generateForAnnotatedElement method

@override String generateForAnnotatedElement(Element element, ConstantReader annotation, BuildStep buildStep)

Implement to return source code to generate for element.

This method is invoked based on finding elements annotated with an instance of T. The annotation is provided as a ConstantReader.

Supported return values include a single String or multiple String instances within an Iterable or Stream. It is also valid to return a Future of String, Iterable, or Stream. When multiple values are returned through an iterable or stream they will be deduplicated. Typically each value will be an independent unit of code and the deduplication prevents re-defining the same member multiple times. For example if multiple annotated elements may need a specific utility method available it can be output for each one, and the single deduplicated definition can be shared.

Implementations should return null when no content is generated. Empty or whitespace-only String instances are also ignored.

Implementation

@override
String generateForAnnotatedElement(
  Element element,
  ConstantReader annotation,
  BuildStep buildStep,
) {
  helpers.validateClassElement(element, 'Page');

  // Verify the class extends SparkPage
  if (!helpers.checkInheritance(element as ClassElement, 'SparkPage')) {
    throw InvalidGenerationSourceError(
      '@Page classes must extend SparkPage<T>',
      element: element,
    );
  }

  final className = element.name;
  final path = annotation.read('path').stringValue;
  final methods = annotation
      .read('methods')
      .listValue
      .map((e) => e.toStringValue()!)
      .toList();

  // Parse path parameters from the route pattern
  final pathParams = helpers.parsePathParams(path);

  // Convert path pattern to shelf_router format
  // /users/:id -> /users/<id>
  final shelfPath = helpers.convertToShelfPath(path);

  // Get the generic type parameter T from SparkPage<T>

  final buffer = StringBuffer();

  // Generate the route info annotation for the aggregating builder
  buffer.writeln('// Route: $path');
  buffer.writeln('// Methods: $methods');
  buffer.writeln('// Path params: $pathParams');
  buffer.writeln();

  // Generate static route info constant
  buffer.writeln('/// Route information for [$className].');
  buffer.writeln('const _\$${className}Route = (');
  buffer.writeln("  path: '$shelfPath',");
  buffer.writeln('  methods: <String>$methods,');
  buffer.writeln(
    '  pathParams: <String>[${pathParams.map((p) => "'$p'").join(', ')}],',
  );
  buffer.writeln('  className: \'$className\',');
  buffer.writeln(');');
  buffer.writeln();

  // Generate the handler function
  buffer.writeln('/// Handler for [$className] at `$path`.');
  buffer.writeln('Future<Response> _\$handle$className(');
  buffer.writeln('  Request request,');
  for (final param in pathParams) {
    buffer.writeln('  String $param,');
  }
  buffer.writeln(') async {');
  buffer.writeln('  final page = $className();');

  buffer.writeln('  var pipeline = const Pipeline();');
  buffer.writeln('  for (final middleware in page.middleware) {');
  buffer.writeln('    pipeline = pipeline.addMiddleware(middleware);');
  buffer.writeln('  }');
  buffer.writeln();
  buffer.writeln('  final handler = (Request req) async {');
  buffer.writeln('    final pageRequest = PageRequest(');
  buffer.writeln('      shelfRequest: req,');
  buffer.writeln('      pathParams: {');
  for (final param in pathParams) {
    buffer.writeln("        '$param': $param,");
  }
  buffer.writeln('      },');
  buffer.writeln('    );');
  buffer.writeln();
  buffer.writeln('    final response = await page.loader(pageRequest);');
  buffer.writeln();
  buffer.writeln('    return switch (response) {');
  // Check if the page overrides the components getter
  // We want to generate the script if the page or any of its parents (except SparkPage)
  // defines components.
  final componentsGetter = element.lookUpGetter(
    name: 'components',
    library: element.library,
  );
  final hasComponents =
      componentsGetter != null &&
      componentsGetter.enclosingElement.name != 'SparkPage';

  String? scriptName;
  if (hasComponents) {
    if (buildStep.inputId.path.startsWith('lib/pages/')) {
      scriptName =
          "'${buildStep.inputId.path.substring('lib/pages/'.length).replaceAll('.dart', '.dart.js')}'";
    } else {
      scriptName =
          "'${buildStep.inputId.pathSegments.last.replaceAll('.dart', '.dart.js')}'";
    }
  } else {
    scriptName = 'null';
  }
  buffer.writeln(
    "      PageData(:final data, :final statusCode, :final headers, :final cookies) =>",
  );
  buffer.writeln(
    "        _\$renderPageResponse(page, data, pageRequest, statusCode, headers, cookies, $scriptName, req.context['spark.nonce'] as String?),",
  );
  buffer.writeln(
    '      PageRedirect(:final location, :final statusCode, :final headers, :final cookies) =>',
  );
  buffer.writeln(
    "        Response(statusCode, headers: {...headers, 'location': location, if (cookies.isNotEmpty) HttpHeaders.setCookieHeader: cookies.map((c) => c.toString()).toList()}),",
  );
  buffer.writeln(
    '      PageError(:final message, :final statusCode, :final cookies) =>',
  );
  buffer.writeln(
    '        _\$renderErrorResponse(message, statusCode, cookies),',
  );
  buffer.writeln('    };');
  buffer.writeln('  };');
  buffer.writeln();
  buffer.writeln('  return pipeline.addHandler(handler)(request);');
  buffer.writeln('}');

  return buffer.toString();
}