import 'dart:async';
import 'package:flutter/material.dart';
import 'package:flutter_keyboard_visibility/flutter_keyboard_visibility.dart';
import 'package:eatvio_app/core/widgets/custom_text_form_field.dart';

class MarkdownEditor extends StatefulWidget {
  const MarkdownEditor({
    super.key,
    this.initialText,
    this.hintText,
    this.hasError = false,
    this.minLines = 4,
    this.maxLines = 6,
    this.heightPreview = 120,
    this.onChanged,
    this.onToolbarVisibilityChanged,
    this.showInlineToolbar = true,
  });

  final String? initialText;
  final String? hintText;
  final bool hasError;
  final int minLines;
  final int maxLines;
  final double heightPreview;
  final void Function(String value)? onChanged;
  final void Function(bool visible)? onToolbarVisibilityChanged;
  final bool showInlineToolbar;

  @override
  State<MarkdownEditor> createState() => MarkdownEditorState();
}

class MarkdownEditorState extends State<MarkdownEditor> {
  late final TextEditingController _controller;
  final FocusNode _focusNode = FocusNode();
  bool _isPreview = false;
  bool _enablePanel = false;
  late final KeyboardVisibilityController _keyboardVisibilityController;
  late final StreamSubscription<bool> _keyboardSubscription;

  bool get isToolbarVisible => _enablePanel || _isPreview;

  @override
  void initState() {
    super.initState();
    _controller = TextEditingController(text: widget.initialText ?? '');
    _keyboardVisibilityController = KeyboardVisibilityController();
    _keyboardSubscription = _keyboardVisibilityController.onChange.listen((visible) {
      setState(() {
        _enablePanel = visible;
      });
      widget.onToolbarVisibilityChanged?.call(isToolbarVisible);
    });
    WidgetsBinding.instance.addPostFrameCallback((_) {
      widget.onToolbarVisibilityChanged?.call(isToolbarVisible);
    });
  }

  @override
  void dispose() {
    _keyboardSubscription.cancel();
    _focusNode.dispose();
    _controller.dispose();
    super.dispose();
  }

  bool _hasFormatting(String prefix, String suffix) {
    final text = _controller.text;
    final selection = _controller.selection;
    if (selection.isValid && !selection.isCollapsed) {
      final selectedText = text.substring(selection.start, selection.end);
      return selectedText.startsWith(prefix) && selectedText.endsWith(suffix);
    } else {
      final cursorPosition = selection.baseOffset;
      if (cursorPosition >= prefix.length && text.length >= cursorPosition + suffix.length) {
        final beforeCursor = text.substring(cursorPosition - prefix.length, cursorPosition);
        final afterCursor = text.substring(cursorPosition, cursorPosition + suffix.length);
        return beforeCursor == prefix && afterCursor == suffix;
      }
    }
    return false;
  }

  void _removeFormatting(String prefix, String suffix) {
    final text = _controller.text;
    final selection = _controller.selection;
    if (selection.isValid && !selection.isCollapsed) {
      final selectedText = text.substring(selection.start, selection.end);
      final unformattedText = selectedText.substring(prefix.length, selectedText.length - suffix.length);
      final newText = text.replaceRange(selection.start, selection.end, unformattedText);
      _controller.text = newText;
      _controller.selection = TextSelection(baseOffset: selection.start, extentOffset: selection.start + unformattedText.length);
    } else {
      final cursorPosition = selection.baseOffset;
      if (cursorPosition >= prefix.length && text.length >= cursorPosition + suffix.length) {
        final beforeCursor = text.substring(0, cursorPosition - prefix.length);
        final afterCursor = text.substring(cursorPosition + suffix.length);
        final newText = beforeCursor + afterCursor;
        _controller.text = newText;
        _controller.selection = TextSelection.collapsed(offset: cursorPosition - prefix.length);
      }
    }
    widget.onChanged?.call(_controller.text);
  }

  void _applyMarkdownFormat(String prefix, String suffix) {
    final text = _controller.text;
    final selection = _controller.selection;
    if (selection.isValid && !selection.isCollapsed) {
      final selectedText = text.substring(selection.start, selection.end);
      final formattedText = '$prefix$selectedText$suffix';
      final newText = text.replaceRange(selection.start, selection.end, formattedText);
      _controller.text = newText;
      _controller.selection = TextSelection(baseOffset: selection.start, extentOffset: selection.start + formattedText.length);
    } else {
      final cursorPosition = selection.baseOffset;
      final newText = '${text.substring(0, cursorPosition)}$prefix$suffix${text.substring(cursorPosition)}';
      _controller.text = newText;
      _controller.selection = TextSelection.collapsed(offset: cursorPosition + prefix.length);
    }
    widget.onChanged?.call(_controller.text);
  }

