using System.Collections;
using System.Collections.Generic;
using System.Text;
using TMPro;
using UnityEngine;
using UnityEngine.UI;
using BaseGames.Localization;

namespace BaseGames.Dialogue
{
    /// <summary>
    /// 对话框 UI 组件（架构 14_NarrativeModule §5）。
    /// 挂载在 Canvas_Overlay 下的 DialogueBox 子对象。
    /// 负责打字机效果、头像显示、继续提示。
    /// </summary>
    public class DialogueUI : MonoBehaviour
    {
        [SerializeField] private GameObject  _rootPanel;
        [SerializeField] private TMP_Text    _speakerNameText;
        [SerializeField] private TMP_Text    _dialogueText;
        [SerializeField] private GameObject  _speakerNamePanel;  // 无名称时隐藏整个名称框
        [SerializeField] private GameObject  _continuePrompt;    // "▼" 图标，打字完成后显示
        [SerializeField] private Image       _speakerPortrait;   // 角色头像框
        [SerializeField] private Image       _speakerNameBackground; // 说话人名称框背景，用于应用 accentColor（可选）
        [SerializeField] private AudioSource _voiceSource;       // 语音播放源（可不配置）

        [Header("选项系统（可选）")]
        [Tooltip("选项按钮的父节点容器。ShowChoices 通过对象池激活/停用按钮，HideChoices 停用全部。\n留空则分支选项功能静默禁用。")]
        [SerializeField] private Transform  _choicesContainer;
        [Tooltip("选项按钮预制体（需包含 Button 组件和 TMP_Text 子组件）。\n首次使用时预热 PoolInitialSize 个到对象池，后续零 GC。")]
        [SerializeField] private GameObject _choiceButtonPrefab;
        [Tooltip("选项按钮池初始大小。设为预期最大选项数，默认 8 覆盖绝大多数情况。")]
        [SerializeField] [Range(2, 16)] private int _choicePoolSize = 8;

        // 说话人名称框背景的默认色（Awake 时记录，切换角色后可还原）
        private Color _defaultNameBgColor = Color.white;
        // 缓存名称框 RectTransform，避免 ShowLine 每次调用 GetComponent（零堆分配）
        private RectTransform _speakerNamePanelRT;

        // 选项按钮对象池：Awake 时按 _choicePoolSize 预热，ShowChoices/HideChoices 零 GC
        private readonly List<(GameObject go, Button btn, TMP_Text lbl)> _choicePool = new();

        private Coroutine    _typingCoroutine;
        private DialogueLine _currentLine;
        private const float  DefaultTypewriterDelay = 0.03f;

        // 缓存 WaitForSecondsRealtime：delay 值不变时直接复用，避免每行 new 分配。
        private WaitForSecondsRealtime _cachedTypeDelay;
        private float                  _cachedTypeDelayValue = -1f;

        // 缓存 StringBuilder：每行 Clear() 复用，避免每行 new StringBuilder(n) 的堆分配。
        // 初始容量 256，足以容纳绝大多数对话行，超长时会自动扩容（扩容极少发生）。
        private readonly StringBuilder _typingSB = new(256);

        /// <summary>当前是否仍在执行打字机效果。</summary>
        public bool IsTyping { get; private set; }

        private void Awake()
        {
            if (_speakerNameBackground != null)
                _defaultNameBgColor = _speakerNameBackground.color;
            if (_speakerNamePanel != null)
                _speakerNamePanelRT = _speakerNamePanel.GetComponent<RectTransform>();

            // 预热选项按钮对象池：在此时创建可避免首次对话时的 Instantiate 停顿
            if (_choicesContainer != null && _choiceButtonPrefab != null)
            {
                for (int i = 0; i < _choicePoolSize; i++)
                {
                    var go  = Instantiate(_choiceButtonPrefab, _choicesContainer);
                    var btn = go.GetComponent<Button>();
                    var lbl = go.GetComponentInChildren<TMP_Text>();
                    go.SetActive(false);
                    _choicePool.Add((go, btn, lbl));
                }
            }
        }

