import 'dart:async';
import 'dart:math';
import 'dart:ui';

import 'package:flutter/material.dart';
import 'package:provider/provider.dart';
import 'package:flutter/services.dart'; // 复制功能需要
import 'package:win_text_editor/app/providers/editor_provider.dart';
import 'package:file_picker/file_picker.dart';
import 'dart:io';
import 'package:flutter_highlight/flutter_highlight.dart';
import 'package:win_text_editor/app/providers/logger.dart';
import 'package:win_text_editor/app/utils/file_utils.dart';

class TextTab extends StatefulWidget {
  final String tabId;

  const TextTab({super.key, required this.tabId});

  @override
  State<TextTab> createState() => _TextTabState();
}

class _TextTabState extends State<TextTab> {
  late TextEditingController _controller;
  late EditorProvider _provider;
  late FocusNode _focusNode;

  String _language = 'plaintext';

  bool _showFullContent = false;
  final int _displayThreshold = 50000; // 显示阈值

  final Map<int, String> _visibleLines = {};
  final ScrollController _scrollController = ScrollController();
  final double _lineHeight = 20.0; // 单行高度
  int _firstVisibleLine = 0;
  int _lastVisibleLine = 0;

  @override
  void initState() {
    super.initState();
    _provider = Provider.of<EditorProvider>(context, listen: false);
    _controller = TextEditingController(text: _getCurrentContent());
    _focusNode = FocusNode();
    _scrollController.addListener(_calculateVisibleLines);
    _detectLanguage();

    // 初始加载可见区域
    WidgetsBinding.instance.addPostFrameCallback((_) {
      _calculateVisibleLines();
    });
  }

  void _calculateVisibleLines() {
    final scrollOffset = _scrollController.offset;
    final viewportHeight = _scrollController.position.viewportDimension;

    _firstVisibleLine = (scrollOffset / _lineHeight).floor();
    _lastVisibleLine = ((scrollOffset + viewportHeight) / _lineHeight).ceil();

    // 初始加载时至少加载前 500 行
    if (scrollOffset == 0) {
      _lastVisibleLine = min(500, _lastVisibleLine);
    }

    _preloadLines(); // 预加载附近行
  }

  void _preloadLines() {
    final tab = _provider.tabs.firstWhere((t) => t.id == widget.tabId);
    final lines = tab.fullContent.split('\n');

    // 仅缓存可见区域附近的行
    final preloadStart = max(0, _firstVisibleLine - 20);
    final preloadEnd = min(lines.length, _lastVisibleLine + 20);

    for (int i = preloadStart; i < preloadEnd; i++) {
      _visibleLines[i] = lines[i];
    }
  }

  Widget _buildLine(int lineIndex) {
    final tab = _provider.tabs.firstWhere((t) => t.id == widget.tabId);
    final lineContent = _visibleLines[lineIndex] ?? '';

    return tab.isHighlightEnabled
        ? HighlightView(
          lineContent,
          language: _language,
          textStyle: const TextStyle(fontFamily: 'monospace', fontSize: 14),
        )
        : Text(lineContent, style: const TextStyle(fontFamily: 'monospace'));
  }

  String _getCurrentContent() {
    return _provider.tabs.firstWhere((t) => t.id == widget.tabId).fullContent;
  }

  void _detectLanguage() {
    final tab = _provider.tabs.firstWhere((t) => t.id == widget.tabId);
    final fileName = tab.title.toLowerCase();
    final content = tab.content.trim();

    if (fileName.endsWith('.dart')) {
      _language = 'dart';
    } else if (fileName.endsWith('.java')) {
      _language = 'java';
    } else if (fileName.endsWith('.py')) {
      _language = 'python';
    } else if (fileName.endsWith('.js')) {
      _language = 'javascript';
    } else if (fileName.endsWith('.html')) {
      _language = 'html';
    } else if (fileName.endsWith('.css')) {
      _language = 'css';
    } else if (fileName.endsWith('.json')) {
      _language = 'json';
    } else if (fileName.endsWith('.yaml') || fileName.endsWith('.yml')) {
      _language = 'yaml';
    } else if (fileName.endsWith('.xml')) {
      _language = 'xml';
    }
    // 如果扩展名未识别，检查内容特征
    else if (_isLikelyXml(content)) {
      _language = 'xml';
    } else {
      _language = 'plaintext';
    }
  }

  bool _isLikelyXml(String content) {
    if (content.isEmpty) return false;

    // 简单检查：内容以'<'开头，以'>'结尾
    final trimmed = content.trim();
    if (!trimmed.startsWith('<') || !trimmed.endsWith('>')) {
      return false;
    }

    // 更复杂的检查：包含常见的XML标签模式
    final xmlTagRegex = RegExp(r'<[^/>]+>.*<\/[^>]+>|<[^/>]+\/>');
    return xmlTagRegex.hasMatch(content);
  }

  @override
  void didUpdateWidget(TextTab oldWidget) {
    super.didUpdateWidget(oldWidget);
    if (oldWidget.tabId != widget.tabId) {
      _visibleLines.clear(); // 修复问题2：清空缓存
      _controller.text = _getCurrentContent();
      _detectLanguage();
      _calculateVisibleLines(); // 重新加载
    }
  }

  @override
  void dispose() {
    _controller.dispose();
    _focusNode.dispose();
    _scrollController.dispose(); // 添加这行
    // 关闭时取消加载
    if (_provider.isTabLoading(widget.tabId)) {
      _provider.cancelLoading(widget.tabId);
    }
    super.dispose();
  }