  void _applyHeading() {
    if (_hasFormatting('# ', '')) {
      _removeFormatting('# ', '');
    } else {
      _applyMarkdownFormat('# ', '');
    }
  }

  void _applyBold() {
    if (_hasFormatting('**', '**')) {
      _removeFormatting('**', '**');
    } else {
      _applyMarkdownFormat('**', '**');
    }
  }

  void _applyItalic() {
    if (_hasFormatting('*', '*')) {
      _removeFormatting('*', '*');
    } else {
      _applyMarkdownFormat('*', '*');
    }
  }

  void _applyNumberedList() {
    if (_hasFormatting('1. ', '')) {
      _removeFormatting('1. ', '');
    } else {
      _applyMarkdownFormat('1. ', '');
    }
  }

  void _applyBulletedList() {
    if (_hasFormatting('- ', '')) {
      _removeFormatting('- ', '');
    } else {
      _applyMarkdownFormat('- ', '');
    }
  }

  void _applyLink() {
    final text = _controller.text;
    final selection = _controller.selection;
    if (selection.isValid && !selection.isCollapsed) {
      final selectedText = text.substring(selection.start, selection.end);
      final linkRegex = RegExp(r'^\[(.*?)\]\((.*?)\)$');
      if (linkRegex.hasMatch(selectedText)) {
        final match = linkRegex.firstMatch(selectedText);
        final linkText = match?.group(1) ?? selectedText;
        final newText = text.replaceRange(selection.start, selection.end, linkText);
        _controller.text = newText;
        _controller.selection = TextSelection(baseOffset: selection.start, extentOffset: selection.start + linkText.length);
      } else {
        final formattedText = '[$selectedText](url)';
        final newText = text.replaceRange(selection.start, selection.end, formattedText);
        _controller.text = newText;
        _controller.selection = TextSelection(baseOffset: selection.start + selectedText.length + 2, extentOffset: selection.start + selectedText.length + 5);
      }
    } else {
      _applyMarkdownFormat('[', '](url)');
    }
    widget.onChanged?.call(_controller.text);
  }

  void _applyHorizontalRule() {
    final cursorPosition = _controller.selection.baseOffset;
    final text = _controller.text;
    final newText = '${text.substring(0, cursorPosition)}\n---\n${text.substring(cursorPosition)}';
    _controller.text = newText;
    _controller.selection = TextSelection.collapsed(offset: cursorPosition + 5);
    widget.onChanged?.call(_controller.text);
  }

  void _togglePreview() {
    setState(() {
      _isPreview = !_isPreview;
    });
    if (!_isPreview) {
      Future.delayed(const Duration(milliseconds: 100), () {
        _focusNode.requestFocus();
      });
    } else {
      _focusNode.unfocus();
    }
    widget.onToolbarVisibilityChanged?.call(isToolbarVisible);
  }

  Widget _mdButton(IconData icon, VoidCallback onTap) {
    return Expanded(
      child: GestureDetector(
        onTap: onTap,
        child: Container(
          height: 36,
          decoration: BoxDecoration(color: const Color(0xFFF1F2F6), borderRadius: BorderRadius.circular(10)),
          child: Icon(icon),
        ),
      ),
    );
  }

  Widget _mdTextButton(String text, VoidCallback onTap) {
    return Expanded(
      child: GestureDetector(
        onTap: onTap,
        child: Container(
          height: 36,
          decoration: BoxDecoration(color: const Color(0xFFF1F2F6), borderRadius: BorderRadius.circular(10)),
          child: Center(
            child: Text(
              text,
              style: const TextStyle(fontSize: 18, fontWeight: FontWeight.w900, color: Colors.black87),
            ),
          ),
        ),
      ),
    );
  }

  Widget _buildMarkdownPreview(BuildContext context) {
    return Container(
      height: widget.heightPreview,
      padding: const EdgeInsets.all(16),
      width: MediaQuery.of(context).size.width - 32,
      decoration: BoxDecoration(
        color: const Color(0xFFF6F6F6),
        borderRadius: BorderRadius.circular(20),
        border: Border.all(color: const Color(0xFFE0E0E0)),
      ),
      child: SingleChildScrollView(child: _parseMarkdown(_controller.text)),
    );
  }