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

        /// <summary>显示一行对话并开始打字机效果。</summary>
        public void ShowLine(DialogueLine line)
        {
            _currentLine = line;
            if (_rootPanel != null) _rootPanel.SetActive(true);
            if (_continuePrompt != null) _continuePrompt.SetActive(false);

            // 说话人名称（actor 优先，回退到直接字段）
            string resolvedNameKey = line.ResolvedNameKey;
            bool hasSpeaker = !string.IsNullOrEmpty(resolvedNameKey);
            if (_speakerNamePanel != null) _speakerNamePanel.SetActive(hasSpeaker);
            if (hasSpeaker && _speakerNameText != null)
                _speakerNameText.text = LocalizationManager.Get(resolvedNameKey, LocalizationTable.Dialogue);

            // 说话人名称框背景颜色（accentColor）：有 actor 时着色，无 actor 时还原默认色
            if (_speakerNameBackground != null)
                _speakerNameBackground.color = hasSpeaker ? line.ResolvedAccentColor : _defaultNameBgColor;

            // 排版方向：玩家角色说话时名称框靠右，NPC 靠左
            SetLayoutSide(line.ResolvedIsPlayer);

            // 头像（actor 优先，回退到直接字段）
            var resolvedPortrait = line.ResolvedPortrait;
            if (_speakerPortrait != null)
            {
                _speakerPortrait.gameObject.SetActive(resolvedPortrait != null);
                if (resolvedPortrait != null) _speakerPortrait.sprite = resolvedPortrait;
            }

            // 语音播放
            if (_voiceSource != null)
            {
                _voiceSource.Stop();
                if (line.voiceClip != null)
                {
                    _voiceSource.clip = line.voiceClip;
                    _voiceSource.Play();
                }
            }

            // 开始打字机协程
            if (_typingCoroutine != null) StopCoroutine(_typingCoroutine);
            _typingCoroutine = StartCoroutine(TypeLine(line));
        }

        /// <summary>立即显示全部文字（跳过打字机效果）。</summary>
        public void SkipTyping()
        {
            if (!IsTyping) return;
            if (_typingCoroutine != null)
            {
                StopCoroutine(_typingCoroutine);
                _typingCoroutine = null;
            }
            _voiceSource?.Stop();
            if (_dialogueText != null)
            {
                string key = _currentLine.textKey;
                if (string.IsNullOrEmpty(key))
                {
#if UNITY_EDITOR || DEVELOPMENT_BUILD
                    Debug.LogWarning("[DialogueUI] 当前对话行 textKey 为空，跳过打字机后显示空文本。");
#endif
                    _dialogueText.text = "";
                }
                else
                {
                    _dialogueText.text = LocalizationManager.Get(key, LocalizationTable.Dialogue);
                }
            }
            IsTyping = false;
            if (_continuePrompt != null) _continuePrompt.SetActive(true);
        }

        /// <summary>隐藏对话框面板。</summary>
        public void Hide()
        {
            _voiceSource?.Stop();
            if (_rootPanel != null) _rootPanel.SetActive(false);
        }

        // ── 布局辅助 ──────────────────────────────────────────────────────

        /// <summary>
        /// 切换名称框的横向对齐方向：玩家说话时靠右，NPC 靠左。
        /// 修改 RectTransform 的 anchorMin.x / anchorMax.x / pivot.x，保持纵向不变。
        /// </summary>
        private void SetLayoutSide(bool isPlayer)
        {
            if (_speakerNamePanelRT == null) return;
            float x = isPlayer ? 1f : 0f;
            _speakerNamePanelRT.anchorMin = new Vector2(x, _speakerNamePanelRT.anchorMin.y);
            _speakerNamePanelRT.anchorMax = new Vector2(x, _speakerNamePanelRT.anchorMax.y);
            _speakerNamePanelRT.pivot     = new Vector2(x, _speakerNamePanelRT.pivot.y);
        }