  @override
  Widget build(BuildContext context) {
    final tab = _provider.tabs.firstWhere((t) => t.id == widget.tabId);
    final progress = _provider.getLoadedChunks(widget.tabId);
    final totalChunks = (tab.content.length / 10000).ceil();
    final lineCount = tab.fullContent.split('\n').length;
    return Column(
      children: [
        Container(
          height: 40,
          padding: const EdgeInsets.symmetric(horizontal: 16),
          decoration: BoxDecoration(
            color: Colors.grey[100],
            border: Border(bottom: BorderSide(color: Colors.grey[300]!)),
          ),
          child: Row(
            mainAxisAlignment: MainAxisAlignment.spaceBetween,
            children: [
              Text(
                '源文本${tab.content.isEmpty ? '' : ' (${tab.fileName!.isEmpty ? '' : '${tab.fileName},'}${tab.content.length}字符)'}',
                style: const TextStyle(fontWeight: FontWeight.bold),
              ),
              Row(
                children: [
                  IconButton(
                    icon: const Icon(Icons.folder_open, size: 20),
                    tooltip: '打开文件',
                    onPressed: () => _openFile(context),
                  ),
                  IconButton(
                    icon: const Icon(Icons.content_copy, size: 20),
                    tooltip: '复制内容',
                    onPressed:
                        tab.content.isEmpty ? null : () => _copyToClipboard(context, tab.content),
                  ),
                  IconButton(
                    icon: const Icon(Icons.save, size: 20),
                    tooltip: '保存到文件',
                    onPressed: tab.content.isEmpty ? null : () => _saveFile(context, tab.content),
                  ),
                  DropdownButton<String>(
                    value: _language,
                    icon: const Icon(Icons.code, size: 20),
                    underline: Container(),
                    onChanged: (String? newValue) {
                      setState(() {
                        _language = newValue!;
                      });
                    },
                    items:
                        <String>[
                          'xml',
                          'plaintext',
                          'dart',
                          'java',
                          'python',
                          'javascript',
                          'html',
                          'css',
                          'json',
                          'yaml',
                        ].map<DropdownMenuItem<String>>((String value) {
                          return DropdownMenuItem<String>(value: value, child: Text(value));
                        }).toList(),
                  ),
                ],
              ),
            ],
          ),
        ),
        if (_provider.isTabLoading(widget.tabId))
          LinearProgressIndicator(value: progress / totalChunks, minHeight: 2),
        Expanded(
          child: ListView.builder(
            controller: _scrollController,
            itemCount: lineCount,
            itemExtent: _lineHeight, // 固定行高优化性能
            itemBuilder: (ctx, index) => _buildLine(index),
          ),
        ),
      ],
    );
  }

  Future<void> _openFile(BuildContext context) async {
    final filePath = await FileUtils.pickFile(context);
    if (filePath == null || !mounted) return;

    try {
      final content = await FileUtils.readFileContent(context, filePath);
      if (content == null || !mounted) return;

      final fileName = filePath.split('\\').last;

      // 根据文件大小选择加载方式
      if (content.length > 100000) {
        // 超过100k使用分块加载
        await _provider.updateContentInChunks(widget.tabId, content, fileName);
      } else {
        await _provider.updateContent(widget.tabId, content, fileName);
      }

      if (mounted) {
        setState(() {
          _controller.text = content;
          _detectLanguage();
          _showFullContent = content.length <= _displayThreshold;
          _visibleLines.clear(); // 清空缓存
          _calculateVisibleLines(); // 重新计算可见行
        });
      }
    } catch (e) {
      // 错误处理保持不变
    }
  }

  // 复制到剪贴板
  Future<void> _copyToClipboard(BuildContext context, String content) async {
    await Clipboard.setData(ClipboardData(text: content));
    if (context.mounted) {
      ScaffoldMessenger.of(context).showSnackBar(const SnackBar(content: Text('已复制到剪贴板')));
    }
  }

  // 保存文件模拟功能
  // 保存文件功能
  Future<void> _saveFile(BuildContext context, String content) async {
    try {
      // 让用户选择保存位置
      String? outputPath = await FilePicker.platform.saveFile(
        dialogTitle: '保存文件',
        fileName: 'untitled.txt',
        allowedExtensions: ['txt'],
        type: FileType.any,
      );

      if (outputPath == null) return;

      final file = File(outputPath);

      // 检查文件是否存在
      if (await file.exists()) {
        // 如果存在，显示确认对话框
        final shouldOverwrite = await showDialog<bool>(
          context: context,
          builder:
              (context) => AlertDialog(
                title: const Text('文件已存在'),
                content: const Text('要覆盖现有文件吗？'),
                actions: [
                  TextButton(
                    onPressed: () => Navigator.pop(context, false),
                    child: const Text('取消'),
                  ),
                  TextButton(
                    onPressed: () => Navigator.pop(context, true),
                    child: const Text('覆盖'),
                  ),
                ],
              ),
        );

        if (shouldOverwrite != true) return;
      }

      // 写入文件
      await file.writeAsString(content);

      if (context.mounted) {
        ScaffoldMessenger.of(context).showSnackBar(SnackBar(content: Text('已保存到: ${file.path}')));
      }
    } on FileSystemException catch (e) {
      if (context.mounted) {
        ScaffoldMessenger.of(context).showSnackBar(SnackBar(content: Text('保存失败: ${e.message}')));
      }
    } catch (e) {
      if (context.mounted) {
        ScaffoldMessenger.of(
          context,
        ).showSnackBar(SnackBar(content: Text('保存失败: ${e.toString()}')));
      }
    }
  }
}