  Widget buildToolbar(BuildContext context) {
    return Row(
      mainAxisAlignment: MainAxisAlignment.center,
      children: [
        Container(
          width: MediaQuery.of(context).size.width - 76,
          height: 52,
          decoration: BoxDecoration(
            color: Colors.white,
            borderRadius: BorderRadius.circular(20),
            boxShadow: [BoxShadow(color: const Color(0x00000000).withAlpha((255 * 0.2).toInt()), spreadRadius: 0, blurRadius: 32, offset: const Offset(0, 0))],
          ),
          child: Row(
            children: [
              const SizedBox(width: 8),
              _mdTextButton('H', _applyHeading),
              const SizedBox(width: 8),
              _mdButton(Icons.format_bold, _applyBold),
              const SizedBox(width: 8),
              _mdButton(Icons.format_italic, _applyItalic),
              const SizedBox(width: 8),
              _mdButton(Icons.format_list_numbered, _applyNumberedList),
              const SizedBox(width: 8),
              _mdButton(Icons.format_list_bulleted, _applyBulletedList),
              const SizedBox(width: 8),
              _mdButton(Icons.link, _applyLink),
              const SizedBox(width: 8),
              _mdButton(Icons.horizontal_rule, _applyHorizontalRule),
              const SizedBox(width: 8),
            ],
          ),
        ),
        const SizedBox(width: 8),
        Container(
          width: 52,
          height: 52,
          padding: const EdgeInsets.symmetric(horizontal: 8),
          decoration: BoxDecoration(
            color: Colors.white,
            borderRadius: BorderRadius.circular(20),
            boxShadow: [BoxShadow(color: const Color(0x00000000).withAlpha((255 * 0.2).toInt()), spreadRadius: 0, blurRadius: 32, offset: const Offset(0, 0))],
          ),
          child: Row(children: [_mdButton(_isPreview ? Icons.edit : Icons.visibility, _togglePreview)]),
        ),
      ],
    );
  }

  Widget _parseMarkdown(String text) {
    if (text.isEmpty) {
      return Text(widget.hintText ?? '');
    }
    final lines = text.split('\n');
    final widgets = <Widget>[];
    for (int i = 0; i < lines.length; i++) {
      final line = lines[i];
      if (line.trim().isEmpty) {
        widgets.add(const SizedBox(height: 8));
        continue;
      }
      if (line.startsWith('# ')) {
        widgets.add(
          Text(
            line.substring(2),
            style: const TextStyle(fontSize: 24, fontWeight: FontWeight.bold, color: Colors.black),
          ),
        );
      } else if (line.startsWith('## ')) {
        widgets.add(
          Text(
            line.substring(3),
            style: const TextStyle(fontSize: 20, fontWeight: FontWeight.bold, color: Colors.black),
          ),
        );
      } else if (line.startsWith('### ')) {
        widgets.add(
          Text(
            line.substring(4),
            style: const TextStyle(fontSize: 18, fontWeight: FontWeight.bold, color: Colors.black),
          ),
        );
      } else if (line.startsWith('- ') || line.startsWith('* ')) {
        widgets.add(
          Padding(
            padding: const EdgeInsets.only(left: 16),
            child: Row(
              crossAxisAlignment: CrossAxisAlignment.start,
              children: [
                const Text('• ', style: TextStyle(fontSize: 16)),
                Expanded(child: _parseInlineMarkdown(line.substring(2))),
              ],
            ),
          ),
        );
      } else if (RegExp(r'^\d+\. ').hasMatch(line)) {
        final match = RegExp(r'^(\d+)\. ').firstMatch(line);
        final number = match?.group(1) ?? '1';
        widgets.add(
          Padding(
            padding: const EdgeInsets.only(left: 16),
            child: Row(
              crossAxisAlignment: CrossAxisAlignment.start,
              children: [
                Text('$number. ', style: const TextStyle(fontSize: 16)),
                Expanded(child: _parseInlineMarkdown(line.substring(number.length + 2))),
              ],
            ),
          ),
        );
      } else if (line.trim() == '---') {
        widgets.add(const Divider(color: Colors.grey, thickness: 1));
      } else {
        widgets.add(_parseInlineMarkdown(line));
      }
      if (i < lines.length - 1) {
        widgets.add(const SizedBox(height: 4));
      }
    }
    return Column(crossAxisAlignment: CrossAxisAlignment.start, children: widgets);
  }

