import 'package:flutter/material.dart';
import 'package:flutter/scheduler.dart';
import 'package:flutter/semantics.dart';

void main() {
  runApp(const ScreenReaderIssueApp());
}

class ScreenReaderIssueApp extends StatelessWidget {
  const ScreenReaderIssueApp({super.key});

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Screen Reader Issue Demo',
      theme: ThemeData(
        colorScheme: ColorScheme.fromSeed(seedColor: Colors.blue),
        useMaterial3: true,
      ),
      home: const ScreenReaderIssuePage(),
    );
  }
}

class ScreenReaderIssuePage extends StatefulWidget {
  const ScreenReaderIssuePage({super.key});

  @override
  State<ScreenReaderIssuePage> createState() => _ScreenReaderIssuePageState();
}

class _ScreenReaderIssuePageState extends State<ScreenReaderIssuePage> {
  final TextEditingController _textController = TextEditingController();
  final FocusNode _focusNode = FocusNode();
  bool _isTyping = false;
  String _lastAnnounced = '';

  @override
  void initState() {
    super.initState();
    _textController.addListener(_onTextChanged);
    _focusNode.addListener(_onFocusChanged);
  }

  @override
  void dispose() {
    _textController.removeListener(_onTextChanged);
    _focusNode.removeListener(_onFocusChanged);
    _textController.dispose();
    _focusNode.dispose();
    super.dispose();
  }

  void _onFocusChanged() {
    setState(() {
      // Update UI based on focus changes
      if (_focusNode.hasFocus) {
        _isTyping = true;
      } else {
        _isTyping = false;
      }
    });
  }

  void _onTextChanged() {
    // This demonstrates the issue - sometimes the screen reader announces text
    // changes but the text doesn't actually update in the field
    if (_textController.text != _lastAnnounced && _focusNode.hasFocus) {
      _lastAnnounced = _textController.text;

      // Log for debugging
      debugPrint('Text changed to: ${_textController.text}');

      // In the actual issue, sometimes this text would be announced by the screen reader
      // but wouldn't appear in the field
      SchedulerBinding.instance.addPostFrameCallback((_) {
        // Simulate the issue where screen reader announces but text doesn't appear
        if (_isTyping) {
          SemanticsService.announce(
            'Typing: ${_textController.text}',
            TextDirection.ltr,
          );
        }
      });
    }
  }

  void _sendMessage() {
    if (_textController.text.trim().isNotEmpty) {
      setState(() {
        // In a real app, this would send the message
        debugPrint('Message sent: ${_textController.text}');
        _textController.clear();
      });
    }
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: const Text('Screen Reader Issue Demo'),
      ),
      body: Column(
        children: [
          Expanded(
            child: Center(
              child: Text(
                'This demo reproduces the screen reader issue where the screen reader '
                'announces typing but text doesn\'t appear in the field.\n\n'
                'Current text: "${_textController.text}"',
                textAlign: TextAlign.center,
                style: const TextStyle(fontSize: 16),
              ),
            ),
          ),
          Padding(
            padding: const EdgeInsets.all(16.0),
            child: AccessibleSearchBar(
              controller: _textController,
              focusNode: _focusNode,
              onSubmit: (_) => _sendMessage(),
              isTyping: _isTyping,
            ),
          ),
        ],
      ),
    );
  }
}

class AccessibleSearchBar extends StatefulWidget {
  final TextEditingController controller;
  final FocusNode focusNode;
  final Function(String) onSubmit;
  final bool isTyping;

  const AccessibleSearchBar({
    super.key,
    required this.controller,
    required this.focusNode,
    required this.onSubmit,
    required this.isTyping,
  });

  @override
  State<AccessibleSearchBar> createState() => _AccessibleSearchBarState();
}

class _AccessibleSearchBarState extends State<AccessibleSearchBar> {
  int _calculateLines(String text, double maxWidth) {
    if (text.isEmpty) return 1;

    final TextPainter textPainter = TextPainter(
      text: TextSpan(text: text, style: const TextStyle(fontSize: 16)),
      textDirection: TextDirection.ltr,
      maxLines: 5,
    )..layout(maxWidth: maxWidth);

    return textPainter.computeLineMetrics().length;
  }

  @override
  Widget build(BuildContext context) {
    return LayoutBuilder(
      builder: (context, constraints) {
        final lines =
            _calculateLines(widget.controller.text, constraints.maxWidth - 80);
        final currentLines = lines.clamp(1, 5);

        return Container(
          padding: const EdgeInsets.symmetric(horizontal: 16.0),
          decoration: BoxDecoration(
            color: Colors.grey[200],
            border: Border.all(color: Colors.grey[400]!),
            borderRadius: BorderRadius.circular(8.0),
          ),
          child: Row(
            crossAxisAlignment: CrossAxisAlignment.end,
            children: [
              Expanded(
                child: Semantics(
                  textField: true,
                  // This is part of the reproduction of the issue
                  // The semantic properties don't always match the actual text field
                  label: 'Type your message here',
                  value: widget.controller.text,
                  hint: 'Type your message here',
                  onDidGainAccessibilityFocus: () {
                    // This helps demonstrate the issue where screen reader focus
                    // doesn't correctly sync with the input field
                    widget.focusNode.requestFocus();
                  },
                  child: TextFormField(
                    controller: widget.controller,
                    focusNode: widget.focusNode,
                    maxLines: currentLines,
                    minLines: 1,
                    style: const TextStyle(fontSize: 16),
                    decoration: const InputDecoration(
                      border: InputBorder.none,
                      hintText: 'Type your message',
                      contentPadding: EdgeInsets.symmetric(vertical: 12.0),
                    ),
                    onFieldSubmitted: widget.onSubmit,
                  ),
                ),
              ),
              if (widget.controller.text.trim().isNotEmpty)
                Padding(
                  padding: const EdgeInsets.only(bottom: 8.0),
                  child: ElevatedButton(
                    onPressed: () => widget.onSubmit(widget.controller.text),
                    style: ElevatedButton.styleFrom(
                      shape: const CircleBorder(),
                      padding: const EdgeInsets.all(12),
                    ),
                    child: const Icon(Icons.send),
                  ),
                ),
            ],
          ),
        );
      },
    );
  }
}