using System;
using System.Collections.Generic;
using System.Linq;
using UnityEditor;
using UnityEngine;
using BaseGames.Localization;

namespace BaseGames.Editor.Localization
{
    /// <summary>
    /// 带搜索框的本地化 Key 选择器窗口。
    /// 替代 <c>GenericMenu</c>，支持 1000+ 条目的快速模糊搜索（key 和译文均可搜索）。
    ///
    /// 键盘操作：
    ///   ↑ / ↓      — 上下移动高亮行
    ///   Enter      — 确认选择当前高亮行
    ///   Esc        — 关闭窗口（不选中任何 key）
    ///
    /// 用法：
    ///   <code>
    ///   LocalizationKeyPickerWindow.Show(table, currentKey, selectedKey => {
    ///       _keyProp.stringValue = selectedKey;
    ///       serializedObject.ApplyModifiedProperties();
    ///   });
    ///   </code>
    /// </summary>
    public class LocalizationKeyPickerWindow : EditorWindow
    {
        // ── 状态 ──────────────────────────────────────────────────────────────
        private string                             _searchText  = "";
        private Vector2                            _scroll;
        private List<(string key, string preview)> _allEntries  = new();
        private List<(string key, string preview)> _filtered    = new();
        private Action<string>                     _onSelected;
        private string                             _currentKey;
        private int                                _hoveredIndex  = -1;
        private int                                _keyboardIndex = -1;   // 键盘当前高亮行

        // 预缓存样式，避免每帧 new GUIStyle
        private GUIStyle _keyStyle;
        private GUIStyle _previewStyle;

        private const float RowHeight    = 40f;
        private const float SearchHeight = 22f;

        // ── 公开入口 ──────────────────────────────────────────────────────────

        /// <summary>
        /// 打开 Key 选择器窗口。
        /// </summary>
        /// <param name="table">要从哪张表加载 Key（先查简体中文，找不到查英文）。</param>
        /// <param name="currentKey">当前已选 Key（高亮显示）。</param>
        /// <param name="onSelected">选中 Key 后的回调。</param>
        public static void Show(string table, string currentKey, Action<string> onSelected)
        {
            var dict = LocalizationManager.GetEditorTable(Language.ChineseSimplified, table)
                    ?? LocalizationManager.GetEditorTable(Language.English, table);

            if (dict == null || dict.Count == 0)
            {
                EditorUtility.DisplayDialog("Key 选择器",
                    $"表「{table}」尚无可用 Key。\n" +
                    $"请先用「BaseGames / Localization / 表格编辑器」或在 {LocalizationPaths.DataRoot}/{{语言}}/{table}.json 中添加条目。",
                    "确定");
                return;
            }

            var win = CreateInstance<LocalizationKeyPickerWindow>();
            win.titleContent = new GUIContent($"Key 选择器 — {table}");
            win.minSize      = new Vector2(440, 520);
            win._currentKey  = currentKey;
            win._onSelected  = onSelected;
            win._allEntries  = dict
                .Select(kvp => (kvp.Key, kvp.Value))
                .OrderBy(t => t.Item1, StringComparer.Ordinal)
                .ToList();
            win.ApplyFilter();

            // 把键盘索引初始化到当前 key 所在行
            int idx = win._filtered.FindIndex(t => t.key == currentKey);
            if (idx >= 0)
            {
                win._keyboardIndex = idx;
                win._scroll        = new Vector2(0, idx * RowHeight);
            }

            win.ShowUtility();
        }

        // ── GUI ───────────────────────────────────────────────────────────────

        private void OnGUI()
        {
            EnsureStyles();
            HandleKeyboardInput();   // 在绘制之前处理按键，当帧即生效
            DrawSearchBar();
            DrawEntryCount();
            DrawList();
        }

        // ── 键盘导航 ──────────────────────────────────────────────────────────

        private void HandleKeyboardInput()
        {
            var e = Event.current;
            if (e.type != EventType.KeyDown) return;

            switch (e.keyCode)
            {
                case KeyCode.UpArrow:
                    MoveKeyboardSelection(-1);
                    e.Use();
                    break;

                case KeyCode.DownArrow:
                    MoveKeyboardSelection(+1);
                    e.Use();
                    break;

                case KeyCode.Return:
                case KeyCode.KeypadEnter:
                    if (_keyboardIndex >= 0 && _keyboardIndex < _filtered.Count)
                    {
                        _onSelected?.Invoke(_filtered[_keyboardIndex].key);
                        e.Use();
                        Close();
                    }
                    break;

                case KeyCode.Escape:
                    e.Use();
                    Close();
                    break;
            }
        }

        private void MoveKeyboardSelection(int delta)
        {
            if (_filtered.Count == 0) return;

            _keyboardIndex = _keyboardIndex < 0
                ? (delta > 0 ? 0 : _filtered.Count - 1)
                : Mathf.Clamp(_keyboardIndex + delta, 0, _filtered.Count - 1);

            ScrollToKeyboardIndex();
            Repaint();
        }

        /// <summary>调整滚动位置，保证 _keyboardIndex 行始终在可见视口内。</summary>
        private void ScrollToKeyboardIndex()
        {
            float viewportH = position.height - SearchHeight - 30f;
            float rowTop    = _keyboardIndex * RowHeight;
            float rowBot    = rowTop + RowHeight;

            if (rowTop < _scroll.y)
                _scroll.y = rowTop;
            else if (rowBot > _scroll.y + viewportH)
                _scroll.y = rowBot - viewportH;
        }

