时仍在运行，Unity 会强制杀死协程但不调用
            // EndDialogue()，导致 Action Map 永久停留在 UI 模式。此处主动恢复。
            if (IsDialogueActive)
            {
                StopAllCoroutines();
                _dialogueBox?.Hide();
                IsDialogueActive = false;
                _inputReader?.EnableGameplayInput();
            }
        }

        // ── 公开 API ──────────────────────────────────────────────────────

        /// <summary>
        /// 启动对话序列。
        /// 若已有对话在播放，请求会进入等待队列（上限 <see cref="PendingCapacity"/>），
        /// 待当前对话结束后依序自动播放；超出上限的请求被丢弃。
        /// 由 InteractableNPC.Interact() 调用。
        /// </summary>
        /// <param name="sequence">要播放的对话序列 SO。</param>
        /// <param name="npcId">NPC 标识符，对话结束时随 EVT_NpcDialogueCompleted 广播。</param>
        public void StartDialogue(DialogueSequenceSO sequence, string npcId = "")
        {
            if (sequence == null) return;
            if (IsDialogueActive)
            {
                if (_pending.Count < PendingCapacity)
                    _pending.Enqueue((sequence, npcId));
                return;
            }
            PlayImmediate(sequence, npcId);
        }

        private void PlayImmediate(DialogueSequenceSO sequence, string npcId)
        {
            IsDialogueActive = true;
            _skipRequested   = false;
            if (_inputReader != null) _inputReader.EnableUIInput();
            _onDialogueStarted?.Raise();
            StartCoroutine(PlaySequence(sequence, npcId));
        }

        // ── 输入回调 ──────────────────────────────────────────────────────

        private void OnSubmit() => _skipRequested = true;

        // ── 内部协程 ──────────────────────────────────────────────────────

        private IEnumerator PlaySequence(DialogueSequenceSO sequence, string npcId)
        {
            var resolved = ResolveVariant(sequence);

            if (resolved.lines == null || resolved.lines.Length == 0)
            {
                EndDialogue(npcId);
                yield break;
            }

            foreach (var line in resolved.lines)
            {
                _skipRequested = false;
                _dialogueBox.ShowLine(line);
                _onLineStarted?.Raise();

                // 等待打字完成，期间允许跳过
                yield return _waitTypingOrSkip;
                if (_dialogueBox.IsTyping) _dialogueBox.SkipTyping();

                // 等待玩家按 Submit 推进下一行
                _skipRequested = false;
                yield return _waitSkip;
                _onLineEnded?.Raise();
            }

            EndDialogue(npcId);
        }

        private void EndDialogue(string npcId)
        {
            _dialogueBox.Hide();
            IsDialogueActive = false;

            if (_inputReader != null) _inputReader.EnableGameplayInput();

            _onDialogueEnded?.Raise();

            if (!string.IsNullOrEmpty(npcId))
                _onNpcDialogueCompleted?.Raise(npcId);

            // 自动播放队首等待中的对话（脚本触发的连续序列）
            if (_pending.Count > 0)
            {
                var (seq, id) = _pending.Dequeue();
                PlayImmediate(seq, id);
            }
        }

        /// <summary>
        /// 根据 ConditionalVariant 选择正确的序列版本。
        /// 按顺序检查 variants：所有 requiredFlags 均满足的第一个变体胜出（AND 关系）；
        /// 未注入 WorldStateRegistry 或无满足条件的变体时，返回原序列（默认）。
        /// </summary>
        private DialogueSequenceSO ResolveVariant(DialogueSequenceSO sequence)
        {
            if (sequence.variants == null || sequence.variants.Length == 0)
                return sequence;

            if (_worldState != null)
            {
                foreach (var variant in sequence.variants)
                {
                    if (variant.sequence == null) continue;
                    if (variant.requiredFlags == null || variant.requiredFlags.Length == 0)
                        return variant.sequence;   // 无条件变体：直接采用

                    bool allMet = true;
                    foreach (var flag in variant.requiredFlags)
                    {
                        if (!string.IsNullOrEmpty(flag) && !_worldState.HasFlag(flag))
                        {
                            allMet = false;
                            break;
                        }
                    }
                    if (allMet) return variant.sequence;
                }
            }
#if UNITY_EDITOR || DEVELOPMENT_BUILD
            else if (sequence.variants.Length > 0)
            {
                Debug.LogWarning(
                    $"[DialogueManager] 序列 '{sequence.sequenceId}' 有 {sequence.variants.Length} 个条件变体，" +
                    "但 WorldStateRegistry 未注入，将使用默认序列。请检查 Inspector 中的 _worldState 字段。",
                    this);
            }
#endif

            return sequence;
        }
    }
}