feat: migrate markdown parser

lib/shared/widgets/markdown/streaming_markdown_widget.dart

@@ -0,0 +1,200 @@
+import 'dart:async';
+import 'package:flutter/material.dart';
+import 'package:markdown_widget/markdown_widget.dart';
+import 'package:conduit/shared/widgets/markdown/markdown_config.dart';
+
+class StreamingMarkdownWidget extends StatefulWidget {
+  final Stream<String>? contentStream;
+  final String? staticContent;
+  final bool isStreaming;
+  final ScrollController? scrollController;
+  final EdgeInsetsGeometry? padding;
+
+  const StreamingMarkdownWidget({
+    super.key,
+    this.contentStream,
+    this.staticContent,
+    required this.isStreaming,
+    this.scrollController,
+    this.padding,
+  });
+
+  @override
+  State<StreamingMarkdownWidget> createState() => _StreamingMarkdownWidgetState();
+}
+
+class _StreamingMarkdownWidgetState extends State<StreamingMarkdownWidget> {
+  final _buffer = StringBuffer();
+  Timer? _debounceTimer;
+  String _renderedContent = '';
+  StreamSubscription<String>? _streamSubscription;
+
+  @override
+  void initState() {
+    super.initState();
+    if (widget.contentStream != null) {
+      _streamSubscription = widget.contentStream!.listen(_handleChunk);
+    } else if (widget.staticContent != null) {
+      _renderedContent = widget.staticContent!;
+    }
+  }
+
+  void _handleChunk(String chunk) {
+    _buffer.write(chunk);
+
+    // Debounce rendering for performance
+    _debounceTimer?.cancel();
+    _debounceTimer = Timer(const Duration(milliseconds: 50), () {
+      if (mounted) {
+        setState(() {
+          _renderedContent = _fixIncompleteMarkdown(_buffer.toString());
+        });
+      }
+    });
+  }
+
+  String _fixIncompleteMarkdown(String content) {
+    // Auto-close unclosed code blocks for valid markdown during streaming
+    final fenceCount = '```'.allMatches(content).length;
+    if (fenceCount % 2 != 0) {
+      content += '\n```';
+    }
+    
+    // Fix incomplete bold/italic markers
+    final boldCount = RegExp(r'\*\*').allMatches(content).length;
+    if (boldCount % 2 != 0) {
+      content += '**';
+    }
+    
+    final italicCount = RegExp(r'(?<!\*)\*(?!\*)').allMatches(content).length;
+    if (italicCount % 2 != 0) {
+      content += '*';
+    }
+    
+    // Fix incomplete link brackets
+    final openBrackets = '['.allMatches(content).length;
+    final closeBrackets = ']'.allMatches(content).length;
+    if (openBrackets > closeBrackets) {
+      content += ']' * (openBrackets - closeBrackets);
+    }
+    
+    final openParens = '('.allMatches(content).length;
+    final closeParens = ')'.allMatches(content).length;
+    if (openParens > closeParens) {
+      content += ')' * (openParens - closeParens);
+    }
+    
+    return content;
+  }
+
+  @override
+  void didUpdateWidget(StreamingMarkdownWidget oldWidget) {
+    super.didUpdateWidget(oldWidget);
+    
+    // Handle stream changes
+    if (widget.contentStream != oldWidget.contentStream) {
+      _streamSubscription?.cancel();
+      if (widget.contentStream != null) {
+        _streamSubscription = widget.contentStream!.listen(_handleChunk);
+      }
+    }
+    
+    // Handle static content changes
+    if (widget.staticContent != oldWidget.staticContent) {
+      setState(() {
+        _renderedContent = widget.staticContent ?? '';
+      });
+    }
+  }
+
+  @override
+  Widget build(BuildContext context) {
+    final isDark = Theme.of(context).brightness == Brightness.dark;
+    final config = ConduitMarkdownConfig.getConfig(
+      isDark: isDark,
+      context: context,
+      isStreaming: widget.isStreaming,
+    );
+
+    if (_renderedContent.isEmpty) {
+      return const SizedBox.shrink();
+    }
+
+    if (widget.isStreaming && _renderedContent.isNotEmpty) {
+      // Use MarkdownBlock for streaming - it's optimized for live updates
+      return Container(
+        padding: widget.padding,
+        child: MarkdownBlock(
+          data: _renderedContent,
+          config: config,
+          selectable: true,
+        ),
+      );
+    } else {
+      // Use MarkdownWidget for completed messages
+      // This provides better interactivity and selection
+      return MarkdownWidget(
+        data: _renderedContent,
+        config: config,
+        selectable: true,
+        shrinkWrap: true,
+        physics: const NeverScrollableScrollPhysics(),
+        padding: widget.padding,
+      );
+    }
+  }
+
+  @override
+  void dispose() {
+    _debounceTimer?.cancel();
+    _streamSubscription?.cancel();
+    super.dispose();
+  }
+}
+
+/// Extension to provide easy access to streaming markdown
+extension StreamingMarkdownExtension on String {
+  Widget toMarkdown({
+    required BuildContext context,
+    bool isStreaming = false,
+    EdgeInsetsGeometry? padding,
+  }) {
+    return StreamingMarkdownWidget(
+      staticContent: this,
+      isStreaming: isStreaming,
+      padding: padding,
+    );
+  }
+}
+
+/// Helper widget for displaying markdown with loading state
+class MarkdownWithLoading extends StatelessWidget {
+  final String? content;
+  final bool isLoading;
+  final EdgeInsetsGeometry? padding;
+
+  const MarkdownWithLoading({
+    super.key,
+    this.content,
+    required this.isLoading,
+    this.padding,
+  });
+
+  @override
+  Widget build(BuildContext context) {
+    if (isLoading && (content == null || content!.isEmpty)) {
+      return Container(
+        padding: padding ?? const EdgeInsets.all(16),
+        child: const Center(
+          child: CircularProgressIndicator(),
+        ),
+      );
+    }
+
+    return StreamingMarkdownWidget(
+      staticContent: content ?? '',
+      isStreaming: isLoading,
+      padding: padding,
+    );
+  }
+}