        // ── 搜索栏 ────────────────────────────────────────────────────────────

        private void DrawSearchBar()
        {
            EditorGUILayout.BeginHorizontal(EditorStyles.toolbar);
            GUI.SetNextControlName("SearchField");
            var newSearch = EditorGUILayout.TextField(_searchText, EditorStyles.toolbarSearchField);
            if (GUILayout.Button("✕", EditorStyles.toolbarButton, GUILayout.Width(22)))
                newSearch = "";
            EditorGUILayout.EndHorizontal();

            if (newSearch != _searchText)
            {
                _searchText    = newSearch;
                _hoveredIndex  = -1;
                _keyboardIndex = -1;
                ApplyFilter();
            }
        }

        private void DrawEntryCount()
        {
            EditorGUILayout.LabelField(
                $"共 {_filtered.Count} 个结果（总 {_allEntries.Count} 条）  |  ↑↓ 导航  Enter 选中  Esc 关闭",
                EditorStyles.centeredGreyMiniLabel);
            EditorGUILayout.Space(2);
        }

        // ── 列表（虚拟渲染）──────────────────────────────────────────────────

        private void DrawList()
        {
            float viewportH = position.height - SearchHeight - 30f;

            _scroll = EditorGUILayout.BeginScrollView(_scroll,
                GUILayout.Height(viewportH));

            int firstVisible = Mathf.Max(0, (int)(_scroll.y / RowHeight) - 1);
            int lastVisible  = Mathf.Min(_filtered.Count - 1,
                (int)((_scroll.y + viewportH) / RowHeight) + 1);

            // 顶部占位（未渲染行）
            if (firstVisible > 0)
                GUILayout.Space(firstVisible * RowHeight);

            for (int i = firstVisible; i <= lastVisible && i < _filtered.Count; i++)
            {
                var  (key, preview) = _filtered[i];
                bool isCurrent      = string.Equals(key, _currentKey, StringComparison.Ordinal);
                bool isKeyboard     = i == _keyboardIndex;
                bool isHovered      = i == _hoveredIndex;

                var rowRect = GUILayoutUtility.GetRect(0, RowHeight, GUILayout.ExpandWidth(true));

                // 背景优先级：当前选中 > 键盘高亮 > 鼠标悬停
                Color bg = isCurrent  ? new Color(0.25f, 0.55f, 1f,  0.25f)
                         : isKeyboard ? new Color(0.40f, 0.75f, 0.4f, 0.20f)
                         : isHovered  ? new Color(1f,    1f,    1f,   0.05f)
                         : Color.clear;

                if (bg.a > 0)
                    EditorGUI.DrawRect(rowRect, bg);

                // 当前 key 左边蓝色竖条
                if (isCurrent)
                    EditorGUI.DrawRect(new Rect(rowRect.x, rowRect.y, 3, rowRect.height),
                        new Color(0.3f, 0.7f, 1f, 1f));
                // 键盘选中绿色竖条
                else if (isKeyboard)
                    EditorGUI.DrawRect(new Rect(rowRect.x, rowRect.y, 3, rowRect.height),
                        new Color(0.4f, 0.9f, 0.4f, 1f));

                // Key 文本
                EditorGUI.LabelField(
                    new Rect(rowRect.x + 8, rowRect.y + 4, rowRect.width - 12, 18),
                    key, _keyStyle);

                // 预览文本（绿色）
                string previewText = preview.Length > 60 ? preview[..60] + "…" : preview;
                EditorGUI.LabelField(
                    new Rect(rowRect.x + 8, rowRect.y + 22, rowRect.width - 12, 14),
                    previewText, _previewStyle);

                // 鼠标交互
                var ev = Event.current;
                if (rowRect.Contains(ev.mousePosition))
                {
                    if (_hoveredIndex != i) { _hoveredIndex = i; Repaint(); }

                    if (ev.type == EventType.MouseDown && ev.button == 0)
                    {
                        _onSelected?.Invoke(key);
                        ev.Use();
                        Close();
                        return;
                    }
                }
            }

            // 底部占位（未渲染行）
            int remaining = _filtered.Count - lastVisible - 1;
            if (remaining > 0)
                GUILayout.Space(remaining * RowHeight);

            EditorGUILayout.EndScrollView();
        }

        // ── 辅助 ──────────────────────────────────────────────────────────────

        private void ApplyFilter()
        {
            if (string.IsNullOrEmpty(_searchText))
            {
                _filtered = new List<(string, string)>(_allEntries);
                return;
            }

            _filtered = _allEntries
                .Where(t => t.key.IndexOf(_searchText, StringComparison.OrdinalIgnoreCase) >= 0
                         || t.preview.IndexOf(_searchText, StringComparison.OrdinalIgnoreCase) >= 0)
                .ToList();
        }

        private void EnsureStyles()
        {
            _keyStyle ??= new GUIStyle(EditorStyles.boldLabel)
            {
                fontSize = 11,
            };
            _previewStyle ??= new GUIStyle(EditorStyles.miniLabel)
            {
                normal = { textColor = new Color(0.5f, 0.88f, 0.5f) },
                fontSize = 10,
            };
        }
    }
}