        /// <summary>
        /// 显示玩家可选的分支选项列表。打字机效果结束后由 DialogueManager 调用。
        /// 使用对象池（零 GC）：池不足时动态扩容；点击后回调 onSelected(index)。
        /// 若 _choicesContainer 或 _choiceButtonPrefab 未配置，则静默跳过（不影响流程）。
        /// </summary>
        public void ShowChoices(DialogueChoice[] choices, System.Action<int> onSelected)
        {
            if (_choicesContainer == null || _choiceButtonPrefab == null) return;

            // 确保池中有足够按钮
            while (_choicePool.Count < choices.Length)
            {
                var go  = Instantiate(_choiceButtonPrefab, _choicesContainer);
                var btn = go.GetComponent<Button>();
                var lbl = go.GetComponentInChildren<TMP_Text>();
                go.SetActive(false);
                _choicePool.Add((go, btn, lbl));
            }

            // 激活前 N 个并绑定数据
            for (int i = 0; i < choices.Length; i++)
            {
                int captured = i;
                var (go, btn, lbl) = _choicePool[i];
                go.SetActive(true);
                if (lbl != null)
                    lbl.text = LocalizationManager.Get(choices[i].textKey ?? "", LocalizationTable.Dialogue);
                if (btn != null)
                {
                    btn.onClick.RemoveAllListeners();
                    btn.onClick.AddListener(() => onSelected?.Invoke(captured));
                }
            }

            // 多余的池对象保持隐藏
            for (int i = choices.Length; i < _choicePool.Count; i++)
                _choicePool[i].go.SetActive(false);

            // 有选项时隐藏继续提示，避免与选项按钮视觉重叠
            if (_continuePrompt != null) _continuePrompt.SetActive(false);
            _choicesContainer.gameObject.SetActive(true);
        }

        /// <summary>隐藏选项列表，将池中按钮全部停用（零 GC）。</summary>
        public void HideChoices()
        {
            if (_choicesContainer == null) return;
            foreach (var (go, btn, _) in _choicePool)
            {
                if (btn != null) btn.onClick.RemoveAllListeners();
                go.SetActive(false);
            }
            _choicesContainer.gameObject.SetActive(false);
        }

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

        private IEnumerator TypeLine(DialogueLine line)
        {
            IsTyping = true;
            float delay = line.typewriterDelay > 0f ? line.typewriterDelay : DefaultTypewriterDelay;

            // 复用缓存的 WaitForSecondsRealtime；仅当 delay 值变化时才重新 new
            if (_cachedTypeDelay == null || !Mathf.Approximately(_cachedTypeDelayValue, delay))
            {
                _cachedTypeDelay      = new WaitForSecondsRealtime(delay);
                _cachedTypeDelayValue = delay;
            }

            string text;
            if (string.IsNullOrEmpty(line.textKey))
            {
#if UNITY_EDITOR || DEVELOPMENT_BUILD
                Debug.LogWarning("[DialogueUI] 对话行 textKey 为空，打字机将显示空文本。请检查 DialogueSequenceSO 配置。");
#endif
                text = "";
            }
            else
            {
                text = LocalizationManager.Get(line.textKey, LocalizationTable.Dialogue);
            }

            // 复用缓存 StringBuilder，避免每行 new 分配；TMP SetText(StringBuilder) 零分配
            _typingSB.Clear();
            if (_dialogueText != null) _dialogueText.text = "";

            foreach (char c in text)
            {
                _typingSB.Append(c);
                if (_dialogueText != null) _dialogueText.SetText(_typingSB);
                yield return _cachedTypeDelay;
            }

            IsTyping = false;
            if (_continuePrompt != null) _continuePrompt.SetActive(true);
            _typingCoroutine = null;
        }
    }
}