automatically create and wire part/part of in dart

main.dart

// dart run main.dart -f foo_form.dart -f foo_state.dart --link-to foo_screen.dart

import 'dart:io';

import 'package:args/args.dart';

const linkToOption = 'link-to';

void main(List<String> arguments) async {
  final parser = ArgParser()
    ..addMultiOption('file', abbr: 'f', help: 'File names to create')
    ..addOption(linkToOption, abbr: 'l', help: 'Filename to link parts to');

  final results = parser.parse(arguments);

  final fileNames = results['file'] as List<String>;
  final linkTo = results[linkToOption] as String?;

  if (fileNames.isEmpty || linkTo == null) {
    print(parser.usage);
    exit(1);
  }

  final linkToFile = File(linkTo);
  if (!await linkToFile.exists()) {
    stderr.writeln('File "$linkTo" does not exist, cannot modify.');
    exit(1);
  }

  final originalContent = await linkToFile.readAsString();

  // Build the updated content with part directives
  final lines = originalContent.split('\n');
  final lastImportLine =
      lines.lastIndexWhere((line) => line.startsWith('import'));
  final partStart = lastImportLine == -1 ? 0 : lastImportLine + 1;

  for (final fileName in fileNames.reversed) {
    lines.insert(partStart, 'part \'$fileName\';');
  }

  if (fileNames.isNotEmpty) {
    lines.insert(partStart, '');
  }

  await linkToFile.writeAsString(lines.join('\n'));

  // Create new files as before
  for (final fileName in fileNames) {
    final file = File(fileName);
    if (await file.exists()) {
      stderr.writeln('File "$fileName" already exists, skipping.');
      continue;
    }

    final content = '''
part of '$linkTo';


''';

    await file.writeAsString(content);
    print('Created file: $fileName');
  }
}