  Widget _parseInlineMarkdown(String text) {
    final spans = <TextSpan>[];
    final regex = RegExp(r'(\*\*.*?\*\*|\*.*?\*|\[.*?\]\(.*?\))');
    int lastEnd = 0;
    for (final match in regex.allMatches(text)) {
      if (match.start > lastEnd) {
        spans.add(
          TextSpan(
            text: text.substring(lastEnd, match.start),
            style: const TextStyle(fontSize: 16, color: Colors.black),
          ),
        );
      }
      final matchedText = match.group(0)!;
      if (matchedText.startsWith('**') && matchedText.endsWith('**')) {
        spans.add(
          TextSpan(
            text: matchedText.substring(2, matchedText.length - 2),
            style: const TextStyle(fontSize: 16, fontWeight: FontWeight.bold, color: Colors.black),
          ),
        );
      } else if (matchedText.startsWith('*') && matchedText.endsWith('*')) {
        spans.add(
          TextSpan(
            text: matchedText.substring(1, matchedText.length - 1),
            style: const TextStyle(fontSize: 16, fontStyle: FontStyle.italic, color: Colors.black),
          ),
        );
      } else if (matchedText.startsWith('[') && matchedText.contains('](')) {
        final linkMatch = RegExp(r'\[(.*?)\]\((.*?)\)').firstMatch(matchedText);
        if (linkMatch != null) {
          final linkText = linkMatch.group(1)!;
          spans.add(
            TextSpan(
              text: linkText,
              style: const TextStyle(fontSize: 16, color: Colors.blue, decoration: TextDecoration.underline),
            ),
          );
        }
      }
      lastEnd = match.end;
    }
    if (lastEnd < text.length) {
      spans.add(
        TextSpan(
          text: text.substring(lastEnd),
          style: const TextStyle(fontSize: 16, color: Colors.black),
        ),
      );
    }
    return RichText(text: TextSpan(children: spans));
  }

  @override
  Widget build(BuildContext context) {
    return Column(
      crossAxisAlignment: CrossAxisAlignment.start,
      children: [
        if (_isPreview)
          _buildMarkdownPreview(context)
        else
          CustomTextFormField(
            controller: _controller,
            focusNode: _focusNode,
            maxLines: widget.maxLines,
            minLines: widget.minLines,
            hintText: widget.hintText,
            hasError: widget.hasError,
            onChanged: (value) => widget.onChanged?.call(value),
          ),
        const SizedBox(height: 8),
        if (widget.showInlineToolbar && (isToolbarVisible || !_isPreview))
          Row(
            children: [
              Expanded(
                child: Container(
                  height: 52,
                  decoration: BoxDecoration(
                    color: Colors.white,
                    borderRadius: BorderRadius.circular(20),
                    boxShadow: [
                      BoxShadow(color: const Color(0x00000000).withAlpha((255 * 0.2).toInt()), spreadRadius: 0, blurRadius: 32, offset: const Offset(0, 0)),
                    ],
                  ),
                  child: Row(
                    children: [
                      const SizedBox(width: 8),
                      _mdTextButton('H', _applyHeading),
                      const SizedBox(width: 8),
                      _mdButton(Icons.format_bold, _applyBold),
                      const SizedBox(width: 8),
                      _mdButton(Icons.format_italic, _applyItalic),
                      const SizedBox(width: 8),
                      _mdButton(Icons.format_list_numbered, _applyNumberedList),
                      const SizedBox(width: 8),
                      _mdButton(Icons.format_list_bulleted, _applyBulletedList),
                      const SizedBox(width: 8),
                      _mdButton(Icons.link, _applyLink),
                      const SizedBox(width: 8),
                      _mdButton(Icons.horizontal_rule, _applyHorizontalRule),
                      const SizedBox(width: 8),
                    ],
                  ),
                ),
              ),
              const SizedBox(width: 8),
              Container(
                width: 52,
                height: 52,
                padding: const EdgeInsets.symmetric(horizontal: 8),
                decoration: BoxDecoration(
                  color: Colors.white,
                  borderRadius: BorderRadius.circular(20),
                  boxShadow: [
                    BoxShadow(color: const Color(0x00000000).withAlpha((255 * 0.2).toInt()), spreadRadius: 0, blurRadius: 32, offset: const Offset(0, 0)),
                  ],
                ),
                child: Row(children: [_mdButton(_isPreview ? Icons.edit : Icons.visibility, _togglePreview)]),
              ),
            ],
          ),
      ],
    );
  }
}