Implement a popup card that renders description markdown

lib/bbcode_converter.dart

@@ -0,0 +1,174 @@
+/// Utility class to convert BBCode to Markdown for RimWorld mod descriptions
+class BBCodeConverter {
+  /// Converts BBCode formatted text to Markdown format
+  static String toMarkdown(String bbcode) {
+    if (bbcode.isEmpty) return '';
+    
+    // First, normalize line endings
+    String result = bbcode.replaceAll('\r\n', '\n');
+    
+    // Fix unclosed tags - RimWorld descriptions often have unclosed tags
+    final List<String> tagTypes = ['b', 'i', 'color', 'size', 'url', 'code', 'quote'];
+    for (final tag in tagTypes) {
+      final openCount = '[${tag}'.allMatches(result).length;
+      final closeCount = '[/${tag}]'.allMatches(result).length;
+      if (openCount > closeCount) {
+        result = result + '[/${tag}]' * (openCount - closeCount);
+      }
+    }
+    
+    // URLs
+    // [url=http://example.com]text[/url] -> [text](http://example.com)
+    result = RegExp(r'\[url=([^\]]+)\](.*?)\[/url\]', dotAll: true)
+        .allMatches(result)
+        .fold(result, (prev, match) {
+          final url = match.group(1);
+          final text = match.group(2);
+          return prev.replaceFirst(
+            match.group(0)!, 
+            '[$text]($url)'
+          );
+        });
+    
+    // Simple URL [url]http://example.com[/url] -> <http://example.com>
+    result = result.replaceAllMapped(
+      RegExp(r'\[url\](.*?)\[/url\]', dotAll: true), 
+      (match) => '<${match.group(1)}>'
+    );
+    
+    // Bold
+    result = result.replaceAll('[b]', '**').replaceAll('[/b]', '**');
+    
+    // Italic
+    result = result.replaceAll('[i]', '_').replaceAll('[/i]', '_');
+    
+    // Headers
+    result = result.replaceAllMapped(
+      RegExp(r'\[h1\](.*?)\[/h1\]', dotAll: true), 
+      (match) => '# ${match.group(1)}'
+    );
+    result = result.replaceAllMapped(
+      RegExp(r'\[h2\](.*?)\[/h2\]', dotAll: true), 
+      (match) => '## ${match.group(1)}'
+    );
+    result = result.replaceAllMapped(
+      RegExp(r'\[h3\](.*?)\[/h3\]', dotAll: true), 
+      (match) => '### ${match.group(1)}'
+    );
+    
+    // Lists - handle nested lists too
+    result = result.replaceAll('[list]', '\n').replaceAll('[/list]', '\n');
+    
+    // Handle list items - giving them proper indentation
+    int listLevel = 0;
+    result = result.replaceAllMapped(
+      RegExp(r'\[\*\](.*?)(?=\[\*\]|\[/list\]|$)', dotAll: true), 
+      (match) {
+        final content = match.group(1)?.trim() ?? '';
+        return '* $content\n'; 
+      }
+    );
+    
+    // Color - convert to bold since Markdown doesn't support color
+    result = result.replaceAllMapped(
+      RegExp(r'\[color=([^\]]+)\](.*?)\[/color\]', dotAll: true), 
+      (match) {
+        final content = match.group(2) ?? '';
+        if (content.trim().isEmpty) return '';
+        return '**${match.group(2)}**';
+      }
+    );
+    
+    // Images
+    // [img]url[/img] -> ![Image](url)
+    result = result.replaceAllMapped(
+      RegExp(r'\[img\](.*?)\[/img\]', dotAll: true), 
+      (match) => '![Image](${match.group(1)})'
+    );
+    
+    // Image with size [img width=300]url[/img] -> ![Image](url)
+    result = result.replaceAllMapped(
+      RegExp(r'\[img[^\]]*width=(\d+)[^\]]*\](.*?)\[/img\]', dotAll: true),
+      (match) => '![Image](${match.group(2)})'
+    );
+
+    // Tables - convert tables to markdown tables
+    if (result.contains('[table]')) {
+      // Process tables
+      final tableRegex = RegExp(r'\[table\](.*?)\[/table\]', dotAll: true);
+      final tables = tableRegex.allMatches(result);
+      
+      for (final tableMatch in tables) {
+        final tableContent = tableMatch.group(1) ?? '';
+        final rows = RegExp(r'\[tr\](.*?)\[/tr\]', dotAll: true).allMatches(tableContent);
+        
+        final markdownTable = StringBuffer();
+        var isFirstRow = true;
+        
+        for (final rowMatch in rows) {
+          final rowContent = rowMatch.group(1) ?? '';
+          final cells = RegExp(r'\[td\](.*?)\[/td\]', dotAll: true).allMatches(rowContent);
+          
+          if (cells.isEmpty) continue;
+          
+          final rowBuffer = StringBuffer('|');
+          
+          for (final cellMatch in cells) {
+            final cellContent = cellMatch.group(1)?.trim() ?? '';
+            // Clean up any newlines inside cell content
+            final cleanCell = cellContent.replaceAll('\n', ' ').trim();
+            rowBuffer.write(' $cleanCell |');
+          }
+          
+          markdownTable.writeln(rowBuffer.toString());
+          
+          // Add header separator after first row
+          if (isFirstRow) {
+            final cellCount = RegExp(r'\[td\]').allMatches(rowContent).length;
+            markdownTable.writeln('|${' --- |' * cellCount}');
+            isFirstRow = false;
+          }
+        }
+        
+        result = result.replaceFirst(tableMatch.group(0)!, '\n${markdownTable.toString()}\n');
+      }
+    }
+    
+    // Size - remove since Markdown doesn't directly support font size
+    result = result.replaceAllMapped(
+      RegExp(r'\[size=[^\]]+\](.*?)\[/size\]', dotAll: true), 
+      (match) => match.group(1) ?? ''
+    );
+    
+    // Code
+    result = result.replaceAll('[code]', '\n```\n').replaceAll('[/code]', '\n```\n');
+    
+    // Quote
+    result = result.replaceAllMapped(
+      RegExp(r'\[quote\](.*?)\[/quote\]', dotAll: true), 
+      (match) {
+        final content = match.group(1)?.trim() ?? '';
+        if (content.isEmpty) return '';
+        return '\n> ${content.replaceAll('\n', '\n> ')}\n';
+      }
+    );
+    
+    // Handle any remaining custom BBCode tags - just remove them
+    result = result.replaceAllMapped(
+      RegExp(r'\[([a-zA-Z0-9_]+)(?:=[^\]]+)?\](.*?)\[/\1\]', dotAll: true),
+      (match) => match.group(2) ?? ''
+    );
+    
+    // Handle RimWorld-specific patterns
+    // [h1] without closing tag is common
+    result = result.replaceAllMapped(
+      RegExp(r'\[h1\]([^\[]+)'), 
+      (match) => '# ${match.group(1)}\n'
+    );
+    
+    // Replace multiple newlines with at most two newlines
+    result = result.replaceAll(RegExp(r'\n{3,}'), '\n\n');
+    
+    return result;
+  }
+}