import 'package:kroki/kroki.dart';
import 'package:markdown/markdown.dart' as markdown;

final Kroki kroki = Kroki();

class DiagramTransfomer extends markdown.CodeBlockTransformer {
  @override
  markdown.Node? transformCodeBlock(
      String codeBlockType, String rawCodeBlock, markdown.BlockParser parser) {
    final markdown.AsyncText asyncText = markdown.AsyncText(
        kroki.convertDiagram(codeBlockType, rawCodeBlock), parser,
        uncompletedFutureTextValue:
            rawCodeBlock // fall back to showing diagram source
        );
    return asyncText;
  }

  DiagramTransfomer() :
    super(handledCodeBlockTypes:KrokiDiagramEndpoints.supportedEndpoints);
}

final diagramTransformingFencedCodeBlock =
    markdown.TransformableFencedCodeBlockSyntax([DiagramTransfomer()]);

main() {
    final finalHtml = await markdown.markdownToHtmlWithAsyncTransforms(markdownSource,
      blockSyntaxes: [diagramTransformingFencedCodeBlock],
      extensionSet: markdown.ExtensionSet.gitHubWeb);
}   

final String markdownSource = r'''
# Example mermaid diagram

```mermaid
graph TD;
    A-->B;
    A-->C;
    B-->D;
    C-->D;
```
''';